1. Chapter 28
Nervous Systems

2. Introduction Spinal cord injuries disrupt communication between
Spinal cord injuries disrupt communication between
the central nervous system (brain and spinal cord) and
the rest of the body.
© 2012 Pearson Education, Inc. 2

3. Introduction
Over 250,000 Americans are living with spinal cord injuries.
Spinal cord injuries
happen more often to men,
happen mostly to people in their teens and 20s,
are caused by vehicle accidents, gunshots, and falls, and
are usually permanent because the spinal cord cannot be repaired.
© 2012 Pearson Education, Inc. 3

4. Nervous System Structure and Function
Figure 28.0_1
Chapter 28: Big Ideas
Nervous System Structure and Function
Nerve Signals and Their Transmission
Figure 28.0_1 Chapter 28: Big Ideas
An Overview of Animal Nervous Systems
The Human Brain 4

5. NERVOUS SYSTEM STRUCTURE AND FUNCTION
NERVOUS SYSTEM STRUCTURE AND FUNCTION
© 2012 Pearson Education, Inc. 5

6. 28.1 Nervous systems receive sensory input, interpret it, and send out appropriate commands
The nervous system
obtains sensory information, sensory input,
processes sensory information, integration, and
sends commands to effector cells (muscles) that carry out appropriate responses, motor output.
Student Misconceptions and Concerns
1. As students absorb additional details, often they lose sight of the fundamental functions of the nervous system, creating the risk that they will miss the forest for the trees. Remember to regularly connect the three fundamental functions of the nervous system, (a) sensory input, (b) integration, and (c) motor output, to an image of the PNS and CNS, noting where these functions occur (as in Figure 28.1A, for example). Returning to this or another familiar figure throughout lectures on the nervous system can help to remind students of key functions while allowing them to visually organize additional information. Such figures serve as “intellectual anchors” for a discussion.
2. Students often confuse the terms spinal column, spinal cord, spine, and backbone. They may fail to distinguish between the series of bones (vertebrae) and the extension of the central nervous system (the spinal cord) that runs through them. Figure 28.12B can help to clarify any confusion.
Teaching Tips
1. Challenge students to explain the adaptive advantages of reflexes. What is the benefit of an “automatic” response to a stimulus?
2. Challenge your students to provide examples of computer systems that have the same three functions as the nervous system. For example, many automobiles use built-in computers that detect signals indicating engine performance, interpret the signals, and then send signals to make adjustments.
© 2012 Pearson Education, Inc. 6

7. Peripheral nervous system (PNS) Central nervous system (CNS)
Figure 28.1A
Sensory input
Integration
Sensory receptor
Motor output
Figure 28.1A Organization of a nervous system
Brain and spinal cord
Effector cells
Peripheral nervous system (PNS)
Central nervous system (CNS) 7

8. 28.1 Nervous systems receive sensory input, interpret it, and send out appropriate commands
The central nervous system (CNS) consists of the
brain and
spinal cord (vertebrates).
The peripheral nervous system (PNS)
is located outside the CNS and
consists of
nerves (bundles of neurons wrapped in connective tissue) and
ganglia (clusters of neuron cell bodies).
Student Misconceptions and Concerns
1. As students absorb additional details, often they lose sight of the fundamental functions of the nervous system, creating the risk that they will miss the forest for the trees. Remember to regularly connect the three fundamental functions of the nervous system, (a) sensory input, (b) integration, and (c) motor output, to an image of the PNS and CNS, noting where these functions occur (as in Figure 28.1A, for example). Returning to this or another familiar figure throughout lectures on the nervous system can help to remind students of key functions while allowing them to visually organize additional information. Such figures serve as “intellectual anchors” for a discussion.
2. Students often confuse the terms spinal column, spinal cord, spine, and backbone. They may fail to distinguish between the series of bones (vertebrae) and the extension of the central nervous system (the spinal cord) that runs through them. Figure 28.12B can help to clarify any confusion.
Teaching Tips
1. Challenge students to explain the adaptive advantages of reflexes. What is the benefit of an “automatic” response to a stimulus?
2. Challenge your students to provide examples of computer systems that have the same three functions as the nervous system. For example, many automobiles use built-in computers that detect signals indicating engine performance, interpret the signals, and then send signals to make adjustments.
© 2012 Pearson Education, Inc. 8

9. 28.1 Nervous systems receive sensory input, interpret it, and send out appropriate commands
Sensory neurons
convey signals from sensory receptors
to the CNS.
Interneurons
are located entirely in the CNS,
integrate information, and
send it to motor neurons.
Motor neurons convey signals to effector cells.
Student Misconceptions and Concerns
1. As students absorb additional details, often they lose sight of the fundamental functions of the nervous system, creating the risk that they will miss the forest for the trees. Remember to regularly connect the three fundamental functions of the nervous system, (a) sensory input, (b) integration, and (c) motor output, to an image of the PNS and CNS, noting where these functions occur (as in Figure 28.1A, for example). Returning to this or another familiar figure throughout lectures on the nervous system can help to remind students of key functions while allowing them to visually organize additional information. Such figures serve as “intellectual anchors” for a discussion.
2. Students often confuse the terms spinal column, spinal cord, spine, and backbone. They may fail to distinguish between the series of bones (vertebrae) and the extension of the central nervous system (the spinal cord) that runs through them. Figure 28.12B can help to clarify any confusion.
Teaching Tips
1. Challenge students to explain the adaptive advantages of reflexes. What is the benefit of an “automatic” response to a stimulus?
2. Challenge your students to provide examples of computer systems that have the same three functions as the nervous system. For example, many automobiles use built-in computers that detect signals indicating engine performance, interpret the signals, and then send signals to make adjustments.
© 2012 Pearson Education, Inc. 9

10. Spinal cord Interneuron Nerve PNS CNS
Figure 28.1B
Sensory receptor 2
Sensory neuron 1
Brain
Ganglion
Spinal cord
Motor neuron 3 4
Quadriceps muscles
Interneuron
Figure 28.1B The knee-jerk reflex
Nerve
Flexor muscles
PNS
CNS 10

11. 28.2 Neurons are the functional units of nervous systems
Neurons are
cells specialized for carrying signals and
the functional units of the nervous system.
A neuron consists of
a cell body and
two types of extensions (fibers) that conduct signals,
dendrites and
axons.
Student Misconceptions and Concerns
Students often confuse the terms spinal column, spinal cord, spine, and backbone. They may fail to distinguish between the series of bones (vertebrae) and the extension of the central nervous system (the spinal cord) that runs through them. Figure 28.12B can help to clarify any confusion.
Teaching Tips
1. The proportion of neurons to glial cells in the brain is often quite surprising to students who might have little appreciation for the roles or even the existence of glial cells. Like the president of the United States or the head of any major organization, neurons have a large “support staff” of cells that help them perform their function.
2. Myelination is like the insulation on an electrical cord that ensures the wires are only exposed in specific locations. Breaks in this insulation, like disruption of myelin sheaths, will reduce the effectiveness of signal conduction.
3. Myelin sheaths and the nodes of Ranvier may also be described using the following analogy: Imagine that you are preparing a long hot dog (axon), maybe one 20 inches long. However, your hot dog buns (myelin) are only 6 inches long. You use three buns spaced 1 inch apart. That leaves two gaps (nodes of Ranvier), 1 inch each, separating the buns. If you really want to make the point, you could find a fake hot dog item and bring along three hot dog buns.
© 2012 Pearson Education, Inc. 11

