Muscle Physiology and Function

These flashcards cover key concepts from the lecture notes on muscle physiology, including definitions, descriptions of muscle contraction types, energy pathways, and characteristics of different muscle types.

What neurotransmitter is found at the neuromuscular junction (NMJ)?

Acetylcholine.

Does acetylcholine activate chemically or voltage-gated Na+ channels?

It activates chemically gated Na+ channels.

What is a motor unit?

A single motor neuron and all the muscle fibers it innervates.

What are the three types of muscle contractions?

Isotonic concentric, isotonic eccentric, and isometric contractions.

Define isotonic concentric contraction.

Muscle shortens as it contracts.

Define isotonic eccentric contraction.

Muscle lengthens as it contracts.

Define isometric contraction.

Muscle contracts but does not change length.

What are the two locations where ATP is used during muscle contraction?

Myosin head and sarcoplasmic reticulum.

What is the relationship between muscle tension and the number of cross-bridges?

The amount of muscle tension is directly related to the number of cross-bridges formed.

List three adaptations of skeletal muscle in response to exercise.

Hypertrophy, increased mitochondrial density, and increased myoglobin content.

Which hormones are involved in muscle metabolism?

Growth hormone, testosterone, and thyroid hormones.

What is the difference between force and endurance in muscle function?

Force refers to the maximum amount of weight, while endurance relates to the muscle's ability to sustain repeated contractions.

Describe the characteristics of cardiac muscle.

Involuntary, striated, branched, with intercalated discs.

How is cardiac muscle able to contract without neural stimulation?

Through autorhythmicity.

What structures are found in skeletal muscle that are not found in smooth muscle?

Sarcomeres and T-tubules.

What are the properties of muscle tissue?

Excitability, contractibility, extensibility, and elasticity.

Which muscle cell type is able to repair muscle damage?

Myosatellite cells.

List the three myofilaments found in sarcomeres.

Thin filament (actin), thick filament (myosin), and elastic filament.

What happens during muscle contraction according to the sliding filament theory?

Thin filaments slide toward the center of the sarcomere.

What occurs during depolarization of the resting membrane potential?

The cell becomes less negative due to an influx of sodium ions.

What is the resting membrane potential value in mV?

Approximately -85 mV.