Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

BMS Neuroscience > The Eye and Retina > Flashcards

The Eye and Retina Flashcards

1
Q

Major anatomical structures in the eye

A
  • Ciliary body
  • Cornea
  • Iris
  • Retina
  • Optic nerve
  • Choroid
  • Sclera
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Tunica of the eye

A
  • Tunica fibrosa
  • Tunica vasculosa
  • Tunica interna
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Cell types in the retina

A
  • Ganglion cells
  • Amacrine cell
  • Bipolar cell
  • Horizontal cell
  • Cone
  • Rod
  • Retinal pigment epithelium (RPE)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Retinal pigment epithelium

A

Maintains photoreceptor health by transporting nutrients and recycling shed photoreceptor parts

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Bruch’s membrane

A

Extracellular matrix structure at the interface between the choroid and retina

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Rods and cones

A

Light-sensing photoreceptors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Amacrine, bipolar and horizontal cells

A

Connecting neurons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Ganglion cells

A

Transmit signals originating in the photoreceptor layer through the optic nerve and into the brain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What type of stem cell have RPE, photoreceptors and ganglion cells been differentiated from?

A

Pluripotent stem cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What does the iris do?

A

Regulates light levels

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is the pupillary constrictor?

A

Smooth circular muscle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the pupillary dilator?

A

Smooth radial muscle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Photopupillary reflex

A

Light reflex which changes pupil diameter

Occurs in both eyes even when only one is stimulated

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the pupil?

A

A hole in the retina

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is a cataract?

A

A cloudy lens

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

How do rods and cones differ?

A

Rods simply detect light whereas cones detect colour

17
Q

Where are cones concentrated?

A

Fovea

18
Q

How does the eye focus light?

A
  • Light is partially focused when it passes through the cornea
  • Then travels through the aqueous humour to the crystalline lens, which lets the eye focus on different depths
  • The light converges in the lens and travels out the other side flipped, traveling through the vitreous humour to the retina on the inner back surface of the eye, where rods and cones detect light
  • Then your brain presents a coherent, correctly-oriented image
19
Q

Resting potential of photoreceptors

A
  • 40mV
20
Q

What type of polarisation occurs when light stimulates photoreceptors?

A

Hyperpolarisation

21
Q

Phototransduction steps

A
  • Light entering the eye activates the opsin molecules in the photoreceptors
  • Activated rhodopsin causes a reduction in the cGMP intracellular concentration
  • The photoreceptor is hyperpolarized following exposure to light
22
Q

How is phototransduction terminated?

A

(1) Inactivation of rhodopsin occurs through phosphorylation by the opsin kinase, followed by the binding of arrestin to phosphorylated rhodopsin.
(2) Inactivation of transducin occurs through the hydrolysis of bound GTP to GDP (Tα-GTP to Tα-GDP) via an intrinsic GTPase activity that is accelerated by the GTPase activating protein RGS9 (regulator of G-protein signaling).
(3) Inactivation of phosphodiesterase (PDE) is coupled to the inactivation of transducin. Inactivated transducin (Tα-GDP) dissociates from PDE, resulting in a cessation of PDE-mediated cGMP hydrolysis.
(4) Activation of guanylate cyclase by guanylate cyclase activating protein (GCAP) restores cGMP levels and thus promotes the re-opening of cGMP-gated channels.

23
Q

A single photoactivated rhodopsin catalyses the activation of ____ transducin molecules

A

500

24
Q

a single activated rhodopsin can cause the hydrolysis of more than ____ molecules of cGMP per second.

A

10^5

25
Q

Duplicity theory

A

Can’t have high sensitivity and high resolution in a single receptor, hence separate systems for colour and monochrome

26
Q

Types of bipolar cells

A
  • ON

- OFF

27
Q

ON bipolar cells inhibition

A

Glutamate inhibits ON bipolar cells via metabotropic glutamate receptors

28
Q

OFF bipolar cells excitation

A

Glutamate excites OFF bipolar cells via inotropic glutamate receptors

29
Q

ON bipolar cell

A
  • Hyperpolarised in the dark
  • Depolarised by central illumination
  • Metabotropic glutamate receptors
  • Conductance increases in light
  • Light response leads to loss of inhibition by glutamate
30
Q

OFF bipolar cells

A
  • Depolarised in dark
  • Hyperpolarised by central illumination
  • Ionotropic glutamate receptors
  • Conductance decreases in light
  • Light response leads to loss of excitation by glutamate
31
Q

Retinal ganglion cell types

A
  • W
  • X
  • Y
  • Melanopsin RGCs
32
Q

W cells

A
  • Mainly from rods
  • Slow conducting
  • Broad fields, dendrites spread
  • Directional movement
  • Vision in low light
33
Q

X cells

A
  • Medium conduction
  • Small fields, dendrites not spread
  • Image formation
  • Colour vision
34
Q

Y cells

A
  • Fast conduction
  • Broad fields, dendrites spread
  • Rapid responses to changes in visual fields
35
Q

Melanopsin RGCs

A
  • Large-slow-light responsive
  • Independent of rods and cones
  • Circadian rhythm
36
Q

Why is vitamin A important in our diet?

A
  • It is the precursor for 11-cis-retinal which is important in light transduction
  • Vitamin A cannot be synthesised by humans
37
Q

Vitamin D on vision

A
  • Preventing angiogenesis (new blood vessel formation)
  • Anti-inflammatory, inflammation plays a role in the development of age-related macular degeneration (AMD)
  • Vitamin D may help prevent dry eyes by inducing cathelicidin, an anti-microbial protein that can be produced by cells in the eyes and heal eye wounds

BMS Neuroscience (23 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions