Chapter 5: muscle tissues

Vocabulary flashcards covering bone growth, remodeling, and muscle tissue concepts from the notes.

Skeletal Muscle

Voluntary, striated muscle tissue that moves the skeleton.

Muscle Fiber

A single muscle cell; elongated, multinucleated, containing myofibrils.

Pericytes

Contractile cells around small vessels; can differentiate into smooth muscle; aid blood flow.

Myofibroblasts

Fibroblast-like cells with smooth muscle features involved in wound contraction.

Myoepithelial Cells

Cells surrounding glands’ acini/ducts that help expel secretions.

Muscle

Tissue composed of contractile cells that generate force and movement.

Sarcolemma

Cell membrane of a muscle fiber.

Sarcoplasm

Cytoplasm of a muscle fiber.

Sarcoplasmic Reticulum

Smooth ER in muscle cells storing and releasing calcium for contraction.

Sarcosome

Mitochondria in muscle cells.

Voluntary Muscle

Skeletal muscle under conscious control (except some pharyngeal parts).

Muscle

Tissue composed of contractile cells that generate force and movement.

Sarcoplasm

Cytoplasm of a muscle fiber.

Cardiac Muscle

Involuntary, striated muscle tissue found in the heart, responsible for pumping blood.

Smooth Muscle

Involuntary, non-striated muscle tissue found in walls of internal organs and blood vessels, responsible for various autonomous movements.

Myofibril

A rod-like unit of a muscle fiber, composed of myofilaments (actin and myosin).

Sarcomere

The basic contractile unit of a myofibril, extending from one Z-disc to the next.

Actin

Thin myofilament protein, involved in muscle contraction; forms the I-band.

Myosin

Thick myofilament protein, with globular heads that bind to actin; forms the A-band.

Troponin

Protein complex that binds calcium and regulates the interaction of actin and myosin.

Tropomyosin

Protein filament that covers myosin-binding sites on actin in a resting muscle.

Z-disc

A protein disc that anchors the thin filaments and marks the boundaries of a sarcomere.

M-line

A protein line in the center of the H-zone that anchors thick filaments.

A-band

The dark region of a sarcomere containing the entire length of the thick (myosin) filaments.

I-band

The light region of a sarcomere containing only thin (actin) filaments; bisected by the Z-disc.

H-zone

The central part of the A-band where only thick (myosin) filaments are present in a relaxed state.

Epimysium

The outermost connective tissue layer surrounding an entire muscle.

Perimysium

The connective tissue layer that surrounds a bundle of muscle fibers (fascicle).

Fascicle

A bundle of muscle fibers enclosed by the perimysium.

Endomysium

The thin connective tissue layer surrounding individual muscle fibers.

Tendon

A strong cord of fibrous connective tissue that attaches muscle to bone.

Aponeurosis

A broad, flat sheet of tendon that serves to attach muscle to bone or other muscles.

Neuromuscular Junction (NMJ)

The synapse between a motor neuron and a muscle fiber.

Motor Unit

A single motor neuron and all the muscle fibers it innervates.

Acetylcholine (ACh)

Neurotransmitter released at the NMJ, initiating muscle contraction.

Acetylcholinesterase (AChE)

Enzyme that breaks down ACh, allowing muscle relaxation.

T-tubules (Transverse Tubules)

Invaginations of the sarcolemma that carry action potentials deep into the muscle fiber.

Sliding Filament Theory

Model describing muscle contraction where thin filaments slide past thick filaments, shortening the sarcomere.

Cross-bridge Cycle

The series of events during which myosin heads bind to actin, pivot, and pull the thin filaments, requiring ATP.

ATP (Adenosine Triphosphate)

The primary energy source for muscle contraction and relaxation.

Creatine Phosphate

A high-energy phosphate compound that rapidly regenerates ATP in muscle cells during short bursts of activity.

Glycolysis

An anaerobic metabolic pathway in the sarcoplasm that produces ATP and lactic acid, used for short, intense muscle activity.

Oxidative Phosphorylation

An aerobic metabolic pathway in mitochondria that produces large amounts of ATP for sustained muscle activity.

Oxygen Debt

The extra oxygen required after exercise to restore ATP, creatine phosphate, and glycogen levels, and to oxidize lactic acid.

Isotonic Contraction

Muscle contraction where muscle length changes (shortens or lengthens) and the force (tension) remains relatively constant.

Isometric Contraction

Muscle contraction where muscle length remains constant, but the force (tension) increases.

Origin

The immovable or less movable attachment point of a muscle.

Insertion

The movable attachment point of a muscle, which is pulled towards the origin during contraction.

types of skeletal muscle fibers

There are three main types of skeletal muscle fibers: red muscle fibers, white muscle fibers, and intermediate muscle fibers

Red muscle fibers

Type I muscle fibers, characterized by a richer blood supply, slow twitch, and high myoglobin content.

white muscle fibers

• fast twitch

• more forceful and fatigues faster

intermediate muscle fibers

Type IIa muscle fibers, which have a combination of characteristics from both red and white muscle fibers.

faster exercise = more white muscle fibers

General sensory receptors

• common stimuli (pain and pressure)

• simple nerve endings

• vater-pacinian corpuscles

• ruffini’s corpuscles

proprioceptors

sensory receptors that detect body position and movement

• simple nerve endings

• neuromuscular spindles

• golgi tendon organs

skeletal muscle tissue

capable of regenerating through satellite cells

smooth muscle tissue

can regenerate through pericytes

cardiac muscle tissue

very limited to no regeneration

calmodulin-myosin light chain kinase

calcium binds to what in contractions in smooth muscle

neuromuscular spindle

detects the degree and velocity stretch applied in a muscle

golgi tendon organ

sensitive to muscle contractions

purkinje fibers

non contractile muscle cells

conduct electrical impulses