1. Presentation title slide

2. UNIT B: Human Body Systems
Chapter 8: Human Organization
Chapter 9: Digestive System
Chapter 10: Circulatory System and Lymphatic System
Chapter 11: Respiratory System
Chapter 12: Nervous System:
Section 12.4
Chapter 13: Urinary System
Chapter 14: Reproductive System

3. Chapter 12: Nervous System
UNIT B
Chapter 12: Nervous System
Chapter 12: Nervous System
In this chapter, you will learn about the structure and function of the nervous system.
How might a researcher study the effects of frequent head trauma?
How might one determine which part of the brain has been affected by repeated blunt impacts?
Given the available information about CTE, what steps do you feel should be taken to prevent its occurrence (if any)?
Sport-Related Head Trauma and Brain Function. Neurosurgeon Dr. Robert Cantu has studied the brains of many deceased athletes, including hockey and football players. He has found that these players often suffered from chronic traumatic encephalopathy (CTE), a degenerative brain disease caused by repeated blunt impact to the head.
Chapter opener figure background:
Former NHL players Rick Rypien, Wade Belak, and Derek Boogaard had something in common; they were all “enforcers.” They were expected to
fight during hockey games.
There is another similarity among these men. They are all dead. Each died of causes that increasingly seem tied to their activities on the ice. Neurosurgeon Dr. Robert Cantu has studied the brains of many deceased athletes, including hockey and football players. He has found that these players often suffered from chronic traumatic encephalopathy (CTE), a degenerative brain disease caused by repeated blunt impact to the head. CTE seems to manifest itself in addiction, depression, and anxiety, conditions suffered by some or all of the deceased players.
Dr. David Goldbloom, senior medical adviser at Toronto’s Centre for Addiction and Mental Health, thinks it is important not to assume that the deaths of the players were all the result of the same thing. Each was an individual and each had his own mental health history. Rypien and Belak had battled depression, and Boogaard was still recovering from previous concussions. Goldbloom feels that attributing the deaths to CTE is an oversimplification, but he does think further study in this area is worth pursuing.
TO PREVIOUS SLIDE

4. 12.4 The Peripheral Nervous System
UNIT B
Chapter 12: Nervous System
Section 12.4
12.4 The Peripheral Nervous System
The peripheral nervous system (PNS) contains the motor and sensory pathways.
peripheral nervous system (PNS): lies outside the central nervous system and is composed of nerves and ganglia
TO PREVIOUS SLIDE

5. Structure of the PNS UNIT B The PNS is composed of nerves and ganglia.
Chapter 12: Nervous System
Section 12.4
Structure of the PNS
The PNS is composed of nerves and ganglia.
Nerves: bundles of axons; the axons in nerves are called nerve fibres
Ganglia: swellings associated with nerves that contain collections of cell bodies
nerves: fibres bound by connective tissue; found outside the brain and spinal cord
nerve fibres: axons that occur in nerves
ganglia: (sing., ganglion) swellings associated with nerves that contain collections of cell bodies
TO PREVIOUS SLIDE

6. UNIT B
Chapter 12: Nervous System
Section 12.4
Cranial nerves
Humans have 12 pairs of cranial nerves attached to the brain
Nerves can contain sensory input fibres, motor output fibres, or a combination of both
Largely concerned with the head, neck, and facial regions
Vagus nerve (X) branches to internal organs
cranial nerves: nerves that arise from the brain
Figure Cranial and spinal nerves a. Ventral surface of the brain showing the attachments of the 12 pairs of cranial nerves.
TO PREVIOUS SLIDE

7. UNIT B
Chapter 12: Nervous System
Section 12.4
Spinal nerves
Humans have 31 pairs of spinal nerves (mix of motor and sensory fibres)
Dorsal root: contains sensory fibres that conduct impulses toward the spinal cord
Dorsal root ganglion: contains cell bodies of sensory neurons
Ventral root: contains motor fibres that conduct impulses away from the spinal cord to effectors
Each spinal nerve serves a region of the body in which it is located
spinal nerves: nerves that arise from the spinal cord
dorsal root ganglia: structures that house the cell body of a sensory neuron
Figure Cranial and spinal nerves. b. Cross section of the spinal cord showing three pairs of spinal nerves. The human body has 31 pairs of spinal nerves altogether, and each spinal nerve has a dorsal root and a ventral root attached to the spinal cord.
TO PREVIOUS SLIDE

8. UNIT B
Chapter 12: Nervous System
Section 12.4
Somatic System
The PNS is divided into the somatic system and the autonomic system.
The somatic system takes sensory information from external sensory receptors to the CNS and motor commands away from the CNS to skeletal muscles
Serves the skin, skeletal muscles, and tendons
Some actions are due to reflex actions (automatic responses to a stimulus)
somatic system: a subdivision of the peripheral nervous system that serves the skin, skeletal muscles, and tendons
reflex actions: automatic responses to a stimulus
TO PREVIOUS SLIDE

9. UNIT B
Chapter 12: Nervous System
Section 12.4
The Reflex Arc
A reflex arc is a nerve pathway that carries out a reflex.
Reflexes are built-in circuits that allow for protection and survival
Reflexes allow the body to react quickly to stimuli that could disrupt homeostasis
Reflexes are present at birth and do not require conscious thought
Example: withdrawal reflex when touching a sharp object
TO PREVIOUS SLIDE

10. UNIT B Chapter 12: Nervous System Section 12.4
Figure A somatic reflex arc showing the path of a spinal reflex. A stimulus (for example, a sharp pin) causes sensory receptors in the skin to generate nerve impulses that travel in sensory axons to the spinal cord. Interneurons integrate data from sensory neurons and then relay signals to motor axons. Motor axons convey nerve impulses from the spinal cord to a sketetal muscle, which contracts. Movement of the hand away from the pin is the response to the stimulus.
TO PREVIOUS SLIDE

