Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

.. > Cerebral Blood Flow And CNS Homeostasis > Flashcards

Cerebral Blood Flow And CNS Homeostasis Flashcards

1
Q

What ion in particular alters the RMP and thus excitability of the nuerons in the brain?

A

Changes in the concentration of potassium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

How is the CSF recirculated?

A

It’s not!!

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

How much CSF Is made per day?

A

550 mL

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

How much CSF do we have at any given point in time?

A

150 mL

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are the two lateral ventricles separated by?

A

Septum pellucidum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the ventricular system made of?

A

4 ventricles

2 lateral
3rd
4th

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What connects the lateral ventricle to the 3rd?

A

Intraventricular foramen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What connects the 3rd ventricle to the 4th?

A

Cerebral aqueduct

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What connects the 4th ventricle to the cisternae magna?

A

Median aperture

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What connects the 4th ventricle to the arachnoid space?

A

Lateral aperture

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What makes CSF?

A

Choroid plexus (50-70%)

Tissues lining ventricles and blood vessels (remaining %)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are the 2 stages of CSF production?

A

1 - passive filtration of plasma across choroidal capillary endothelium

2 - modification of composition of choroid plexus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What drive the passive filtration of plasma across choroidal capillary endothelium?

A

Pressure gradients

Hydrostatic and oncotic pressures

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the biggest factor in the getting plasma across choroidal capillary endothelium?

A

Hydrostatic pressure inside the capillary

Aka Blood pressure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are the two hydrostatic pressures present in stage 1 of CSF production?

A

Inside cap hydrostatic pressure (BP)

Outside cap hydrostatic pressure (tissue hydrostatic press.)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are the two oncotic pressures present in stage 1 of CSF production?

Which is greater? What do they do?

A

Oncotic P of tissue (pushes out)
Oncotic P of cap. (Pushes in)

Equal to each other
Cancel each other out

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Is blood pressure or tissue hydrostatic pressure greater?

A

Blood pressure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

How is the entry of HCO3, Cl, and K into the choroid plexus CSF controlled?

A

Via channels on apical surface of epithelial cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

How is the entry of water to choroid plexus CSF controlled?

A

Aquaporin 1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

How does production of CSF change w/ ICP?

A

Constant over a wide range of ICP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

CSF has similar concentration to plasma in what?

A

Sodium

HCO3

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What is high in CSF than in Plasma?

A

Magnesium
CO2
Creatine
Chloride

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is the role of Mg in the CSF?

A

Blocker of calcium channels

Controls calcium influx into brain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Why is CO2 greater in CSF than plasma?

A

Greater levels of activity in brain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What is lower in the CSF than in the plasma?

A

Potassium
Calcium
Protein
Glucose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Why is potassium lower in CSF than plasma?

A

K leak channels on neurons alter RMP and change extracellular K level

Could impact Vm of neurons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Why is calcium lower in CSF than plasma?

A

Natural blocker of voltage gate Na channels

Could be toxic to excitable tissues in high concentrations

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What are the pHs of CSF and plasma?

A

7.33 and 7.4

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

WHat is the flow of CSF?

A

One way path where it is reasbored by arachnoid villi at the end

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

What is the pathway for the flow of CSF?

A

Ventricle —> foramen of magendie and Luschka —> subarachnoid space

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

Where are arachnoid villi present?

A

Subarachnoid space

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

What are villi?

A

Extensions wher earachnoid membrane is fused with the endothelium of sinus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

Where do the villi extend into?

A

Into venous sinuses

Mostly superior sagittal sinus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

What is the flow of CSF across the arachnoid membrane considered to be mostly? What is also seen?

A

Most is build flow

Pinocytosis w/ mesothelial cells of arachnoid villi

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

What is the average pressure of the CSF?

A

112 mm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

Can CSF be compressed?

A

No

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

What is the absorption of the CSF proportional to?

A

Intracranial pressure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

At what pressure will absorption not continue?

A

68 mm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

what is the function of the CSF?

A

Protection of the brain by providing it buoyancy

40
Q

What is the weight of the brain without the CSF? W/ CSF?

A

1400 g

50 g

41
Q

How is the BBB made?

