Physiology

Question 1

How much CSF is present in the CNS at any one time? How often is it replaced?

Answer 1

150mL, replaced 3-4 times per day

Question 2

Why is the CSF important to the brain/ spinal cord?

Answer 2

Supplies the spine and brain with nutrients, removes metabolites

Question 3

What are the 3 main functions of the CSF?

Answer 3

1) Mechanical protection (shock absorbing)
2) Homeostatic function (maintains pH)
3) Circulation

Question 4

Normal CSF has lots of/ little protein, how many cells per mL?

Answer 4

Little protein and only 1-5 cells per mL

Question 5

Which structure in embryological development gives rise to the brain’s ventricles?

Answer 5

Neural canal

Question 6

What’s the earliest structure in the developing choroid plexus?

Answer 6

Choroid fissure

Question 7

The choroid plexus is found in which brain ventricles?

Answer 7

3rd, 4th and lateral ventricles

Question 8

CSF secretion involves the transport of which specific ions?

Answer 8

Sodium, calcium and bicarbonate (from blood to CSF)

Question 9

Chloride and sodium ion concentration is higher in the CSF/blood?

Answer 9

CSF

Question 10

T/F: Production of CSF is dependent upon arterial blood pressure?

Answer 10

False - it is an active process dependent mainly on moving of ions

Question 11

Which structure connects the lateral to the third ventricle?

Answer 11

Intraventricular foramina / Foramen of Monroe

Question 12

Which structure connects the third ventricle to the fourth?

Answer 12

Cerebral Aqueduct of Sylvius

Question 13

Which structure connects the fourth ventricle to the subarachnoid space (median side)?

Answer 13

Foramen of Magendie (single)

Question 14

Which structure connects the fourth ventricle to the subarachnoid space (lateral)?

Answer 14

Foramen of Luschka (paired)

Question 15

Where is the “starting point” for producing CSF?

Answer 15

Lateral ventricle

Question 16

The CSF enters the subarachnoid space through how many openings in the roof of which ventricle?

Answer 16

3 openings in the roof of the fourth ventricle (single median and 2 paired lateral apertures)

Question 17

How does CSF return to the venous blood?

Answer 17

Through the arachnoid granulations in the superior sagital sinus

Question 18

Which junctions are present at the BBB?

Answer 18

Tight

Question 19

Do all parts of the brain have a BBB?

Answer 19

No (e.g. pineal gland)

Question 20

Tight junctions of the BBB prevent which type of movement?

Answer 20

Paracellular movement

Question 21

Hydrocephalus is what condition

Answer 21

Accumulation of CSF within the ventricular system around the brain

Question 22

Does a normal CT rule out raised intracranial pressure?

Answer 22

No - due to idiopathic intracranial hypertension (no imaging features of hydrocephalus, symptoms of excess present (e.g. visual disturbance due to papillodema))

Question 23

Where is the aqueous humour produced? Is this an active/passive process?

Answer 23

Ciliary body - active process

Question 24

Which drugs can be used to halt aqueous humour production (and example)?

Answer 24

Carbonic anhydrase inhibitor (examples: dorzolamide)

Question 25

What's the volume of the posterior chamber of the anterior segment?

Answer 25

60mL

Question 26

What's the volume of the anterior chamber of the anterior segment?

Answer 26

250mL

Question 27

What's the normal IOP of the anterior segment?

Answer 27

17mmHg

Question 28

The aqueous of which part of the anterior segment is replaced faster in which chamber: anterior or posterior?

Answer 28

Posterior

Question 29

What are the 4 main regions in the photoreceptors?

Answer 29

Outer segment, inner segment, cell body, synaptic terminal

Question 30

What's the basis of phototransduction?

Answer 30

Resting potential of a photoreceptor is around -20mV, when exposed to light this hyperolarises.

Question 31

Why is the resting photoreceptor potential slightly more positive than other neurones?

Answer 31

The Dark Current (a cAMP-gated sodium channel that opens in dark and closes in the light)

Question 32

Rods are better at seeing in bright/ dim light?

Answer 32

Dim

Question 33

Visual acuity is determined by which 2 factors

Answer 33

Photoreceptor spacing & refractive power

Question 34

Cones are better at seeing in bright/ dim light?

Answer 34

Bright

Question 35

What is convergence, in relation to vision?

Answer 35

The number of cells transmitting to a ganglion (high convergence = many cells)

Question 36

How many photoreceptor types are present in colour vision?

Answer 36

4 (rods and blue, green and red cones)

Question 37

Which photoreceptor type is present at the fovea?

Answer 37

Cones

Question 38

Do cones have low or high convergence?

Answer 38

Low (greatest acuity)

Question 39

Do rods have low or hgih convergence?

Answer 39

High (lower acuity, better sensitivity)

Question 40

Which photoreceptor has higher visual acuity?

Answer 40

Cones

Question 41

What is the bigger visual field: nasal or temporal?

Answer 41

Nasal