PhysioEx9.0 Exercise 2.1 and 2.2 Skeletal Muscle Physiology

A single action potential and a single contractile event in the muscle fibers it innervates

A single action potential propagating down a motor axon results in

One contractile response to a single action potential

A skeletal muscle twitch is

Active tension in a skeletal muscle fiber results from

Activation of cross bridge cycling via increased intracellular calcium levels

Acetycholine (ACh)

An action potental in a motor neuron triggers the release of which neurotransmitter?

Why was a maximal voltage observed in this experiment?

At the maximal voltage, all the muscle fibers contained in this muscle are depolarized and they all develop active force

Tendons

Connect muscle to bone

The cellular events involved in excitation-contraction coupling occur

During the latent period for an isometric contraction

Sarcoplasmic reticulum (SR)

In resting skeletal muscle, calcium is stored in

Threshold voltage

Lowest stimulus voltage that induces active force in the skeletal muscle

Hyperpolarization phase

Not a phase of a skeletal muscle twitch

Motor Unit

One motor neuron and all of the skeletal fibers it innervates

Fibers

Skeletal muscles are composed of hundreds to thousands of individual cells called _______

Motor neurons

Skeletal muscles fibers are stimulated by

An EPP (end plate potential)

The graded depolarization in the skeletal muscle fiber that is elicited in response to one action potential from the motor neuron is called

An individual skeletal muscle cell

The term skeletal muscle fiber refers to

0.0 g; there was no activation of skeletal muscle fibers by this stimulus

What do you see in the active force display when the stimulus voltage is set to 0.0, and why does this observation make sense

The electrical stimulus mimics acetylcholine release at a neuromuscular junction

a sufficiently strong electrical stimulus applied to an isolated, mounted skeletal muscle induces the development of muscle force, or muscle tension. Which is TRUE?

Motor Unit recruitment

an increase in the number of active muscle fibers to increase the force developed in a muscle

Twitch

one contractile response to a single action potential

Relaxation phase

period of time from peak tension until the end of the muscle contraction

Maximal Voltage

the amount of stimulus required to successfully recruit all the muscle fibers into developing active force

All steps of excitation-contration coupling occurs during

the latent period of isometric contraction

Neuromuscular Junction

the motor neuron and muscle fiber intersect at what is called

Latent Period

the period of time that elapses between the generation of an action potential and the start of muscle tension development in a muscle fiber

Latent period

the period of time that elapses between the generation of an action potential in a muscle cell and the start of muscle contraction

Contraction phase

the time between the end of the latent period and peak muscle tension