Mechanism of Muscle Contraction

These flashcards cover the key concepts related to the mechanism of muscle contraction, including anatomical structures, physiological processes, and the biochemistry of muscle function.

What are the components that make up muscle fibers?

Muscle fibers are muscle cells that contain myofibrils, with most of the volume being made up of myofibrils.

What is the function of the sarcoplasmic reticulum in muscle contraction?

It constantly uses energy to extract calcium and releases it upon receiving electrical signals.

What role does calcium play in muscle contraction?

Calcium acts as an on and off switch for muscles.

What is a sarcomere?

The basic unit of skeletal muscle located between Z discs.

What is the sliding filament model?

It describes how myosin and actin filaments slide past each other during muscle contraction without changing length.

What triggers the power stroke in cross-bridge cycling?

ATP binds to myosin, allowing the myosin head to pivot and pull actin.

What distinguishes a motor unit?

A motor unit consists of a single motor neuron and multiple muscle fibers it innervates, controlling muscle contraction.

How does temporal summation affect muscle contraction?

It refers to the cumulative effect of repeated activation of a motor unit, potentially increasing force produced when the fiber is relaxing.

What are the three pathways for ATP generation in muscle?

Direct phosphorylation, anaerobic respiration, and aerobic respiration.

What adaptations occur in muscles with extensive aerobic exercise?

Increased capillaries, more mitochondria, and greater myoglobin production.

What happens at the neuromuscular junction?

Chemical signals called neurotransmitters are released to communicate between motor neurons and muscle fibers.

What is the resting membrane potential of a neuron?

Approximately -70 mV, with positive charges outside and negative charges inside.

What is the significance of the sodium-potassium pump?

It actively maintains the resting membrane potential by moving 3 Na+ ions out and 2 K+ ions into the cell.

What is the difference between chemically gated ion channels and voltage gated ion channels?

Chemically gated ion channels open in response to specific chemicals, while voltage gated ion channels respond to changes in membrane voltage.

What is a characteristic feature of fast-twitch muscle fibers?

Fast-twitch fibers are typically associated with anaerobic respiration and have a higher fatigue rate.

Which ATP generation pathway is most important immediately after the creatine phosphate pathway?

Free-floating ATP generation is crucial following creatine-phosphate utilization.