12. 28.2 Neurons are the functional units of nervous systems
Myelin sheaths
enclose axons,
form a cellular insulation, and
speed up signal transmission.
Student Misconceptions and Concerns
Students often confuse the terms spinal column, spinal cord, spine, and backbone. They may fail to distinguish between the series of bones (vertebrae) and the extension of the central nervous system (the spinal cord) that runs through them. Figure 28.12B can help to clarify any confusion.
Teaching Tips
1. The proportion of neurons to glial cells in the brain is often quite surprising to students who might have little appreciation for the roles or even the existence of glial cells. Like the president of the United States or the head of any major organization, neurons have a large “support staff” of cells that help them perform their function.
2. Myelination is like the insulation on an electrical cord that ensures the wires are only exposed in specific locations. Breaks in this insulation, like disruption of myelin sheaths, will reduce the effectiveness of signal conduction.
3. Myelin sheaths and the nodes of Ranvier may also be described using the following analogy: Imagine that you are preparing a long hot dog (axon), maybe one 20 inches long. However, your hot dog buns (myelin) are only 6 inches long. You use three buns spaced 1 inch apart. That leaves two gaps (nodes of Ranvier), 1 inch each, separating the buns. If you really want to make the point, you could find a fake hot dog item and bring along three hot dog buns.
© 2012 Pearson Education, Inc. 12

13. Signal direction Cell body Nucleus Node of Ranvier Signal pathway
Figure 28.2
Signal direction
Cell body
Nucleus
Node of Ranvier
Signal pathway
Layers of myelin
Nodes of Ranvier
Myelin sheath
Figure 28.2 Structure of a myelinated motor neuron
Schwann cell
Synaptic terminals
Nucleus
Dendrites
Cell body
Schwann cell
Axon 13

14. NERVE SIGNALS AND THEIR TRANSMISSION
NERVE SIGNALS AND THEIR TRANSMISSION
© 2012 Pearson Education, Inc. 14

15. 28.3 Nerve function depends on charge differences across neuron membranes
At rest, a neuron’s plasma membrane has potential energy—the membrane potential, in which
just inside the cell is slightly negative and
just outside the cell is slightly positive.
The resting potential is the voltage across the plasma membrane of a resting neuron.
Student Misconceptions and Concerns
1. The abstract and complex nature of action potentials requires a careful and gradual discussion. Students with minimal backgrounds in cell biology are likely to struggle with this concept. Consider an initial presentation that provides an overview of the movement of charges before addressing the specific details.
2. Students who lack a background in chemistry and electricity are likely to struggle with the basic process of action potentials. Assumptions about the limited permeability of membranes, charges on ions, and natural electrical attractions may be unfamiliar to them. Students who read carefully through the text before action potentials are discussed in class are much more likely to understand the related lecture(s).
3. Consider presenting the diverse actions of neurotransmitters and related drugs in a table for quick and easy reference during lecture. Many students will have an interest in a particular drug, but soon forget the related effect if it was discussed earlier. A table permits easy reference to check drug effects.
Teaching Tips
Students may require a review of the basic concept of potential energy. A simple demonstration in class, such as holding an object and then letting it plummet to the floor, can provide a quick, clear demonstration. As noted in the text, potential electrical energy can be stored in a battery.
© 2012 Pearson Education, Inc. 15

16. 28.3 Nerve function depends on charge differences across neuron membranes
The resting potential exists because of differences in ion concentration of the fluids inside and outside the neuron.
Inside the neuron
K+ is high and
Na+ is low.
Outside the neuron
K+ is low and
Na+ is high.
Student Misconceptions and Concerns
1. The abstract and complex nature of action potentials requires a careful and gradual discussion. Students with minimal backgrounds in cell biology are likely to struggle with this concept. Consider an initial presentation that provides an overview of the movement of charges before addressing the specific details.
2. Students who lack a background in chemistry and electricity are likely to struggle with the basic process of action potentials. Assumptions about the limited permeability of membranes, charges on ions, and natural electrical attractions may be unfamiliar to them. Students who read carefully through the text before action potentials are discussed in class are much more likely to understand the related lecture(s).
3. Consider presenting the diverse actions of neurotransmitters and related drugs in a table for quick and easy reference during lecture. Many students will have an interest in a particular drug, but soon forget the related effect if it was discussed earlier. A table permits easy reference to check drug effects.
Teaching Tips
Students may require a review of the basic concept of potential energy. A simple demonstration in class, such as holding an object and then letting it plummet to the floor, can provide a quick, clear demonstration. As noted in the text, potential electrical energy can be stored in a battery.
© 2012 Pearson Education, Inc. 16

17. Animation: Resting Potential
Student Misconceptions and Concerns
1. The abstract and complex nature of action potentials requires a careful and gradual discussion. Students with minimal backgrounds in cell biology are likely to struggle with this concept. Consider an initial presentation that provides an overview of the movement of charges before addressing the specific details.
2. Students who lack a background in chemistry and electricity are likely to struggle with the basic process of action potentials. Assumptions about the limited permeability of membranes, charges on ions, and natural electrical attractions may be unfamiliar to them. Students who read carefully through the text before action potentials are discussed in class are much more likely to understand the related lecture(s).
3. Consider presenting the diverse actions of neurotransmitters and related drugs in a table for quick and easy reference during lecture. Many students will have an interest in a particular drug, but soon forget the related effect if it was discussed earlier. A table permits easy reference to check drug effects.
Teaching Tips
Students may require a review of the basic concept of potential energy. A simple demonstration in class, such as holding an object and then letting it plummet to the floor, can provide a quick, clear demonstration. As noted in the text, potential electrical energy can be stored in a battery.
Animation: Resting Potential
Right click on animation / Click play
© 2012 Pearson Education, Inc. 17

18. Neuron Axon Plasma membrane Figure 28.3 Outside of neuron Na Na NaK
Na K K
Na
Na
Na
Na
Na
Na channel
Na
Na
Figure 28.3 How the resting potential is generated
Plasma membrane K K
Na-K pump
ATP
Na
K channel K K
Na K K
Na K
Na K K K K K K K
Inside of neuron 18

19. 28.4 A nerve signal begins as a change in the membrane potential
A stimulus is any factor that causes a nerve signal to be generated. A stimulus
alters the permeability of a portion of the membrane,
allows ions to pass through, and
changes the membrane’s voltage.
Student Misconceptions and Concerns
1. The abstract and complex nature of action potentials requires a careful and gradual discussion. Students with minimal backgrounds in cell biology are likely to struggle with this concept. Consider an initial presentation that provides an overview of the movement of charges before addressing the specific details.
2. Students who lack a background in chemistry and electricity are likely to struggle with the basic process of action potentials. Assumptions about the limited permeability of membranes, charges on ions, and natural electrical attractions may be unfamiliar to them. Students who read carefully through the text before action potentials are discussed in class are much more likely to understand the related lecture(s).
3. Consider presenting the diverse actions of neurotransmitters and related drugs in a table for quick and easy reference during lecture. Many students will have an interest in a particular drug, but soon forget the related effect if it was discussed earlier. A table permits easy reference to check drug effects.
Teaching Tips
1. Students might benefit most by first learning how sodium and potassium ions move during an action potential before addressing the resulting changes in membrane potential.
2. Students may better comprehend the idea of the threshold for an action potential by considering an analogy to the various annoying stimuli in our lives. A blaring TV might be annoying, but one tolerates it for a while. However, a person can reach a “threshold” where he or she is stimulated enough to get up and turn it off.
© 2012 Pearson Education, Inc. 19

