Cellular Organization and Excitability

Question 1

What are the 2 classes of cells in the CNS?

Answer 1

Neurons

Glia

Question 2

True or false: excitatory axons project locally and inhibitory axons project at a distance.

Answer 2

False - the opposite is true

Question 3

[…] is the neurotransmitter for excitatory synapses.

Answer 3

Glutamate

Question 4

[…] is the neurotransmitter of inhibitory synapses.

Answer 4

GABA

Question 5

[…] are the neurotransmitters of modulatory synapses.

Answer 5

Serotonin

Dopamine

Acetylcholine

Norepinephrine

Question 6

What are the 4 types of glial cells to know?

Answer 6

Oligodendrocytes

Astrocytes

Microglia

Ependymal

Question 7

In the PNS, the equivalent of both astrocytes and microglia is […]

Answer 7

Satellite cells

Question 8

What is the role of astrocytes and microglia in the CNS?

Answer 8

• Support of CNS
• Astrocytes are close to synapses to participate in phagocytosis and maintain homeostasis of neurotransmitters and ions by absorbing these molecules
• Microglia play a neuroimmune response and help clean up the CNS

Question 9

What is the function of ependymal cells in the CNS?

Answer 9

• Produce and secrete CSF
• Form blood brain barrier

Question 10

Unlike neurons, glial cells are […]

Answer 10

Mitotic

Question 11

What is the choroid plexus?

Answer 11

• Clusters of ependymal cells in the ventricles in the brain

Question 12

What aspect of the structure of ependymal cells helps them circulate CSF?

Answer 12

They have cilia that beat to help it circulate

Question 13

Describe the pathway that CSF takes in the brain

Answer 13

Produced in choroid plexus, drains to ventricles, traverses brain via cerebral aqueduct and central canal, exits into subarachnoid space via foramens in skull, subarachnoid space drains to sinuses, sinuses drain to blood (venous blood supply)

Question 14

Describe the smooth endoplasmic reticulum of neurons.

Answer 14

The smooth ER spans the entire length of dendrites of neuron. It is a continuous network within the dendrites. It stores and releases calcium and is also thought to package and process proteins. As such, it has been implicated in protein misfolding diseases and neurodegeneration.

Question 15

What is a nucleus?

Answer 15

Neurons in the CNS with similar function

Question 16

What is the equivalent of a nucleus in the PNS?

Answer 16

Ganglion

Question 17

What does the term “layer” mean?

Answer 17

Collection of neurons in cortical layer (grey matter)

Question 18

What does the term “Column” mean?

Answer 18

Group of neurons across layers but within a column of the cortex that are involved in a cogitive task

Question 19

With regards to membrane potential:

• There is more […] inside the cell
• There is more […] outside the cell

Answer 19

K+

Na+, Ca2+, Cl-

Question 20

Why does the interior of a cell have a net negative resting membrane potential?

Answer 20

• There is a large density of positive charge outside the cell (Na+, Ca2+)
• There is a large density of negatively charged proteins inside the cell

Question 21

What is an action potential?

Answer 21

A sudden, brief reversal of resting membrane potential

Question 22

Describe the sequence of events in an action potential.

Answer 22

Question 23

What is a significant change in the structure of the brain from when we are children to when we are young adults?

Answer 23

The brain becomes more myelinated –> more connections are made and strengthened by myelination. This can appear in imaging as a loss of gray matter but it isn’t so much a loss of grey matter as it is a gain of white matter.