Exam 2 - Lecture 17 (Neuroglia 1) Flashcards Preview

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Flashcards in Exam 2 - Lecture 17 (Neuroglia 1) Deck (40)
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1
Q

What are the neuroglia of the CNS?

A
  1. Ependymal cells
  2. Astrocytes
  3. Oligodendrocytes
  4. Microglia
2
Q

What are the neuroglia of the PNS?

A

Schwann cells

3
Q

Where are ependymal cells located?

A

Line central canal and ventricles

4
Q

What % of nervous tissue do neuroglia make up?

A

> 90%

5
Q

What is the basic structure of neuroglia?

A

Small cells with little cytoplasm; only its nucleus can be seen with routine stains.

6
Q

What is the division rate of neuroglia?

A

Continue to divide throughout life.

7
Q

Ependymal cells and astrocytes provide optimal _____ environment for neurons.

A

extracellular

8
Q

What is on the apical surface of ependymal cells?

A

Cilia

9
Q

What is the role of ependymal cells?

A

Assist with CSF circulation

10
Q

What do ependymal cells form?

A

choroid plexus

11
Q

What is the choroid plexus made up of and what does it do?

A

choroid epithelium; produces CSF

12
Q

What cells make up the choroid epithelium?

A

modified ependymal cells lined with microvilli

13
Q

Why do the modified ependymal cells of the choroid epithelium have microvilli and not cilia?

A

To increase SA due to production of CSF

14
Q

What are the cell types/shapes of ependymal cells?

A

Cuboidal to columnar

15
Q

What does the choroid epithelium serve as a barrier for?

A

Blood-CSF barrier

16
Q

What type of junctions are present in the choroid epithelium and why?

A

tight junctions so that nothing can travel between cells

17
Q

What is special about the c.t. of the choroid plexus?

A

Has fenestrated capillaries that cause it to be “leaky” so that Na+ can leave endothelial cells

18
Q

What is CSF?

A

Filtrates of the blood that pass through capillary endothelium and choroid epithelium of the choroid plexus.

19
Q

Where does CSF circulate?

A

Ventricles and subarachnoid space

20
Q

How does CSF get from the ventricles to the subarachnoid space?

A

Through a channel

21
Q

What are the 3 functions of the CSF?

A
  1. Physical support of the CNS
  2. Maintains chemical environment of the CNS
  3. Regulates intracranial pressure
22
Q

What does CSF remove from the CNS?

A

metabolites

23
Q

How is the ICP maintained within normal limits?

A

CSF volume and blood volume vary inversely

24
Q

What occurs with CSF absorption/production in regulation of ICP?

A

Absorption increases, production decreases

25
Q

What are astrocytes?

A

Most abundant neuroglia of the CNS (~50%)

26
Q

What 3 things do astrocytes do?

A
  1. Respond to injury
  2. Proliferate to form scar tissue
  3. Maintain optimal CSF environment
27
Q

What are the 5 ways in which astrocytes maintain optimal CNS environment?

A
  1. Induct and maintain capillary endothelium as the BBB
  2. Help transport glucose to neurons
  3. Store glycogen - energy reserves
  4. Promote neuronal survival
  5. Prevent glutamate toxicity
28
Q

What is the morphology of astrocytes?

A

Neuroglia with numerous cell processes

29
Q

What does the capillary endothelium/BBB do?

A

Regulates exchange of solutes between blood and CNS tissue

30
Q

What do astrocytes release?

A

Glial cell line-derived neurotrophic factor (GDNF)

31
Q

Why do astrocytes release GDNF?

A

To promote formation and maintenance of capillary tight junctions

32
Q

What is the structure of the capillary endothelium?

A

Perivascular endfeet of astrocytes contact the basement membrane, which contacts the endothelium

33
Q

What are 3 ways in which things get across the BBB?

A
  1. Diffusion
  2. Transporter
  3. Carrier-mediated transport
34
Q

What 3 things can get thru the BBB by diffusion?

A
  1. Water
  2. Gases
  3. Lipophilic substances (alcohol, heroin, nicotine, cyanide)
35
Q

What can get thru the BBB by transporter?

A

Glucose

36
Q

What is the transporter for glucose that gets it across the BBB?

A

GLUT 1

37
Q

What 2 things can get thru the BBB by carrier-mediated transport?

A
  1. Amino acids

2. Vitamins

38
Q

What AAs are transported vs. which ones aren’t?

A

Transported if not synthesized in brain (large neutral)

Not transported if synthesized in the brain

39
Q

What 4 AAs are large and neutral and not synthesized in the brain?

A
  1. Leucine
  2. Tyrosine (NTM = catecholamine)
  3. Valine
  4. Tryptophan (NTM = serotonin)
40
Q

What AAs are small and neutral and synthesized in the brain?

A
  1. Glycine

2. GABA