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Neuroendocrine Exam 2 > cerebral blood flow and CNS homeostasis > Flashcards

cerebral blood flow and CNS homeostasis Flashcards

1
Q

What is the impact of the little mixing of the blood from the different sources in the brain?

A

disruption of one of the inputs produces localized (discrete) areas of ischemia–> there will not be a global ischemic event–> protective mechanism

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2
Q

What are the neurotransmitters involved in the sympathetic innervation of the cerebral circulation?

A

norepinephrine and neuropeptide Y (NPY)

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3
Q

What are the receptors for the neurotransmitters involved in the sympathetic innervation of the cerebral circulation?

A

alpha-adrenergic receptors

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4
Q

What happens when norepinephrine or NPY bind to an alpha adrenergic receptor?

A

it causes vasoconstriction

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5
Q

What type of blood vessels are involved in the parasympathetic innervation of the cerebral circulation?

A

larger blood vessels

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6
Q

what is the major neurotransmitters of the parasympathetic innervation of the cerebral circulation?

A

ACh, Vasoactive intestinal polypeptide (VIP) and PHM-27

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7
Q

what do the neurotransmitters involved in the parasympathetic innervation of the cerebral circulation cause?

A

vasodilation

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8
Q

Besides the sympathetic and parasympathetic innervation of the cerebral circulation, there is an additional source of innervation. What is it?

A

sensory innervation of the distal blood vessels

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9
Q

distal blood vessels will contain nociceptors. These nociceptors will release neuropeptides when the blood vessels of the brain experience torsion/manipulation. What are these neuropeptides?

A

substance P, neurokinin A, and CGRP

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10
Q

When does torsion/manipulation of the brain’s blood vessels occur?

A

in the presence of reduced CSF

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11
Q

The activation of those afferent C fibers will also cause what in addition to causing pain?

A

vasodilation and increase the blood flow

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12
Q

What kind of control is cerebral blood flow under?

A

local control

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13
Q

what does it mean when it is said that cerebral blood flow is under local control?

A

oxygen consumption dictates where in the brain the blood will go

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14
Q

What does it mean when it is said that cerebral blood flow is strongly autoregulated?

A

it is held constant over a wide range of systemic (mean arterial) blood pressures

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15
Q

At about what pressure does the brain begin to autoregulate the cerebral blood flow?

A

~60 mmHg

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16
Q

Before sympathetics kick in, at about what pressure would we see the cerebral blood flow start to increase as the mean arterial blood pressure increases?

A

140 mmHg

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17
Q

What happens when the sympathetics are activated with the cerebral circulation?

A

the autoregulation is extended and the brain will vasoconstrict prior to the capillaries

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18
Q

As intracranial pressure goes up, what happens to the venous outflow?

A

it can compress the vein and collapse it,

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19
Q

what does a compressed/collapsed vein in the brain cause?

A

reduced arterial flow aka the brain suddenly doesn’t have enough blood flow and therefore less o2

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20
Q

What happens when a vein is compressed/ collapses in the brain?

A

the brain will activate the cardiovascular control centers in the medulla and increase systemic BP, sometimes drastically–> trying to force open the vein so blood can get through

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21
Q

What could increase the intracranial pressure?

A

hydrocephalus (Increased CSF), cerebral edema, intracranial bleeding, tumor

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22
Q

How is the lateral ventricles connected to the third ventricle?

A

intraventricular foramen

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23
Q

how is the 3rd ventricle connected to the 4th ventricle?

A

cerebral aquaduct

24
Q

how is the 4th. ventricle connected to the cisterna magna?

A

median aperture

25
Q

how is the 4th ventricle connected to the arachnoid space?

A

lateral apertures

26
Q

What is the first step in the production of CSF?

A

filtration of serum

27
Q

The filtration of serum is driven by what two pressures?

A

hydrostatic pressure and oncotic pressure

28
Q

There are two types of hydrostatic pressure what are they?

A

there is one in the capillary (pushed fluid out) and a small one surrounding the capillary (pushes fluid into the capillary)

29
Q

At the choroid plexus, what could be said about the oncotic pressure inside the capillary and surrounding the capillary?

A

they are equal and opposite so they cancel each other out

30
Q

What is the 2nd step of the production of CSF?

A

modification of the ion composition in the CSF

31
Q

What ions have equal concentrations in both the plasma and the CSF?

A

Na+ and HCO3

32
Q

what is the significance of HCO3 in CSF?

A

it is critical for controlling the pH of CSF

33
Q

What ions are found to have higher concentrations in the CSF compared to the plasma?

A

Mg2+ and Cl- and Co2

34
Q

what is the increased CO2 in the CSF caused from?

A

neuronal metabolism

35
Q

what ions are found to have a smaller concentration in the CSF when compared to the plasma?

A

K+, Ca2+, protein, and glucose

36
Q

how is CSF reabsorbed?

A

by the arachnoid villi

37
Q

at what pressures will the CSF not be absorbed by the arachnoid villi?

A

at pressures below 68 mmCSF

38
Q

what is the normal pressure in the brain?

A

112 mm CSF

39
Q

Capillaries in the brain have two components that limit exchange. What are they?

A

tight junctions between endothelial cells and glial end feet that come into close contact with the blood vessel

40
Q

What are the four substances that absolutely need to cross the BBB?

A

H2O, CO2, O2, and free steroid hormones

41
Q

how does H2O cross the BBB?

A

via a AQP 4 channel

42
Q

how does CO2 get out of the CSF?

A

it is lipid soluble

43
Q

how does O2 move from the blood vessel into the neuron?

A

it is lipid soluble

44
Q

How does glucose cross the endothelial cell?

A

the 55 K Glut 1 transporter

45
Q

How does glucose cross the glial end foot?

A

the 45 K Glut 1 transporter

46
Q

How does glucose get into the neuron?

A

using the Glut 3 transporter

47
Q

What is present in the CSF that keeps the composition of ions in check?

A

the Na/K/2Cl transporter

48
Q

How is the expression of the Na/K/2Cl transporter controlled?

A

by the release of two peptides released from the endothelial cells of the blood vessels–> endothelin 1 and endothelin 3

49
Q

There are a lot of drugs and chemical that still cross the BBB. How does the brain account for this?

A

those drugs are moved back to the blood via p-glycoprotein (MDR-1)

50
Q

the maintenance of the electrolyte composition is particularly related to what ion?

A

K+

51
Q

What does it mean when we say we are going to handicap the BBB?

A

in the 4 regions that need it, the capillaries do not have tight junctions between the endothelial cells

52
Q

What are the four circumventricular organs?

A

the posterior pituitary, the area postrema, the OVLT, and the subfornical organ

53
Q

why does the posterior pituitary need access to the blood?

A

it releases hormones into the blood

54
Q

why does the area postrema need access to the blood?

A

it induces vomiting as a protection mechanism if there is a toxin in the blood

55
Q

why do the OVLT and subfornical organ need access to the blood?

A

they both control water/ thirst/ and blood volume control

56
Q

what is the significance of the sympathetics causing vasoconstriction to happen prior to the capillaries?

A

it will increase the systemic vascular resistance but it protects the capillaries in the brain and the BBB from damage

57
Q

What is the net result of the first step of CSF production?

A

the hydrostatic pressure in the capillary dominates everything and pushes water out into the ventricle

Neuroendocrine Exam 2 (17 decks)

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