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BIOL 203 > Lecture 24 > Flashcards

Lecture 24 Flashcards

1
Q

The path through which tears travel….
1.
2.
3.
4.
5.
6.
7.
8.

A
  1. lacrimal gland
  2. ducts
  3. lacrimal punctum
  4. lacrimal canaliculus
  5. lacrimal sac
  6. nasolacrimal duct
  7. inferior meatus of nasal cavity
  8. nostril
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2
Q

Three functions of tears:
- ________ and ________ the eye surface
- deliver ___________ and _________ to the conjunctiva
- _______ from infection

A
  • cleanse; lubricate
  • oxygen; nutrients
  • protect
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3
Q

The lacrimal apparatus is connected to the nostril which means an abundance of tears from crying or watery eyes can result in a ______________

A

runny nose

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4
Q

Three layers or tunics of the eyeball
1.
2.
3.

A
  1. Fibrous tunic
  2. Vascular tunic
  3. Neural tunic
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5
Q

Fibrous tunic:
1. _________: protects the eye and give its shape (white part of the eye) and covered majority of outer surface area
2. _________: located at the front of the eye and covers the central portion

A
  1. sclera
  2. cornea
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6
Q

Vascular tunic:
1. __________
2. __________: muscular ring around lens and secretes aqueous humor
3. _________: high density of blood vessels and provides nutrients & removes waste

A
  1. Iris
  2. Ciliary body
  3. Choroid
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7
Q

Neural tunic:
1. _________: it lines the back of the eye (inner-most layer)

A
  1. retina
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8
Q

Cornea:
- it is a ____________________ membrane that protects the eye
- It allows ______ to enter the eye
- it contains ______ cells which allows for regeneration after injury

A
  • transparent
  • light
  • stem
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9
Q

refraction: _____________________________
- As light passes through the eye, the ________ (mostly) and _____ bend and focus it on the retina
- These structures make refraction possible because they are _______ structures: cause parallel rays of light to converge (come together)–> essential for focusing light onto the retina
- Result of image on retina: Image (2D) is _____________ (upside down) and _____________

A

bending of light rays
- cornea; lens
- convex
- inverted; reversed

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10
Q
  • Light rays striking the very center of the cornea pass _________ ________
  • Light rays striking off center are _____ toward the center (because of the curvature of the cornea)
A
  • straight through
  • bent
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11
Q

The ______ is located between the cornea and lens.
- the colored part of the eye because it contains cells with ________ (black, brown, or hazel color)
- Function: adjustable diaphragm that controls pupil __________ (______), thus the amount of light entering- it enlarges and shrinks, depending on how much light is entering the eye

A

iris; melanin; diameter (size)

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12
Q

_______: aperture through which light enters the eye

Two iris muscles that control pupil diameter:
1. _________:
2. _________: closet to pupil

A

pupil
1. dilator pupillae
2. sphincter pupillae

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13
Q

Muscles of the iris
- __________ receives sympathetic input
- __________ receives parasympathetic input

A
  • dilator pupillae
  • sphincter pupillae
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14
Q
  • _____________ stimulation of the dilator pupillae causes the muscle to contract (pupil dilates) which occurs in ______ light
  • _____________ stimulation of the sphincter pupillae causes the muscle to contract (pupil constricts) which occurs in ________ light
A
  • sympathetic; dim
  • parasympathetic; bright
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15
Q

Response that the pupil has for close-up vision:
- stimulation of _____________ fibers in sphincter pupillae= pupil _________
- this ____________ depth of focus and ____________ spherical aberration

A
  • parasympathetic; constriction
  • increases; decreases
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16
Q

Spherical aberration: occurs when light rays passing through the __________ of the cornea and lens come to a focus at a slightly different location than light rays passing through the center of the cornea and lens. This results in ___________ image quality

A

periphery; decreased

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17
Q

__________ refers to the specific point on the retina where light rays converge after being refracted by the cornea and lens

A

focal point

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18
Q

The lens: clear, biconvex, and flexible structure suspended within the eye by the__________ ligaments (________)

Function:
- _________ and ________ its width (called ____________) in order to focus light rays

A

suspensory; zonules
- shorten; widen; accommodation

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19
Q

The __________ muscles controls the lens shape

A

ciliary

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20
Q

Structures that form the ciliary body:
1.
2.
3.

A
  1. ciliary muscles
  2. ciliary process
  3. ciliary ligaments or zonules
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21
Q

Aqueous humor:
- transparent fluid produced by the _____________ and it flows out through the _________ ___________ in the drainage angle

Function
- to supply _________ to the avascular structures of the eye, cornea, and lens
- to maintain ___________ ________ within its physiological range

Location
- found in the __________ __________ of the eye which is between the cornea and lens

A
  • ciliary body (specifically ciliary process); trabecular meshwork
  • nutrients
  • intraocular pressure
  • anterior chamber
22
Q

____________: change in the curvature of the lens which allows for the eye to focus on objects at different distances

A

accommodation

23
Q

Close-up vision= ___________
- there is ____________ stimulation of the ciliary muscles which causes the muscles to contract and ____________ of the zonules leading to the _________ (rounding) of the lens

A

accommodated
- parasympathetic; relaxation; bulging

24
Q

At rest vision= ______________
- relaxation of the ciliary muscles causes the ____________ of zonules which leads to the lens _____________

A

non-accommodated
- tightening; flattening

25
Q

_____________: means normal eye that sees distant objects clearly without using accommodation

A

emmetropia

26
Q
  • Eye convergence is produced by the contraction of both ____________ muscles
  • If the eyes cannot converge accurately= __________
A
  • medial rectus
  • double vision (diplopia)
27
Q

Three processes involved in the adjustment to close-range vision:
1.
2.
3.

