Module B-07 Flashcards

1
Q

Which are the 3 extracellular fluid compartments and the volume of each?

A

1) Plasma
2) Interstitial fluid
3) CSF

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2
Q

Where is majority of fluid of body found ?

A

Intracellular 60%

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3
Q

Where is CSF found?

A

1) Intraventricular (23ml)

2) Subarachnoid space (67-117 ml)

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4
Q

volume of CSF

A

90-140ml

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5
Q

4 functions of CSF

A

1) Maintains Extracellular environment
2) Removes metabolites from CNS
3) regulated cerebral blood flow and pulomonary ventilation
4) Cushions brain

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6
Q

How does CSF influence cerebral blood flow and pulmonary ventilation?

A

Owing to changes in its pH

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7
Q

What is present in high levels in CSF compared to plasma?

A

Cl-, Mg++ and Na+ (only slightly higher)

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8
Q

What is present in low levels in CSF compared to palsma

A

protein, glucose, K+ ,Ca++

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9
Q

At what levels is lumbar puncture done

A

L3/L4 or L4/L5

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10
Q

What is relevance of a lumbar puncture?

A

1) analysis of CSF

2) measurement of intracranial pressure

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11
Q

4 adverse effects of Elevated intracranial pressure (ICP)

A

1) Nausea
2) Bradycardia
3) Systemic hypertension
4) Papilledema

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12
Q

What does the Monroe-Kellie Doctrine state?

A

An increase in volume of one component (e.g., brain, blood, or cerebrospinal fluid) will elevate pressure (ICP) or decrease the volume of one of the other elements.

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13
Q

What are the 3 components of the Blood Brain Barrier

A

1) Endothelial cells,
2) Astrocytic endfeet
3) Capillary basement membranes

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14
Q

What are 2 characteristics of capillaries of the brain

A

lack fenestrations and have tight junctions to prevent paracellular flow (only Transcellular flow takes place)

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15
Q

What can pass through the BBB?

A

Small hydrophobic molecules, blood gases, small uncharged polar molecules,urea and glycerol

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16
Q

The higher the Oil/water partition coefficient the ____ (less/more) effective the transfer of the solute across the BBB

A

more

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17
Q

What are 2 substances moved by facilitated diffusion across the BBB

A

L-DOPA and Glucose

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18
Q

Ratio of solubility in oil versus water predicts

A

transcellular transfer of solutes into CNS

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19
Q

What transporter is used in BBB endothelial cells for glucose transport?

A

GLUT-1

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20
Q

What transporter is used in BBB endothelial cells for L-DOPA transport?

A

Neutral amino acid carrier

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21
Q

How does glycine cross the BBB (brain to blood)

A

Na+-dependent cotransporter ( secondary active transport)

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22
Q

What can cause the tight junctions of BBB to become leaky?

A

1) Hypertension (high blood pressure)
2) Hyperosmolality
3) Trauma, ischemia, inflammation or pressure
4) Infection

23
Q

How does hyperosmolarity cause leaky endothelium

A

hypertonic infusions shrink endothelial cells and disable tight junction but this is reversible

24
Q

Clinical use of hyperosmolarity with BBB

A

may permit delivery of lipid-insoluble drugs to

the CNS

25
Q

What differs circumventricular organs from rest of CNS

A

lack tight junctions in capillaries and thus lack

the BBB

26
Q

Name the Circumventricular organs

A

1) Area postrema
2) Median eminence
3) Neurohypophysis
4) Organum vasculosum
5) Pineal body
6) Subcommissural organ
7) Subfornical organ

27
Q

What cells line the ventricles

A

Ependymal cells (group1)

28
Q

What cells form the choroid plexuses?

A

Secretory Ependymal cells (group 2 )

29
Q

where does CSF circulate?

A

the ventricles, the spinal canal and the entire

subarachnoid space

30
Q

Where does CSF come from?

A

1) Choroid plexus (70%)

2) specialized secretory ependymal cells of the subcommisural organ (30%)

31
Q

How is CSF transported by choroid plexus?

A
  • co-transporters for Na+ , K+ and Cl in the basolateral membrane
  • co-transporters for K+ and Cl ions in the microvilli
    of the apical membrane.
  • The membranes also have ion channels for Na+, K+
    and Cl in addition to Na/K pumps.
  • net transport of Na+, K+ and Cl into ventricles, with water following by local osmosis.
  • transport of water also involves specific water
    channels (aquaporins) of which AQP1 is expressed in the choroid plexus.
32
Q

How much CSF is produced per day?

A

500ml per day

33
Q

CSF accumulation leads to________

A

Hydrocephalus

34
Q

Where does CSF drain into

A

Subarachnoid space=> Arachnoid villi(granulations) =>Superior Sagittal SInus => venous system

35
Q

CSF composition: Increased protein, normal glucose, RBCs present

A

Subarachnoid hemmorhage

36
Q

CSF composition: Very high protein, normal glucose, few WBCs present

A

Guillian-Barre syndrome

37
Q

CSF composition: increased protein, normal to decreased glucose, Increased number of WBC Tumor cells

A

Metastatic cancer in the meninges

38
Q

CSF composition: Increased protein, normal glucose, excessive WBCs (lymphocytes)

A

Viral meningitis

39
Q

CSF composition: Increased protein, Decreased glucose, increased WBCs (lymphocytes)

A

Tubercular meningitis

40
Q

CSF composition: Increased protein, decreased glucose, increased number of WBCs (polymorphonuclear leukocytes)

A

Bacterial Meningitis

41
Q

Where are changes in CSF composition detected in the CNS

A

CSF osmolality are sensed by mechanosensitive, nonselective cation channels expressed in the supraoptic and paraventricular nuclei.
These nuclei also bear osmolarity sensing volume regulated anion channels in glial cells

42
Q

2 types of hydrocephalus

A

noncommunicating( obstructive)

communicating

43
Q

Common feature of both types of hydrocephalus

A

increased ventricular volume

44
Q

What causes Obstructive hydrocephalus

A

obstruction (conegnital or cellular debris)of

  • interventricular foramina,
  • cerebral aqueduct
  • or foramina of fourth ventricle
45
Q

What causes Communicating hydrocephalus

A

• Overproduction – Choroid tumor
• Insufficient drainage – Malfunction of arachnoid villi
• Ex vacuo – Enlargement secondary to tissue
loss

46
Q

What happens in Hydrocephalus ex vacuo

A

ventricular enlargement arises as spatial compensation for neurodegenerative losses of brain mass without increasing
intracranial pressure

47
Q

what happens in Normal pressure hydorcephalus

A

Transient increases in ICP ( not seen in older patients)

48
Q

What forms blood CSF barrier

A

Choroid plexus

49
Q

what is brain edema?

A

localized or generalized excess accumulation of water in the intracellular and/or extracellular spaces of both the grey and white matter

50
Q

Two types of Brain edema

A

1) Vasogenic

2) Cytotoxic

51
Q

What causes Vasogenic edema?

A

disruption of the BBB => increase in capillary permeability

52
Q

What causes cytotoxic edema

A
  • tissue damage or by an inadequate blood supply to neurons and glia.
  • When the Na/K pump eventually fails in the ATP-starved cells, ionic gradients dissipate, leading to cellular
    swelling
53
Q

Treatment fro Brain edema

A

Osmotherapy

54
Q

Why arent astrocytes damaged during brain edema

A

capable of regulating their cellular volume

after the initial swelling