Skeletal Muscle Contraction and Nerve Impulse

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Where do axons leave the central nervous system?

via skeletal muscles directly
via the brainstem only
via peripheral nerves only
via spinal nerves and cranial nerves (correct)

What is the result of the sliding filament theory of contraction?

Muscle atrophy
Muscle contraction (correct)
Muscle relaxation
Muscle fatigue

What is the role of calcium in muscle contraction?

To detach myosin cross bridges from actin
To block the binding sites on actin
To expose binding sites on actin (correct)
To inhibit the release of myosin cross bridges

What is a muscle twitch?

A brief contraction followed by relaxation (C) Signup and view all the answers

What is a characteristic of fast muscle fibers?

Large fibers for great strength of contraction (A) Signup and view all the answers

What is the purpose of the troponin-tropomyosin complex?

To facilitate muscle contraction (C) Signup and view all the answers

What occurs in an isometric muscle contraction?

The muscle length remains constant while tension increases (B) Signup and view all the answers

What is the definition of an isotonic contraction?

A contraction where muscle shortens with approximation of the ends (C) Signup and view all the answers

What is muscle tone?

The amount of tautness that remains in a muscle at rest (C) Signup and view all the answers

What is an example of an isometric contraction?

Pushing against a wall without moving (C) Signup and view all the answers

What is the definition of work in muscle contractions?

Force multiplied by distance (A) Signup and view all the answers

What is the purpose of the skeletal muscle load tension diagram?

To represent the relationship between load and tension (B) Signup and view all the answers

What is the primary function of the more extensive blood vessel system and capillaries in slow muscle fibers?

To support high levels of oxidative metabolism (D) Signup and view all the answers

What characterizes fast muscle fibers?

Large amounts of glycolytic enzymes and fewer mitochondria (A) Signup and view all the answers

What is the primary function of myoglobin in slow muscle fibers?

To store oxygen for rapid contraction (B) Signup and view all the answers

What is the difference between fast and slow muscle fibers in terms of innervation?

Fast muscle fibers are innervated by larger nerve fibers, while slow muscle fibers are innervated by smaller nerve fibers (D) Signup and view all the answers

What is the definition of the force exerted on an object by a contracting muscle?

Tension (B) Signup and view all the answers

What is the primary cause of muscle fatigue?

Depletion of muscle glycogen (C) Signup and view all the answers

At what frequency of stimulation do successive contractions eventually become so rapid that they fuse together?

100 stimuli per second (D) Signup and view all the answers

What occurs when the frequency of stimulation is increased, leading to partial addition of the second contraction to the first?

Frequency summation (C) Signup and view all the answers

What is the term for the state of muscle contraction when successive contractions become so rapid that they fuse together?

Tetanization (C) Signup and view all the answers

What is the result of prolonged and strong contraction of a muscle?

Muscle fatigue (B) Signup and view all the answers

What is the state of muscle contraction when individual twitch contractions occur one after another?

Unfused tetanus (D) Signup and view all the answers

What is the outcome of delivering a series of maximal stimuli to skeletal muscle at a frequency just below the tetanizing frequency?

An increase in the tension developed during each twitch until a plateau is reached (A) Signup and view all the answers

What is the primary difference between summation and tetanus?

Summation is the addition of individual twitch contractions, while tetanus is a sustained muscle contraction (C) Signup and view all the answers

What is the advantages of motor unit recruitment in multiple fiber summation?

It allows for the gradation of muscle force in small steps during weak contractions (B) Signup and view all the answers

What is the outcome of frequency summation?

An increase in muscle force, leading to tetanization (C) Signup and view all the answers

What is the primary mechanism of multiple fiber summation?

Increasing the number of motor units contracting simultaneously (D) Signup and view all the answers

What is the characteristic of the first muscle fibers recruited during multiple fiber summation?

They have high resistance to fatigue (A) Signup and view all the answers