20. 28.4 A nerve signal begins as a change in the membrane potential
A nerve signal, called an action potential, is
a change in the membrane voltage,
from the resting potential,
to a maximum level, and
back to the resting potential.
Student Misconceptions and Concerns
1. The abstract and complex nature of action potentials requires a careful and gradual discussion. Students with minimal backgrounds in cell biology are likely to struggle with this concept. Consider an initial presentation that provides an overview of the movement of charges before addressing the specific details.
2. Students who lack a background in chemistry and electricity are likely to struggle with the basic process of action potentials. Assumptions about the limited permeability of membranes, charges on ions, and natural electrical attractions may be unfamiliar to them. Students who read carefully through the text before action potentials are discussed in class are much more likely to understand the related lecture(s).
3. Consider presenting the diverse actions of neurotransmitters and related drugs in a table for quick and easy reference during lecture. Many students will have an interest in a particular drug, but soon forget the related effect if it was discussed earlier. A table permits easy reference to check drug effects.
Teaching Tips
1. Students might benefit most by first learning how sodium and potassium ions move during an action potential before addressing the resulting changes in membrane potential.
2. Students may better comprehend the idea of the threshold for an action potential by considering an analogy to the various annoying stimuli in our lives. A blaring TV might be annoying, but one tolerates it for a while. However, a person can reach a “threshold” where he or she is stimulated enough to get up and turn it off.
© 2012 Pearson Education, Inc. 20

21. Animation: Action Potential
Student Misconceptions and Concerns
1. The abstract and complex nature of action potentials requires a careful and gradual discussion. Students with minimal backgrounds in cell biology are likely to struggle with this concept. Consider an initial presentation that provides an overview of the movement of charges before addressing the specific details.
2. Students who lack a background in chemistry and electricity are likely to struggle with the basic process of action potentials. Assumptions about the limited permeability of membranes, charges on ions, and natural electrical attractions may be unfamiliar to them. Students who read carefully through the text before action potentials are discussed in class are much more likely to understand the related lecture(s).
3. Consider presenting the diverse actions of neurotransmitters and related drugs in a table for quick and easy reference during lecture. Many students will have an interest in a particular drug, but soon forget the related effect if it was discussed earlier. A table permits easy reference to check drug effects.
Teaching Tips
1. Students might benefit most by first learning how sodium and potassium ions move during an action potential before addressing the resulting changes in membrane potential.
2. Students may better comprehend the idea of the threshold for an action potential by considering an analogy to the various annoying stimuli in our lives. A blaring TV might be annoying, but one tolerates it for a while. However, a person can reach a “threshold” where he or she is stimulated enough to get up and turn it off.
Animation: Action Potential
Right click on animation / Click play
© 2012 Pearson Education, Inc. 21

22. Membrane potential (mV)
Figure 28.4
Na
Na
Na
Na K 3
Additional Na channels open, K channels are closed; interior of cell becomes more positive. K
50
Action potential 4
Na channels close and inactivate; K channels open, and K rushes out; interior of cell is more negative than outside. 3
Na
Na 4
Membrane potential (mV) 2
50
Threshold 1 1 5
Resting potential K
100 5
The K channels close relatively slowly, causing a brief undershoot.
Time (msec) 2
A stimulus opens some Na channels; if threshold is reached, an action potential is triggered.
Figure 28.4 The action potential
Sodium channel
Potassium channel
Na
Na
Outside of neuron
Na
Na
Plasma membrane
Inside of neuron K K 1
Resting state: Voltage-gated Na and K channels are closed; resting potential is maintained by ungated channels (not shown). 1
Return to resting state. 22

23. Membrane potential (mV)
Figure 28.4_s1
50
Action potential
Membrane potential (mV)
Threshold
50 1
Resting potential
100
Time (msec) 1
Resting state: Voltage- gated Na and K channels are closed; resting potential is maintained by ungated channels (not shown).
Sodium channel
Potassium channel
Na
Na
Outside of neuron
Figure 28.4_s1 The action potential (step 1)
Plasma membrane
Inside of neuron K 23

24. Membrane potential (mV)
Figure 28.4_s2
50
Action potential
Membrane potential (mV) 2
Threshold
50 1
Resting potential
100
Time (msec) 2
A stimulus opens some Na channels; if threshold is reached, an action potential is triggered.
Figure 28.4_s2 The action potential (step 2)
Na
Na K 24

25. Membrane potential (mV)
Figure 28.4_s3
50
Action potential 3
Membrane potential (mV) 2
Threshold
50 1
Resting potential
100
Time (msec) 3
Additional Na channels open, K channels are closed; interior of cell becomes more positive.
Na
Na
Figure 28.4_s3 The action potential (step 3) K 25

26. Membrane potential (mV)
Figure 28.4_s4
50
Action potential 3 4
Membrane potential (mV) 2
Threshold
50 1
Resting potential
100
Time (msec) 4
Na channels close and inactivate; K channels open, and K rushes out; interior of cell is more negative than outside.
Na
Na
Figure 28.4_s4 The action potential (step 4) K 26

27. Membrane potential (mV)
Figure 28.4_s5
50
Action potential 3 4
Membrane potential (mV) 2
Threshold
50 1 5
Resting potential
100
Time (msec) 5
The K channels close relatively slowly, causing a brief undershoot.
Figure 28.4_s5 The action potential (step 5) 27

28. Membrane potential (mV)
Figure 28.4_s6
50
Action potential 3 4
Membrane potential (mV) 2
Threshold
50 1 1 5
Resting potential
100
Time (msec) 1
Return to resting state.
Figure 28.4_s6 The action potential (step 6)
Na
Na K 28

29. 28.5 The action potential propagates itself along the axon
Action potentials are
self-propagated in a one-way chain reaction along a neuron and
all-or-none events.
Student Misconceptions and Concerns
1. The abstract and complex nature of action potentials requires a careful and gradual discussion. Students with minimal backgrounds in cell biology are likely to struggle with this concept. Consider an initial presentation that provides an overview of the movement of charges before addressing the specific details.
2. Students who lack a background in chemistry and electricity are likely to struggle with the basic process of action potentials. Assumptions about the limited permeability of membranes, charges on ions, and natural electrical attractions may be unfamiliar to them. Students who read carefully through the text before action potentials are discussed in class are much more likely to understand the related lecture(s).
3. Consider presenting the diverse actions of neurotransmitters and related drugs in a table for quick and easy reference during lecture. Many students will have an interest in a particular drug, but soon forget the related effect if it was discussed earlier. A table permits easy reference to check drug effects.
Teaching Tips
1. An action potential spreading along the length of an axon retains its strength. The overall process is therefore like the “wave” sometimes created by audiences at sporting events.
2. Challenge students to explain how the intensity of a signal can be expressed when the strength of an action potential signal is steady. As noted in the text, signal intensity is communicated by the frequency of the signals. This is like knocking on a door again and again to communicate urgency.
© 2012 Pearson Education, Inc. 29

30. Action potential Plasma membrane Axon segment Figure 28.5_s1 Na Na
Figure 28.5_s1 Propagation of the action potential along an axon (detail, step 1) 30

31. Action potential Plasma membrane Axon segment Action potential
Figure 28.5_s2
Action potential
Plasma membrane
Na 1
Axon segment
Na
Action potential
Na K 2 K
Na
Figure 28.5_s2 Propagation of the action potential along an axon (detail, step 2) 31

32. Action potential Plasma membrane Axon segment Action potential
Figure 28.5_s3
Action potential
Plasma membrane
Na 1
Axon segment
Na
Action potential
Na K 2 K
Na
Figure 28.5_s3 Propagation of the action potential along an axon (detail, step 3)
Action potential
Na K 3 K
Na 32

33. Figure 28.5 Propagation of the action potential along an axon
Plasma membrane
Na 1
Axon segment
Na
Action potential
Na K 2
Figure 28.5 Propagation of the action potential along an axon K
Na
Action potential
Na K 3 K
Na 33

