Muscle Tissue and Contraction

Flashcards based on muscle tissue, its structure, function, and physiology for exam preparation.

Muscle Tissue

Specialized tissue responsible for movement in the body.

Functions of the Muscular System

Movement, generate heat, venous return.

Smooth Muscle

Maintains blood pressure; movement within visceral organs.

Cardiac Muscle

Pumps blood throughout the body.

Skeletal Muscle

Muscle type responsible for voluntary movements.

Excitability

Ability of muscle tissue to depolarize and send an electrical wave.

Contractility

Ability of muscle to shorten and create force.

Calcium (Ca2+)

Required for muscle contraction.

ATP+

Required for muscle relaxation.

Elasticity

Ability of muscle to recoil to its original length.

Extensibility

Ability of muscle to stretch beyond its original length.

Fascicles

Bundles of muscle fibers.

Epimysium

Connective tissue that wraps an entire muscle.

Perimysium

Connective tissue that surrounds fascicles.

Endomysium

Connective tissue that surrounds individual muscle fibers.

Tendon

Connects muscle to bone.

Aponeurosis

Broad, flat tendon connecting muscles.

Fascia

Connective tissue sheets beneath the skin.

Myoblasts

Embryonic cells that fuse to form muscle fibers.

Sarcolemma

Cell membrane of a muscle cell.

Sarcoplasm

Cytoplasm of a muscle cell.

Sarcoplasmic Reticulum

Specialized endoplasmic reticulum for calcium storage.

Sarcomere

Functional contractile unit of a muscle fiber.

Z Disc

Attachment site for the actin filament in a sarcomere.

M Line

Middle line that holds myosin filaments in a sarcomere.

I Band

Light colored stripe where only thin actin is present.

A Band

Dark stripe where actin and myosin overlap.

H Zone

Region in a sarcomere that contains only myosin.

Action Potential

Electrical signal travelling across the muscle membrane.

Neuromuscular Junction (NMJ)

Contact point between nerve and muscle.

Acetylcholine (ACh)

Neurotransmitter released at the NMJ.

Motor Neuron

Nerve cell that stimulates muscle contraction.

Synaptic Cleft

Gap between nerve and muscle at the NMJ.

T-Tubules

Invaginations of the cell membrane that help distribute action potential.

Calcium Pumps

Transport calcium ions back into the sarcoplasmic reticulum.

Rigor Mortis

Post-mortem stiffness due to calcium binding.

Hypertrophy

Muscle growth due to increased myofibrils.

Atrophy

Decrease in muscle mass due to disuse.

Duchenne Muscular Dystrophy (DMD)

Genetic disorder causing muscle degeneration.

Isotonic Contraction

Muscle contraction involving movement at a joint.

Isometric Contraction

Muscle contraction without changing joint angle.

Motor Unit

A motor neuron and the muscle fibers it controls.

Muscle Tone

Slight contraction of muscles to maintain posture.

Hypotonia

Decreased muscle tone.

Hypertonia

Increased muscle tone; rigidity.

Tetany

Sustained muscle contraction.

Slow Oxidative Fibers

Muscle fibers that use oxygen for sustained activity.

Fast Glycolytic Fibers

Muscle fibers that generate ATP anaerobically.

Cardiac Muscle

Striated muscle tissue found only in the heart.

Intercalated Discs

Connections between cardiac muscle fibers.

Autorhythmicity

Ability of cardiac muscle to contract without neural input.

Smooth Muscle

Involuntary muscle found in walls of hollow organs.

Visceral Muscle

Smooth muscle of internal organs.

Creatine Phosphate

Molecule that transfers phosphate to ATP for energy.

Glycolysis

Anaerobic breakdown of sugar for ATP.

Aerobic Respiration

Oxygen-dependent breakdown of glucose for ATP.

Myoglobin

Protein that stores oxygen in muscles.

Nerve Injury

Damage to nerves affecting muscle function.

Calcium Dihydrate (Ca++),

Ion essential for muscle contraction.

Skeletal Muscle Fiber Size

Muscle fibers are large and can be multi-nucleated.

Fibroblast

Cell responsible for producing connective tissue.

Skeletal Muscle Cell Repair

Slow repair primarily through satellite cells.

Compressive Strength

Ability of muscle to endure forces that compress.

Mitochondria

Cell organelles responsible for ATP production.

Calcium Ion Concentration

Critical for muscle excitability and contraction.

Denervation Atrophy

Muscle deterioration due to loss of nerve supply.

Intermediate Muscle Fibers

Muscles with mixed oxidative and glycolytic properties.

Neurotransmitter Release

Process where ACh is released to stimulate muscle.

Active Site on Actin

Binding region exposed by calcium binding to troponin.

Myosin Head

Part of myosin that attaches to actin during contraction.

Sartorius Muscle

Longest muscle in the human body.

Generative Strength

Power exerted by muscle contraction.

Tension Development

Force generated by the interaction of actin and myosin.

Muscle Motor Units

Combination of motor neuron and the fibers it controls.

Ion Channels

Proteins that allow ions to flow across the cell membrane.

Entropic Collapse

State in which the muscle contracts and shortens.

Muscle Fatigue

Condition resulting from prolonged contraction.

Stretch Reflex

Involuntary response to stretching of muscle.

Connective Tissue Wrappings

Sheaths that enclose and protect muscle tissues.

Calcium-induced Calcium Release (CICR)

Mechanism of calcium release in cardiac cells.

Electrical Gradient

Difference in charge across a cell membrane.

Calcium Reabsorption

Process that returns calcium to the SR.

Troponin

Protein that binds calcium and regulates contraction.

Myofibrils

Thread-like structures in muscle cells for contraction.

Skeletal Muscle Characteristics

Striated, multi-nucleated, voluntary controlled.

Muscle Fiber Types

Categories based on contraction speed and metabolism.

Rhabdomyolysis

Breakdown of muscle tissue releasing unwanted substances.

Contractile Proteins

Proteins involved in muscle contraction.

Sliding Filament Model

Theory explaining muscle contraction through filament sliding.

Phosphate Group

Part of ATP that releases energy when hydrolyzed.

Force-generating Mechanism

Interactions between actin and myosin during cycling.

Muscle Contraction Cycle

Sequence of events during muscle contraction and relaxation.

Motor Control

Regulatory mechanisms of muscle contraction and movement.

Myo-

Prefix relating to muscle.

Sarco-

Prefix relating to flesh or muscle.

Calmodulin

Calcium-binding messenger protein in cells.

Fast Twitch Fibers

Muscle fibers that contract rapidly and fatigue quickly.

Slow Twitch Fibers

Muscle fibers that contract slowly and are resistant to fatigue.

Cellular Respiration

Metabolic reactions that convert biochemical energy from nutrients.

Energy Systems

Different pathways muscles use to generate ATP.