Physiology

Question 1

Hydrocephalus

Answer 1

Obstruction of CSF flow/increased production
Enlarged ventricles
Headache, N+V, visual disturbance, coma

Question 2

CSF production involves transport of what ions?

Answer 2

Na, Cl, HCO3-

Question 3

CSF compared with plasma

Answer 3

Lower K, gluose, bicarb and protein

Higher, Na and Cl

Question 4

BBB consists of

Answer 4

Endothelium
Basal membrane
Perivascular astrocytes

Question 5

Tumours associatd with the venricles

Answer 5

Colloid cyst (glioma at IV foramen)
Pinealoma (pineal gland in midbrain)
Ependymoma (glioma of ependymal cells of ventricles, kids)
Choroid plexus tumours (kids)

Question 6

Epidural haematoma

Answer 6

Between skull and dura

Question 7

Subdural haematoma

Answer 7

Between dura and arachnoid

Question 8

Normal pressure hydrocephalus

Answer 8

Incontinence, dementia, gait disturbance

Question 9

Idiopathic Intracranial HT

Answer 9

Obese females, childbearing age
Headache, visual disturbance, papilloedema, NO imaging features
Tx: weight loss, meds, shunt

Question 10

Papilloedema

Answer 10

Optic disc swelling due to raised ICP
Blind spot, blurring, loss of vision
Bulging optic disc, flame haemorrhage
Bilateral

Question 11

2 layers of ciliary body epithelium

Answer 11

Inner pigmented epithelium

Outer non-pigmented epithelium

Question 12

How is aqueous formed?

Answer 12

Net movement of NaCl from IF to aqueous = water follows

Question 13

Which is replaced faster, posterior or anterior chamber?

Answer 13

Posterior

Question 14

CA inhibitors

Answer 14

Reduce production of aqueous = treats glaucoma (blocks NaCl and water)
Dorzolamide - local
Acetazolamide - systemic effect on kidney = acidosis

Question 15

Transduction

Answer 15

Light to electrical energy

Question 16

Layers light has to cross

Answer 16

Ganglion cells
Bipolar cells
Photoreceptors

Question 17

Horizontal cells

Answer 17

Receive from photoreceptors

Transmit to photoreceptors and bipolar cells

Question 18

Amacrine cells

Answer 18

Receive from bipolar cells

Transmit to bipolar cells and ganglion cells

Question 19

Constant/Dark current

Answer 19

More active in dark (more depolarisation = more glutamate released), Na channel open (positive charge enters = depol)

Question 20

Resting membrane potential

Answer 20

-20mV

Question 21

What happens with light exposure?

Answer 21

Hyperpolarisation (more negative)

Na channel closes

Question 22

In the dark which is greater Pna or Pk?

Answer 22

Pna = Pk

Question 23

In the light which is greater Pna or Pk?

Answer 23

Pk is greater than Pna

Question 24

Rhodopsin

Answer 24

Visual pigment molecules

Allows reactions to different amounts of light

Question 25

Light converts 11-cis-retinal to:

Answer 25

all-trans-retinal (activated form of rhodopsin)

Question 26

What does all-trans-retinal do?

Answer 26

Decreases cGMP = closes Na channel = hyperpol

Question 27

More or less glutamate in the dark?

Answer 27

More glutamate in dark | Less glutamate in light

Question 28

Define visual acuity

Answer 28

Ability to distinguish between 2 points (determined by photoreceptor spacing)

Question 29

Rods activated in:

Answer 29

dim light

Question 30

Cones activated in:

Answer 30

bright light (less sensitive than rods)

Question 31

Acuity of rods and cones

Answer 31

Cones: high acuity Rods: low acuity

Question 32

Convergence of rods and cones

Answer 32

Cones: low convergence Rods: high convergence

Question 33

3 types of cone

Answer 33

Blue: short wave Green: middle wave Red: long wave

Question 34

Features of rods

Answer 34

``` Achromatic Peripheral retina High convergence Low acuity Sensitive ```

Question 35

Features of cones

Answer 35

``` Chromatic Central retina Low convergence High acuity Not very sensitive ```

Question 36

Define receptive field

Answer 36

Part of retina that needs to be stimulated to elicit AP from a ganglion cell

Question 37

What layer of the striate cortex are inputs segregated?

Answer 37

Layer 4 = monocular info

Question 38

In most of visual cortex inputs are segrgated into:

Answer 38

Ocular dominance columns (each column dominated by one eye)

Question 39

Amblyopia

Answer 39

Cortical blindness | One eye has better vision than the other

Question 40

Cause of amblyopia

Answer 40

Strabysmus = surgery or patch