Lecture 5: Vision

Question 1

Special Senses of the body include:

Answer 1

1)Vision
2)Chemical Senses
- Taste
- Smell
3) Hearing
4) Equilibrium

Question 2

All special sensory receptors are distinct receptor cells localized in the: _____ region

Answer 2

head

Question 3

The Function of the Accessory Structures of the Eye is to:

Answer 3

Protect the eye and aid eye function

Question 4

What is Conjunctiva?

Answer 4

transparent mucous membrane that produces lubricating secretions

Question 5

Palebral Conjunctiva:

Answer 5

membrane that lines the underside of the eye

Question 6

What is the Bulbar Conjunctiva:

Answer 6

membrane that covers the white of the eyes (not the cornea)

Question 7

What is the Conjunctival Sac:

Answer 7

space between palpebral and bulbar conjunctiva (area where contact lens sit)

Question 8

There are ___ straplike extrinsic eye muscles

Answer 8

6

Question 9

The extrinsic eye muscles originate from the: _____ ____

Answer 9

bony orbit

Question 10

THe extrinsic muscles of the eye originate from the bony structure and insert on the ________

Answer 10

eyeball

Question 11

Name three motor inputs of the eye

Answer 11

1: CN III - Oculomotor
2. CN IV - Trochlear
3. CN VI - Abducens

Question 12

The walls of the eyeball contain 3 layers. What are they?

Answer 12

1. Fibrous Layer
2. Vascular Layer
3. Inner Layer

Question 13

The internal cavity of the eye is filled with fluid called:

Answer 13

humors

Question 14

The internal cavity of the eye is separated. by the _____

Answer 14

lens

Question 15

The eye is separated by the lens into the ____ and ____ segments

Answer 15

anterior and psoterior

Question 16

Pupil constriction is controlled by the ______ nervous system

Answer 16

parasympathetic

Question 17

The iris consists of two muscles

Answer 17

Sphincter pupillae
Dilator pupillae

Question 18

Pupil dilation is controlled by the ______ nervous system

Answer 18

sympathetic

Question 19

Focus on Distance requires 3 simultaneous Processes. What are they?

Answer 19

1. Accommodations of lenses
2. Constriction of pupils
3. Convergence of the eyeball

Question 20

What is Presbyopia?

Answer 20

loss of lens accommodation over the age of 50

Question 21

To focus on distance the lens of the eyeball will

Answer 21

flatten

Question 22

When focusing on distance, the ______ muscle is relaxed. Which causes a pull on ciliary zonule

Answer 22

Ciliary

Question 23

Myopia is a problem of

Answer 23

Refraction

Question 24

Myopia (nearsightedness) is a result of the eyeball being:

Answer 24

too long - the focal point is in front of the retina

Question 25

To correct for Myopia, corrected lens need to be:

Answer 25

concave

Question 26

Hyperopia is a problem of

Answer 26

Refraction

Question 27

Hyperopia (farsightedness) results from the eyeball being:

Answer 27

too short - the focal point is behind the retina

Question 28

Hyperopia is corrected with _____ lens

Answer 28

convex

Question 29

What is the optic disc?

Answer 29

Site where the optic nerve leaves the eye

Question 30

Why is the optic disc also known as the blind spot?

Answer 30

it lacks photoreceptors

Question 31

What is the function of the pigmented layer of the Retina? (3)

Answer 31

1. Absorbs light and prevents scattering 2. Phagoctyizes photoreceptor cell fragments 3. Stores vitamin A

Question 32

The Neural layer of the retina contains ___ and ____

Answer 32

rods cones

Question 33

The three main types of neurons in the neural layer of the retina are:

Answer 33

1. Photoreceptors 2. Bipolar cells 3. Ganglion cells

Question 34

Rods are required to see colours. True or False

Answer 34

False. Rods do not produce colour vision or sharp images.