11. Autonomic System UNIT B
Chapter 12: Nervous System
Section 12.4
Autonomic System
The autonomic system of the PNS regulates the activity of cardiac and smooth muscle, and glands.
autonomic system: part of the peripheral nervous system that regulates the activity of cardiac and smooth muscle, and glands
TO PREVIOUS SLIDE

12. Both divisions function automatically and usually involuntarily
UNIT B
Chapter 12: Nervous System
Section 12.4
The autonomic system is composed of the sympathetic and parasympathetic divisions.
Both divisions function automatically and usually involuntarily
Innervate all internal organs
For each signal, they use two motor neurons that synapse at a ganglion
Involved in reflex actions such as blood pressure and breathing rate
TO PREVIOUS SLIDE

13. Sympathetic Division UNIT B
Chapter 12: Nervous System
Section 12.4
Sympathetic Division
The sympathetic division is involved in the “fight or flight” response.
Inhibits tears
Dilates pupils
Inhibits salivation
Increases heartbeat
Dilates airways
Stimulates liver to release glucose
Inhibits digestive tract and urination
Uses the neurotransmitters epinephrine (adrenaline) and norepinephrine (NE), which act on different cells to add to the “fight or flight” response
sympathetic division: division of the autonomic system that is active when an organism is under stress; activates the adrenal medulla to secrete the hormones epinephrine and norepinephrine
TO PREVIOUS SLIDE

14. UNIT B Chapter 12: Nervous System Section 12.4
Figure Autonomic system structure and function. Sympathetic preganglionic fibres (left) arise from the cervical, thoracic, and lumbar portions of the spinal cord. Parasympathetic preganglionic fibres (right) arise from the cranial and sacral portions of the spinal cord. Each system innervates the same organs but has contrary effects.
TO PREVIOUS SLIDE

15. Parasympathetic Division
UNIT B
Chapter 12: Nervous System
Section 12.4
Parasympathetic Division
The parasympathetic division is involved in the “rest and digest” response.
Stimulates tears
Constricts pupils
Stimulates salivation
Decreases heartbeat and blood pressure
Constricts airways
Stimulates gall bladder to release bile
Stimulates digestive tract and urination
Uses the neurotransmitter acetylcholine (ACh), which acts on different cells to add to the “rest and digest” response
parasympathetic division: division of the autonomic system that is active under normal conditions; uses acetylcholine as a neurotransmitter
TO PREVIOUS SLIDE

16. UNIT B Chapter 12: Nervous System Section 12.4
Figure Autonomic system structure and function. Sympathetic preganglionic fibres (left) arise from the cervical, thoracic, and lumbar portions of the spinal cord. Parasympathetic preganglionic fibres (right) arise from the cranial and sacral portions of the spinal cord. Each system innervates the same organs but has contrary effects.
TO PREVIOUS SLIDE

17. UNIT B
Chapter 12: Nervous System
Section 12.4
TO PREVIOUS SLIDE

18. Check Your Progress UNIT B Contrast cranial and spinal nerves.
Chapter 12: Nervous System
Section 12.4
Check Your Progress
Contrast cranial and spinal nerves.
Explain why, if you touch a hot stove, you usually withdraw your hand before feeling the pain.
Summarize the features of the autonomic system that are different from the somatic system.
ANSWERS
1. Cranial nerves:
Generally associated with sensing and motor control of the head, neck, and facial regions (except the vagus, which controls many organs, tissues, and glands in the neck and body).
12 pairs
some contain only sensory fibres, some only motor fibres, and some are mixed nerves with both sensory and motor fibres
Spinal nerves:
Generally associated with sensing and motor control in the rest of the body; they are found in the area they serve—e.g., intercostal muscles are innervated by thoracic nerves.
31 pairs
contain sensory and motor fibres (mixed nerves)
2. When you touch a hot stove, your hand withdraws before you feel the pain, because the nerve pathway for a reflex arc travels directly through the spinal cord without input from the brain. The pain impulse is travelling up the neck to the brain as the motor impulse is travelling back to the effector muscle. 3.
Somatic
Type of control: Voluntary
Number of neurons per message: one
Neurotransmitter: Acetylcholine
Effectors: Skeletal muscle
Autonomic
Type of control: Involuntary
Number of neurons per message: two
Neurotransmitter: Acetylcholine and norepinephrine
Effectors: Smooth and cardiac muscle, glands
TO PREVIOUS SLIDE

19. Check Your Progress UNIT B
Chapter 12: Nervous System
Section 12.4
Check Your Progress
Provide the neurological explanation for the following: You eat a big lunch, then go for a jog, during which your stomach starts to ache.
Explain the following: How does the bite of a black widow spider, which injects a powerful AChE inhibitor, cause muscle cramps, salivation, fast heart rate, and high blood pressure?
ANSWERS
4. The brain has stimulated your somatic nervous and sympathetic nervous systems more than your parasympathetic. As a result, there is an increase in blood flow to the muscles, heart rate and depth and rate of breathing increase, and digestion is inhibited. There is decreased peristalsis and blood flow to the intestine, which results in discomfort.
5. AChE normally breaks down acetylcholine in the synaptic cleft. The black widow venom is an AChE inhibitor, so acetylcholine in the synaptic cleft is not being broken down. The symptoms of muscle cramps, salivation, fast heart rate, and high blood pressure all are a result of the action of the acetylcholine as a neurotransmitter in the somatic and parasympathetic nervous systems.
TO PREVIOUS SLIDE

20. UNIT B
Chapter 12: Nervous System
Section 12.4
TO PREVIOUS SLIDE