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Perception > Tut 2 Completly done !!! > Flashcards

Tut 2 Completly done !!! Flashcards

1
Q

The eye exist out of:

A
  1. Cornea
  2. Aqueous Humor
  3. Lens
  4. Pupil
  5. Iris
  6. Retina
  7. Fovea
    Draw it !
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2
Q

Name the function of cornea :

A
  • Entering of light without interruption (which means Transparent)
  • It is transparent because it has no blood vessels which observe light
  • serves as protection
  • 80 % of focus power
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3
Q

Name the function of aqueous humor :

A
  • fluid which supplies oxygen to cornea and lens and removing waste from cornea and lens.
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4
Q

Name the function of Pupil:

A

It controls via the pupillary light reflexes how much light reaches the retina trough out expansion or conteraction.

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5
Q

Pupillary light reflexes

Mainly just iris !

A
  • it is just a muscle hole called iris

- it controls the expansion and conteraction

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6
Q

Name the function of retina:

A

Network of neurons that covers the back of the eye.
- contains photoreceptors (rods and cons) responsible for receiving image from lens and send it to the brain through the optic nerve.

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7
Q

Name the function of Fovea:

A

Part in the center of retina responsible for producing the highest visual acuity and point of fixation. (cons)

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8
Q

Define Rods which are photorecpetors and contain pigments !

A
  • Rods are in the periphery area
  • have high convergence, Low acuity and are high sensitive to light
  • slow respone
  • Good when it is dark
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9
Q

Define Cons which are photoreceptors which conatin pigments !

A
  • Mainly located in foeva:
  • little convergence
    High acuity
  • Low sensitivity to light
  • Fast response
  • responsible for colour vison
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10
Q

Process of seing: 3 major layers

A
  1. Starts at the back of the retina
  2. Photoreceptor respond to light 1 Layer
  3. Photoreceptor pass the signal on to bipolar cells 2 Layer
  4. Which than sends the signal to ganglia cell 3 layer
  5. which then passes the signal on to the axon of the ganglion cell which then passes the signal to the brain
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11
Q

Describe the direct pathway regarding on center cell:

A
  • photoreceptor gets activated by light
  • That leads to hyperpolarization
  • which means a decrease of the neurotransmitter glutamate which wil lead to more glutamate on bipolar cell and ganglion cell if these are on center cells !
  • If light is off then receptor will produce more glutamate which will lead to less glutamate on bipolar and ganglion cell.
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12
Q

How does the Indirect pathway work ?

A
  • via lateral inhibition and horizonal cells Horizontal cells which inhibit the activity of surronding neurons !
  • Now u have the activity of two receptor fields which influence each other. (Lecture example in reality more!)
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13
Q

What is anatagonsim ?

A

When the activity on a receptor field between on center + and off surrunding crosses each other out. (or visa versa)

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14
Q

Horizontal cells

- 1 intermedate layer

A
  • They make adjustment to the signals form photoreceptors bipolar cells.
  • support the activity of neighbouring cells
  • they produce gaba
  • causes lateral inhibition
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15
Q

What is Presbyopia?

A

When a person get older they lose the foucisng power gained by the ciliary muscle / iris which becomes weaker so the lens ages.
- Can not focus on close by object

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16
Q

Define transduction:

A
  • light (chemical) is converted into electrical signals (energy) in the rod cells and cone cells.
17
Q

Descirbe the Dark adaption

A
  • Cones: only need 3-6 minuets to regenrate to light
  • Rods cone break by 7 min
  • after 7 min rods take over
18
Q

What is special about our blind spot?

A
  • There are no receptors

- mechansim fill in the missing inofmration which is why we do not recognize our blind spot

19
Q

Explain the visual pigment bleaching process :

A
  • Retinal seperates from the opsin after being activated from light.
  • which leads to colour bleeching
  • The activation of the pigment statrts the enzyme cascade
  • It is also called isomerization (activation of photopigment)
20
Q

What does a pigment do and what does it contain ?

A
  • It changes light into electrical energy.
  • Contains molecules which is made of by opsin, for determing which wavelength the molecule observes and the retinal which catches light protons.
21
Q

Definiton of Acuity (regarding cones and rods):

A

How fine in spatial detail

can you see?

22
Q

What is sensitivity (regarding cones and rods):

A

How easily can you see

in very dim light?

23
Q

What do short wavelengths show for a colour ?

A

Blue

24
Q

What do middle wavelength show for a colour ?

A

Green

25
Q

What do long wavelength show for a colour ?

A

Yellow orange and red

26
Q

What is Myopia ?

Name the 2 differnt types:

A

Problems to see in a further distance
- Refractive myopia: the cornea and/or the lens bends the light too much
Axial myopia: eyball is to long

27
Q

What is Hyperopia?

A

Trouble seeing close by obejcts

- Because eyball is to short

28
Q

What is the function of the Lens:

A
  • Transparent so light goes directly trough.
    Also includes
  • Accomodation: unconscious tightening or widening of shape in order to adjust eye’s focus by ciliary muscles
  • 20% of focusing power
29
Q

Describe the direct pathway regarding off center cell:

A

Light is on so less glutamate is produced by receptors.

  • which means less glutamate will be produced by bipolar and ganglion cells.
  • If light is off everything will be exitotory
30
Q

What is the enzyme cascade ?

A
  • one visual pigment molecule can cause a chemical effect that is large enough to a activate the entire rod receptor (so thousands of pigments)
31
Q

How does the visual pigment regenerat ?

A

In the darkness, retinal re-attaches to the opsin

- Which is why then retina only contains intact pigments at night

32
Q

What is convergence ?

A

When a one cell effects a lot of neurons !

- that is why we have high acuity in cones cause they have less convergence

33
Q

How is a photoreceptor constructed?

A
  • inner and outer segments
  • Inner segment just contains the nucleus
  • Outer segment Contain disk files with opsin and retinal
34
Q

What is isomerization?

A
  • the change of the retinal molecule to another molecule when a light comes in.

Perception (9 decks)

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