Ch. 10 Muscle Tissue (group 2)

Muscle ___ is simply a succession of crossbridge cycles and the resulting production of force.

contraction

ATP is rapidly consumed when muscle contraction begins but is regenerated almost immediately by ___.

creatine phosphate

The binding of a myosin head to an actin molecule is termed a ___.

crossbridge

When a myosin head binds to an actin molecule, a(n) ___ is formed.

crossbridge

The amount of time it takes for an action potential to spread through the sarcolemma is known as the:

latent period

Where are receptors for acetylcholine located?

motor end plate

Fibers with low myosin ATPase activity found in muscles that require slow sustained contractions, are known as ___.

slow-twitch fibers

Type I fibers lack __________.

speed

Each connection where a single motor neuron communicates with many muscle fibers is known as a ___.

synapse

The narrow space between the axon terminal and the muscle fiber is known as the:

synaptic cleft

The first step of the crossbridge cycle begins when:

ATP hydrolysis "cocks" the myosin head.

Muscles remain in a contracted state during rigor mortis because:

ATP is required to release the attached actin and myosin molecules.

Which of the following substances is released from synaptic knobs in order to initiate a skeletal muscle contraction?

Acetylcholine

The fastest muscle contraction would be produced by which of the following fiber types?

Type II x fibers

Which statement best describes the function of myoglobin?

Myoglobin stores oxygen in muscle cells

Through which ATP-generating mechanism can long-lasting contractions be sustained?

Oxidative catabolism

What causes the release of myosin heads from actin filaments after the power stroke?

The binding of ATP molecules to the myosin heads

Calcium ions bind to which regulatory protein?

Troponin

The neurotransmitter used in a neuromuscular junction is:

acetylcholine (ACh).

During muscle contraction, myosin crossbridges bind to active sites on ___.

actin filaments

Local depolarization of the motor end plate is called:

an end-plate potential

The transmission of a signal from the motor neuron to the sarcolemma of a muscle fiber occurs during the:

excitation phase

The order in which the three phases of muscle contraction occur is:

excitation phase, excitation-contraction coupling, contraction phase

When muscle fibers are stimulated at a high frequency and the tension remains constant at a maximal level the muscle fiber has transitioned into ___.

fused or complete tetanus

When muscle fibers are stimulated so frequently they do not have an opportunity to relax, they are experiencing ___.

fused or complete tetanus

A pathway of ATP production that results in the formation of lactic acid is ___.

glycolytic catabolism

Between the start of the latent period and the start of the contraction period, there is a time interval during which the muscle cannot respond to another stimulus. This brief period is known as the ___.

refractory period

Muscle ___ occurs when ACh release is stopped, the remaining ACh in the synaptic cleft is broken down, and the calcium ion concentration in the cytosol returns to its resting levels.

relaxation

When a muscle fiber is relaxed, calcium ions would be:

within lateral sacs of the sarcoplasmic reticulum