34. 28.5 The action potential propagates itself along the axon
The frequency of action potentials (but not their strength) changes with the strength of the stimulus.
Student Misconceptions and Concerns
1. The abstract and complex nature of action potentials requires a careful and gradual discussion. Students with minimal backgrounds in cell biology are likely to struggle with this concept. Consider an initial presentation that provides an overview of the movement of charges before addressing the specific details.
2. Students who lack a background in chemistry and electricity are likely to struggle with the basic process of action potentials. Assumptions about the limited permeability of membranes, charges on ions, and natural electrical attractions may be unfamiliar to them. Students who read carefully through the text before action potentials are discussed in class are much more likely to understand the related lecture(s).
3. Consider presenting the diverse actions of neurotransmitters and related drugs in a table for quick and easy reference during lecture. Many students will have an interest in a particular drug, but soon forget the related effect if it was discussed earlier. A table permits easy reference to check drug effects.
Teaching Tips
1. An action potential spreading along the length of an axon retains its strength. The overall process is therefore like the “wave” sometimes created by audiences at sporting events.
2. Challenge students to explain how the intensity of a signal can be expressed when the strength of an action potential signal is steady. As noted in the text, signal intensity is communicated by the frequency of the signals. This is like knocking on a door again and again to communicate urgency.
© 2012 Pearson Education, Inc. 34

35. 28.6 Neurons communicate at synapses
Synapses are junctions where signals are transmitted between
two neurons or
between neurons and effector cells.
Student Misconceptions and Concerns
1. The abstract and complex nature of action potentials requires a careful and gradual discussion. Students with minimal backgrounds in cell biology are likely to struggle with this concept. Consider an initial presentation that provides an overview of the movement of charges before addressing the specific details.
2. Students who lack a background in chemistry and electricity are likely to struggle with the basic process of action potentials. Assumptions about the limited permeability of membranes, charges on ions, and natural electrical attractions may be unfamiliar to them. Students who read carefully through the text before action potentials are discussed in class are much more likely to understand the related lecture(s).
3. Consider presenting the diverse actions of neurotransmitters and related drugs in a table for quick and easy reference during lecture. Many students will have an interest in a particular drug, but soon forget the related effect if it was discussed earlier. A table permits easy reference to check drug effects.
Teaching Tips
The transmission of a signal across a chemical synapse is like driving along a road to a river, then taking a ferry across the river, then driving away on a road on the other side. The movement of the traveler (or the signal) continues, but changes mechanisms along the way.
© 2012 Pearson Education, Inc. 35

36. 28.6 Neurons communicate at synapses
Electrical signals pass between cells at electrical synapses.
At chemical synapses
the ending (presynaptic) cell secretes a chemical signal, a neurotransmitter,
the neurotransmitter crosses the synaptic cleft, and
the neurotransmitter binds to a specific receptor on the surface of the receiving (postsynaptic) cell.
Student Misconceptions and Concerns
1. The abstract and complex nature of action potentials requires a careful and gradual discussion. Students with minimal backgrounds in cell biology are likely to struggle with this concept. Consider an initial presentation that provides an overview of the movement of charges before addressing the specific details.
2. Students who lack a background in chemistry and electricity are likely to struggle with the basic process of action potentials. Assumptions about the limited permeability of membranes, charges on ions, and natural electrical attractions may be unfamiliar to them. Students who read carefully through the text before action potentials are discussed in class are much more likely to understand the related lecture(s).
3. Consider presenting the diverse actions of neurotransmitters and related drugs in a table for quick and easy reference during lecture. Many students will have an interest in a particular drug, but soon forget the related effect if it was discussed earlier. A table permits easy reference to check drug effects.
Teaching Tips
The transmission of a signal across a chemical synapse is like driving along a road to a river, then taking a ferry across the river, then driving away on a road on the other side. The movement of the traveler (or the signal) continues, but changes mechanisms along the way.
© 2012 Pearson Education, Inc. 36

37. Animation: Synapse Student Misconceptions and Concerns
Student Misconceptions and Concerns
1. The abstract and complex nature of action potentials requires a careful and gradual discussion. Students with minimal backgrounds in cell biology are likely to struggle with this concept. Consider an initial presentation that provides an overview of the movement of charges before addressing the specific details.
2. Students who lack a background in chemistry and electricity are likely to struggle with the basic process of action potentials. Assumptions about the limited permeability of membranes, charges on ions, and natural electrical attractions may be unfamiliar to them. Students who read carefully through the text before action potentials are discussed in class are much more likely to understand the related lecture(s).
3. Consider presenting the diverse actions of neurotransmitters and related drugs in a table for quick and easy reference during lecture. Many students will have an interest in a particular drug, but soon forget the related effect if it was discussed earlier. A table permits easy reference to check drug effects.
Teaching Tips
The transmission of a signal across a chemical synapse is like driving along a road to a river, then taking a ferry across the river, then driving away on a road on the other side. The movement of the traveler (or the signal) continues, but changes mechanisms along the way.
Animation: Synapse
Right click on animation / Click play
© 2012 Pearson Education, Inc. 37

38. Figure 28.6 Neuron communication at a typical chemical synapse1
Sending cell
Action potential arrives
Axon of sending
cell
Synaptic vesicles
Synaptic terminal of sending cell
Synaptic terminal 2
Vesicle fuses with plasma membrane 3
Neurotransmitter is released into synaptic cleft
Dendrite of receiving cell
Synaptic cleft 4
Neurotransmitter binds to receptor
Receiving cell
Neurotransmitter molecules
Ion channels
Neurotransmitter
Neurotransmitter broken down and released
Figure 28.6 Neuron communication at a typical chemical synapse
Receptor
Ions 5
Ion channel opens 6
Ion channel closes 38

39. 28.7 Chemical synapses enable complex information to be processed
Some neurotransmitters
excite a receiving cell, and
others inhibit a receiving cell’s activity by decreasing its ability to develop action potentials.
Student Misconceptions and Concerns
1. The abstract and complex nature of action potentials requires a careful and gradual discussion. Students with minimal backgrounds in cell biology are likely to struggle with this concept. Consider an initial presentation that provides an overview of the movement of charges before addressing the specific details.
2. Students who lack a background in chemistry and electricity are likely to struggle with the basic process of action potentials. Assumptions about the limited permeability of membranes, charges on ions, and natural electrical attractions may be unfamiliar to them. Students who read carefully through the text before action potentials are discussed in class are much more likely to understand the related lecture(s).
3. Consider presenting the diverse actions of neurotransmitters and related drugs in a table for quick and easy reference during lecture. Many students will have an interest in a particular drug, but soon forget the related effect if it was discussed earlier. A table permits easy reference to check drug effects.
Teaching Tips
1. The authors compare a neuron’s diverse contacts with other neurons (potentially, hundreds of them) to a living circuit board.
2. Another analogy to the diverse signal input to a neuron might be helpful, even amusing. A neuron receiving diverse and potentially opposing signals is like a sports team hearing the crowd cheering for and against them. Game shows often demonstrate similar situations, as players’ decisions are influenced by the shouted suggestions of the audience.
© 2012 Pearson Education, Inc. 39

40. 28.7 Chemical synapses enable complex information to be processed
A receiving neuron’s membrane may receive signals
that are both excitatory and inhibitory and
from many different sending neurons.
The summation of excitation and inhibition determines if a neuron will transmit a nerve signal.
Student Misconceptions and Concerns
1. The abstract and complex nature of action potentials requires a careful and gradual discussion. Students with minimal backgrounds in cell biology are likely to struggle with this concept. Consider an initial presentation that provides an overview of the movement of charges before addressing the specific details.
2. Students who lack a background in chemistry and electricity are likely to struggle with the basic process of action potentials. Assumptions about the limited permeability of membranes, charges on ions, and natural electrical attractions may be unfamiliar to them. Students who read carefully through the text before action potentials are discussed in class are much more likely to understand the related lecture(s).
3. Consider presenting the diverse actions of neurotransmitters and related drugs in a table for quick and easy reference during lecture. Many students will have an interest in a particular drug, but soon forget the related effect if it was discussed earlier. A table permits easy reference to check drug effects.
Teaching Tips
1. The authors compare a neuron’s diverse contacts with other neurons (potentially, hundreds of them) to a living circuit board.
2. Another analogy to the diverse signal input to a neuron might be helpful, even amusing. A neuron receiving diverse and potentially opposing signals is like a sports team hearing the crowd cheering for and against them. Game shows often demonstrate similar situations, as players’ decisions are influenced by the shouted suggestions of the audience.
© 2012 Pearson Education, Inc. 40

