Muscles prep for Lab exam 2

Skeletal Muscle

Striated and voluntary muscle tissue attached to bones, responsible for body movement.

Cardiac Muscle

Striated, involuntary muscle located in the heart walls, responsible for pumping blood.

Smooth Muscle

Non-striated and involuntary muscle found in the walls of hollow organs, responsible for moving substances through these organs.

Sliding Filament Theory

Describes how myosin heads attach to actin and pull it toward the center of the sarcomere to shorten muscles.

Origin of a muscle

The fixed attachment of a muscle that allows less movement during contraction.

Insertion of a muscle

The movable attachment that shifts when the muscle contracts.

Motor Unit

A motor neuron and the muscle fibers it controls, functioning like a light switch and light bulbs.

Agonist (Prime mover)

The muscle responsible for the main action, like the biceps brachii which flexes the elbow.

Antagonist

The muscle that opposes the agonist in action, like the triceps brachii extending the elbow.

Synergist

A muscle that assists the agonist and helps stabilize movements.

Fixators

Muscles that stabilize a body part allowing other muscles to work smoothly.

Fascicle Arrangement: Parallel

Fibers run parallel to the muscle's long axis, allowing for a greater range of movement.

Fascicle Arrangement: Pennate

Fibers attach at angles, providing greater strength but less range of motion.

Fascicle Arrangement: Convergent

Fibers have a fan shape, converging toward a single tendon for versatility.

Fascicle Arrangement: Circular

Fibers arranged in rings, which act to close openings.

Slow Oxidative Fibers (Type I)

Fatigue-resistant muscle fibers contracting slowly, used for endurance activities.

Fast Oxidative-Glycolytic Fibers (Type IIa)

Moderately fatigue-resistant muscle fibers used for moderate-intensity activities.

Fast Glycolytic Fibers (Type IIb or IIx)

Muscle fibers contracting very quickly and fatiguing rapidly, used for explosive activities.

Tendon

A flexible but inelastic cord of strong fibrous collagen tissue connecting a muscle to a bone.

Neuromuscular Junction

The synapse where a motor neuron communicates with a muscle fiber, akin to a doorbell ringing to start muscle contraction.