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