41. Synaptic terminals Inhibitory Excitatory Dendrites Myelin sheath
Figure 28.7
Synaptic terminals
Inhibitory
Excitatory
Dendrites
Myelin sheath
Receiving cell body
Axon
Synaptic terminals
Figure 28.7 A neuron’s multiple synaptic inputs 41

42. 28.8 A variety of small molecules function as neurotransmitters
Many small, nitrogen-containing molecules are neurotransmitters.
Acetylcholine is a neurotransmitter
in the brain and
at synapses between motor neurons and muscle cells.
Biogenic amines
are important neurotransmitters in the CNS and
include serotonin and dopamine, which affect sleep, mood, and attention.
Student Misconceptions and Concerns
1. The abstract and complex nature of action potentials requires a careful and gradual discussion. Students with minimal backgrounds in cell biology are likely to struggle with this concept. Consider an initial presentation that provides an overview of the movement of charges before addressing the specific details.
2. Students who lack a background in chemistry and electricity are likely to struggle with the basic process of action potentials. Assumptions about the limited permeability of membranes, charges on ions, and natural electrical attractions may be unfamiliar to them. Students who read carefully through the text before action potentials are discussed in class are much more likely to understand the related lecture(s).
3. Consider presenting the diverse actions of neurotransmitters and related drugs in a table for quick and easy reference during lecture. Many students will have an interest in a particular drug, but soon forget the related effect if it was discussed earlier. A table permits easy reference to check drug effects.
Teaching Tips
1. Students may have heard about chemical imbalances in the brain without specifically knowing what this means. Abnormal concentrations of neurotransmitters in the central nervous system resulting from disease or chemical exposure can change our ability to perceive and respond to our world. Many drugs, both legal and illegal, can create imbalances with potentially disastrous consequences.
2. The treatment of psychological disorders is complicated by the diversity of neurotransmitters and their interactions. Therefore, predicting how a specific prescription drug will function in a particular patient is often difficult. Students may begin with the assumption that scientists currently understand much more about these complex reactions than we actually do. Emphasizing the need for additional research in these fields may encourage students to ponder career directions they have not previously considered.
3. Here is a bit of logic you might share with your students. Ask your students if they would avoid purchasing prescription drugs from a pharmacist convicted of some crime. If the answer is yes, ask why. The likely response will be that one might not trust a criminal pharmacist to carefully provide medicine. Why, then, you might wonder aloud, would anyone trust the quality of illegal drugs obtained from criminals (who are not likely trained pharmacists) who sell them on the street?
© 2012 Pearson Education, Inc. 42

43. 28.8 A variety of small molecules function as neurotransmitters
Many neuropeptides
consist of relatively short chains of amino acids important in the CNS and
include endorphins, decreasing our perception of pain.
Student Misconceptions and Concerns
1. The abstract and complex nature of action potentials requires a careful and gradual discussion. Students with minimal backgrounds in cell biology are likely to struggle with this concept. Consider an initial presentation that provides an overview of the movement of charges before addressing the specific details.
2. Students who lack a background in chemistry and electricity are likely to struggle with the basic process of action potentials. Assumptions about the limited permeability of membranes, charges on ions, and natural electrical attractions may be unfamiliar to them. Students who read carefully through the text before action potentials are discussed in class are much more likely to understand the related lecture(s).
3. Consider presenting the diverse actions of neurotransmitters and related drugs in a table for quick and easy reference during lecture. Many students will have an interest in a particular drug, but soon forget the related effect if it was discussed earlier. A table permits easy reference to check drug effects.
Teaching Tips
1. Students may have heard about chemical imbalances in the brain without specifically knowing what this means. Abnormal concentrations of neurotransmitters in the central nervous system resulting from disease or chemical exposure can change our ability to perceive and respond to our world. Many drugs, both legal and illegal, can create imbalances with potentially disastrous consequences.
2. The treatment of psychological disorders is complicated by the diversity of neurotransmitters and their interactions. Therefore, predicting how a specific prescription drug will function in a particular patient is often difficult. Students may begin with the assumption that scientists currently understand much more about these complex reactions than we actually do. Emphasizing the need for additional research in these fields may encourage students to ponder career directions they have not previously considered.
3. Here is a bit of logic you might share with your students. Ask your students if they would avoid purchasing prescription drugs from a pharmacist convicted of some crime. If the answer is yes, ask why. The likely response will be that one might not trust a criminal pharmacist to carefully provide medicine. Why, then, you might wonder aloud, would anyone trust the quality of illegal drugs obtained from criminals (who are not likely trained pharmacists) who sell them on the street?
© 2012 Pearson Education, Inc. 43

44. 28.9 CONNECTION: Many drugs act at chemical synapses
Many psychoactive drugs
act at synapses and
affect neurotransmitter action.
Caffeine counters the effect of inhibitory neurotransmitters.
Nicotine acts as a stimulant by binding to acetylcholine receptors.
Alcohol is a depressant.
Student Misconceptions and Concerns
1. The abstract and complex nature of action potentials requires a careful and gradual discussion. Students with minimal backgrounds in cell biology are likely to struggle with this concept. Consider an initial presentation that provides an overview of the movement of charges before addressing the specific details.
2. Students who lack a background in chemistry and electricity are likely to struggle with the basic process of action potentials. Assumptions about the limited permeability of membranes, charges on ions, and natural electrical attractions may be unfamiliar to them. Students who read carefully through the text before action potentials are discussed in class are much more likely to understand the related lecture(s).
3. Consider presenting the diverse actions of neurotransmitters and related drugs in a table for quick and easy reference during lecture. Many students will have an interest in a particular drug, but soon forget the related effect if it was discussed earlier. A table permits easy reference to check drug effects.
Teaching Tips
1. Students may have heard about chemical imbalances in the brain without specifically knowing what this means. Abnormal concentrations of neurotransmitters in the central nervous system resulting from disease or chemical exposure can change our ability to perceive and respond to our world. Many drugs, both legal and illegal, can create imbalances with potentially disastrous consequences.
2. The treatment of psychological disorders is complicated by the diversity of neurotransmitters and their interactions. Therefore, predicting how a specific prescription drug will function in a particular patient is often difficult. Students may begin with the assumption that scientists currently understand much more about these complex reactions than we actually do. Emphasizing the need for additional research in these fields may encourage students to ponder career directions they have not previously considered.
3. Here is a bit of logic you might share with your students. Ask your students if they would avoid purchasing prescription drugs from a pharmacist convicted of some crime. If the answer is yes, ask why. The likely response will be that one might not trust a criminal pharmacist to carefully provide medicine. Why, then, you might wonder aloud, would anyone trust the quality of illegal drugs obtained from criminals (who are not likely trained pharmacists) who sell them on the street?
© 2012 Pearson Education, Inc. 44

