When a skeletal muscle contracts to cause a given movement, the relatively stationary end of attachment of the muscle is termed?
This statement best describes the muscle property of "extensibility?
a. muscles recoil to original shape
b. muscles shorten forcefully
c. muscles can stretch when needed
d. muscles contract when stimulated
These statements about creatine phosphate are true except:
a. accumulates in cells to store energy
b. ADP reacts with it to produce ATP
c. creatine kinase is used as a catalyst
d. supports intense exercise for up to 3 minutes.
These statements about myosin myofilaments are all true except:?
a. are thicker than actin.
b. make up the H zone.
c. attached to the Z disc
d. attached to filaments that form the M line.
The resting membrane potential occurs when:?
a. Na+ ions diffuse into the cell
b. Na+ ions diffuse out of the cell.
c. K+ ions diffuse into the cell.
d. K+ ions diffuse out of the cell.
These events occur during contraction except:?
a. exposure of active sites on actin.
b. active transport of Ca+ back into sarcoplasmic reticulum
c. cross-bridges are formed and released.
d. power stroke.
Depolarization must reach this value in a cell to trigger an action potential:
a. 0 mv
b. +20 mv
c. -85 mv
This stimulus results in the greatest force of contraction because all motor units of a muscle are responding:
List the events occurring at a neuromuscular junction in order.
1. ACh binds to receptors on postsynaptic membrane.
2 acetylcholinestrerase breaks down ACh
3. choline is reabsorbed by presynaptic membrane
4. depolarization of sarcolemma
5. ligand gated Na+ ion channels open
This kind of contraction results in an increase of tension, but the length of the muscle does not change:
These conditions occur in both physiologic contracture and rigor mortis except:
a. low levels of ATP
b. cross-bridges are formed
c. release of cross-bridges
d. Ca2+ builds up in the sarcoplasm
3. active transport of Ca2+ slows or stops.
Given the following:
1. Ca2+ ions are actively transported back into sarcoplasmic reticulum
2. Troponin-tropomyosin complexed move to inhibit cross-bridge formation
3. muscle fibers lengthen passively
These events best describe?
b. lag phase
c. contraction phase
d. relaxation phase
Johnny's primary source of energy comes from this as he runs on his treadmill for 20 minutes every morning?:
a. stored ATP
b. aerobic respiration
c. anaerobic respiration
d. creatine phosphate.
This statement is true about anaerobic respiration:
a. produces 38 ATPs per glucose molecule
b. uses fatty acids for sustained exercises.
c. can produce ATP rapidly
d. uses citric acid cycle.
These are the most important neurotransmitters that regulate smooth muscle:
a. acetylcholine, dopamine
b. norepinephrine, dopamine
c. acetylcholine, norepinephrine,
d. GABA, Ach
Because large amounts of ATP are stored in muscle fibers, it does not need to be continuously synthesized in order to sustain muscle contraction