A
  1. pupil constriction
  2. Lens thickening (accommodation)
  3. Inward rotation of the eyes (convergence)
28
Q

___________ _______ fills the globe of the eyeball

Function:
- it maintains the ______ of the eye
- it helps with vision clarity (it is _____ “glassy” so that light can pass through it)

Located:
- ___________ part of the eyeball between the lens and retina

A

vitreous humor
- shape; clear
- posterior

29
Q

___________: region in the retina where the optic nerve leaves the eye
- it is considered a “blind spot” because it does not contain any ____________: leaving a blind spot in the visual field

A

optic disk
- photoreceptors

30
Q

The Retina:
- the back surface of the eye
- it receives the image that the cornea focuses through the lens and transforms this image into _________ ________ that are carried by the _______ ______ to the brain

A
  • electrical impulses; optic nerve
31
Q

____________ (yellow spot): a small area about 1mm in diameter from which we get our ____________ vision. This is because of the high concentration of _______ cells. These cells are responsible for color, vision, sharp acuity and central vision.

A

Macula; sharpest; cone

32
Q

Six cell types found in the neural layer of the retina
1.
2.
3.
4.
5.

A
  1. photoreceptors (cones and rods)
  2. bipolar cells
  3. ganglion cells
  4. horizontal cells
  5. amacrine cells
33
Q

Sequence of light path in neural layer:
______–> _________–>_______
—-> ____________

A

photoreceptors–> bipolar cells–> ganglion cells–> optic nerve

34
Q

Horizontal and amacrine cells are ___________ that modify the ______ of electrical firing in __________ cells
- they are NOT apart of the light pathway!

A

interneurons; rate; bipolar

35
Q

_________ cells give rise to the axons that from cranial nerve II (OPTIC NERVE)

A

ganglion

36
Q

____________ capture light (energy) and converts it into electrical signals (this is called _______________)

A

photoreceptors (rods and cones); phototransduction

37
Q

Photoreceptors
- __________: responsible for scotopic (night) vision
- __________: responsible for photopic (day) vision & trichromatic (color) vision

A
  • rods
  • cones
38
Q

Which segment of the rods is specialized to absorb light?

A

outer segment

39
Q

The outer segment in rods is made up of approx. 1,000 ___________ _______ inside which all contain visual _____________

A

membranous discs; pigments

40
Q

Rhodopsin is a light sensitive protein (visual pigment) found in the disc membrane of the ______ cells. Its main components include a protein called _________ and a light-absorbing molecule called ________

A

rod; opsin; retinal

41
Q
  • Visual pigments for
    rods= _____________
    cones= ___________
  • Two conformations of retinal moiety = __________
A
  • rhodopsin; photopsin
  • cis & trans
42
Q

Three types of cones
- they are defined by the wavelength of light to which they are most ___________
1. ________- wavelength: detects ______
2. ________- wavelength: detects ______
3. ________- wavelength:
detects ______

A
  1. short; blue
  2. medium; green
  3. long; red
43
Q

The trichromatic theory of color vision says that human eyes only perceive THREE colors of light: ______, _______, _______. The wavelengths of these three colors can be combined to create every ________ on the visible light spectrum

A

red, blue, green; color

44
Q

Phototransduction in the rods:
- Receptor= ___________
- G protein= __________
- Enzyme= __________
- Secondary messenger= ___________

A
  • rhodopsin
  • transducin
  • phosphodiesterase
  • cGMP
45
Q

Phototransduction in the rods: The Dark Phase
- form of retinal bound to rhodopsin= ___________
- transducin is ____________
- phosphodiesterase (PDE) is _____________
- _____________ triggers the opening of Na+ channels–> leads to an influx of Na+
- this _____________ the mb potential of the ___________ segment which triggers ___________ release to __________ cells

A
  • 11-cis
  • INACTIVE
  • INACTIVE
  • cGMP
  • depolarizes; inner;glutamate; bipolar
46
Q

Upon light absorption, what happens to 11-cis retinal in rods?

A

it is converted to all-trans retinal & dissociated from rhodopsin

47
Q

_____________: refers to the temporary loss of sensitivity to light in rods, where trans retinal needs to be regenerated to 11-cis retinal

A

bleaching

48
Q
  • ________ _____________ activates transducin and phosphodiesterase (PDE)
  • PDE degrades ___________ which leads to the closure of Na+ channels
  • this causes ______________ meaning that there is _____ release of glutamate
A
  • light absorption
  • cGMP
  • hyperpolarization; NO
49
Q
  • The optic nerve starts in the retina ____________ cells (their axons) and finishes in the _________ __________
  • The optic tract starts in the _________ _________ and finishes in the _____________
A
  • ganglion; optic chiasm
  • optic chiasm; thalamus
50
Q

______________: point where the optic nerve in both eyes partially (1/2 fibers) cross in the brain, allowing each hemisphere to receive visual information from both the left and right visual field

A

optic chiasm

51
Q
  • The thalamic nucleus that receives visual information and relays it to the visual cortex is the _________________
  • the visual cortex is located in the ______________ lobe
A
  • lateral geniculate nucleus
  • occipital
52
Q

Two other brain regions that receive visual information
1. ____________: in midbrain related to visual reflexes
2. _____________: in hypothalamus (master circadian clock)

A
  1. Superior colliculi
  2. Suprachiasmatic nucleus

BIOL 203 (27 decks)

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