Intro, nerves, etc

Question 1

Define somatotopy

Answer 1

The correspondence of an area of the body to a point in the CNS

Question 2

Define Hebb’s postulate

Answer 2

Lasting changes in neuronal circuitry occur through growth at synapses

Question 3

Define commissure

Answer 3

The midpoint in cerebrum where R & L cross

Question 4

Define decussation

Answer 4

The midpoint in midbrain where R & L cross

Question 5

What is the function of Microglia? Are these in the CNS or PNS?

Answer 5

CNS; phagocytic & development of chronic pain syndrome

Question 6

What is the function of Oligodendrocytes? Are these in the CNS or PNS?

Answer 6

CNS; myelin-forming, 1 cell –> many axons

Question 7

What is the function of Schwaan cells? Are these in the CNS or PNS?

Answer 7

PNS; myelin-forming, 1 cell –> 1 axon

Question 8

What is the function of Astrocytes? Are these in the CNS or PNS?

Answer 8

CNS; Maintain ionic equilibrium, clearing/recycling of NTs, take up glutamate and convert to glutamine, transport of nutrients from vessels to neurons, local regulation of blood flow

Question 9

When the PNS is damaged, what is the order of events of recovery?

Answer 9

Neuron emits signals such as ATP, attracts microglia which proliferate and produce cytokines and trophic factors, these attract astrocytes. Microglia also promote synaptic organization.

Question 10

Is the PNS microglial response rapid or slow? Short-lived or sustained?

Answer 10

Rapid and shortlived

Question 11

Is the PNS astrocyte response rapid or slow? Short-lived or sustained?

Answer 11

Slow and sustained

Question 12

How is CNS damage response different from PNS damage response?

Answer 12

Unlike Schwaan cells, oligodendrocytes do not clear myelin debris & allow axonal elongation. Instead, oligodendrocyte precursors proliferate and upregulate expression of molecules that inhibit axonal outgrowth. Microglia activate local astrocytes which proliferate to form a glial scar which is also a chemical and physical barrier to axonal regeneration.

Question 13

What are circumventricular organs?

Answer 13

At small sites along the ventricular walls in the caudal medulla and hypothalamus, there’s no BBB. Here blood is monitored or secretions into blood are produced. Astrocytes wall off these areas from rest of CNS.

Question 14

What is a healthy blood flow to the brain?

Answer 14

50ml/min per 100g

Question 15

What blood flow is considered ischemic to the brain?

Question 16

How do arterioles in the brain autoregulate?

Answer 16

When BP rises, arteriole walls stretch, 2nd messenger cascade is activated which culminates in inhibition of Ca-activated K channels (Kca) which leads to depolarization of cell and muscle activation.