Brainscape's Knowledge GenomeTM

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


See full index

Zoology 242 > Vision > Flashcards

Vision Flashcards

1
Q

What is photoreception?

A

The ability to detect a portion of the electromagnetic spectrum between UV and IR.

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

What is the minimal criteria to be considred an eye?

A
  • Photoreceptors
  • Determine directionality of light
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Despite the minimal criteria to be an eye, they are usually a complex organ and…

A
  • include receptor cells
  • pigmented epithelium
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Where are flat sheet eyes seen?

A

In larval eyes or as accessory eyes.

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

Describe cup shaped eyes.

A

Curved eye creates a narrow aprture (allows less light into the eye)

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

Describe convex eyes.

A

Present in annelids, molluscs and arthropodia.

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

What are compound eyes composed of?

A

Ommatidia

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

What are ommatidia?

A
  • modified region of cuticle (cornea) overlying a crystalline cone that forms a lens
  • below lens, retinular cells (rhabdomeric cell receptors)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q
A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are vesticluar eyes?

A

A lens help solve the compromise between image clarity and image intensity.

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

List the structures related to function in the vertebrate eye.

A
  • Sclera
  • Cornea
  • Iris
  • Ciliary body
  • Lens
  • Fovea
  • blindspot
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What does the vertebrate retina look like?

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

What are the two types of photoreceptors?

A

Ciliary and Rhabdomeric

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

What do photoreceptors do?

A

Transduce light signal

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

Describe ciliary photoreceptors.

A

Single cilium with highly-folded ciliary membrane (disks containing photopigments). Vertebrates.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Describe rhabdomeric photoreceptors.

A

Microvillar - projections contain photopigments. Jellyfish, drosophila.

18
Q

Describe signalling in rhabdomeric photoreceptors.

A
  • Gq protein activates PLC pathway
  • IP3 and DAG pathways open nonselective cation channels
  • Ca2+ and Na+ enter the cell
  • Cause a depolarizing receptor potential
  • NT release is increased
19
Q

What are the two types of photoreceptors in vertebrates?

A

Rods and cones

20
Q

What is a photopigment?

A

Chromophore associated with specific receptor protein.

21
Q

How are the chromophore and receptor protein binded?

A

Covalently

22
Q

Receptor proteins in photopigments are…

A

GPCR and members of the opsin family

23
Q

Give an example of a photopigment.

A

Retinal + opsin = rhodopsin

24
Q

Describe

A
25
Q

Describe the unactivated state of rhodopsin.

A
  • chromophore in cis conformation
  • bound to opsin
26
Q

Describe the activated state of rhodopsin.

A
  • chromophore undergoes conformational change to trans
  • released from opsin (process called bleaching)
  • recycled (trans –> cis) in the RPE
27
Q

What enzyme reverses the isomerization of retinal?

A

Isomerase

28
Q

Describe ciliary photoreceptor transduction.

A
29
Q

What does bright light cause?

A
  • Lowest levels of cGMP
  • Most Na+channels
30
Q

What happens to photoreceptors in the dark?

A
  • cGMP levels are high; cGMP binds to ion channels
  • depolarization is triggered
31
Q

What happens to photoreceptors in dim light?

A
  • lower levels of cGMP present
  • some ion channels close
32
Q

Show rhodopsin inactivation.

A
33
Q

Describe how the use of glutamate (inhibitory NT) is utilized in darkness and in light by photoreceptor cells.

A
34
Q

How do vertebrates recycle chromophores?

A
  • released trans form exported to adjacent epithelial cells
  • converted back to cis form
  • exported back to photoreceptor cells
35
Q

Horizontal cells ensure…

A

that only signal from intensely lit photoreceptor cells reaches the ganglion (lateral inhibition).

36
Q

How do horizontal cells inhibit the activity of the bipoalr neurons connected to the photoreceptors at the center of the receptive field?

A

Photoreceptors synapse with bipolar neurons and with horizontal cells. Conflicting signals to these bipolar neurons ersults in reduced signal to retinal ganglion cells.

37
Q

Show the difference between light on the centre of the receptive field and light on surround.

A
38
Q

What is the pathway of APs from the retina to the brain?

A

Optic nerves –> optic chiasm –> optic tract –> lateral geniculate nucleus –> visual cortex

39
Q

Describe binocular vision.

A
  • eyes have overlapping visual fields
    • binocular zone
  • combine and compare information from each eye to form a 3D image
  • depth perception

Zoology 242 (13 decks)

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