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