chapter 8 connect assignment
what are possible outcomes of muscle contractions?
- movement of bones - squeezing of intestinal contents - secretion of hormones
what is the role of calcium in muscle contraction?
It binds to troponin, moving tropomyosin, so that myosin heads can bind to actin.
how does an electrical impulse travel into the interior of a muscle fiber?
along the transverse tubules
what term describes the muscle that is primarily responsible for opposing a particular action?
antagonist
muscles that flex the wrist are found on the ____ side of the forearm while those that extend the wrist are found on the _____ side of the forearm
anterior; posterior
what is the action of the enzyme acetylcholinesterase?
breaks down acetylcholine
What are fascicles?
bundles of muscle fibers
which of the following best describes myofibrils?
compromised of thick and thin filaments
what is muscle atrophy?
decrease in size and strength
cardiac muscle is located in the walls of blood vessels T or F
false
muscle fatigue results from a combination of insufficient calcium and an excess of acetylcholine T or F
false
Most muscles that move the thigh have their insertions on the ____.
femur
what muscles can act as a prime mover for plantar flexion of the foot?
gastrocnemius
which muscles share the same primary action?
gastrocnemius and soleus
which of the following describes smooth muscle contraction but not skeletal muscle contraction?
hormones can inhibit muscle contraction
what term refers to the attachments point for the movable end of the muscle?
insertion
describe the role of acetylcholinesterase in a stimulation of a muscle fiber
it is the enzyme that breaks down acetylcholine within the synaptic cleft, ending stimulation of the muscle fiber.
what happens to a muscle that has lost its innervation?
it undergoes atrophy
in muscle anatomy, what is an origin?
less movable end of muscle
what is an example of a partial but sustained contraction of a whole muscle?
maintenance of posture
What is a threshold stimulus?
minimum strength of stimulus required to cause muscle fiber contraction to occur
Site of ATP production
mitochondria
a ____ includes a motor neuron and all of the muscle fibers that is controls.
motor unit
the condition called ___ is inability of a muscle to continue to contract after rigorous exercise
muscle fatigue
what is an alternate name for skeletal muscle cell?
muscle fiber
Threadlike bundles of thick and thin filaments
myofibril
the characteristic reddish color of skeletal muscle is due to the presence of what substance?
myoglobin
what binds to actin at its binding sites, allowing the formation of cross bridges.
myosin
what is the name of the functional connection between a motor neuron and a muscle cell?
neuromuscular junction
motor neurons communicate with muscle cells by releasing chemicals called
neurotransmitters
what statement describes multiunit smooth muscle?
responds to stimulation by neurons and certain hormones
plasma membrane of muscle fiber
sarcolemma
functional unit of contraction within muscle fiber
sarcomere
name the functional units of contraction in a muscle fiber
sarcomeres
cytoplasm of a muscle fiber
sarcoplasm
Site for storage of calcium
sarcoplasmic reticulum
an electrical impulse traveling along the sarcolemma and into transverse tubules causes calcium ions to diffuse from the ____ into the _____.
sarcoplasmic reticulum; sarcoplasm
what type of muscle fiber is more resistant to fatigue
slow fibers
In general, oxygen debt develops as a result of:
strenuous exercise
Name the cordlike structures that connect muscles to bone.
tendons
Channel formed by invagination of plasma membrane
transverse (T) tubule
Name the membranous channels or tunnels that extend inward from multiple locations along the plasma membrane, into and through the muscle cell.
transverse tubules
calcium ions bind to ______ in order to initiate a muscle contraction
troponin
Endomysium separates individual muscle fibers from each other. T or F
true
an isotonic contraction is one that involves a change in length but not a change in tension T or F
true
transverse tubules are invaginations of the sarcolemma of a muscle cell T or F
true
a(n) _____ is a single contraction of a muscle fiber in response to a single stimulus
twitch
by what means does an electrical impulse travel deep into a skeletal muscle fiber in order to trigger a contraction?
via transverse tubules
what type of smooth muscle is found in the wall of the stomach?
visceral muscle
What is peristalsis?
wavelike smooth muscle contraction
what neurotransmitter is used to stimulate skeletal muscle contraction?
acetylcholine
in order for muscle contraction to occur, cross-bridges form between what components of the muscle fiber?
actin and myosin
what are the major proteins forming the myofibrils of skeletal muscle cells?
actin and myosin