45. Figure 28.9
Figure 28.9 Alcohol, nicotine, and caffeine—drugs that alter the effects of neurotransmitters 45

46. AN OVERVIEW OF ANIMAL NERVOUS SYSTEMS
AN OVERVIEW OF ANIMAL NERVOUS SYSTEMS
© 2012 Pearson Education, Inc. 46

47. 28.11 Vertebrate nervous systems are highly centralized
In the vertebrates, the central nervous system (CNS)
consists of the brain and spinal cord and
includes spaces filled with cerebrospinal fluid
forming ventricles of the brain,
forming the central canal of the spinal cord, and
surrounding the brain.
The vertebrate peripheral nervous system (PNS) consists of
cranial nerves,
spinal nerves, and
ganglia.
Student Misconceptions and Concerns
Students may think of the human brain as completely unique. Yet, the anatomical components of the human brain mirror the basic components found in many other vertebrates. These similarities are so extensive that sheep brains are often studied in biology laboratories to better understand human anatomy.
Teaching Tips
Students often are surprised to learn that their brain is hollow, although some students may know that the central nervous system is surrounded by cerebrospinal fluid. The basic development of the brain and spinal cord from an embryonic tube is addressed in Module
© 2012 Pearson Education, Inc. 47

48. Central nervous system (CNS) Brain Cranial nerves Spinal cord
Figure 28.11A
Central nervous system (CNS)
Brain
Cranial nerves
Spinal cord
Peripheral nervous system (PNS)
Ganglia outside CNS
Spinal nerves
Figure 28.11A A vertebrate nervous system (back view) 48

49. Spinal cord (cross section)
Figure 28.11B
Gray matter
Cerebrospinal fluid
Brain
Dorsal root ganglion (part of PNS)
Meninges
White matter
Spinal nerve (part of PNS)
Central canal
Ventricles
Figure 28.11B Fluid-filled spaces of the vertebrate CNS
Central canal of spinal cord
Spinal cord (cross section)
Spinal cord 49

50. 28.12 The peripheral nervous system of vertebrates is a functional hierarchy
The PNS can be divided into two functional components:
the motor system, mostly voluntary, and
the autonomic nervous system, mostly involuntary.
Student Misconceptions and Concerns
Students often think of the motor nervous system as “voluntary” and directed by conscious thoughts. You might point out to your students that they are not likely concentrating on contracting the various muscles needed to maintain their posture as they sit in class. As noted in Module 28.12, many skeletal muscles are actually controlled by reflexes.
Teaching Tips
1. Students often remember the functions of the autonomic nervous system better by thinking of them as “automatic.”
2. Students may remember the functions of the sympathetic division as “sympathetic” to our problems. For example, the sympathetic nervous system may react to stressful situations by preparing us to fight or to run (although we often choose to do neither).
3. The automatic functions of the enteric division may not be appreciated by your students. You might note that given our busy days, with so many activities and obligations, we are fortunate that our digestive system can secrete, mix, propel, and absorb our meals without our focused mental attention! Can you imagine adding all that to our to-do list?
4. Many of the sympathetic division responses are the products of hormones released into the bloodstream. These responses cannot be quickly reversed. You might want to encourage students to think of how long it usually takes for them or others to calm down after having become extremely nervous or upset. Time and separation from the source of stress are usually required. For example, those who take a long walk in order to calm down often find, in the mild exercise and the retreat from the situation, an emotional comfort that also makes biological sense.
© 2012 Pearson Education, Inc. 50

51. 28.12 The peripheral nervous system of vertebrates is a functional hierarchy
The motor nervous system
carries signals to and from skeletal muscles and
mainly responds to external stimuli.
The autonomic nervous system
regulates the internal environment and
controls smooth and cardiac muscle and organs and glands of the digestive, cardiovascular, excretory, and endocrine systems.
Student Misconceptions and Concerns
Students often think of the motor nervous system as “voluntary” and directed by conscious thoughts. You might point out to your students that they are not likely concentrating on contracting the various muscles needed to maintain their posture as they sit in class. As noted in Module 28.12, many skeletal muscles are actually controlled by reflexes.
Teaching Tips
1. Students often remember the functions of the autonomic nervous system better by thinking of them as “automatic.”
2. Students may remember the functions of the sympathetic division as “sympathetic” to our problems. For example, the sympathetic nervous system may react to stressful situations by preparing us to fight or to run (although we often choose to do neither).
3. The automatic functions of the enteric division may not be appreciated by your students. You might note that given our busy days, with so many activities and obligations, we are fortunate that our digestive system can secrete, mix, propel, and absorb our meals without our focused mental attention! Can you imagine adding all that to our to-do list?
4. Many of the sympathetic division responses are the products of hormones released into the bloodstream. These responses cannot be quickly reversed. You might want to encourage students to think of how long it usually takes for them or others to calm down after having become extremely nervous or upset. Time and separation from the source of stress are usually required. For example, those who take a long walk in order to calm down often find, in the mild exercise and the retreat from the situation, an emotional comfort that also makes biological sense.
© 2012 Pearson Education, Inc. 51

52. Peripheral nervous system (to and from the central nervous system)
Figure 28.12A
Peripheral nervous system (to and from the central nervous system)
Motor system (voluntary and involuntary; to and from skeletal muscles)
Autonomic nervous system (involuntary; smooth and cardiac muscles, various glands)
Parasympathetic division (“Rest and digest”)
Sympathetic division (“Flight and fight”)
Enteric division (muscles and glands of the digestive system)
Figure 28.12A Functional divisions of the vertebrate PNS 52

53. 28.12 The peripheral nervous system of vertebrates is a functional hierarchy
The autonomic nervous system is composed of three divisions.
The parasympathetic division primes the body for activities that gain and conserve energy for the body.
The sympathetic division prepares the body for intense, energy-consuming activities.
The enteric division consists of networks of neurons in the digestive tract, pancreas, and gallbladder that control secretion and peristalsis.
Student Misconceptions and Concerns
Students often think of the motor nervous system as “voluntary” and directed by conscious thoughts. You might point out to your students that they are not likely concentrating on contracting the various muscles needed to maintain their posture as they sit in class. As noted in Module 28.12, many skeletal muscles are actually controlled by reflexes.
Teaching Tips
1. Students often remember the functions of the autonomic nervous system better by thinking of them as “automatic.”
2. Students may remember the functions of the sympathetic division as “sympathetic” to our problems. For example, the sympathetic nervous system may react to stressful situations by preparing us to fight or to run (although we often choose to do neither).
3. The automatic functions of the enteric division may not be appreciated by your students. You might note that given our busy days, with so many activities and obligations, we are fortunate that our digestive system can secrete, mix, propel, and absorb our meals without our focused mental attention! Can you imagine adding all that to our to-do list?
4. Many of the sympathetic division responses are the products of hormones released into the bloodstream. These responses cannot be quickly reversed. You might want to encourage students to think of how long it usually takes for them or others to calm down after having become extremely nervous or upset. Time and separation from the source of stress are usually required. For example, those who take a long walk in order to calm down often find, in the mild exercise and the retreat from the situation, an emotional comfort that also makes biological sense.
© 2012 Pearson Education, Inc. 53

54. Figure 28.12B
Parasympathetic division
Sympathetic division
Brain
Eye
Constricts pupil
Dilates pupil
Salivary glands
Stimulates saliva secretion
Inhibits saliva secretion
Lung
Constricts bronchi
Relaxes bronchi
Accelerates heart
Slows heart
Heart
Adrenal gland
Spinal cord
Stimulates epinephrine and norepi- nephrine release
Liver
Stomach
Stimulates stomach, pancreas, and intestines
Figure 28.12B The parasympathetic and sympathetic divisions of the autonomic nervous system
Pancreas
Stimulates glucose release
Inhibits stomach, pancreas, and intestines
Intestines
Bladder
Stimulates urination
Inhibits urination
Promotes erection of genitalia
Promotes ejacu- lation and vaginal contractions
Genitalia 54

