Lec 2: Muscle Anatomy and Physiology

These flashcards cover essential vocabulary related to muscle anatomy and physiology, including muscle types, contraction mechanisms, disorders, and relevant cellular structures.

Skeletal Muscle

Type of muscle that is under voluntary control and is attached to bones.

Cardiac Muscle

Involuntary muscle found only in the heart.

Smooth Muscle

Involuntary muscle found in internal organs.

Neuromuscular Junction (NMJ)

The synapse between a motor neuron and a muscle fiber.

Action Potential

An electrical signal that triggers muscle contraction.

T-tubules

Extensions of the sarcolemma that allow action potentials to penetrate deep into the muscle fiber.

Sarcoplasmic Reticulum (SR)

The smooth endoplasmic reticulum in muscle cells that stores calcium ions.

Myofibril

Basic rod-like unit of a muscle cell.

Sarcomere

The structural unit of a muscle, defined between two Z-disks.

Myosin

A thick filament protein that interacts with actin to contract muscle.

Actin

A thin filament protein that interacts with myosin during muscle contraction.

Troponin

A protein that binds to calcium ions and causes tropomyosin to move, exposing binding sites on actin.

Tropomyosin

A protein that blocks myosin-binding sites on actin when muscle is relaxed.

Power Stroke

The process by which myosin heads pull actin filaments during contraction.

ATP (Adenosine Triphosphate)

Energy molecule required for muscle contraction and relaxation.

Skeletal Muscle Disorders

Conditions affecting the structure and function of skeletal muscles.

Muscle Spasm

A sudden, involuntary muscle contraction.

Muscle Strain

Stretching or tearing of muscle fibers.

Muscle Sprain

Injury to a ligament caused by twisting or overstretching.

Fatigue

Depletion of muscle glycogen reserves leading to reduced performance.

Myoglobin

Muscle protein that binds oxygen for use during contraction.

Fast-Twitch Fibers

Muscle fibers designed for strength and rapid contraction.

Slow-Twitch Fibers

Muscle fibers designed for endurance and prolonged activity.

Summation

The process by which multiple muscle twitches combine to create a stronger contraction.

Tetany

A sustained muscle contraction due to high frequency stimulation.

Muscular Dystrophy

A group of genetic disorders resulting in progressive muscle weakness.

Myasthenia Gravis

An autoimmune disorder that disrupts communication between nerves and muscles.

Amyotrophic Lateral Sclerosis (ALS)

A degenerative disease affecting motor neurons, leading to loss of muscle control.

Satellite Cells

Stem cells in skeletal muscle that can differentiate and aid in muscle repair.

Intercalated Discs

Specialized junctions between cardiac muscle cells that allow rapid transmission of signals.

Syncytium

A multinucleate cell formed by the fusion of multiple cells.

Atria

The two upper chambers of the heart that receive blood.

Ventricles

The two lower chambers of the heart that pump blood out.

Acetylcholine (ACh)

A neurotransmitter released at the NMJ that initiates muscle contraction.

Calcium Ions (Ca2+)

Essential ions that trigger muscle contraction by binding to troponin.

Excitation-Contraction Coupling

The process through which an action potential leads to muscle contraction.

Muscle Fiber

A single muscle cell.

Myofibrils

Long, threadlike structures in muscle fibers that contain actin and myosin.

Mitochondria

Organelles that produce ATP; more prevalent in slow-twitch fibers.

Bursitis

Inflammation of the bursa, typically caused by repetitive use.

Tendonitis

Inflammation of a tendon, causing pain and limited movement.

Fibromyalgia

A condition causing widespread muscle pain and fatigue.

Pulmonary Valve

A heart valve that controls blood flow from the right ventricle to the pulmonary artery.

Mitral Valve

A heart valve that controls blood flow from the left atrium to the left ventricle.

Tricuspid Valve

A heart valve located between the right atrium and right ventricle.

Calcium Pump

Protein that transports calcium ions back into the sarcoplasmic reticulum.

Neurotransmitter-Gated Channel

Channel that opens in response to a neurotransmitter binding.

Action Potential Propagation

The process by which an action potential travels along a muscle fiber.