Lecture 28

Question 1

Two types of axons:

Answer 1

myelinated and unmyelinated

Question 2

Unmyelinated axons:

Answer 2

Small diameter, slow transmission of APs, continuous

Question 3

Myelinated axons:

Answer 3

Large diameter, fast transmission of APs, saltatory

Question 4

Two stages of action potential transmission

Answer 4

Passive spread, generation of action potentials

Question 5

Myelination of the axon ____ the action potential conduction velocity How?

Answer 5

increases. By increasing the efficiency of passive spread.

Question 6

APs are generated only at ____

Answer 6

nodes of Ranvier, and current flows passively between nodes. This process is known as saltatory conduction.

Question 7

Why do unmyelinated axons have a slower conduction velocity than myelinated axons?

Answer 7

Passive current flow between two adjacent points is fast, but AP must be regenerated at every point on the membrane. This takes time and therefore conduction velocity is slow.

Question 8

Myelin sheath for CNS neurons is formed by

Answer 8

oligodendroocytes

Question 9

Myelin sheath for PNS neurons is formed by:

Answer 9

Schwann cells

Question 10

Schwann cells and oligodendrocytes are types of:

Answer 10

Glia cells

Question 11

Passive conduction occurs in which direction?

Answer 11

Both

Question 12

Why does AP conduct in only one direction?

Answer 12

Due to the absolute refractory period