MQ skeletal muscle Flashcards
Which statement best describes the propagation of the action potential from the motor plate to the sarcoplasmic reticulum during the latent phase of skeletal muscle contraction?
Question 1Select one:
a.
Voltage gated channels on the sarcolemma and transvers tubules open and close.
b.
Acetylcholine binding to cholinergic receptors on chemically gated potassium channels.
c.
Voltage gated channels on transverse tubules open.
d.
The entry of positive ions brings the motor end plate to activation threshold.
a.
Voltage gated channels on the sarcolemma and transvers tubules open and close.
Which function is not carried out by skeletal muscle?
Question 2Select one:
a.
Help maintain body temperature.
b.
Pull on tendons to move elements of the skeleton.
c.
Maintain posture and bear weight.
d.
Push food through the digestive tract.
d.
Push food through the digestive tract.
Organophosphates from insecticides inactivate the acetylcholinesterase enzyme. How does organophosphate poisoning from insecticides affect skeletal muscles?
Question 3Select one:
a.
The organophosphates promote muscle contraction by increasing the voltage of the sarcoplasm towards activation threshold at the motor end plate.
b.
The organophosphates prevent muscle contraction by maintaining the post synaptic potential away from the activation threshold at the motor end plate.
a.
The organophosphates promote muscle contraction by increasing the voltage of the sarcoplasm towards activation threshold at the motor end plate.
Place in chronological order the statements describing propagation of an action potential during muscle contraction.
a.
The action potential propagates from the superficial sarcolemma to the t-tubule that invaginates deep the muscle fiber.
b.
As the inner surface of the sarcolemma reaches 30mV, sodium ions diffuse to adjacent areas along the sarcolemma. Simultaneously, voltage-gated potassium channels open and potassium ions diffuse from the sarcoplasm to the extramuscular fluid.
c. The opening of voltage-gated sodium channels embedded in the membrane of the t-tubule causes a repercussive movement of the V-g-Na-channel.
d.
Sodium-potassium pumps re-establish the K+ and Na+ concentrations on either side of the sarcolemma where the action potential has already propagated.
1.b
2. d
3. a
4. c
Which function is not carried out by smooth muscle?
Question 10Select one:
a.
closing digestive and urinary sphincters
b.
pumping blood from veins to arteries
c.
pushing food along the digestive tract by peristalsis
d.
vasodilation
e.
constriction of pupils
b.
pumping blood from veins to arteries
Muscle contraction (power stroke) within the sarcomere involves:
Question 11Select one:
a.
Shortening of both myosin and actin filaments.
b.
Actin fibers sliding past myosin fibers.
c.
Shortening of myosin filaments and lengthening of actin filaments.
d.
Lengthening of myosin and shortening of actin filaments.
b.
Actin fibers sliding past myosin fibers.
In order to initiate muscle contraction, calcium is bound by:
Question 12Select one:
a.
myosin
b.
troponin
c.
actin
d.
tropomyosin
b.
troponin
Which function is carried out by skeletal muscle?
Question 13Select one:
a.
opening of digestive tract during swallow reflex
b.
breathing
c.
dilation of airways
d.
vasoconstriction
b.
breathing
Place in chronological order the statements describing transmission during muscle contraction.
a.
Acetylcholine binds to acethylcholine receptors on chemically-gated sodium channels, triggering the partial opening of the channel.
b.
An action potential reaches the synaptic terminal as a result of propagation, which results in an influx of sodium into the synaptic terminal.
c.
Calcium ions diffuse from the extracellular fluid to the synaptic terminal.
d.
As the positively charged sodium ion accumulates, the voltage of the synaptic terminal increases.
e.
The influx of calcium ions into the synaptic terminal triggers the exocytosis of synaptic vesicles containing acethycholine.
f.
A voltage increase in the synaptic terminal triggers the opening of voltage-gated calcium channels.
g.
Sodium ions trickle from the neuromuscular junction into the sarcoplasm.
h.
The membrane of the synaptic vesicles merge with the cytoplasmic membrane of the synaptic terminal, releasing acethycholine into the neuro-muscular junction.
- b
- d
- f
- c
- e
- h
- a
- g
Place in chronological order the statements describing muscle contraction.
a.
Ca2+–bound troponin changes the conformation of tropomyosin, exposing the myosin binding sites on the actin myofilament.
b.
Sodium ions trickle from the neuromuscular junction into the sarcoplasm.
c.
The accumulation of positive sodium ions near the sarcolemma increases that area’s potential difference from resting potential to activation threshold.
d.
The myosin head moves from its high energy confirmation to its low energy confirmation. The resulting power stroke pulls the actin filaments towards the middle of the myosin.
e.
A voltage increase in the synaptic terminal triggers the opening of voltage-gated calcium channels.
- e
- b
- c
- a
- d
In the context of the generation and propagation of an action potential in skeletal muscle, what step immediately follows sodium ions rushing from the extra-muscular space into the sarcoplasm, causing the depolarization of the T-tubule.
Question 16Select one:
a.
The change of voltage from -70 mV to -50 mV at the sarcolemma.
b.
The opening of voltage-gated sodium channels embedded in the membrane of the sarcolemma.
c.
The diffusion of sodium ions through the t-tubule.
d.
The diffusion of sodium ions within the muscle fiber to adjacent areas along the membrane.
e.
The diffusion of sodium ions within the muscle fiber, from the motor end plate to the sarcolemma.
d.
The diffusion of sodium ions within the muscle fiber to adjacent areas along the membrane.
Place in chronological order the statements describing muscle contraction.
a.
As the inner surface of the sarcolemma reaches 30mV, sodium ions diffuse to adjacent areas along the sarcolemma. Simultaneously, voltage-gated potassium channels open and potassium ions diffuse from the sarcoplasm to the extramuscular fluid.
b.
The myosin head returns from low to high energy position as it hydrolyzes ATP to ADP
c.
Mechanically-gated calcium channels embedded in the membrane of the sarcoplasmic reticulum are triggered open by the repercussive movement of the V-g-Na-channel embedded in the t-tubule.
d.
The action potential propagates from the superficial sarcolemma to the t-tubule that invaginates deep the muscle fiber.
- a
2.d - c
- b
Which statement best describes stimulation of skeletal muscle?
Question 18Select one:
a.
Acetylcholine binds to a cholinergic receptor on a chemically gated potassium channel.
b.
The entry of positive ions brings the motor end plate to activation threshold
c.
Voltage gated channels on the sarcolemma and transvers tubules open and close
d.
Mechanically gated channels on the sarcoplasmic open
b.
The entry of positive ions brings the motor end plate to activation threshold
Name the type and subtype of tissue that can voluntarily contract with relative low endurance.
Question 20Select one:
a.
nervous tissue
b.
cardiac muscle tissue
c.
smooth muscle
d.
skeletal muscle tissue
d.
skeletal muscle tissue
Botulin toxin interferes with the exocytosis of acetylcholine (Ach) into the neuromuscular junction. How does botulin toxin affect skeletal muscles?
Question 21Select one:
a.
Botulin toxin promotes muscle contraction by increasing the voltage of the sarcoplasm towards activation threshold at the motor end plate.
b.
Botulin toxin prevents muscle contraction by maintaining the post synaptic potential away from the activation threshold at the motor end plate.
b.
Botulin toxin prevents muscle contraction by maintaining the post synaptic potential away from the activation threshold at the motor end plate.