55. 28.13 The vertebrate brain develops from three anterior bulges of the neural tube
The vertebrate brain evolved by the enlargement and subdivision of the
forebrain,
midbrain, and
hindbrain.
In the course of vertebrate evolution, the forebrain and hindbrain gradually became subdivided
structurally and
functionally.
Teaching Tips
The basic organization of the embryonic brain of humans is very similar to the early developmental stages in fish, amphibians, reptiles, and other mammals. The formation of a neural tube and subdivision into three and then five brain regions reflects the common ancestry of vertebrates. For biology teachers, such connections are commonplace. However, pointing out such evidence of evolution can help students understand why evolution has been widely accepted by the scientific community as a fundamental process of life.
© 2012 Pearson Education, Inc. 55

56. Embryonic Brain Regions Brain Structures Present in Adult
Figure 28.13
Embryonic Brain Regions
Brain Structures Present in Adult
Cerebrum (cerebral hemispheres; includes cerebral cortex, white matter, basal ganglia)
Forebrain
Diencephalon (thalamus, hypothalamus, posterior pituitary, pineal gland)
Midbrain
Midbrain (part of brainstem)
Pons (part of brainstem), cerebellum
Hindbrain
Medulla oblongata (part of brainstem)
Diencephalon
Cerebrum
Midbrain
Midbrain
Figure Embryonic development of the human brain
Hindbrain
Pons
Cerebellum
Medulla oblongata
Spinal cord
Forebrain
Embryo (1 month old)
Fetus (3 months old) 56

57. 28.13 The vertebrate brain develops from three anterior bulges of the neural tube
In birds and mammals the cerebrum
is much larger and
correlates with their sophisticated behavior.
Teaching Tips
The basic organization of the embryonic brain of humans is very similar to the early developmental stages in fish, amphibians, reptiles, and other mammals. The formation of a neural tube and subdivision into three and then five brain regions reflects the common ancestry of vertebrates. For biology teachers, such connections are commonplace. However, pointing out such evidence of evolution can help students understand why evolution has been widely accepted by the scientific community as a fundamental process of life.
© 2012 Pearson Education, Inc. 57

58. THE HUMAN BRAIN
© 2012 Pearson Education, Inc. 58

59. 28.14 The structure of a living supercomputer: The human brain
The human brain is
more powerful than the most sophisticated computer and
composed of three main parts:
forebrain,
midbrain, and
hindbrain.
Student Misconceptions and Concerns
Students often think of vertebrate skulls as just a place to house the brain. In most vertebrates, the brain is a relatively small item housed deep in the skull. The skull also houses all the major sense organs, is the site of firm muscle attachments, and is the entry point for the respiratory and digestive systems.
Teaching Tips
Tables such as Table 28.14, which provide summaries of structures and functions, can relieve lectures from the repetition of tedious detail. Instead, more class time can be spent on more interesting and meaningful aspects of the topic. Such tables also facilitate the creation of matching questions on exams!
© 2012 Pearson Education, Inc. 59

60. Cerebral cortex (outer region of cerebrum)
Figure 28.14A
Cerebral cortex (outer region of cerebrum)
Cerebrum
Forebrain
Thalamus
Hypothalamus
Pituitary gland
Figure 28.14A The main parts of the human brain
Midbrain
Pons
Spinal cord
Medulla oblongata
Hindbrain
Cerebellum 60

61. 28.14 The structure of a living supercomputer: The human brain
The midbrain, subdivisions of the hindbrain, the thalamus, and the hypothalamus
conduct information to and from higher brain centers,
regulate homeostatic functions,
keep track of body position, and
sort sensory information.
Student Misconceptions and Concerns
Students often think of vertebrate skulls as just a place to house the brain. In most vertebrates, the brain is a relatively small item housed deep in the skull. The skull also houses all the major sense organs, is the site of firm muscle attachments, and is the entry point for the respiratory and digestive systems.
Teaching Tips
Tables such as Table 28.14, which provide summaries of structures and functions, can relieve lectures from the repetition of tedious detail. Instead, more class time can be spent on more interesting and meaningful aspects of the topic. Such tables also facilitate the creation of matching questions on exams!
© 2012 Pearson Education, Inc. 61

62. Left cerebral hemisphere Right cerebral hemisphere
Figure 28.14B
Left cerebral hemisphere
Right cerebral hemisphere
Cerebrum
Thalamus
Cerebellum
Figure 28.14B A rear view of the brain
Basal nuclei
Corpus callosum
Medulla oblongata 62

63. Table 28.14
Table Major Structures of the Human Brain 63

64. 28.14 The structure of a living supercomputer: The human brain
The cerebrum is
part of the forebrain and
the largest and most complex part of the brain.
Most of the cerebrum’s integrative power resides in the cerebral cortex of the two cerebral hemispheres.
Student Misconceptions and Concerns
Students often think of vertebrate skulls as just a place to house the brain. In most vertebrates, the brain is a relatively small item housed deep in the skull. The skull also houses all the major sense organs, is the site of firm muscle attachments, and is the entry point for the respiratory and digestive systems.
Teaching Tips
Tables such as Table 28.14, which provide summaries of structures and functions, can relieve lectures from the repetition of tedious detail. Instead, more class time can be spent on more interesting and meaningful aspects of the topic. Such tables also facilitate the creation of matching questions on exams!
© 2012 Pearson Education, Inc. 64

65. 28.15 The cerebral cortex is a mosaic of specialized, interactive regions
The cerebral cortex
is less than 5 mm thick and
accounts for 80% of the total human brain mass.
Specialized integrative regions of the cerebral cortex include
the somatosensory cortex and
centers for vision, hearing, taste, and smell.
Student Misconceptions and Concerns
1. Students often think of vertebrate skulls as just a place to house the brain. In most vertebrates, the brain is a relatively small item housed deep in the skull. The skull also houses all the major sense organs, is the site of firm muscle attachments, and is the entry point for the respiratory and digestive systems.
2. Popular media often suggests that lateralization is a fixed human trait; i.e., certain people are “left-brained” while others are “right-brained.” Students might therefore believe that they are one or the other. As biology frequently reveals, little about life is that clear and distinct. The traits associated with each side of the brain are matters of degree, and studies of surgical procedures, disease, and injury have revealed that the brain’s hemispheres have considerable plasticity.
Teaching Tips
As students learn about the structure and function of the cerebral cortex, they are actually using these sets of cells to think about these cells. As student understanding grows, these sets of cells become increasingly aware of their own properties, in a process that is like looking in a mirror!
© 2012 Pearson Education, Inc. 65

66. 28.15 The cerebral cortex is a mosaic of specialized, interactive regions
The motor cortex directs responses.
Association areas
make up most of the cerebrum and
are concerned with higher mental activities such as reasoning and language.
In a phenomenon known as lateralization, right and left cerebral hemispheres tend to specialize in different mental tasks.
Student Misconceptions and Concerns
1. Students often think of vertebrate skulls as just a place to house the brain. In most vertebrates, the brain is a relatively small item housed deep in the skull. The skull also houses all the major sense organs, is the site of firm muscle attachments, and is the entry point for the respiratory and digestive systems.
2. Popular media often suggests that lateralization is a fixed human trait; i.e., certain people are “left-brained” while others are “right-brained.” Students might therefore believe that they are one or the other. As biology frequently reveals, little about life is that clear and distinct. The traits associated with each side of the brain are matters of degree, and studies of surgical procedures, disease, and injury have revealed that the brain’s hemispheres have considerable plasticity.
Teaching Tips
As students learn about the structure and function of the cerebral cortex, they are actually using these sets of cells to think about these cells. As student understanding grows, these sets of cells become increasingly aware of their own properties, in a process that is like looking in a mirror!
© 2012 Pearson Education, Inc. 66

