Muscle Physiology and Sarcoplasmic Reticulum

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Questions and Answers

What role does the sarcoplasmic reticulum play in muscle function?

It produces ATP for muscle contractions.
It ensures muscle excitation-contraction coupling. (correct)
It breaks down lactic acid during exercise.
It generates action potentials.

How many Ca2+ molecules are moved into the sarcoplasmic reticulum for each ATP molecule hydrolyzed?

Three
Two (correct)
One
Four

What is the function of the Ca2+ binding protein, calsequestrin?

To release calcium ions into the cytoplasm.
To transport calcium ions to the mitochondria.
To deactivate voltage-gated calcium channels.
To help store calcium at high concentration in the terminal cisternae. (correct)

What initiates the release of calcium from the sarcoplasmic reticulum during muscle contraction?

A conformational change in the ryanodine receptor. (D) Signup and view all the answers

What happens to muscle contraction when cytoplasmic calcium concentration declines?

Muscle contraction stops, causing relaxation. (C) Signup and view all the answers

Where are calcium ions stored within the sarcoplasmic reticulum?

In the terminal cisternae. (C) Signup and view all the answers

What action takes place in the T-tubules during muscle contraction?

Voltage-gated Ca2+ channels open. (C) Signup and view all the answers

What mechanism allows calcium ions to move into the longitudinal part of the sarcoplasmic reticulum?

Ca2+-Mg2+ ATPase pumps. (C) Signup and view all the answers

Flashcards

Sarcoplasmic Reticulum (SR)

A specialized type of endoplasmic reticulum found in muscle cells. It plays a crucial role in regulating the concentration of calcium ions within the muscle fiber.

Ca2+ ATPase Pump

A protein found within the sarcoplasmic reticulum that actively pumps calcium ions from the cytoplasm into the SR, where they are stored.

Terminal Cisternae

Specialized compartments within the sarcoplasmic reticulum where calcium ions are stored at high concentrations.

Calsequestrin

A protein that binds to calcium ions within the terminal cisternae, allowing for the storage of high concentrations of calcium.