Chapter 10 kai cards

What are the seven functions of muscles?

Movement of body, maintenance of posture, respiration, production of body heat, communication, constriction of organs and vessels, contraction of the heart.

What does contractility refer to in muscle properties?

The ability of a muscle to shorten with force.

What is fascia?

A connective tissue that surrounds muscles, providing support and structure while allowing for movement between muscle groups.

What characterizes a complete muscle tetanus?

No relaxation between contractions.

What is the definition of isometric contractions?

No change in length but tension increases.

What is the primary function of slow twitch muscle fibers?

To contract more slowly, be more fatigue resistant, have more mitochondria, and are better supplied with blood.

What occurs during the contraction phase of a muscle twitch?

Calcium is released and myosin performs the power stroke on actin.

How is muscle fatigue defined?

Decreased capacity to work and reduced efficiency of performance.

What does the sliding filament mechanism describe?

The process by which muscle fibers contract, involving the sliding of actin and myosin filaments past each other, resulting in shortening of the muscle.

What is the role of tropomyosin in muscle contraction?

It regulates interaction between actin and myosin.

What happens to sarcomeres during relaxation?

They lengthen because of external force.

What is motor unit summation?

The process by which multiple motor units are activated to produce a stronger muscle contraction.

What is the duration of energy support provided by creatine phosphate during activity?

10-15 seconds of high intensity activity.

What describes wave summation?

Muscle tension increases as contraction frequencies increase.

What is the presynaptic terminal in the neuromuscular junction (NMJ)?

The axon terminal with synaptic vesicles containing acetylcholine.

What is atrophy in terms of muscle?

Decrease in muscle size.

What is the difference between incomplete and complete muscle tetanus?

Incomplete muscle tetanus involves partial relaxation between contractions, while complete muscle tetanus has no relaxation.

What role does the motor neuron play at the NMJ?

It carries electrical signals called action potentials to stimulate muscle fiber action potentials, leading to muscle contraction.

What occurs in synaptic fatigue?

It occurs in the NMJ due to lack of acetylcholine.

What are the key components of a muscle twitch myogram?

It reflects the three phases: lag, contraction, and relaxation.

What happens during the relaxation phase of a muscle twitch?

Calcium returns to the sarcoplasmic reticulum, and muscle fibers return to their precontraction state.

Describe the characteristics of fast twitch muscle fibers.

They contract quickly and powerfully but fatigue faster; they have fewer mitochondria and are associated with sprinters.

What are isotonic contractions?

Contractions that change in length while tension remains constant.

What defines a motor unit?

A motor neuron and all the muscle fibers it innervates.

What is the function of the endomysium in muscle tissues?

It separates individual muscle fibers within each fascicle.