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NSB Extra Lecture Cards > Global Brain Activity > Flashcards

Global Brain Activity Flashcards

1
Q

How does CSF differ from serum?

A

Less protein & less K

Similar Na & HCO3 & osmolality

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2
Q

What is homeostasis?

A

Maintenance of the environment to optimise conditions for the brain to work.

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3
Q

Which is the most important ion in terms of osmosis?

A

Na - H2O follows Na.

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4
Q

Where does K+ levels have significant influence?

A

In the peripheral system - important in maintaining the heart beating at the right pace.

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5
Q

How is acid-base balance affected by ventilation?

A

Hypoventilation - acidosis
Hyperventilation - alkalosis

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6
Q

What is the normal values of Na in the blood?

A

135-145

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7
Q

What is hyponatremia?

A

Low levels of Na outside the cell - means the intracellular content of Na is higher - so water floods into cells causing cerebral oedema

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8
Q

How does the brain try to compensate for hyponatremia?

A

Shifts out the CSF & pushes K+ & osmoloytes out of the cells trying to draw the water out.

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9
Q

How does cerebral oedema affect the blood flow to the brain?

A

It causes decreased blood flow.

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10
Q

What is the difference between acute and chronic hyponatremia?

A

Acute - no time to adapt - cerebral oedema & compression can occur.

Chronic - body is able to adapt if the hyponatremia is gradual.

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11
Q

How does carbamazepine affect Na levels?

A

Causes hyponatremia.

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12
Q

How does compression of the brainstem affect breathing regulation?

A

It can depress breathing

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13
Q

What is central pontine myelinolysis?

A

Hyponatremia = swollen cells - if you treat (with Na) and overcorrect - can cause shrunken cells - this damages the cytoskeleton of the cell & demyelinates neurons –> problems.

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14
Q

What are the symptoms of Central Pontine Myelinosis?

A

Quadriplegia
Emotional incontinence
Seizures
Coma
Death
Pseudobulbar Palsy

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15
Q

What is Central Pontine Myelinosis caused by?

A

Rapid overcorrection of low Na levels.

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16
Q

What is hypernatremia?

A

Lots of Na in the interstitium - water leaves cells and moves to the extracellular space = shrinkage of cells.

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17
Q

How can hypernatremia affect veins and arteries?

A

It can cause them to tear & haemorrhage

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18
Q

What does the brain do to try and compensate for hypernatremia?

A

Uptakes K+ into cells
Uptakes osmolytes into the cells

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19
Q

What can overcorrection of hypernatremia cause?

A

Cerebral oedema

20
Q

What is the ideal pH range for the brain?

A

7.35 - 7.45

21
Q

What does the Henderson Hasselbach equation demonstrate?

A

That there is an inverse relationship between HCO3 and CO2.

22
Q

Can CO2 cross the BBB?

A

Yes - easily

23
Q

What regulates cerebral blood flow?

A

CO2 levels in the brain (more CO2 - inc BF & vice versa)

24
Q

How does hyperventilation affect Ca?

A

Causes hypocalcemia.

25
Q

What are the symptoms of hyperventilation?

A

Lightheadedness, syncope, seizures & hypocalcaemia

26
Q

What are the symptoms of hypoventilation?

A

Morning headaches, visual disturbances, confusion

27
Q

How does hypoventilation affect the brain?

A

Increased CO2 = inc blood flow to the brain - causing increase pressure - - headaches, disturbances and confusion.

28
Q

Apart from Na, K, HCO3 - which other ions have impacts on the brain?

A

Ca, Mg & P

Ca & Mg - help stabilise neuronal signalling pathways - so low levels = abnormal firing.

29
Q

What is it called when the brain is affected by an external agent or condition.

A

Encephalopathy

30
Q

Hypocalcaemia is associated with low/high levels of which ions?

A

Low K & Mg
High P

31
Q

What does a CT scan with contrast show?

A

If there is breakdown of the BBB

32
Q

What are CT scans based on?

A

Density of different materials

33
Q

What does windowing and levelling do?

A

Allows you get change the pictures you get - and therefore see different materials with different densities - e.g. brain window, bone window, blood window.

34
Q

What are the pros of CT?

A

Quick
Metal compatible
Cheap

35
Q

What are the disadvantages of CT?

A

Low resolution - esp brainstem / cerebellum
Radiation dose

36
Q

What does CT use to image?

A

Lots of X-rays

37
Q

What does MRI use to image?

A

The magnetism of proton molecules

38
Q

Why is MRI preferable over CT?

A

You get more detailed pictures with MRI than CT

39
Q

How can dye show if the BBB is leaky?

A

Dye should remain in the arterial / vascular systems - if there is an injury to the BBB you will get leakiness of the dye into other areas.

40
Q

What are the pros of MRI?

A

Detailed
Wide range of imagining possibilities
No ionising radiation

41
Q

What are the cons of MRI?

A

Metal = issue
Claustrophobia
Time consuming
Loud
Can heat up the body

42
Q

What is an fMRI?

A

Uses characteristics of oxy & deoxy - measures local neuronal activity based on vascular response to glucose - shows which areas of the brain are metabolising glucose.

43
Q

How does transport of glucose affect vessels?

A

Causes the BVs to dilate

44
Q

What are default areas on an fMRI?

A

Areas where the brain is always metabolising - is the background system running when no specific task is assigned.

45
Q

How does PET-CT work?

A

Injection with radioactive substance - uses CT to outline where in the body this is.

46
Q

What are the cons of PET-CT?

A

Radioactive isotopes
Very expensive - used sparingly

47
Q

What is used to determine whether a tremor is Parkinsons?

A

SPECT (single photon emission computed tomography)

NSB Extra Lecture Cards (7 decks)

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