Which of the following will respond to a threshold stimulus with an all-or-none contraction?
A & B a single muscle fiber & a single motor unit (d)
Which of the following is called the thin myofilament?
actin
Troponin
has a calcium-binding site
Which of the following is composed of myosin molecules
thick myofilaments
The active sites to which cross-bridges attach are found on the
actin myofilaments
You are hired to work in a laboratory to measure the rate of human muscle contraction. Which of the following might decrease in quantity in muscle cells undergoing contractions?
ATP
T tubules are invaginations of the
sarcolemma
T tubules
conduct action potentials deep into the muscle cell
Sarcoplasmic reticulum
stores calcium ions
Sliding filament model
Both actin and myosin myofilaments shorten during contraction (false statement)
If sodium ions cannot enter a muscle fiber in response to a stimulus,
contraction cannot occur
(Neuromuscular junctions) The
sites where a chemical substance is transmitted from the presynaptic terminal
of an axon to the postsynaptic membrane of a muscle fiber are called
Neuromuscular junctions
A drug that interferes with the active transport of calcium ions from the sarcoplasm back into sarcoplamic reticulum would result in
contraction with no relaxation
ATP molecule is required
(*e*) A, B, C
A)for formation of the cross-bridge.
B) for movement of the cross-bridge.
C) for release of the cross-bridge.
After contraction has occurred,
released from troponin
Depolarization of the cell membrane occurs when there is a rapid influx (inflow) of
Sodium ions
an all or non-response
synaptic vesicles in the neuromuscular junction contain
acetylcholine
Curare blocks acetylcholine receptors at the motor end plate. This would result in
inability of the muscle fiber to respond to nervous stimulation
Arrange these structures as they participate in excitation
sarcolemma, T tubules, sarcoplasmic reticulum, calcium ions
Arrange the following list of biochemical events in the correct sequence
1. An action potential is conducted deep into the muscle fiber by the T tubule
3. The membranes of the sarcoplasmic reticulum become more permeable to calcium ions.
4. Calcium ions diffuse into the sarcoplasm around the myofibril.
2. Calcium ions bind to troponin.5. The troponin-tropomyosin complex moves exposing active sites
Movement of the myosin molecule while the cross bridge is attached in a ________
power stroke
During the contraction phase of a muscle twitch
actin-myosin cross-bridges form.
Tetanus of a muscle is thought to be caused by
high calcium ion concentrations in the sarcoplasm
Rigor mortis occurs after death because
cross-bridges form but can't release.
Oxygen debt
amount of oxygen that cells need to replenish ATP supplies after exercise.
Consider the following four phrases and select the one that does not belong with the others
fuels runner in a marathon
Which of the following correctly describes myoglobin's special function in muscle tissue?