Textbook Question
During a neurobiology lecture, a professor repeatedly refers to group A and group B fibers, absolute refractory period, and myelin sheath gaps. Define these terms.
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Ch. 11 Fundamentals of the Nervous System and Nervous Tissue
Marieb, Hoehn7th EditionHuman Anatomy & PhysiologyISBN: 9780805359091
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Table of contents
- Ch. 1 The Human Body: An Orientation24
- Ch. 2 Chemistry Comes Alive25
- Ch. 3 Cells: The Living Units24
- Ch. 4 Tissue: The Living Fabric19
- Ch. 5 The Integumentary System10
- Ch. 6 Bones and Skeletal Tissues19
- Ch. 7 The Skeleton11
- Ch. 8 Joints7
- Ch. 9 Muscles and Muscle Tissue26
- Ch. 10 The Muscular System26
- Ch. 11 Fundamentals of the Nervous System and Nervous Tissue23
- Ch. 12 The Central Nervous System26
- Ch. 13 The Peripheral Nervous System and Reflex Activity28
- Ch. 14 The Autonomic Nervous System18
- Ch. 16 The Endocrine System26
- Ch. 17 Blood27
- Ch. 18 The Cardiovascular System: The Heart22
- Ch. 19 The Cardiovascular System: Blood Vessels27
- Ch. 20 The Lymphatic System and Lymphoid Organs and Tissues16
- Ch. 21 The Immune System: Innate and Adaptive Body Defenses29
- Ch. 22 The Respiratory System20
- Ch. 23 The Digestive System30
- Ch. 24 Nutrition, Metabolism, and Energy Balance26
- Ch. 25 The Urinary System25
- Ch. 26 Fluid, Electrolyte, and Acid-Base Balance24
- Ch. 27 The Reproductive System23
Marieb, Hoehn7th EditionHuman Anatomy & PhysiologyISBN: 9780805359091Not the one you use?Change textbook
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Marieb, Hoehn 7th EditionCh. 11 Fundamentals of the Nervous System and Nervous TissueProblem 15
Marieb, Hoehn 7th EditionCh. 11 Fundamentals of the Nervous System and Nervous TissueProblem 15Chapter 11, Problem 15
a. Describe the composition and function of the cell body.
b. How are axons and dendrites alike? In what ways (structurally and functionally) do they differ?
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For part (a), start by defining the cell body (also called the soma) of a neuron. Explain that it contains the nucleus and most of the organelles, such as mitochondria, ribosomes, and endoplasmic reticulum, which are essential for the neuron's metabolic activities and protein synthesis.
Next, describe the function of the cell body, emphasizing that it integrates incoming signals from the dendrites and generates outgoing signals to the axon. It also maintains the neuron's health and supports its overall function.
For part (b), begin by identifying the similarities between axons and dendrites: both are extensions of the neuron that conduct electrical signals and are covered by the plasma membrane with cytoplasm inside.
Then, explain the structural differences: dendrites are typically short, branched, and numerous, while axons are usually long, singular, and may have branches called axon collaterals. Also, dendrites have a rough surface due to synaptic inputs, whereas axons have a smooth surface.
Finally, discuss the functional differences: dendrites receive incoming signals from other neurons and transmit them toward the cell body, whereas axons carry outgoing signals away from the cell body to other neurons, muscles, or glands.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Cell Body (Soma) Composition and Function
The cell body, or soma, contains the nucleus and cytoplasm with organelles like mitochondria and ribosomes. It integrates incoming signals and maintains cell health by producing proteins and energy necessary for neuron function.
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Cell Junctions
Structure and Function of Axons
Axons are long, slender projections that transmit electrical impulses away from the cell body to other neurons or muscles. They often have myelin sheaths to speed signal conduction and end in terminal branches for communication.
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06:04Functional Groups
Structure and Function of Dendrites
Dendrites are branched extensions from the cell body that receive incoming signals from other neurons. They have numerous receptors and increase the surface area for synaptic input, playing a key role in signal integration.
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06:04Functional Groups
Related Practice
Textbook Question
The velocity of nerve impulse conduction is greatest in
a. Heavily myelinated, large-diameter fibers
b. Myelinated, small-diameter fibers
c. Nonmyelinated, small-diameter fibers
d. Nonmyelinated, large-diameter fibers
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Textbook Question
a. Contrast unipolar, bipolar, and multipolar neurons structurally.
b. Indicate where each is most likely to be found.
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Textbook Question
Describe the events that must occur to generate an AP. Relate the sequence of changes in permeability to changes in the ion channels, and explain why the AP is an all-or-none phenomenon.
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Textbook Question
What is the polarized membrane state? How is it maintained? (Note the relative roles of both passive and active mechanisms.)
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Textbook Question
Since all APs generated by a given nerve fiber have the same magnitude, how does the CNS 'know' whether a stimulus is strong or weak?
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