A single somatic motor neuron and all of the muscle fibers it stimulates is known as a _________ .
motor unit
The wasting away of muscle due to lack of use is known as [a] while the replacement of skeletal muscle fibers with scar tissue is known as [b].
a. muscular atrophy
b. fibrosis
The synaptic end bulbs of somatic motor neurons contain synaptic vesicles filled with the neurotransmitter _________ .
acetycholine
The ability of muscle cells to respond to stimuli and produce electrical signals is known as excitability.
true
The sequence of events resulting in skeletal muscle contraction are (a) generation of a nerve impulse, (b) release of the neurotransmitter acetylcholine, (c) generation of a muscle action potential, (d) release of calcium ions from the sarcoplasmic reticulum, (e) calcium ion binding to the troponin-tropomyosin complex, (f) power stroke with actin and myosin binding and release.
true
In muscle physiology, the latent period refers to
a brief delay that occurs between application of a stimulus and the beginning of contraction
Which of the following muscle proteins and their descriptions are mismatched?
titin: regulatory protein that holds troponin in place
During muscle contraction all of the following occur except
the thick filaments slide inward toward the M line
Which of the following is not true concerning muscle fiber length–tension relationships?
If sarcomeres shorten, the tension in them increases
Which of the following are sources of ATP for muscle contraction? (1) creatine phosphate, (2) glycolysis, (3) anaerobic cellular respiration, (4) aerobic cellular respiration, (5) acetylcholine
1, 2, 3, and 4
What would happen if ATP were suddenly unavailable after the sarcomere had begun to shorten?
The myosin heads would be unable to detach from actin.
sheath of areolar connective tissue that wraps around individual skeletal muscle fibers
endomysium
dense irregular connective tissue that separates a muscle into groups of individual muscle fibers
perimysium
bundles of muscle fibers
fascia
the outermost connective tissue layer that encircles an entire skeletal muscle
tendon (synovial) sheath
dense irregular connective tissue that lines the body wall and limbs and holds functional muscle units together
fascia
a cord of dense regular connective tissue that attaches muscle to the periosteum of bone
tendon
elongated muscle cell
muscle fiber
areolar and adipose connective tissue that separates muscle from skin
subcutaneous layer
connective tissue elements extended as a broad, flat layer
aponeurosis
a two-layer tube of fibrous connective tissue enclosing certain tendons
tendon (synovial) sheath
synapse between a motor neuron and a muscle fiber
neuromuscular junction
invaginations of the sarcolemma from the surface toward the center of the muscle fiber
transverse (T) tubules
myoblasts that persist in mature skeletal muscle
satellite cells
plasma membrane of a muscle fiber
sarcolemma
oxygen-binding protein found only in muscle fibers
myoglobin
Ca2+-storing tubular system similar to smooth endoplasmic reticulum
sarcoplasmic reticulum
the contracting unit of a skeletal muscle fiber
sarcomere
middle area in the sarcomere where thick and thin filaments are found
A band
area in the sarcomere where only thin filaments are present but thick filaments are not
I band
separates the sarcomeres from each other
Z disc
area of only thick filaments
H zone
cytoplasm of a muscle fiber
sacroplasm
composed of supporting proteins holding thick filaments together at the H zone
M line
has fibers joined by intercalated discs
cardiac
thick and thin filaments are not arranged as orderly sarcomeres
smooth
uses satellite cells to repair damaged muscle fibers
skeletal
striated
skeletal and cardiac
contraction begins slowly but lasts for long periods
smooth
has an extended contraction due to prolonged calcium delivery from both the sarcoplasmic reticulum and the interstitial fluid
cardiac
does not exhibit autorhythmicity
skeletal
uses pericytes to repair damaged muscle fibers
smooth
uses troponin as a regulatory protein
skeletal and cardiac
can be classified as single-unit or multiunit
smooth
can be autorhythmic
cardiac and smooth
uses calmodulin as a regulatory protein
smooth