Physiology / Pathology

Question 1

What chemical action occurs during phototransduction

Answer 1

Hydrolysis of cGMP by phosphodiesterase
Leads to
Closure of cation channels

Question 2

What happens to secondary lens fibres during differentiation?

Answer 2

Lost cytoplasmic organelles and nuclei during differentiation

Question 3

What is the lens capsule

Answer 3

Basement membrane

Question 4

What do burst cells in the horizontal gaze centre in pons do?

Answer 4

Initiate saccadic movement to ipsilateral side

Question 5

What NT do amacrine cells use

Answer 5

Glycine inhibtiroy

Question 6

What is the major NT between photoreceptor cells and bipolar cells

Answer 6

Glutamate

Question 7

What are the waves on a normal ERG

Answer 7

Negative a wave from photorecetpros

Positive b wave from Muller cells

Question 8

What is the equation using a Goldmann tonometer

Answer 8

IOP = (force applied to cornea + tear meniscus force - corneal rigidity) / Area of cornea applanated

IOP = (F+M-N)/A

Question 9

How does basal secretion occur in lacrimal gland?

Answer 9

Na/K/ATPase pump

Question 10

Yoke pair of right superior rectus

Answer 10

Left inferior oblique

Question 11

Hormones secreted from ant pit and post pit

Answer 11

Ant pit:
LH, FSH, TSH, ACTH, GH, prolactin

Post pit:
Oxytocin, ADH (vasopressin)

Question 12

What is Sherrington’s law

Answer 12

When an agonist receives an impulse to contract, an equivalent inhibitory impulse is sent to its antagonist, which relaxes and legthens

Question 13

Early pathological feature of DR

Answer 13

Loss of capillary pericytes

Question 14

What are risk of medial canthal BCC

Answer 14

Orbital extension

Question 15

What is xeroderma pigmentosum associated with

Answer 15

Failure of DNA repair

Autosomal recessive - failure of mutation excision repair

Question 16

What is atrophy

Answer 16

Decrease in cell size or number

Question 17

What is used to culture Neisseria?

Answer 17

Chocolate agar

Question 18

Mycobacterium culture

Answer 18

Lowenstein Jensen

Question 19

What are toll receptors?

Answer 19

Present on all cell
Mediators of innate immunity

Question 20

How can cutaneous SCC spread

Answer 20

To lymph nodes

Question 21

What are cellular mechanisms for ageing and death

Answer 21

Cross linking of DNA
Free radical generaiton
Time dependent activation of ageing and death

Question 22

What can cause autoimmune disease

Answer 22

Defect in T regulatory cells

Question 23

What drugs cause optic neuropathy

Answer 23

Ethambutol

Question 24

How does botox work

Answer 24

Inhibits acetylcholine release form the presynaptic membrane

Question 25

What is the action of penicillin

Answer 25

Cross linking of polysaccharides chains of peptidoglycan

Question 26

How do ciprofloxacin, moxifloxacin work

Answer 26

Fluoroquinolones
Inhibit DNA gyrase - interfere with DNA syntehsis

Question 27

Which abx bind to 50S subunit of ribosome

Answer 27

chloramphenicol
macrolides - erythromycin

Question 28

What does dexamethasone do

Answer 28

Increase synthesis of lipocortin

Question 29

Effect of cocaine on Horner’s syndrome

Answer 29

No dilation as lack of NA in synaptic cleft

(Cocaine inhibits reuptake of NA)

Question 30

How does pyridostigmine work?

Answer 30

Acetylcholisterase inhibitor

Question 31

X-linked recessive transmission

Answer 31

No male to male transmission