Muscle Physiology & Respiratory System

These flashcards cover vocabulary and key concepts from the lecture on Muscle Physiology and the Respiratory System, designed to aid studying for the upcoming exam.

Origin

The fixed end of a muscle that attaches to a bone.

Insertion

The moving end of a muscle that attaches to a bone.

Flexors

Muscles that decrease the angle between joint elements.

Extensors

Muscles that increase the angle between joint elements.

Agonist

The prime mover muscle that is primarily responsible for a movement.

Antagonist

The muscle that opposes the action of the agonist.

Epimysium

Connective tissue layer that surrounds the whole muscle.

Perimysium

Connective tissue layer that surrounds bundles of muscle fibers called fascicles.

Endomysium

Connective tissue layer that surrounds each individual muscle fiber.

Multinucleated

Describes muscle fibers that contain multiple nuclei.

Striated

Muscle tissue that appears striped under a microscope, characteristic of skeletal and cardiac muscles.

A band

The dark region on a sarcomere where thick and thin filaments overlap.

I band

The light region on a sarcomere where only thin filaments are present.

Z disc

The boundary of a sarcomere.

H zone

The central region of the A band where only thick filaments are present.

Neuromuscular Junction

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

Acetylcholine (ACh)

The neurotransmitter released at the neuromuscular junction.

Nicotinic receptors

Receptors that bind acetylcholine at the neuromuscular junction.

Action Potential

A rapid rise and fall in membrane potential that leads to muscle contraction.

Motor Unit

A motor neuron and all the muscle fibers it innervates.

Fine control

Movement that requires precision, typically involving small motor units.

Strength

The ability to exert force, typically requiring large motor units.

Thin filaments

Filaments in muscle fibers composed mainly of actin.

Thick filaments

Filaments in muscle fibers composed mainly of myosin.

Sliding Filament Theory

The theory that explains how muscle contraction occurs through the sliding of actin and myosin filaments.

Calcium ions (Ca²⁺)

Ions that trigger muscle contraction by binding to troponin.

Tropomyosin

A protein that covers actin binding sites and prevents contraction at rest.

Troponin

A protein that binds calcium and changes shape to move tropomyosin and allow muscle contraction.

Power Stroke

The action of myosin pulling actin during muscle contraction.

Serca pump

A pump responsible for returning calcium ions back to the sarcoplasmic reticulum.

Twitch

A single contraction of muscle fibers.

Summation

The process of twitch contractions piggybacking to increase tension.

Tetanus

A sustained muscle contraction resulting from rapid stimulation.

Isotonic contraction

Muscle contraction that results in movement; includes concentric and eccentric contractions.

Isometric contraction

Muscle contraction that increases tension without changing length.

Type I fibers

Slow oxidative fibers that are resistant to fatigue and support endurance activities.

Type IIA fibers

Fast oxidative-glycolytic fibers, which are intermediate in properties.

Type IIX fibers

Fast glycolytic fibers that are optimized for power and strength.

Muscle spindle

A sensory receptor that detects the length of muscles.

Golgi tendon organ

A sensory receptor that detects tension in tendons.

Alpha motor neurons

Nerve cells that innervate extrafusal muscle fibers.

Gamma motor neurons

Nerve cells that innervate intrafusal fibers in muscle spindles.

Monosynaptic stretch reflex

A reflex that involves a direct connection between a sensory neuron and a motor neuron.

Gas exchange

The process of exchanging oxygen and carbon dioxide in the lungs.

Conducting zone

Part of the respiratory system that does not participate in gas exchange.

Respiratory zone

Part of the respiratory system where gas exchange occurs.

Type I alveolar cells

Thin cells in the alveoli responsible for gas exchange.

Type II alveolar cells

Cells that secrete surfactant to reduce surface tension in the alveoli.

Partial pressure

The pressure exerted by a particular gas in a mixture, affecting gas diffusion.

External respiration

Exchange of gases between the alveoli and the blood.

Internal respiration

Exchange of gases between the blood and tissues.

Bicarbonate (HCO₃⁻)

The primary form in which carbon dioxide is transported in the blood.

Carbonic anhydrase

An enzyme that catalyzes the formation of carbonic acid from carbon dioxide and water.

Hypoventilation

Decreased rate or depth of breathing leading to increased carbon dioxide.

Hyperventilation

Increased rate or depth of breathing leading to decreased carbon dioxide.