A

Endothelial cells with tight junctions

Glial endfeet covering capillaries

42
Q

What does the BBB allow for?

A

Capillary modification that control the diffusion out of the capillary

43
Q

What does the tight control of the BBB result in?

A

Prevention of proteins from entering CSF

Reduced movement of many smaller molecules

44
Q

What can enter the BBB via passive diffusion?

A

Water
Oxygen
CO2
Free steroid hormones

45
Q

How does water enter the BBB?

A

Passive diffusion via Aquaporin4 (AQP4)

46
Q

What are the 2 forms of AQP4?

A

Monomer responsible for water movement

Tetramer that forms distinct freeze fractures and plays role in gas transport

47
Q

What do AQP4s control?

A

Overall water homeostasis, protective against cerebral edema

Impacts neuronal function - even indirectly

48
Q

What uses mediated transport to get across BBB?

A

Glucose

Na
K
CL

49
Q

What does glucose use to get from the blood to the CSF?

How does glucose get from blood to neurons?

A

Glut 1 - insulin independent

Glut 3 - insulin dependent

50
Q

Where is glut 3 found?

A

On neuronal cell membranes

51
Q

What are the 2 forms of Glut 1?

Where are they found?

A

Glut1 55k - on endothelial cells of capillaries

Glut1 45k- on astroglia/podocytes

52
Q

What is glut5 used by?

A

Microglia

53
Q

How do Na, k and CL cross bbb?

Where are they moving from and to?

A

Na/K/2Cl transporter

From CSF to blood

54
Q

What controls the expression of the Na/K/2cl transporter?

A

Endothelial cells of blood vessels need to express

Endothelin 1 and 3

(Expression tied to astrocytes)

55
Q

How are drugs transported back to the blood after tossing the BBB?

A

P-glycoprotein (pump)

56
Q

What does P-glycoprotein bind to?

A

A WIDE variety of substances

57
Q

What is the role of P-glycoprotein?

A

Limits brain exposure to drugs that are systematically delivered

58
Q

Where else is P-glycoprotein located besides the brain?

A

Gut

59
Q

What are the functions of the BBB (more specific)

A

Protect chemical composition of CSF from blood borne agents

Maintains Vm - by maintaining ionic composition of CSF
(Particularly potassium)

Protects brain from endogenous and exogenous poison

Prevents NTRs from escaping into general circulation

60
Q

What are the circumventricular organs?

A

Posterior pituitary
Area postrema
Organum vasculosum of lamina terminalis
Subfornical organ

61
Q

What is special about the circumventricular organs?

A

They do not have tight BBB

Endothelial cell’s capillaries do not have tight junctions between them, caps are fenestrated

Allows chemicals to move freely from blood to CSF in these organs.

62
Q

Why is it important that the posterior pituitary be a circumventricular organ?

A

Modified neural tissue that needs to release hormones into the blood in response to blood driven messages

(Also Called neruohypoPhysis)

63
Q

Why is it important that the area postrema be a circumventricular organ?

Where is it located?

A

Caudal portion of 4th ventricle

Chemotactic trigger zone that has a role in detecting irritants/poisons in blood

Initiates vomiting

64
Q

Why is it important that the organum vasculosum be a circumventricular organ?

A

Osmoreceptor for ADH (vasopressin)

Controls body water, thirst and blood volume

65
Q

Why is it important that the Subfornical organ be a circumventricular organ?

A

Control body water, thirst and blood volume

Along with Organum vasculosum

66
Q

How much blood does the brain require a minute?

What percent of the blood from the heart is used for this?

A

750 ml/min

14% of blood pumped from heart every minute

67
Q

What is the arterial supply for cerebral blood flow?

A

2 ICAs + basilar a. = circle of Willis

68
Q

What makes the Basilar a.?

A

2 vertebral As. That unite to form basilar a.

69
Q

Why is reduced blood flow to a vessel of circle of willis bad?

A

Very little mixing/crossing of blood in circle of willis

Disrupted blood flow can not be corrected by other vesicles

70
Q

What does the interruption of blood flow in the circle of willis allow for?

A

Gives specific neurological signs that allow us to pinpoint damage

71
Q

What is the venous drainage of cerebral blood?

