CELL, MUSCLE, NERVE PHYSIOLOGY Flashcards
A bundle of muscle fiber in the skeletal muscles is called
a. fasciculus
b. myofilaments
c. myofibrils
d. sarcomere
a. fasciculus
Type Ia afferents in the muscle spindle is/are also known as:
a. annulospiral nerve endings
b. flowerspray nerve endings
c. alpha motor neuron
d. gamma motor neuron
e. A-beta nerve fibers
a. annulospiral nerve endings
b: Type II
The following statement describes the principle of all or none law, EXCEPT:
a. Physiologic mechanism exist for fine gradation of the force of muscle contraction.
b. The law applies only to individual motor units.
c. All muscle fibers in a given motor unit contract or relax simultaneously.
d. Activated muscle fibers contract maximally if the nerve activates the motor fibers of a motor unit sufficiently.
e. In the same motor unit, it is possible for some muscle fiber to contract while others are relaxed.
e. In the same motor unit, it is possible for some muscle fiber to contract while others are relaxed.
True about myelin sheath:
a. Increases conduction velocity in large A beta and C fibers.
b. Absent at the nodes of Ranvier thereby facilitating saltatory conduction.
c. The myelin sheath acts as a conductor of electricity.
d. A and B
e. All of these are correct.
a. Increases conduction velocity in large A beta and C fibers.
Glial cell responsible for myelin production in the PNS.
a. oligodendrocytes
b. ependymal
c. Schwann cells
d. microglia
e. astrocytes
c. Schwann cells
Generation of end plate potential in the sarcolemma of skeletal muscle is linked with
a. voltage-gated channels
b. ligand-gated channels
c. mechanical-gated channels
d. thermal-gated channels
b. ligand-gated channels
The connective tissue that covers individual muscle bundle:
a. epimysium
b. perineurium
c. perimysium
d. subcutaneous fascia
e. endomysium
c. perimysium
The portion between two Z-discs is called:
a. H zone
b. I band
c. A band
d. Y band
e. sarcomere
e. sarcomere
The plasma membrane of a skeletal muscle fiber is called:
a. sarcoplasm
b. sarcolemma
c. sarcomere
d. sarcoplasmic reticulum
e. neurolemma
b. sarcolemma
Type of nerve fiber that has the fastest conduction:
a. large myelinated axons
b. small myelinated axons
c. small unmyelinated axons
d. large unmyelinated axons
a. large myelinated axons
The main neurotransmitter of the neuromuscular junction:
a. calcium
b. acetylcholine
c. serotonin
d. norepinephrine
e. epinephrine
b. acetylcholine
This thin filament has a high affinity for calcium:
a. Troponin I
b. Troponin C
c. Troponin T
d. Actin
e. Tropomyosin
b. Troponin C
Which among the following is the correct sequence for muscle contraction?
I. action potentials arrive at the presynaptic terminal
II. troponin C of the actin filament binds with calcium
III. acetylcholine is released in the synaptic cleft
IV. power stroke occurs
V. ATP attaches to the myosin head
a. I II III IV V
b. I III II V IV
c. I II IV III V
d. I III II IV V
d. I III II IV V
Location of the “triad” in skeletal muscles I
a. at A-H junction
b. I band contains thin filaments
c. the H-zone contains thin and thick filaments
d. width of I-band changes during contraction, A-band does not
actin filaments slide toward each other during contraction
c. the H-zone contains thin and thick filaments
Which of the following does NOT properly describe a sarcomere?
a. the M line divides the A band
b. I band contains thin filaments
c. the H zone contains thin and thick filaments
d. width of I band changes during contraction, A band does not
e. actin filaments slide toward each other during contraction
c. the H zone contains thin and thick filaments
True of thin filaments:
a. actin is the only thin filament
b. consists of two heads: one is a binding site for ATP, the other is for the formation of cross bridges
c. its backbone is a double stranded filamentous G actin, made of individual globular molecules called F actin
d. tropomyosin spiral around the binding sites and attached intermittently are troponin molecules altogether forming a troponin-tropomyosin complex
e. none of these
d. tropomyosin spiral around the binding sites and attached intermittently are troponin molecules altogether forming a troponin-tropomyosin complex
a: 3 filaments
b: thick filament
c: interchange G and F
In comparing electron micrographs of a relaxed skeletal muscle fiber and a fully contracted muscle fiber, which would be seen only in the relaxed fiber?
a. Z lines
b. triads
c. myosin
d. A bands
e. H zones
e. H zones
Which of the following generates the lowest tension?
a. fast concentric
b. slow concentric
c. fast eccentric
d. slow eccentric
e. isometric
a. fast concentric
Skeletal muscle contraction stops when:
a. AT is released from myosin
b. decreased concentration of intracellular calcium ions
c. ionization of cell
d. sodium pump reversal
e. depolarization of the cell
b. decreased concentration of intracellular calcium ions
Which of the following muscle is involuntary non-striated?
a. cardiac and smooth muscles
b. cardiac muscles
c. skeletal and cardiac muscles
d. smooth muscles
d. smooth muscles