Nervous System Review

1. What is the function of each type of neuron? (motor - signals to effectors; sensory - signals to CNS;inter - connects the other two)

2. Describe the function of each of the following:

a) dendrites (receive info) (b) myelin sheath (insulates and speeds transmisison) (c) Schwann cells (form myelin sheath) (d) cell body (like other cells; contains nucleus) (e) axon (info toward nextcell)

3. Differentiate between the CNS and the PNS. (CNS - brain and spinal cord; PNS - all body nerves)

4. Describe the advantage of a reflex response to an organism. (responds to danger more quickly)

5. How does the nerve impulse cross the space between two nerve cells? (neurotransmitters)

6. You accidentally touch a hot iron. Your hand quickly moves away from the iron. What type of reaction is this? (reflex) Do you feel pain before you pull your hand away? Explain. (No. Response tostimulus occurs before awareness of it. The motor neuron is activated before the sensation of pain reachesthe brain) Describe what happens in the central nervous system to allow you to react so quickly. Sensoryreceptor, sensory neuron, interneuron, motor neuron, effector, also to brain)

7. What are the functions of the somatic and autonomic nervous systems? (control body, control organs)

8. Which part of the peripheral nervous system is involved in throwing a ball? (somatic)

9. Pain receptors are abut 27 times more abundant in the skin than are cold receptors. Explain why this is adaptive for survival. (pain more dangerous than cold)

10. What causes the neuron to be polarized? (Na^+/K⁺pump and different distribution of anions)

11. What changes occur along a cell membrane as it changes from a resting potential to an action potential and then into refractory period? (potential changes from negative to positive and then back)

12. Explain how the polarity of a cell membrane is able to reverse during an action potential. (gates opento allow ions to diffuse across)

13. Imagine you cut yourself and some nerves are severed. What effect would this have on the transmission of impulses? (the impulse will be disrupted)

14. How is the membrane potential of the resting cell restored after a nerve impulse has passed? (membrane remains permeable to ions, and Na-K pump restores ionic concentrations)

15. During a nerve impulse, how do the charges inside and outside the neuron’s membrane compare? (inside positive, outside negative)

16. If a person’s spinal cord was crushed at the neck, resulting in paralysis, what parts of the body would be affected? (all parts below the injury)

17. Why do nerve impulses move faster along myelinated nerve axons? (impulse jumps from one node tothe next)

18. What is the all-or-none response? (neuron fires or doesnt; not graduated)

19. If a stimulus causes an all-or-none response, how can the level of pain you feel vary? (differentthresholds, spatial summation and temporal summation)

20. Use the idea of threshold levels to explain why some individuals can tolerate more pain than others. (genetic differences mean some people may have neurons of higher thresholds so can tolerate more pain)

21. Why can we say that nerve impulses are not electricity but electrochemical events? (involve ionsmoving)

22. Explain the functions of acetylcholine and cholinesterase in the transmission of nerve impulses. (acetylcholine crosses synapse to muscle and causes contraction; cholinesterase is present in synapse todegrade neurotransmitter)

23. Use the idea of a synapse to explain why a nerve impulse can move from neuron A to neuron B but not vice versa. (receptors for neurotransmitter only on post-synaptic membrane)

24. Use the idea of a synapse and neurotransmitters to explain the concept of summation. (effects ofstimuli below threshold can be added up to reach threshold)

25. Which part of your autonomic nervous system is active when you are sleeping peacefully? (parasympathetic) Putting out a grease fire at home? (sympathetic)

26. If you blow a breath of air over your skin, you can feel the air moving. Which type of receptors detect this sensation? (touch)

27. How can drugs act as stimulants or depressants? (stimulants can open Na+ channels or otherwiseincrease the activity of excitatory neurons)

28. What is an endorphin? How does it work? (chemical released in brain to block pain messages)