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Bpk 205 > Lec 15 > Flashcards

Lec 15 Flashcards

1
Q

Light pathway

A

1- cornea
2- aqueous humor
3- pupil
4- lens
5- vitreous fluid
6- retina (fovea)

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2
Q

Optic nerve

A

Primary neurons axon

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3
Q

Optic disk

A

Anatomical blind spot
No photoreceptor

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4
Q

Light is focused by

A

Light is bend by
Cornea (2/3)
Lens (1/3) changeable shape

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5
Q

Photoreceptors

A

Specialized cell in retina that transduce light energy to electrical signal

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6
Q

Eye lens is

A

Convex
Converging light rays on focal point
Focal point=fovea on retina

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7
Q

Light must be focused on ——— for clear vision

A

Retina
How?
Lens change its shape by accommodation

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8
Q

Accommodation is due to

A

Due to Contraction and relaxation of ciliary muscles

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9
Q

Ciliary muscle

A

Ring of smooth muscle surrounding the lens

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10
Q

Ciliary muscle is connected to lens by

A

Ligaments

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11
Q

When ciliary muscle is relaxed,

A

Lens is flattened—more distant objects can be seen

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12
Q

When ciliary muscle is contracted m,

A

Lens is rounded—closer objects can be seen

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13
Q

Presbyopia

A

Loss of accommodation due to loss of lens elasticity

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14
Q

Macula

A

Super-focused region
In the middle is fovea

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15
Q

Fovea

A

Free of neurons and blood vessels

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16
Q

Cells in order from vitreous space

A

1- retina ganglion cell—neurons
2- amacrine cell
3- bipolar neurons—intermediary
4- horizontal cell
5- cone/rods—photoreceptors
6- retina pigment epithelium—melanin absorbs excess light

17
Q

Rods and cons

A

Sensory cell/photoreceptors
Light energy—>Electrical energy
Produce Graded potential(release neurotransmitters)

Rod is dim light
Con is bright light

18
Q

Bipolar-amacrine-horizontal cells

A

-Connect sensory cells to neurons
-Converge signal from several receptors

19
Q

Ganglion cells

A

-Transmitting cells (output to CNS)
-Carry information via optic nerve to brain
-produce AP

20
Q

Periphery of retina vs center of retina

A

Periphery:
— many bipolar cells are synapses with one ganglion cell (bigger receptive field)

Center of fovea:
— one ganglion cell is synapsing with one bipolar cell (very small receptive field)

21
Q

Old disks at tip of cons/rods are

A

Phagocytized by pigment epithelial cells

22
Q

Outer segment of photoreceptors

A

Light transduction takes place using visual disks

23
Q

Inner segment photoreceptors

A

Location of major receptors and metabolic operations

24
Q

Synaptic terminal

A

Synapses with bipolar cells

25
Q

Disks are activated by ———

A

Light

26
Q

Disks have ——— which are ——— that are activated by ———

A

1- opsin in rhodopsin
2- GPCR
3- light

27
Q

Rhodopsin

A

=Opsin + Retinal
Photopigment that is signal transducer

28
Q

Cones are responsible for

A

Sharp vision
Color vison

29
Q

3 different types of cones

A

-Each has different photopigment
-Respond to specific color (red/blue/green)

30
Q

Retinal

A

11-cis retinal
Visual pigment
Derivative of vitamin A

31
Q

When opsin and retinal are tightly bound, rhodopsin is

A

Inactive

32
Q

11-cis retinal

A

Inactive—kinked—required

Change to active by light

All-trans retinal is active

33
Q

G protein in rods

A

Gtransducin

34
Q

Phototransduction in Rods in darkeness

A

1-Retinal(11-cis) and opsin is bound
2-Rhodopsin is inactive
3-PDE is inactive
4-cGMP level inside the cell are high
5-CNG channels are open (Ca will move in)
6-Rod cells are depolarized
7-Voltage-gated Ca channel are open
8-Ca into cell
9-Neurotransmitter=glutamate is released

35
Q

Phototransduction in Rods in light

A

0-Retinal photoisomerizes
0-11-cis to trans
0-cause conformational change in rhodopsin
1-Rhodopsin is activated(opsin released)
2-Activate Gtransducin
3-Active phosphodiesterase (PDE)
4-PDE break down cGMP
5-Decrease in [cGMP] will close CNG channels
6-Cell hyperpolarize (k link channel)
7-V-gated Ca channels close
8-Decrease NT(glutamate) release
9-Excite adjacent bipolar cell by removing inhibition
10-bipolar cell excite
11-receptor potential
12-bipolar cells release glutamate
13- now excitatory on ganglion cell
14- AP in ganglion cell

36
Q

From optic nerve to brain

A

1- optic nerve
2- optic chiasm
cross happens
3- optic tract
4- lateral body
5- thalamus
6- visual cortex on occipital lobe

37
Q

Glutamate is inhibory/excitatory??

A

Inhibitory

Bpk 205 (30 decks)

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