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Fig. 34-1, p.572.

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Presentation on theme: "Fig. 34-1, p.572."— Presentation transcript:

1 Fig. 34-1, p.572

2 p.573a

3 Line of Communication stimulus receptors sensory neurons integrators
interneurons motor neurons effectors muscles, glands response Fig. 34-2, p.574

4 Fig. 34-4, p.575

5 Vertebrate Nervous Systems
Vertebrate nervous system divisions

6 Communication Lines Stimulus (input) Receptors (sensory neurons)
Integrators (interneurons) motor neurons Effectors (muscles, glands) Response (output) Figure 34.5 Page 575

7 Neurons Fig. 34-6d2, p.576

8 Motor Neuron dendrites cell body Input Zone Trigger Zone
Conducting Zone axon Output Zone axon endings Stepped Art Fig. 34-6d1, p.576

9 Neuron structure and function

10 Three Classes of Neurons
Sensory neurons Interneurons Motor neurons

11 dendrites axon cell body Fig. 34-6a, p.576

12 dendrites dendrites cell body axon Fig. 34-6b,c, p.576

13 Structure of a Neuron dendrites input zone cell body trigger zone
conducting zone axon endings axon output zone Fig. 34-6d1, p.576

14 How Ions Move across Membrane
Interstitial fluid Cytoplasm Na+/K+ pump Passive transporters with open channels Passive transporters with voltage-sensitive gated channels Active transporters Lipid bilayer of neuron membrane Figure 34.7 Page 577

15 Pumping and Leaking Interstitial fluid Na+ pumped out Na+ leaks out
Plasma membrane Na+ leaks in K + pumped in K+ leaks out Cytoplasm Figure 34.7 Page 577

16 Ion Movement Ion concentrations

17 Ion Concentrations at Resting Potential
Potassium (K+) Higher inside than outside Sodium (Na+) Higher outside than inside

18 Action potential propagation

19 Positive Feedback more Na+ ions flow into the neuron
more gated channels for Na+ open neuron becomes more positive inside

20 All or Nothing All action potentials are the same size
If stimulation is below threshold level, no action potential occurs If it is above threshold level, cell is always depolarized to the same level

21 Repolarization Once peak depolarization is reached, Na+ gates close and K+ gates open Movement of K+ out of cell repolarizes the cell The inside of the cell once again becomes more negative than the outside

22 Measuring membrane potential

23 action potential +20 -20 Membrane potential (millivolts) threshold -40 resting membrane potential -70 1 2 3 4 5 Figure 34.9f Page 579 Time (milliseconds)

24 Propagation of Action Potentials
An action potential in one part of an axon brings a neighboring region to threshold Action potential occurs in one patch of membrane after another

25 Chemical Synapse Gap between the terminal ending of an axon and the input zone of another cell plasma membrane of axon ending of presynapic cell plasma membrane of postsynapic cell synaptic vesicle synaptic cleft membrane receptor Figure 34.10a Page 580

26 Synaptic Transmission
Action potential at end of presynaptic cell axon causes voltage-gated calcium channels to open Flow of calcium into presynaptic cell causes release of neurotransmitter into synaptic cleft

27 Synaptic Transmission
Neurotransmitter diffuses across cleft and binds to receptors on membrane of postsynaptic cell Binding of neurotransmitter to receptors opens ion channels in the membrane of postsynaptic cell

28 Synaptic Transmission
Synapse function

29 Chemical Synapse Chemical synapse

30 neuromuscular junction
motor neuron axons from spinal cord to skeletal muscle cells transverse slice of spinal cord part of a skeletal muscle Fig a, p.581

31 axon ending muscle fiber Fig b, p.581

32 Neurotransmitters ACh Norepinephrine Epinephrine Dopamine Serotonin
GABA Derived from amino acids

33 Neuroglia More than half the volume of the vertebrate nervous system
A variety of cells that metabolically assist, structurally support, and protect the neurons

34 Nerve A bundle of axons enclosed within a connective tissue sheath
myelin sheath nerve fascicle A bundle of axons enclosed within a connective tissue sheath Figure Page 584

35 Myelin Sheath A series of Schwann cells Sheath blocks ion movements
Action potential must “jump” from node to node Figure 34.15b Page 584

36 Nerve Nerve structure

37 Ion flow in myelinated axons

38 Reflexes Automatic movements made in response to stimuli
In the simplest reflex arcs, sensory neurons synapse directly on motor neurons Most reflexes involve an interneuron

39 Stretch Reflex Figure 34.16 Page 585 STIMULUS Biceps stretches.
sensory neuron motor neuron Response Biceps contracts. Figure Page 585

40 Stretch Reflex Stretch reflex

41 Peripheral Nervous System
Somatic nerves Motor functions (Shown in green) Autonomic nerves Visceral functions (Shown in red)

42 Two Types of Autonomic Nerves
Sympathetic Parasympathetic Most organs receive input from both Usually have opposite effects on organ

43 Sympathetic Nerves Originate in the thoracic and lumbar regions of the spinal cord Ganglia are near the spinal cord Promote responses that prepare the body for stress or physical activity (fight-or-flight response)

44 Parasympathetic Nerves
Originate in the brain and the sacral region of the spinal cord Ganglia are in walls of organs Promote housekeeping responses such as digestion

45 Both Systems Are Usually Active
Most organs are continually receiving both sympathetic and parasympathetic stimulation For example, sympathetic nerves signal heart to speed up; parasympathetic stimulate it to slow down Which dominates depends on situation

46 Function of the Spinal Cord
Expressway for signals between brain and peripheral nerves Sensory and motor neurons make direct reflex connections in the spinal cord Spinal reflexes do not involve the brain

47 Structure of the Spinal Cord
ganglion nerve meninges (protective coverings) vertebra Figure Page 587

48 Organization of the spinal cord

49 Vertebrate Brains olfactory lobe olfactory lobe (part of forebrain)
midbrain hindbrain midbrain fish (shark) hindbrain reptile (alligator) mammal (horse) Figure Page 589

50 Regions of the vertebrate brain
Vertebrate Brains Regions of the vertebrate brain

51 Cerebrospinal Fluid Surrounds the spinal cord
Fills ventricles within the brain Blood-brain barrier controls which solutes enter the cerebrospinal fluid Figure Page 588

52 Anatomy of the Cerebrum
Largest and most complex part of human brain Outer layer (cerebral cortex) is highly folded A longitudinal fissure divides cerebrum into left and right hemispheres

53 Limbic System Controls emotions and has role in memory
(olfactory tract) cingulate gyrus thalamus amygdala hypothalamus Figure Page 591 hippocampus

54 Prefrontal cortex activity when generating words
Visual cortex activity when seeing written words Motor cortex activity when speaking Fig b, p.590

55 Sensory Pathway Path to visual cortex

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