67. Somatosensory association area Frontal association area
Figure 28.15
Frontal lobe
Parietal lobe
Somatosensory association area
Frontal association area
Speech
Motor cortex
Somatosensory cortex
Reading
Speech
Hearing
Visual association area
Smell
Figure Functional areas of the left cerebral hemisphere
Auditory association area
Vision
Temporal lobe
Occipital lobe 67

68. 28.16 CONNECTION: Injuries and brain operations provide insight into brain function
Brain injuries and surgeries reveal brain functions.
After a 13-pound steel rod pierced his skull, Phineas Gage appeared to have an intact intellect but his associates noted negative changes to his personality.
Stimulation of the cerebral cortex during surgeries caused patients to recall sensations and memories.
Cutting the corpus callosum revealed information about brain lateralization.
Student Misconceptions and Concerns
Students often think of vertebrate skulls as just a place to house the brain. In most vertebrates, the brain is a relatively small item housed deep in the skull. The skull also houses all the major sense organs, is the site of firm muscle attachments, and is the entry point for the respiratory and digestive systems.
Teaching Tips
1. Module notes that the cerebrum lacks cells that can detect pain. Consider challenging your students to explain how the source of the pain during a headache. (Some headaches can result from pain outside the brain. For example, sinus pressure, muscle tension, or a toothache can be considered a type of headache. Vascular headaches can result from pain receptors in overstretched or overconstricted blood vessels of the brain.)
2. Much of what we know about brain function comes from damage caused by accidents or disease. Challenge your students to consider the limits of these “natural” experiments. (For instance, disease or damage may have multiple physiological effects, making it difficult to trace them to the malfunction of a particular brain region.) Corroborating data from other technologies, such as fMRI scans, helps verify earlier results. Reviewing the different approaches to understanding the brain reveals how multiple, independent lines of evidence increase confidence in results.
© 2012 Pearson Education, Inc. 68

69. Figure 28.16A
Figure 28.16A Computer model of Phineas Gage’s injury 69

70. 28.18 Several parts of the brain regulate sleep and arousal
Sleep and arousal involve activity by the
hypothalamus,
medulla oblongata,
pons, and
neurons of the reticular formation.
Student Misconceptions and Concerns
Students often think of vertebrate skulls as just a place to house the brain. In most vertebrates, the brain is a relatively small item housed deep in the skull. The skull also houses all the major sense organs, is the site of firm muscle attachments, and is the entry point for the respiratory and digestive systems.
Teaching Tips
As noted in Module 28.18, sleep seems to be involved in learning and memory. Study strategies that involve cramming large amounts of information into the memory in a short period of time may not permit enough sleep and review for deeper understanding. Students who engage in such practices may easily be confused on an exam. The strategy of processing smaller amounts of information over a longer period of time, allowing for both rest and frequent review, is likely to result in the retention of a better-integrated body of information.
© 2012 Pearson Education, Inc. 70

71. 28.18 Several parts of the brain regulate sleep and arousal
Sleep
is essential for survival,
is an active state, and
may be involved in consolidating learning and memory.
Student Misconceptions and Concerns
Students often think of vertebrate skulls as just a place to house the brain. In most vertebrates, the brain is a relatively small item housed deep in the skull. The skull also houses all the major sense organs, is the site of firm muscle attachments, and is the entry point for the respiratory and digestive systems.
Teaching Tips
As noted in Module 28.18, sleep seems to be involved in learning and memory. Study strategies that involve cramming large amounts of information into the memory in a short period of time may not permit enough sleep and review for deeper understanding. Students who engage in such practices may easily be confused on an exam. The strategy of processing smaller amounts of information over a longer period of time, allowing for both rest and frequent review, is likely to result in the retention of a better-integrated body of information.
© 2012 Pearson Education, Inc. 71

72. 28.19 The limbic system is involved in emotions, memory, and learning
The limbic system is
a functional group of integrating centers in the
cerebral cortex,
thalamus,
hypothalamus, and
involved in
emotions, such as nurturing infants and bonding emotionally to other people,
memory, and
learning.
Student Misconceptions and Concerns
Students often think of vertebrate skulls as just a place to house the brain. In most vertebrates, the brain is a relatively small item housed deep in the skull. The skull also houses all the major sense organs, is the site of firm muscle attachments, and is the entry point for the respiratory and digestive systems.
Teaching Tips
1. Moving information from short-term memory to long-term memory requires frequent rehearsal. Using note cards to create questions and answers based upon the information for an exam is one form of rehearsal that can be very effective when studying basic information. This chapter helps students understand the underlying physiological basis of many successful study techniques.
2. The strong emotional reactions to scents and music that many humans have experienced are properties of our limbic system.
© 2012 Pearson Education, Inc. 72

73. Thalamus Cerebrum Hypothalamus Prefrontal cortex Smell Olfactory bulb
Figure 28.19
Thalamus
Cerebrum
Hypothalamus
Prefrontal cortex
Figure The limbic system (shown in shades of gold)
Smell
Olfactory bulb
Amygdala
Hippocampus 73

74. You should now be able to
Describe the structural and functional subdivisions of the nervous system.
Describe the three parts of a reflex, distinguishing the three types of neurons that may be involved in the reaction.
Describe the structures and functions of neurons and myelin sheaths.
Define a resting potential and explain how it is created.
© 2012 Pearson Education, Inc. 74

75. You should now be able to
Explain how an action potential is produced and the resting membrane potential restored.
Explain how an action potential propagates itself along a neuron.
Compare the structures, functions, and locations of electrical and chemical synapses.
Compare excitatory and inhibitory neurotransmitters.
Describe the types and functions of neurotransmitters known in humans.
© 2012 Pearson Education, Inc. 75

76. You should now be able to
Explain how drugs can alter chemical synapses.
Describe the diversity of animal nervous systems and provide examples.
Describe the general structure of the brain, spinal cord, and associated nerves of vertebrates.
Compare the functions of the motor nervous system and autonomic nervous system.
© 2012 Pearson Education, Inc. 76

77. You should now be able to
Compare the structures, functions, and interrelationships of the parasympathetic, sympathetic, and enteric divisions of the peripheral nervous system.
Explain how the vertebrate brain develops from an embryonic tube.
Describe the main parts and functions of the human brain.
Explain how injuries, illness, and surgery provide insight into the functions of the brain.
© 2012 Pearson Education, Inc. 77

78. You should now be able to
Explain how fMRI scans help us understand brain functions.
Explain how the brain regulates sleep and arousal.
Describe the structure and functions of the limbic system.
Describe the causes, symptoms, and treatments of schizophrenia, depression, Alzheimer’s disease, and Parkinson’s disease.
© 2012 Pearson Education, Inc. 78

79. Peripheral nervous system Central nervous system
Figure 28.UN01
Sensory receptor
Sensory input
Integration
Effector cells
Motor output
Figure 28.UN01 Reviewing the Concepts, 28.1
Peripheral nervous system
Central nervous system 79

80. Myelin sheath (speeds signal transmission)
Figure 28.UN02 po te
nti al
Action
signal
Figure 28.UN02 Reviewing the Concepts, 28.2
Dendrites
Axon
Synaptic terminals
Cell body
Myelin sheath (speeds signal transmission) 80

81. Central Nervous System (CNS) Peripheral Nervous System (PNS)
Figure 28.UN03
Central Nervous System (CNS)
Peripheral Nervous System (PNS)
Brain
Spinal cord:
nerve bundle that
communicates with body
Motor system: voluntary control over muscles
Autonomic nervous system: involuntary control over organs
• Parasympathetic division: rest and digest • Sympathetic division: fight or flight
Figure 28.UN03 Reviewing the Concepts, 28.12 81