Neuro Anatomy and Physiology

Question 1

What are neurons?

Answer 1

+Signal-transmitting cells of the nervous system. Permanent cells—do not divide in adulthood.
+Signal-relaying cells with dendrites (receive input), cell bodies, and axons (send output). Cell bodies and dendrites can be seen on Nissle staining (stains RER). RER is not present in the axon.

Question 2

What are astrocytes?

Answer 2

Physical support, repair, K+ metabolism, removal of excess neurotransmitter, component of blood-brain barrier, glycogen fuel reserve buffer. Reactive gliosis in response to neural injury. Astrocyte marker: GFAP. Derived from neuroectoderm.

Question 3

What are microglia?

Answer 3

Phagocytic scavenger cells of CNS (mesodermal, mononuclear origin). Activated
in response to tissue damage. Not readily discernible by Nissl stain.

Question 4

What is myelin?

Answer 4

Elevates conduction velocity of signals transmitted down axons leading toŽsaltatory conduction of action potential at the nodes of Ranvier, where there are high concentrations of Na+ channels.
+CNS—oligodendrocytes; PNS—Schwann cells.

Question 5

What are the functions of the Schwann cells?

Answer 5

Each Schwann cell myelinates only 1 PNS axon. Also promote axonal regeneration. Derived from neural crest.
+May be injured in Guillain-Barré syndrome.
+Acoustic neuroma—type of schwannoma.