A

Deep veins and dural sinuses to IJV

72
Q

What provides innervation to cerebral vasculature?

A

Sympathetic fibers
Parasympathetic fibers
Sensory axons

73
Q

What NTRs do the sympathetic fibers to cerebral vasculature release?

A

NE

Neuropeptide Y

74
Q

What receptors are heavily present for cerebral vasculature and sympathetic fibers?
What will these cause?

A

Alpha-adrenergic receptors

Vasoconstriction

75
Q

When are the sympathetic fibers to cerebral vasculature activated?

A

When systemic BP is increased beyond normal limits

Causing constriction and reduces BP in capillaries in brain - limiting damage to BBB due to hypertension

76
Q

What will hypertension do to the BBB?

A

Disrupt tight junctions of BBB

77
Q

What are the NTRs present in the parasympathetic innervation to cerebral blood flow?

A

ACh
Vasoactive intestinal polypeptide (VIP)
PHM-27 (from pre-pro-VIP)

78
Q

What does parasympathetic innervation to cerebral vasculature cause?

A

Vasodilation

79
Q

Where do we find sensory axons for cerebral blood flow?

A

On smaller arteries, where they are released and act back on the blood vessels

80
Q

What are the sensory axons of cerebral vasculature sensitive to?

What do they release?

Causing what?

A

Sensitive to stretch and torsion of blood vessels

Contain substance p, neurokinin a, and calcitonin gene-related peptide (CGRP)

Vasodilation

81
Q

What happens if the CSF is reduced?

A

Brain is heavier and simple motion can cause pain bc of the torsion of blood vessels

82
Q

What will activation due to torsion of the sensory neurons cause?

A

Vasodilation and increased blood flow bc they are trying to return intracranial volume closer to normal

83
Q

What is cerebral blood flow controlled under mostly?

A

Local control via O2 consumption (activity level dependent)

84
Q

What happens with increased ICP?

A

Reduced blood flow because of compression of blood vessels

85
Q

What happens with decreased ICP?

A

Increased torsion of blood vessels and nerve fibers due to loss of buoyancy

86
Q

What can cause decreased ICP?

A

Lumbar puncture

87
Q

how is perfusion pressure constant over a wide range of systemic mean arterial blood pressure?

A

Autoregulation system of MABP

88
Q

What happens with the Autoregulation system when

Systemic BP is increased?

A

Sympathetics are more active

Release NE —> alpha a Rs —> vasoconstrict

89
Q

What is the result of activating sympathetics when systemic BP is increased?

A

BBB is protected due to constriction of cerebral vasculature, thus preserving brain

Makes sure tight junctions are not damaged bc it wont transmit pressure from systemic system to capillaries

90
Q

What happens with the Autoregulation system when

Systemic BP is decreased?

A

Brainstem detects and controls BP and acts to increase it

91
Q

If BP is low due to hemorrhage/shock what will the brainstem do?

A

Reinforce actions of baroreceptors- activating presser region, activate sympathetics to cause vasoconstriction and increase BP

92
Q

When the sympathetics vasoconstrict cerebral vasculature what does this cause?
For what trade off?

A

Causes increased systemic vascular resistance And can damage body

BUT

It protects caps in brain and the BBB from damage

93
Q

Cerebrovascular is heavily influenced by?

A

Intracranial pressure

94
Q

What will increased ICP cause in terms of cerebrovasculature?

What will this cause in medulla?

A

Reduced blood flow bc of compressed vessels —> reduced arterial flow

Less blood flow to brain activation cardiovascular control centers in medulla - makes systemic BP increase

95
Q

What does an increase of BP indicate in terms of brain?

A

Increased ICP

Due to that reduced blood flow - medulla activation feedback

96
Q

What can cause an increase in ICP ?

A

Hydrocephalus of any variety

Cerebral edema

Intracranial bleeding (from stroke, etc.)

97
Q

If blood flow to the brain is compromised what will the brain do?

What is the consequence?

A

Will drive SYSTEMIC BP UP to force blood to brain

Systemic BP driven up VERY very high so that brain can get blood

.. (19 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions