Chapter 40: Protection, Support, & Movement

Actin

A basic contractile protein found in all eukaryotic cells capable of movement.

Myosin

A protein that works with actin in muscle contraction.

Tropinin & Tropomyosin

Proteins that regulate actin’s interaction with myosin.

Myofibrils

Bundles of myofilaments enclosed by the sarcolemma, containing contractile units called sarcomeres.

Sarcomeres

Contractile units of muscle fibers, consisting of A and I bands.

Neuromuscular Junction

The synapse between a motor neuron and a muscle fiber where acetylcholine is released.

Acetylcholine (ACh)

A neurotransmitter released from neurons that triggers muscle contraction.

Power Stroke

The action in muscle contraction where myosin pulls actin, resulting in muscle shortening.

Skeletal Muscle

Muscle type that includes slow-twitch (Type I) and fast-twitch (Type II) fibers.

Slow-twitch fibers

Type I, red fibers used for endurance activities.

Fast-twitch fibers

Type II, white fibers used for short bursts of energy.

Muscle Tone

A constant partial contraction of muscles for posture and readiness.

Phosphagen System

The immediate energy system that uses stored ATP and phosphocreatine for quick bursts of energy.

Glycolysis

The process that breaks down glycogen into glucose, producing ATP.

Aerobic Respiration

A long-term energy process that occurs in mitochondria, requiring oxygen and producing 36 ATP.

Anaerobic Glycolysis

Glycolysis that occurs without oxygen, producing lactic acid and only 2 ATP.

Fermentation in Yeast

The conversion of pyruvate to ethanol and CO₂ used in baking and brewing.

White Meat

Meat from poultry that contains more fast-twitch fibers for short bursts of energy.

Dark Meat

Meat from poultry that contains more slow-twitch fibers, better suited for sustained activity.

Energy for Muscle Activity

Refers to the different systems (phosphagen, glycolysis, aerobic respiration) providing ATP for muscle function.