Week 4

Involves cross-bridge cycling, force generation, and mechanical influence.

Skeletal, smooth, and cardiac; each has unique structure and function.

About 75% water, 20% protein, and rest is salts, pigments, fats, carbohydrates.

Skeletal muscle has a striped appearance due to organized contractile molecules.

Skeletal muscle is operated consciously and controlled by the nervous system.

A motor neuron and the muscle fibers it controls; responsible for muscle contraction.

Describes how muscle force is regulated, including the size principle.

Refers to the arrangement of muscle fibers affecting functional differences.

Involuntary muscle found in hollow organs and blood vessels. It has non-aligned contractile molecules, leading to a smooth appearance.

Muscle tissue of the heart; has characteristics of both smooth and skeletal muscle with organized striations and involuntary control.

1. Produce movement 2. Maintain posture 3. Aid in breathing 4. Stabilize joints 5. Support tissues 6. Generate heat 7. Guard entrances 8. Support chewing and talking.

Criteria for naming muscles include shape, action, location, division, size relationships, and fiber direction.

Signaling proteins released by skeletal muscles that have hormone-like effects, influencing various body functions.

A muscle that brings limbs closer to the body. It’s an example of a muscle named for its action.

composed of long, cylindrical fibers; supports contraction and movement through organized layers and blood supply.

A muscle with two heads located in the upper arm, responsible for elbow flexion.

A muscle with three heads located in the upper arm, responsible for elbow extension.

A muscle group consisting of four heads located in the thigh, crucial for knee extension.

A muscle that opposes the action of another muscle, often located on opposite sides of a joint.

A muscle primarily responsible for a specific movement, often leading the action.

Muscles that stabilize a joint to allow the prime mover to operate efficiently.

Muscle where all fasciculi insert on one side of the tendon, e.g., semimembranosus.

Muscle fibers that fan out from a single attachment point, e.g., pectoralis major.

Muscle fibers categorized as slow twitch, fast twitch, FOG, and FG based on function and characteristics.

FOG and FG fibers can be changed through training, while slow and fast twitch fibers cannot.

Increasing force production by activating more motor units in larger muscles, up to 2,000 units.

A twitch occurs with a single action potential, while summation increases force with multiple potentials.

High firing rates of motor neurons result in maximally activated muscle, producing up to 5x the twitch force.

As force needs increase, larger axons and motor units are recruited for stronger contractions.

Optimal muscle length allows for maximum cross-bridge formation, affecting force production.

The relationship between muscle length and the force it can produce, showing optimal length for maximum force.

A rapid stretching followed by a shortening of muscle that enhances performance in activities like jumping.

It describes how a muscle's force output changes with the speed of contraction.

Muscle shortening as it contracts, producing positive velocity.

Muscle lengthening while under tension, producing more force at higher speeds.

Muscle remains constant in length while generating tension, no movement occurs.

Power is the product of force and velocity; maximum power occurs at submaximal force and velocity.

The angle at which a muscle pulls on a bone, influencing tension production during contraction.

The part of a motor neuron located in the spinal cord.

The splitting of an axon into multiple branches to innervate muscle fibers.

An electrical signal generated by a strong enough stimulus in a motor neuron.

If a neuron fires, it stimulates all muscle fibers in the motor unit fully or not at all.

Muscle fibers that contract slowly and rely on oxygen for energy.

Muscle fibers that contract quickly, suited for short bursts of strength or speed.

Variation of muscle fiber types across individuals and different muscles.