Agents that paralyze skeletal muscle by simple competitive inhibition of acetylcholine at muscle receptor sites are called?
a. nondepolarizing
b. depolarizing
c. antagonizing
d. repolarizing
Answer:
a. nondepolarizing
Explanation:
As the nerve impulse arrives, the synaptic end bulbs of the motor neurons release acetylcholine in the synapse. Acetylcholine binds to its receptors present at the motor endplate. This results in the opening of an ion channel in the ACh receptor to allow the movement of the Na+ into the cell. This makes the inside of the muscle fiber more positively charged, that is, depolarized.
Depolarization triggers a muscle action potential. Drugs or chemicals that paralyze skeletal muscle by competitive inhibition of acetylcholine at muscle receptor sites are called non-depolarizing as they do not allow the acetylcholine to facilitate the depolarization of the muscle fiber.
Fro the answer to the question above,
<span>Based on fossil evidence, eukaryotes evolved about <u>2.1 billion</u> years ago</span>.
<span>Approximately the first single-celled Eukaryotes appeared 2.1billion years</span>.
But the multicellular eukaryotes first appeared at 1.5 billion years ago.
I hope this helps
B. Mitochondrion. Centriole is unique to animal cells and is used in cell division. Chloroplast and Cell wall are unique to plants cells, together with permanent vacuole. Both have mitochondrion, where energy is released through respiration.
