Chapter 10
How would the loss of acetylcholinesterase from the motor end plate affect skeletal muscle?
it would cause spastic paralysis / contracted muscles unable to relax
Since each myofibril is attached at either end of the muscle fiber, when sarcomeres shorten, the muscle fiber
shortens
Which muscle types are voluntary, and which are involuntary?
skeletal is voluntary cardiac is not
Neurons and ________ have electrically excitable membranes that propagate action potentials.
skeletal muscle fibers
The structural explanation of how a muscle fiber contracts is called the
sliding filament theory
The narrow space between the synaptic terminal and the muscle fiber is the
synaptic cleft
At each end of the muscle, the collagen fibers of the epimysium, and each perimysium and endomysium, come together to form a
tendon
Define tendon and aponeurosis
tendon-projection of connective tissue beyond the end of the muscle that attaches to the bone aponeurosis- broad fibrous sheet of connective tissue that connects muscles to muscles
During the ________ phase of action potential development, voltage-gated sodium channels are open.
depolarization
Individual muscle cells are surrounded by what connective tissue?
endomysium
The dense layer of connective tissue that surrounds an entire skeletal muscle is the
epimysium
During the Cori cycle, what happens in the liver?
glucose is produced from lactic acid
Muscle fibers differ from "typical cells" in that muscle fibers
have many nuclei
Define motor unit
A motor neuron and all of the muscle fibers it innervates
.Identify three sources of stored energy utilized by muscle fibers.
Atp, creatine, phosphate and shygose
Define muscle hypertrophy and muscle atrophy
Hypertrophy-increase in muscle mass atrophy- decrease in muscle mass
Compare incomplete tetanus with wave summation.
Incomplete tetanus refers to a muscle producing near-peak tension during rapid cycles of contraction and relaxation. Wave summation refers to the addition of one twitch to another.
Define depolarization, and describe the events that follow it
a cell is depolarized when a threshold potential is reached and and Na + rushes into the cell.
The rapid rise and fall in force produced by a muscle fiber after a single action potential is a(n)
a twitch
The cytoplasm of the neuromuscular synaptic terminal contains vesicles filled with molecules of the neurotransmitter named.
acetylchlorine
The most important factor in decreasing the intracellular concentration of calcium ion after contraction is
active transport of calcium into sacroplasmic reticulum
During the recovery period, the body's need for oxygen is increased because
additional oxygen is required to restore energy reserves consumed during exercise
A resting muscle generates most of its ATP by
aerobic metabolism of fatty acids
Define oxygen debt (excess post exercise oxygen consumption
amount of oxygen used to aerobic activity minutes amount of oxygen actually used in aerobic activity of EPOC is elevated
What causes calcium to be released from the sarcoplasmic reticulum?
arrival of action potential
What molecule supplies the energy for a muscle fiber contraction?
atp
Na+ and K+ both use ________ to passively diffuse across the plasma membrane.
channel
When a muscle is stimulated repeatedly at a high rate, eliminating a relaxation phase, the amount of tension gradually increases to a steady maximum tension. This is called
complete tetanus
Muscle tissue, one of the four basic tissue groups, consists chiefly of cells that are highly specialized for
contraction
The muscle weakness of myasthenia gravis results from ...........
loss of acetylcholine receptors in the end plate membrane
The Na+ /K+ ion pump is responsible for
maintaining the sodium/potassium concentration gradients constant.
Cellular membrane potential is measured in
millivolts
What happens to the lactate produced by skeletal muscle during peak activity?
most of lacatate enters the electron transport chain to produce more ATP
During activities requiring aerobic endurance,
most of the muscle's energy is produced in mitochondria.
Receptors for acetylcholine are located on the
motor end plate
Skeletal muscle fibers are formed from embryonic cells called
myoblasts
________ are stem cells located between the endomysium and sarcolemma that function in the repair of damaged muscle tissue.
myosatelites
Name the clinical condition affecting skeletal muscle, which is caused by a virus?
polio
Membrane potential is
potential difference across the cell membrane
The advantage of having many nuclei in a skeletal muscle fiber is the ability to
produce large amounts of the muscle proteins needed for growth and repair
After death, muscle fibers run out of ATP and calcium begins to leak from the sarcoplasmic reticulum into the sarcoplasm. This results in a condition known as
rigormortis
The plasma membrane of skeletal muscle is called the
sacrolemere
The repeating contractile unit of a skeletal muscle fiber is the
sarcomere
Describe the neuromuscular junction.
the synapse between the motor neuron and the muscle fiber that it controls
If a second stimulus arrives before the relaxation phase has ended, a second, more powerful contraction occurs. This is called
wave summetial
When do muscle fibers produce lactate?
when there's lack of oxygen