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Ch. 9 Muscles and Muscle Tissue
Hoehn - Marieb Human Anatomy & Physiology, 12th edition
Hoehn, Haynes, Abbott12th EditionMarieb Human Anatomy & PhysiologyISBN: 9780138242732Not the one you use?Change textbook
All textbooksHoehn, Haynes, Abbott 12th EditionCh. 9 Muscles and Muscle TissueProblem 11
Chapter 9, Problem 11

The ions that enter the skeletal muscle cell during the generation of an action potential are
a. Calcium ions
b. Chloride ions
c. Sodium ions
d. Potassium ions

Verified step by step guidance
1
Understand the process of action potential generation in skeletal muscle cells, which involves changes in membrane permeability to specific ions.
Recall that during the depolarization phase of the action potential, the membrane becomes permeable to sodium ions, allowing them to enter the cell.
Recognize that calcium ions play a role in muscle contraction but do not primarily enter the cell during the initial action potential generation.
Note that chloride ions generally help stabilize the resting membrane potential and do not enter the cell during the action potential.
Remember that potassium ions exit the cell during repolarization, not enter during the generation of the action potential.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Action Potential in Skeletal Muscle

An action potential in skeletal muscle is a rapid change in membrane potential that triggers muscle contraction. It involves the movement of ions across the muscle cell membrane, leading to depolarization and repolarization phases essential for signal transmission.
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Action Potential

Role of Sodium Ions (Na⁺) in Depolarization

During the initiation of an action potential, sodium channels open, allowing Na⁺ ions to enter the muscle cell. This influx causes the membrane potential to become more positive, leading to depolarization, which is the key step in generating the action potential.
Recommended video:
01:55
Ions - Sodium and Potassium Example 3

Role of Potassium Ions (K⁺) in Repolarization

After depolarization, potassium channels open to allow K⁺ ions to exit the cell, restoring the negative resting membrane potential. This efflux of K⁺ ions is crucial for repolarization, helping the muscle cell return to its resting state after an action potential.
Recommended video:
01:55
Ions - Sodium and Potassium Example 3
Related Practice
Textbook Question

The neurotransmitter released by somatic motor neurons is:

a. Acetylcholine

b. Acetylcholinesterase

c. Norepinephrine

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Textbook Question

The smooth muscle type found in the walls of digestive and urinary system organs and that exhibits gap junctions and pacemaker cells is:

a. Multi unit

b. Unitary

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Textbook Question

Aerobic exercise results in all of the following except:

a. More capillaries surrounding muscle fibers

b. More mitochondria in muscle cells

c. Increased size and strength of existing muscle cells

d. More myoglobin

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Textbook Question

Characteristics of isometric contractions include all but:

a. Shortening

b. Increased muscle tension throughout the contraction phase

c. Absence of shortening

d. Used in resistance training

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Textbook Question

Myoglobin has a special function in muscle tissue. It:

a. Breaks down glycogen

b. Is a contractile protein

c. Holds a reserve supply of oxygen in the muscle

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Textbook Question

During muscle contraction, ATP is provided by:

a. a coupled reaction of creatine phosphate with ADP

b. aerobic respiration of glucose, and

c. anaerobic glycolysis.

______ (1) Which provides ATP fastest?

______  (2) Which does (do) not require that oxygen be available?

______  (3) Which provides the highest yield of ATP per glucose molecule?

______  (4) Which results in the formation of lactic acid?

______  (5) Which has carbon dioxide and water products?

______  (6) Which is most important in endurance sports?

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