Global Brain Activity

Question 1

Does plasma and CSF have similar ionic compositions?

Answer 1

No. CSF - less protein + K+.
Similar Na+, HCO3- and osmolarity.

Question 2

Is the osmolarity of plasma and CSF the same?

Answer 2

Yes

Question 3

Does K+ directly affect the brain?

Answer 3

No, usually affects heart first then a secondary affect on brain.

Question 4

Which ion is fundamental for osmolarity?

Answer 4

Na+

Question 5

Which ions can affect the brain?

Answer 5

Na+, Ca2+, Mg+, P

Question 6

What is the normal range for Na+?

Answer 6

135-145mmol/L

Question 7

What happens to a cell in hyponatraemia?

Answer 7

Too much water outside of the cell with Na+, so water moves in + swells cell

Question 8

How does hyponatraemia affect the brain?

Answer 8

Cells in brain swell due to water moving into cell to (cerebral oedema), which causes decreased blood flow and cerebral compression.

Question 9

How does the brain compensate in acute hyponatraemia?

Answer 9

Shifts out CSF into systemic circulation, then pushes K+ out to try and also draw water out of cell.
It also pushes other molecules out to shift water + stop cells continuing to expand.

Question 10

What is beer potomania?

Answer 10

Drink large amounts of beer cause dilutional hyponatraemia, no time for compensation mechanisms

Question 11

What common anti-epileptic medication causes hyponatraemia?

Answer 11

Carbamazepine

Question 12

What does it mean when the brain herniates?

Answer 12

Tissue is displaced in the brain to where it shouldn’t be

Question 13

What are some common symptoms of cerebral oedema?

Answer 13

Nausea
Vomiting
Anorexia
Headaches
Lethargy
Disorientation
Muscle cramps

Question 14

What are some common signs of cerebral oedema?

Answer 14

Seizures
Coma
Hyporeflexia
Cheyenne-stoking
Respiratory depression
Hypothermia

Question 15

What system in the brain stem affects our consciousness level?

Answer 15

Reticular activating system

Question 16

When treating chronic hyponatraemia, what should you be careful of?

Answer 16

Raising Na+ too quickly, can cause Central Pontine Myelinolysis (Osmotic Demyelination Syndrome)

Question 17

If you over correct hyponatraemia, instead of drawing water out and having a normal sized cell, what happens to the cell?

Answer 17

It shrivels + damages the cytoskeleton.
Can also get demyelination

Question 18

What can Central Pontine Myelinolysis cause?

Answer 18

Quadriplegia
Pseudobulbar Palsy
Seizures
Coma
Death

Question 19

What happens to a cell in hypernatraemia?

Answer 19

Too little water outside cell, water moves out of cell + cell shrinks

Question 20

How does hypernatraemia affect the brain?

Answer 20

Cells shrink which can cause haemorrhage from tears in veins or arteries

Question 21

How does the brain compensate in hypernatraemia?

Answer 21

Uptake K+ into cell
Uptake of osmolytes into cells (glutamine, glutamate + taurine) which are protective against cell damage

Question 22

What can an overcorrection of hypernatraemia cause?

Answer 22

Cerebral oedema

Question 23

What is the normal serum pH?

Answer 23

7.35-7.45

Question 24

What respiratory mechanism helps correct a metabolic disorder?

Answer 24

Increase or decrease in ventilation

Question 25

Can Co2 cross the BBB?

Answer 25

Yes

Question 26

How does Co2 affect cerebral blood flow?

Answer 26

Co2 regulates cerebral blood flow. More Co2 = more blood flow Less Co2 = less blood flow

Question 27

Would hyperventilation cause acidosis or alkalosis?

Answer 27

alkalosis

Question 28

Would hypoventilation cause acidosis or alkalosis?

Answer 28

Acidosis

Question 29

What are some symptoms as a result of hyperventilation?

Answer 29

Lightheadedness Syncope Seizures Hypocalcaemia

Question 30

What are some symptoms as a result of hypoventilation?

Answer 30

Morning headaches Visual disturbances Confusion

Question 31

Answer 31

Question 32

How is a pneumocephalogram done?

Answer 32

Inject air into spinal cord via lumbar puncture + then rotate patient.

Question 33

Answer 33

Question 34

Answer 34

Question 35

What do you need to change when looking at CT images, in order to look at different components of the brain?

Answer 35

Grey scale

Question 36

What are some benefits to CT scans?

Answer 36

Quick Metal compatible Cheap

Question 37

What are some downsides to CT scans?

Answer 37

Low resolution especially in the posterior fossa Radiation

Question 38

Is an MRI high or low resolution?

Answer 38

High

Question 39

What are some pro's of MRI's?

Answer 39

Detailed Wide range of imaging possibilities No ionising radiation

Question 40

What are some cons of MRI's?

Answer 40

Metal can be a problem e.g. PPM Claustrophobia Time consuming (prone to motion artefact) Loud Can heat up body

Question 41

What is an fMRI?

Answer 41

Functional MRI Brain requires glucose to be transported in, causing arterioles to dilate. Measures characteristic difference of deoxy-Hb + oxy-Hb, indirectly measuring neuronal activity based on vascular response. Poor spatial and temporal resolution.

Question 42

What is meant by default mode network?

Answer 42

Activity of the brain when doing nothing. Consists of the medial prefrontal cortex, medial parietal cortex and medial temporal lobes. Can be affected by ADHA, schizophrenia, autism + Alzheimers.

Question 43

What does nuclear medicine involve?

Answer 43

Radioactive isotope attached to a drug that can bind to an area of interest. Radioactive emissions are measured and imaged with a gamma camera. PET (Positron Emission Tomography); Inject with radioactive substance emitting positrons. Positrons collide with tissue electrons, emitting gamma rays in opposite directions.

Question 44

When might a PET scan be used?

Answer 44

Pre-surgical assessment of complex seizures where MR normal Evaluate memory loss + differentiate types of dementia

Question 45

What is a SPECT?

Answer 45

Single Photon Emission Computed Tomography 2D images from multiple angles, reconstructed into 3D. Can use isotopes with single gamma ray. Worse spatial resolution + more radiation than PET (but cheaper)

Question 46

What scan is most common to determine whether tremors are from Parkinsons?

Answer 46

DaTscan - Dopamine Transporter to ioflupane 123