Muscle Contraction and Relaxation

These flashcards cover key terms and concepts related to muscle contraction, relaxation, and factors affecting muscle function.

Sarcoplasmic Reticulum

An organelle that releases Ca++ into the sarcoplasm during muscle contraction.

Impulse to Neurotransmitter Terminal

The process in which a nerve impulse travels to a terminal and releases neurotransmitters to initiate muscle contraction.

Calcium (Ca++)

An ion that, when present in the sarcoplasm, initiates the contraction of myofibrils by allowing actin and myosin myofilaments to hook and slide together.

ATP (Adenosine Triphosphate)

A molecule required for both muscle contraction and relaxation processes, specifically for pumping calcium back into the sarcoplasmic reticulum.

Hypertrophy

An increase in size of individual muscle cells due to exercise, leading to an overall increase in muscle size.

Atrophy

A decrease in size of muscle fibers after reaching normal adult size, which can occur due to disuse or nerve injury.

Tetany

A continuous state of muscle contraction often caused by conditions such as low blood calcium.

Fatigue

A decrease in work capacity caused by the depletion of ATP and lack of oxygen, leading to reduced muscle contraction.

Rigor

Muscle stiffness due to a lack of ATP, often resulting from extreme fatigue or death (rigor mortis).

Muscle Tone

Slight muscle tautness at rest, due to continuous low-level nervous stimulation that prevents flaccidity.