Physiology Module 7

Apologia A&P

Study Guide

Module 7

Define the following terms: 1) nerves Bundles of axons and their sheaths which extend from the CNS. 2) ganglia A structure containing a number of nerve cell bodies, typically linked by synapses, and often forming a swelling on a nerve fiber. 3) spinal nerves Nerves which originate from the spinal cord.

4) cranial nerves Nerves which originate from the brain.

5) afferent neurons Neurons which transmit action potentials from the sensory organs to the CNS.

6) efferent neurons Neurons which transmit action potentials from the CNS to the effector organs.

7) somatic motor nervous system The system that transmits action potentials from the CNS to the skeletal muscles.

11) association neuron A neuron that conducts action potentials from one neuron to another within the CNS.

12) excitability The ability to create an action potential in response to a stimulus. 13) potential difference A measure of the charge difference across the cell membrane. 14) As you read this question, cells in your eyes are sending information to your brain which your brain uses to form an image of the words that you read. Is this information being sent along afferent or efferent nerves? Afferent nerves, since those are nerves that carry information from your sensory organs (eyes) to the CNS (your brain).

15) When you are digesting food, smooth muscles contract your stomach. Is this controlled by the afferent or efferent division of the PNS? You can be even more specific than that. What would be the most specific way to describe the nerves involved in this situation? Efferent division. The most specific you can be is that the parasympathetic division of the automatic nervous system is being used.

16) Identify the parts of the neuron

It needs to have exactly the same properties at its destination as it did when it started. Should this signal be sent along one very long axon or a few shorter axons that are connected by synapses? A long axon should be used.

33) The potential difference in a postsynaptic neuron changes from -85mV to -95mV at the point of a synapse. What has happened? What can you say about the relative amounts of K+ and Na+ outside the membrane? An inhibitory postsynaptic potential has occurred. The potassium ion concentration will be higher than for the resting state outside of the membrane. The sodium ion concentration will be unchanged.

34) Twelve action potentials are traveling down an axon in a very short time period. They reach a synapse, and the postsynaptic neuron sends only two action potentials down its axon. Is this an excitatory synapse or an inhibitory synapse? An excitatory synapse.

35) In the example above, is this temporal summation or spatial summation? How do you know?

36) We discussed three kinds of circuits which can be formed by neurons. Name the three circuits and what they are used