Ch. 9 Anatomy
Immediately following the arrival of the stimulus at a skeletal muscle cell there is a short period called the ________ period during which the events of excitation-contraction coupling occur.
Latent
The response of a motor unit to a single action potential of its motor neuron is called a:
Muscle twitch
Thick myofilaments are made of:
Myosin
Muscle tissue has all of the following properties except ________.
Secretion
Which of the following is correctly paired?
Skeletal muscle: voluntary control
What is the role of tropomyosin in skeletal muscles?
Tropomyosin serves as a contraction inhibitor by blocking the myosin binding sites on the actin molecules.
Which protein inhibits skeletal muscle contraction, and what ion removes the inhibition?
Tropomyosin; calcium ions
What is the functional unit of a skeletal muscle called?
a sarcomere
The term aponeurosis refers to ________.
a sheetlike indirect attachment to a skeletal element
Muscle tone is...
a state of sustained partial contraction
What is the role of calcium ions in muscle contraction?
bind to regulatory sites on troponin to remove contraction inhibition
In an isotonic contraction, the muscle ________.
changes in length and moves the "load"
Which of the following surrounds the individual muscle cell?
endomysium
The connective tissue sheaths of skeletal muscle, in order from internal to external are the:
endomysium, perimysium, and epimysium.
What is the functional role of the T tubules?
enhance cellular communication during muscle contraction
Which muscle characteristic describes the ability of muscle to respond to a stimulus?
excitability
The strongest muscle contractions are normally achieved by ________.
increasing the stimulation up to the maximal stimulus
Which of the following is a factor that affects the velocity and duration of muscle contraction?
load on the fiber
Which of the following is the correct sequence of events for muscle contractions?
motor neuron action potential, neurotransmitter release, muscle cell action potential, release of calcium ions from SR, ATP-driven power stroke, sliding of myofilaments
Hypothetically, if a muscle were stretched to the point where thick and thin filaments no longer overlapped, ________.
no muscle tension could be generated
The muscle cell membrane is called the ________.
sarcolemma
What structure in skeletal muscle cells functions in calcium storage?
sarcoplasmic reticulum
Myoglobin...
stores oxygen in muscle cells
The force of a muscle contraction is not affected by:
the amount of ATP in the muscle cells.
What produces the striations of a skeletal muscle cell?
the arrangement of myofilaments
Which of the following are composed of myosin?
thick filaments
Which type of muscle can contract without being stimulated by the nervous system?
Cardiac
The distance between Z-discs ______ during muscle contraction.
Decreases
After nervous stimulation stops, what prevents ACh in the synaptic cleft from continuing to stimulate contraction?
acetylcholinesterase destroying the ACh
The sliding filament model of contraction involves
actin and myosin sliding past each other and partially overlapping
During muscle contraction, myosin cross bridges attach to which active sites?
actin filaments