Question 35

The greatest number of rods are found at the _____

Answer 35

periphery

Question 36

Rods are more sensitive to light than cones. True or False

Answer 36

True

Question 37

Photoreceptor are modified neurons of rods and cones that consist of a _____, _____ and 2 ______

Answer 37

Cell body synaptic terminal segements:

Question 38

The outer segment of the photoreceptor are the ____ receiving photopigment

Answer 38

light

Question 39

The outer segment of the photoreceptor change ____ as they absorb light

Answer 39

shape

Question 40

The inner segment of the photoreceptor ____ cell body and is connected via cilium to the outer segment.

Answer 40

joins

Question 41

Retinal is the key ___ -absorbing molecule that combines with 1 or 4 proteins

Answer 41

light-absorbing

Question 42

The protein that retinal combines with are called: ____

Answer 42

opsins

Question 43

4 opsins are called ____ and found in the rods

Answer 43

Rhodopsin

Question 44

3 opsins are found in the cones:

Answer 44

Green Blue Red

Question 45

How do people see different hues?

Answer 45

Cone wavelengths overlap and trigger more than one cone enabling us to see hues

Question 46

Retinal isomer are different 3d forms. Retinal is in ___ form in the dark.

Answer 46

bent

Question 47

When the retinal isomer pigment absorbs light it will

Answer 47

straighten out

Question 48

11-cis-retinal is the ___ form retinal isomer

Answer 48

bent

Question 49

all-trans-retinal is the ___ form of retinal isomer

Answer 49

straight

Question 50

Conervsion of bent to straight retinal initiates electrical impulses along the ____ nerve

Answer 50

optic

Question 51

What are the three steps to converting a bent retinal (11-cis-retinal) to a straight (all-trans-retinal) (3)

Answer 51

1. Pigment synthesis 2. Pigment Bleaching 3. Pigment Regeneration

Question 52

What occurs during Pigment Synthesis?

Answer 52

11-cis-retinal is combined with opsin to form rhodopsin

Question 53

What occurs during Pigment Bleaching?

Answer 53

light absorption by rhodopsin triggers a rapis series of steps in which retinal changes shape (11-cis to all-trans) and eventually release from opsin

Question 54

What occurs during Pigment Regeneration?

Answer 54

Enzymes slowly convert all-trans-retinal to its 11-cis-retinal from cells of the pigmented layer. Requires ATP

Question 55

When moving from darkness to light we see a glare because:

Answer 55

both rods and cones are strongly stimulated

Question 56

Light adaptation occurs in 5-10 minutes as:

Answer 56

rod system turns off transducin moves to inner segment retinal sensitivity decreases

Question 57

Dark adaptation occurs when moving from bright light into darkness. Blackness is seen because:

Answer 57

cones stop functioning in low intensity light Bright light bleached rod pigments are still off

Question 58

Rhodopsin accumulates in the dark so retinal sensitivity starts in increase and transducins return to the outer segment and occur in 20-30 minutes. This results in

Answer 58

Dark Adaptation

Question 59

What occurs at stage 1 of information processing in the retina?

Answer 59

cGMP-gated channels open, allowing cation influx and photoreceptors depolarize

Question 60

What occurs at stage 2 of information processing in the retina?

Answer 60

Voltage-gated Ca+ channels open in synaptic terminals

Question 61

What occurs at stage 3 of information processing in the retina?

Answer 61

Neurotransmitter is release continuously

Question 62

What occurs at stage 4 of information processing in the retina?

Answer 62

Neurotransmitter causes IPSP in bipolar cells causing hyperpolarization

Question 63

What occurs at stage 5 of information processing in the retina?

Answer 63

Hyperpolarization closes voltage gated Ca+ channels, inhibiting neurotransmitters

Question 64

What occurs at stage 6 of information processing in the retina?

Answer 64

No EPSP occur in glanglion cell

Question 65

Action potentials are generated in the _____ cells

Answer 65

ganglion

Question 66

Rods:

Answer 66

Noncolour Vision High sensitivity (functions in dim light ) Low acuity (many rods converge on one ganglion) More numerous Mostly in peripheral

Question 67

Cones:

Answer 67

Colour vision low sensitivity (function in bright) High acuity 1 cone:1ganglion less numerous mostly in central retina