Worksheet #10 on Neuron Anatomy and Physiology PDF

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EXERCISE 10 Neuron Anatomy and Physiology

Name: IDK Time/Date: Monday/Thursday, 1 to 4PM

SECTION: C

Lab

1. The cellular unit of the nervous system is the neuron. What is the major function of this cell type? Transmit and generate messages (nerve impulses) from one part of the body to another.

2. Neuroglia have numerous functions. Name three. (1) Provide structural support to neurons. (2) They Form myelin sheath. (3) Participate in formation of blood – brain barrier.

3. Match each statement with a response chosen from the key. Key: afferent neuron interneuron

peripheral nervous system

central nervous

system

synaptic cleft efferent neuron

nerve tract nuclei

neurotransmitters ganglion

CENTRAL NERVOUS SYSTEM 1. the brain and spinal cord collectively SYNAPTIC CLEFT

2. tiny gap that separates two neurons

GANGLION nervous system INTERNEURON TRACT NUCLEI EFFERENT NUERON CNS to muscles and glands AFFARENT NEURON from the body periphery NEUROTRANSMITTER

3. a bundle of nerve processes outside the central 4. neuron connecting sensory and motor neurons 5. neuron processes running through the CNS 6. collections of nerve cell bodies inside the CNS 7. neuron that conducts impulses away from the 8. neuron that conducts impulses toward the CNS 9. chemicals released by axon terminals

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Neuron Anatomy 4. Draw a “typical” neuron in the space below. Include and label the following structures on your diagram: cell body, nucleus, dendrites, axon, myelin sheath, and myelin sheath gaps.

5. How is one-way conduction at synapses ensured? Neurons have only one axon that carries impulses away from the nerve cell body toward the synapse.

6. What anatomical characteristic determines whether a particular neuron is classified as unipolar, bipolar, or multipolar? It can be determined through the number of processes issuing from the cell body Make a simple line drawing of each type here.

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7. Describe how the Schwann cells form the myelin sheath and the outer collar of the perinuclear cytoplasm encasing an axon. (You may want to diagram the process.) Cells begin to wrap themselves around the axon in jellyroll fashion, thus forming a tight coil of membranous material which forms the myelin sheath. The neurilemma is the bulge of this cell's cytoplasm external to myelin sheath and the outermost (exposed) this cell's membrane.

8. Correctly identify the sensory (afferent) neuron, interneuron, and motor (efferent) neuron in the figure below. Which of these neuron types is/are unipolar? Sensory neuron

Which is/are most likely multipolar? Motor neuron, association neuron, or interneuron

The Nerve Impulse 9.

Match each of the terms in column B to the appropriate definition in column A. Column A Column B

Depolarization

______Repolarization

1. reversal of the resting potential owing to an influx of sodium ions action potential __ 2. period during which Copyright © 2014 Pearson Education, Inc.

action potential

depolarization

potassium

___Action Potential

Sodium Potassium Pump

ions are diffusing out of the neuron _ 3. transmission of the depolariz tion wave along the neuronal membrane 4. mechanism that restores the resting membrane voltage and intracellular ionic concentrations

repolarization

sodium-potassium pump

10.

Would a substance that decreases membrane permeability to sodium increase or decrease the probability of generating a nerve impulse? It would decrease the probability of generating a nerve impulse.

11.

Why don’t the terms depolarization and action potential mean the same thing? (Hint: Under what conditions will a local depolarization not lead to the action potential?)

Because force has to be great enough for an action to occur Structure of a Nerve 12. What is a nerve? It is a macroscopic cordlike structure of the body, comprising a collection of nerve fibers that convey impulses between a part of the central nervous system and some other body region. 13.

State the location of each of the following connective tissue coverings:

Endoneurium Additional sheath that surrounds the myelin sheath surrounding each fiber within a nerve it insulates from the neuron process adjacent to it (delicate). Perineurium Groups of fibers bound by perineurium form bundles of fibers (fascicles) (courser).

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Epineurium Bounds fasiciles together ( white fiberous CT sheath). 14.

What is the value of the connective tissue wrappings found in a nerve?

It helps insulate. 15.

Define mixed nerve: Nerves that carries afferent and efferent neurons. (Most nerves)

75

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