Muscle Physiology Quiz

Study Notes

Muscle Contraction

Muscle contraction is the process by which muscle cells generate force
It occurs when the muscle fiber shortens, resulting in muscle movement
Contraction is a result of the sliding of actin and myosin filaments over each other
There are three types of muscle contractions:
- Isotonic contraction: muscle shortens while maintaining constant tension
- Isometric contraction: muscle generates tension without changing length
- Eccentric contraction: muscle lengthens while maintaining constant tension

Neuromuscular Junction

The neuromuscular junction (NMJ) is the site where a motor neuron terminates and forms a synapse with a muscle fiber
The NMJ is responsible for transmitting the signal from the motor neuron to the muscle fiber
The process of transmission involves:
- Release of neurotransmitters (acetylcholine) from the motor neuron
- Binding of neurotransmitters to receptors on the muscle fiber
- Generation of an action potential in the muscle fiber

Sliding Filament Theory

The sliding filament theory explains how muscle contraction occurs
It proposes that muscle contraction is a result of the sliding of actin and myosin filaments over each other
The theory states that:
- Actin filaments are thin filaments that make up the muscle fiber
- Myosin filaments are thick filaments that make up the muscle fiber
- During contraction, the myosin filaments slide along the actin filaments, resulting in muscle shortening

Excitation-Contraction Coupling

Excitation-contraction coupling is the process by which an action potential in the muscle fiber leads to muscle contraction
The process involves:
- The action potential depolarizing the muscle fiber membrane
- The release of calcium ions from the sarcoplasmic reticulum
- The binding of calcium ions to troponin and tropomyosin, allowing the myosin head to bind to actin
- The contraction of the muscle fiber

Muscle Fatigue

Muscle fatigue is the decline in muscle force and velocity over time
It is a result of:
- Depletion of energy stores (ATP and CP)
- Accumulation of metabolic byproducts (lactic acid and potassium ions)
- Changes in the neuromuscular junction and muscle fiber properties
There are two types of muscle fatigue:
- Peripheral fatigue: fatigue that occurs in the muscle fiber itself
- Central fatigue: fatigue that occurs in the central nervous system (CNS)

Description

Test your knowledge of muscle contraction, neuromuscular junction, sliding filament theory, excitation-contraction coupling, and muscle fatigue. Learn about the processes that enable muscle movement and how they are affected by fatigue.