The Muscular System: Emphasis on Skeletal Muscle

These flashcards cover key concepts related to the muscular system, focusing on skeletal muscle function, structure, and mechanics.

What is the primary function of muscle tissue?

The primary function of muscle tissue is specialized movement of body parts.

What energy molecule is crucial for muscle contraction?

ATP (adenosine triphosphate) is crucial for muscle contraction.

What are the three types of muscles?

Skeletal muscle, cardiac muscle, and smooth muscle.

How is skeletal muscle characterized?

Skeletal muscle is striated and under voluntary control.

What role do sphincter muscles play?

Sphincter muscles control the opening and closing of body orifices.

What surrounds each muscle fiber?

Each muscle fiber is surrounded by a connective tissue called endomysium.

What is the role of myofibrils in muscle fibers?

Myofibrils are smaller fibers within muscle fibers that facilitate contraction.

What structure connects muscle to bone?

A tendon connects muscle to bone.

What is the key protein in thick myofilaments?

The key protein in thick myofilaments is myosin.

What does the sliding filament theory describe?

The sliding filament theory describes how thin filaments slide over thick filaments during contraction.

What initiates the contraction of skeletal muscle?

A chemical released from a nerve cell, acetylcholine, initiates skeletal muscle contraction.

What is a motor unit?

A motor unit consists of a motor neuron and the muscle fibers it innervates.

What causes depolarization in muscle fibers during an action potential?

The influx of sodium ions (Na+) into the muscle fiber causes depolarization.

What happens during the relaxation phase of a muscle contraction?

Calcium ions are pumped back into the sarcoplasmic reticulum, and troponin and tropomyosin block the binding sites on actin.

What is the difference between slow-twitch and fast-twitch muscle fibers?

Slow-twitch fibers have high endurance and primarily use aerobic respiration, while fast-twitch fibers fatigue quickly and generate strength.

What is muscle tone?

Muscle tone is the state of partial contraction observed in relaxed muscles to maintain posture.

What is a neuromuscular junction?

A neuromuscular junction is the connection point between a motor neuron and a muscle fiber.

How does acetylcholine function at the neuromuscular junction?

Acetylcholine binds to receptor proteins on the muscle fiber's membrane, leading to depolarization.

What occurs during the graded muscle responses?

Graded muscle responses vary strength and duration of muscle contractions depending on stimulus frequency and strength.