Question

which cells form myelin sheaths in the spinal cord?
schwann cells
astrocytes
satellite cells
oligodendrocytes
microglia
question 40 (1.7 points)
the opening of_______ gates produces an______.
chloride; ipsp
sodium; ipsp
calcium; ipsp
potassium; epsp
calcium and sodium; ipsp

Explanation:

• For the first question: Oligodendrocytes are responsible for forming myelin sheaths in the central nervous system (which includes the spinal cord). Schwann cells form myelin in the peripheral nervous system. Astrocytes have roles like providing nutrients and support in the CNS. Satellite cells are related to peripheral nerve cell support. Microglia are the immune - like cells of the CNS.
• For the second question: When chloride ($Cl^{-}$) gates open, chloride ions (which are negatively charged) enter the cell (or in some cases, exit depending on the concentration gradient, but overall) hyperpolarize the cell membrane. An inhibitory postsynaptic potential (IPSP) is a change in membrane potential that makes the neuron less likely to fire. Sodium ($Na^{+}$) and calcium ($Ca^{2 +}$) influx (when their gates open) usually depolarize the membrane (related to excitatory postsynaptic potentials - EPSPs in some cases, but sodium influx is a major part of action potential depolarization). Potassium ($K^{+}$) efflux (when its gates open) can hyperpolarize, but the combination of chloride and IPSP is the correct match here.

Answer:

• First question: Oligodendrocytes
• Second question: chloride; IPSP