Which of the following is CORRECTLY paired?
cardiac muscle: nonstriated
cardiac muscle: voluntary control
smooth muscle: striated
skeletal muscle: voluntary control
What causes the release of calcium from the terminal cisternae of the sarcoplasmic reticulum within a muscle cell?
The binding of calcium to which molecule causes the myosin binding sites to be exposed?
A myosin head binds to which molecule to form a cross bridge?
What causes the myosin head to disconnect from actin?
What energizes the power stroke?
In a neuromuscular junction, synaptic vesicles in the motor neuron contain which neurotransmitter?
When an action potential arrives at the axon terminal of a motor neuron, which ion channels open?
What means of membrane transport is used to release the neurotransmitter into the synaptic cleft?
The binding of the neurotransmitter to receptors on the motor end plate causes which of the following to occur?
Excitation-contraction coupling is a series of events that occur after the events of the neuromuscular junction have transpired. The term excitation refers to which step in the process?
Excitation of the sarcolemma is coupled or linked to the contraction of a skeletal muscle fiber. What specific event initiates the contraction?
A triad is composed of a T-tubule and two adjacent terminal cisternae of the sarcoplasmic reticulum. How are these components connected?
Which of the following is most directly responsible for the coupling of excitation to contraction of skeletal muscle fibers?
Yes! Action potentials propagating down the T-tubule cause a voltage-sensitive protein to change shape. This shape change opens calcium release channels in the sarcoplasmic reticulum, allowing calcium ions to flood the sarcoplasm. This flood of calcium ions is directly responsible for the coupling of excitation to contraction in skeletal muscle fibers.
What is the relationship between the number of motor neurons recruited and the number of skeletal muscle fibers innervated?
In which phase would the net movement of Ca2+ into the sarcoplasmic reticulum (SR) be greatest?
1. Latent Period (initial)
2. Period of contraction (middle)
3. Period of Relaxation (end)
Excitation-contraction coupling includes all EXCEPT which of the following events?
1. propagation of an action potential along the sarcolemma and down T tubules
2. release of calcium ions from the terminal cisterns
3. release of acetylcholine from axon terminals at the neuromuscular junction
4. binding of calcium ions to troponin, which removes the blocking action of tropomyosin
What is a cross bridge cycle?
Which muscle fiber type is best suited for endurance activities, such as long-distance jogging?
slow glycolytic fibers
fast glycolytic fibers
fast oxidative fibers
slow oxidative fibers
slow oxidative fibers
Slow oxidative fibers are best suited for endurance (long duration) activities because they produce ATP aerobically, and are thus, fatigue-resistant. Fast glycolytic fibers, and to a lesser extent fast oxidative fibers, rely more on anaerobic glycolysis, and thus produce more lactic acid, which is a major cause of fatigue.
Which of the following factors influence the velocity and duration of muscle contraction?
load placed on the muscle
length of muscle fibers activated
frequency of stimulation
muscle fiber size
Cross bridge formation between myosin heads and actin molecules is caused by the elevation of calcium ion concentration in the cytosol. During rigor mortis, this elevation of calcium ion concentration in the cytosol is permanent because ________.
In a bedridden patient recovering from a badly fractured femur, disuse atrophy in the thigh muscles is caused by _________.