Muscle Tissue and Skeletal Muscle Study Notes

Excitability

The ability of muscle fibers to produce action potentials in response to stimuli.

Extensibility

The capacity of muscle fibers to be stretched without being damaged.

Elasticity

The ability of muscle fibers to return to their original length after being stretched.

Contractility

The property of muscle fibers to shorten forcefully when stimulated.

Action potential

An electrochemical impulse that triggers muscle contraction.

T-tubules

Invaginations of the sarcolemma that carry action potentials into the muscle fiber.

Myofibrils

Cylindrical structures within muscle fibers that contain contractile proteins.

Sarcomere

The functional unit of a muscle fiber, consisting of repeating patterns of filaments.

Neuromuscular Junction (NMJ)

The junction where a motor neuron communicates with a muscle fiber.

Acetylcholine (ACh)

A neurotransmitter released at the NMJ that initiates muscle contraction.

Cross-bridge cycle

The process by which myosin heads attach to actin filaments, pulling them to produce contraction.

Antagonistic muscles

Muscles that work in pairs to create controlled movement, with one muscle opposing the action of another.

Isotonic contraction

Muscle contraction where the muscle changes length while maintaining constant tension.

Isometric contraction

Muscle contraction where the muscle length remains the same while tension increases.

Creatine phosphate

A molecule that quickly regenerates ATP for muscle contraction.

Hypertrophy

The enlargement of muscle fibers due to exercise.

Atrophy

The reduction in size of muscle fibers due to inactivity or disease.

Muscle Naming Convention

Muscles are named based on factors like attachment to bones, shape, size, and action.