Week 10 & 11

Question 1

Nociceptor specifications

Answer 1

• Free nerve endings
• Aδ / C fibers

Question 2

Mechanical nociceptors

Answer 2

Aδ fibers

Question 3

Thermal nociceptors

Answer 3

Aδ fibers
- Heat: 45+
- Cold: <5-10

Question 4

CONTINUE

Answer 4

Pg234

Question 5

Aqueous humor role

Answer 5

Gives nutrients to Lens & Cornea because they lack blood supply

Question 6

Intraocular pressure

Answer 6

15 mmHg

Question 7

Glaucoma

Answer 7

Intraocular pressure increases and eventually presses on the optic nerve
= Blindness

Question 8

Focal length (f)

Answer 8

Distance between Lens & Focal point

Question 9

Focal power (D)

Answer 9

Reciprocal of focal length
D = 1/f
(Dioptre)

Question 10

Lens equation

Answer 10

1/o + 1/i = 1/f

Question 11

Miosis of eye

Answer 11

Pupil constriction

Question 12

Cilliary muscle innervation

Answer 12

Oculomotor Nerve CN III
(ACh - mAChR)
(Atropine antagonist)

Question 13

Accommodation Efferent limb

Answer 13

1) Edinger westphal nucleus
2) Ciliary ggl (PARA)
3) Ciliary muscles & pupil constrictors
4) Oculomotor Nucleus
5) External eye muscles

Question 14

Presbyopia

Answer 14

Decrease in lens elasticity with age

Question 15

What happens when Ciliary muscle contracts?

Answer 15

Suspensory ligaments shorten, lens becomes more round, Increased focal power

Question 16

Myopia and Hyperopia correction

Answer 16

• Hyperopia: Convex lens
• Myopia: Concave lens

Question 17

Visual acuity test

Answer 17

Snellen Chart

Question 18

Scotopic Vision

Answer 18

Only rods used in low light so no color vision

Question 19

Mesopic Vision

Answer 19

Intermediate between scotopic and photopic vision

Question 20

Photopic Vision

Answer 20

Only cones used since rods are saturated at high light intensity

Question 21

Rhodopsin

Answer 21

• GPCR
• Opsin (7TM) & 11-cis retinol
• When light hits 11-cis turns to all trans = activation

Question 22

Vitamin A deficiency in eyes

Answer 22

Leads to Blindness

Question 23

Rods Phototransduction

Answer 23

1) 11-cis retinol, all-trans retinol, meta-rhodopsin-II
2) MRII activates Transducin
3) Transducin (a) act. cGMP PDE
4) PDE degrades cGMP
5) CNG channels close, no Na+ influx
6) Hyperpolarization = no NT

Question 24

High amplification of eye cascade

Answer 24

1 rhodopsin - 700 Gt (transducin) - 700 PDE - 1400 cGMP - 230 closed CNG channels

Question 25

Critical Flicker-Fusion Frequency (CFF)

Answer 25

Frequency at which a flickering light is perceived as continuous

Question 26

Termination of Rhodopsin Signaling

Answer 26

1) Rhodopsin Kinase phosph. receptor 2) Arrestin prevents Gt (transducin) binding - bleaching, retinol removed 3) All-trans retinol converted to 11-cis retinol in pigment ep.

Question 27

Cornea refractive power

Answer 27

40 D

Question 28

Lens refractive power

Answer 28

20 D (relaxed) / 30 D (near)

Question 29

Resting & Accommodation eye power

Answer 29

60D resting 70D accommodation