16 General Neurophysiology - M Flashcards Preview

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Flashcards in 16 General Neurophysiology - M Deck (33)
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1
Q

What are the functions of CSF?

A
  • cushioning of neural tissue
  • distribution of secretory signals
  • regulates neurogenesis
  • waste clearance
2
Q

What is the direction of water flow in the choroid plexus cells (ependymal cells)?

A

Water flows from blood to ventricular lumen (opposite renal tubule cells)

3
Q

What type of gradient moves water from the blood to the ventricles?

A

osmotic gradient

4
Q

What produces the osmotic gradient required for water to move from blood to ventricles?

A

Na+/K+ ATPases on ventricle/apical side —> Na+ into ventricle and K+ into choroid plexus = water follows Na+

5
Q

How does Na+ enter the ependymal cells from the blood?

A

via NHE1 & NCBE

6
Q

What transports Na+ from the choroid plexus to the ventricular lumen?

A

Na+/K+ ATPases

7
Q

How does HCO3- get into the ependymal cells?

A
  • NCBE = (Na+/HCO3- in & Cl- out)
  • CO2 is converted to HCO3- by carbonic anhydrase
8
Q

How does HCO3- leave the ependymal cells and enter the ventricular lumen?

A
  • AE2 (Cl-/HCO3- exchanger)
  • HCO3- channels
9
Q

Why does Cl- accumulate in the ependymal cells?

A

because it followed Na+ into the cells from the blood

10
Q

How does Cl- leave the ependymal cells and enter the ventricular lumen?

A
  • apical Cl- channels
  • NKCCI cotransporters
11
Q

What is the net movement of Na+, Cl-, HCO3- from the blood?

A

Net movement from blood –> ependymal cells –> ventricules

12
Q

What aquaporin channel does water flow through?

A

AQP1

13
Q

What ions are higher in the CSF than in the blood?

A

Na+, Cl-, & Mg2+

14
Q

What is the normal ICP?

A

5-15 mm Hg = 112mm of CSF

15
Q

As ICP increases what happens to CSF levels?

A

that decrease by CSF reabsorption into the subdural sinuses increases

16
Q

What are the regulators of cardiac output to the brain?

A
  • CO2
  • [H+]
  • [O2]
  • astrocyte metabolites
17
Q

An increase of CO2 levels in the CSF causes what?

A

increased cardiac output

18
Q

How does pain sensation from cerebral blood vessels affect blood flow to the brain?

A

causes PNS activity –> vasodilation

19
Q

If ICP increases what happens to arterial blood flow?

A

arterial blood flow decreases –> atrophy/necrosis of brain

20
Q

What mechanism protects the brain from high blood pressure?

A

sympathetic induced vasoconstriction ==> increased vascular resistance = neuroprotective

21
Q

decreased brain profusion causes what sort of response?

A

increase in systemic vascular resistance –> more blood goes to the brain

  • occurs during hemorrhages/traumas
22
Q

Why does acidic CSF cause an increase in cerebral blood flow?

A

because CO2 levels are high so increased CBF will result in removal of CO2 (replaced by O2)

23
Q

What substances are nearly impermeable to the BBB?

A

plasma proteins, non-lipid soluble organic molecules

24
Q

What is the major energy source for the brain?

A

glucose

25
Q

How does glucose cross the BBB?

A

non-insulin dependent GLUT 1 receptors

26
Q

What is the role of P-glycoproteins?

A

To remove drugs that crossed the BBB back into the blood

27
Q

What brain structures express GLUT 3 receptors?

A

neurons

28
Q

What brain structures express GLUT 5?

A

microglia

29
Q

Where are GLUT 1 receptors expressed?

A
  • astrocytes
  • microvessels
  • choroid plexus/ependymal cells
30
Q

What organs/brain structures surround the brain?

A
  • posterior pituitary
  • area of podtrema
  • organum vaculosum of the lamina terminalis (OVLT)
  • subfornical organ
31
Q

What is the role of area postrema?

A

initiation of vomiting in response to chemotactic triggers

32
Q

What is the role of the organum vasculosum of the lamina terminalis (OVLT)?

A

regulation of total body water and thirst; Ang 2 target

33
Q

Where is the glymphatic system found and what is its function?

A

macroscopic waste clearance system of the CNS; primarily engaged during sleep