BSC2085 Unit 3 Practice

Excitability (Responsiveness)

Ability to receive and respond to a stimulus.

Contractility

Ability to shorten forcibly when stimulated.

Extensibility

Ability to be stretched when relaxed.

Elasticity

Ability to recoil after being stretched.

Skeletal Muscle

Attached to bones, striated, voluntary.

Cardiac Muscle

Found in heart, striated, involuntary.

Smooth Muscle

Found in walls of organs (visceral), non-striated, involuntary, slow sustained contractions.

Fascicle

Bundle of muscle fibers.

Sarcolemma

Plasma membrane of muscle fiber.

Sarcoplasm

Similar to cytoplasm containing stored energy.

Myoglobin

Oxygen-binding red pigment; oxygen supply for muscle; found in sarcoplasm.

Sarcoplasmic Reticulum (SR)

Stores calcium that is released during contraction.

T Tubules

Conduct electrical signals into the cell.

Myofibrils

Rod-like structures making up 80% of cell volume.

Sarcomere

Functional unit between Z lines.

Thick Filaments

Myosin; looks dark.

Thin Filaments

Actin.

Tropomyosin

Protein that wraps around actin and covers active site of G actin.

Troponin

Protein attached to actin.

G actin

Globular.

Myosin

Two heavy chains and two heads.

Twitch

Response of a motor unit (nerve+muscle fiber) to an action potential.

Motor Unit

One motor neuron and all fibers it innervates.

All-or-None Law

Fiber contracts fully or not at all.

Treppe

Gradual increase in contraction strength after rest.

Tetanus

Sustained contraction (incomplete or complete; no relaxation between contractions).

Isotonic

Muscle changes length.

Isometric

Muscle length stays same.

Pyloric stenosis

Blocking of pyloric region of the stomach; projectile vomiting.