Textbook Question
Why are the connective tissue wrappings of skeletal muscles important? Name these connective tissue coverings, beginning with the finest and ending with the coarsest.
a.
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9. Muscle Tissue
Structure of a Skeletal Muscle
3:45 minutesProblem 8
Textbook Question
An action potential can travel quickly from one cardiac muscle cell to another because of the presence of
(a) Gap junctions
(b) Tight junctions
(c) Intercalated discs
(d) Both a and c
Verified step by step guidance1
Step 1: Understand the structure of cardiac muscle cells and how they connect to each other. Cardiac muscle cells are connected by specialized structures that allow electrical signals to pass rapidly between cells.
Step 2: Identify the role of gap junctions. Gap junctions are channels that directly connect the cytoplasm of adjacent cells, allowing ions and small molecules to pass freely, which facilitates the rapid spread of action potentials.
Step 3: Recognize the function of intercalated discs. Intercalated discs are complex structures that include gap junctions and desmosomes; they physically and electrically connect cardiac muscle cells.
Step 4: Differentiate tight junctions from gap junctions. Tight junctions create a seal between cells to prevent leakage of extracellular fluid, but they do not facilitate electrical conduction.
Step 5: Conclude that the rapid transmission of action potentials in cardiac muscle cells is due to both gap junctions and intercalated discs working together, making option (d) the correct choice.
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Video duration:
3mKey Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Action Potential in Cardiac Muscle
An action potential is an electrical signal that triggers muscle contraction. In cardiac muscle, it propagates rapidly to ensure coordinated heartbeats, enabling the heart to pump blood efficiently.
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Cardiac Action Potentials Example 3
Gap Junctions
Gap junctions are specialized connections between cardiac muscle cells that allow direct electrical communication. They enable ions and small molecules to pass quickly, facilitating rapid transmission of action potentials.
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Intercalated Discs
Intercalated discs are complex structures that connect cardiac muscle cells. They contain gap junctions and desmosomes, providing both mechanical strength and electrical connectivity for synchronized contraction.
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