Anatomy Questions
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Acetylcholine exerts its effect byA) stimulating the motor neuron's synaptic knob.B) binding to receptors on ligand-gated sodium channels at the motor end plate.C) activating acetylcholinesterase.D) allowing calcium to enter the cell.
Which nerve innervates the muscles of facial expression?a. Musculocutaneous nb. Facial nc. Sciatic nd. Radial ne. Trigeminal n
A power stroke involvesA) an actin molecule pulling a myosin molecule toward the M-line.B) a thin filament shortening in length and thereby shortening the sarcomere.C) a myosin head pulling a thin filament toward the center of the sarcomere.D) a thick filament pushing an actin filament towards the nearest Z-line.
In a lab, wave summation is demonstrated by increasing the __________ of the stimulus.A) intensityB) frequencyC) capacitanceD) warm up time
The action potential of a muscle fiber occurs A) at the end plate.B) along the sarcolemma and down the T-tubules. C) within the sarcoplasmic reticulum.D) in the mitochondria.
Consider the difference between lifting a light pad of paper versus a heavy textbook. The primary way the level of force of muscle contraction is controlled is byA) recruiting a different number of motor units.B) activating different regions of the muscle.C) activating the motor units at a different frequency.D) altering the number of crossbridges each individual fiber uses.
The most abundant form of smooth muscle isA) single-unit, which is also known as visceral smooth muscle. B) cardiac muscle, which is also known as visceral smooth muscle.C) multiunit, which is also known as visceral smooth muscle.D) multiunit, which is also known as varicose muscle.E) single-unit, which is also known as somatic nervous system muscle.
The branch of the nervous system that helps govern smooth muscle contraction is the nervous system.A) autonomicB) somatic
Contraction of the diaphragm assists in A) expiration. B) inspiration.C) flexion at the waist.D) extension at the waist.E) All of the choices are correct.
Rather than tightly coupled synapses between neurons and muscle cells, single-unit smooth muscle contains A) gap junctions that connect neurons to smooth muscle cells.B) varicosities of a subset of muscle fibers so that individual cells can be separately stimulated. C) diffuse junctions where neuron varicosities are responsible for neurotransmitter release.D) plaques and caveolae that contain multiple hormone receptors for discrete endocrine control
During which phase of the crossbridge cycle is ATP split into ADP and Pi? A) Immediately preceding the detachment of the myosin head. B) Immediately preceding the resetting of the myosin head. C) Immediately preceding the power stroke.
When an impulse arrives at the knob of the motor neuron, calciumA) enters through active transport pumps and triggers the release of transmitter.B) enters through voltage-gated channels and triggers the release of transmitter.C) exits through active transport pumps and brings transmitter with it. D) exits through voltage-gated channels and triggers transmitter release. E) is released from synaptic vesicles.
The calcium ions involved in skeletal muscle contraction bind to a(n) subunitA) myosinB) actinC) elastinD) tropomyosin E) troponin
Which structures are reservoirs that store acetylcholine?A) Synaptic vesiclesB) Synaptic cleftsC) Terminal cisternaeD) Lysosomes
A motor unit consists ofA) multiple motor neurons and multiple muscle fibers.B) a single motor neuron and the multiple muscle fibers it controls. C) multiple motor neurons and the one muscle fiber they control. D) one synaptic terminal button, a cleft, and an acetylcholine receptor. E) an end plate, a T-tubule, and sarcoplasmic reticulum.
Invaginations of the muscle cell membrane that extend deep into the cell are known as the A) T-tubules.B) terminal cisternae.C) titin complexes. D) Z-discs. E) end plates.
For relaxation to occur,A) calcium leaves the sarcoplasmic reticulum, and troponin binds calcium and blocks the binding sites on actin.B) calcium enters the myofibril, it detaches from myosin, and the binding sites on myosin become inactive.C) sarcoplasm calcium levels fall, calcium is removed from troponin, and tropomyosin blocks binding sites on actinD) extracellular calcium levels fall, calcium is pumped into the myofibril, and tropomyosin slides away from actin
Which of the following structures has the active sites to which the heads of the thick filaments will bind?A) ActinB) TroponinC) TropomyosinD) MyosinE) Sarcoplasm
Slow Oxidative (SO) fibers areA) dark red and contract for long periods. B) light red and fatigue fast.C) white and contract for long periods. D) white and fatigue fast.
In the sarcomere, crossbridge cycling steps in order from start to end are:A) Power stroke (pull)- Ca2+ binding- Reset myosin head (reset)- Release of myosin head (release)-crossbridge formationB) Ca2+ binding- crossbridge formation (attach)- Power stroke (pull)- Release of myosin head (release)- Reset myosin head (reset)C) Ca2+ binding- Power stroke (pull)- Release of myosin head (release)- Reset myosin head (reset)-crossbridge formation (attach) D) Release of myosin head (release)- Crossbridge formation (attach)- Reset of myosin head (reset)- Ca2+ binding