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Biology Lab > eye lab > Flashcards

eye lab Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

what are the 4 types of tissue that make up the body ?

A

. connective
. epithelial
. nervous
. muscle

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2
Q

what is white material at back of eye ?

A

adipose tissue - fat

we have a lot of fat around the eye ball

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3
Q

what is the function of adipose tissue in eye ?

A

. shock absorber
. provides thermal insulation - keep eye ball warm to focus image
. store lipid in cytoplasm

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4
Q

what is the other structure stuck to the back of eye ?

A

. muscles are directly attached to the back of eye and have a brownish colour
. known as extra ocular muscle

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5
Q

what is the front of eye ?

A

cornea which is made up of collagen fibres which are arranged in a regular dense connective tissue

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6
Q

what do we have behind the cornea ?

A

. the white sclera - made of tough irregular dense connective tissue - made up of collagen
. helps maintain rounded eyeball - rounded eye ball is good for focussing
. provides an anchor where the extra ocular muscle can insert

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7
Q

what are the 6 extra ocular muscle ?

A

. 2 muscles on side of eye
one close to the nose which is the medial rectus muscle and one on the edge called the lateral rectus muscle
these muscle work a antagonistic pair to move eye ball horizontally

. on top of eye ball we have superior rectus - lift eye up

. at the bottom of eye we have inferior rectus - pulls eye down

. 2 other muscles insert at an oblique angle known as superior and inferior oblique muscle and their function is to turn the eyeball torsion plane

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8
Q

what type of muscle are the extra ocular muscle ?

A

. we move our eye under voluntary control so they are striated muscle

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9
Q

what are the muscles inside the eye ?

A

intra ocular muscle and they move involuntary by the nervous system

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10
Q

what is the rod coming out at the back of the eye ?

A

optic nerve - which contains wires that come from neurons in the retina called the retinal ganglion cells
theses cells give rise to a single process which is called an axon which sends information down the optic nerve and connects to structures inside the brain

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11
Q

what is the function of cornea ?

A

. is to operate as the major focusing surface of the anterior eye
. it takes light rays that strike cornea and focus the image of those light rays onto the photosensitive cells ( rods and cons )

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12
Q

what is the power of the cornea ?

A

40 D
. 1D brings light rays to focus 1m behind
. cornea brings parallel rays 1/40 = 2.5 cm behind it

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13
Q

how far are the photoreceptors form the cornea ?

A

2.5 cm

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14
Q

why is the lens transparent ?

A

our lens is transparent because the major function of lens is to help in focusing light rays onto the photoreceptor particularly when looking at near
. when looking at far distance the lens only adds a lit bit of focusing power but when looking at near the lens adds a lot of power around 15-20 D

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15
Q

what type of cells make up the lens fibre ?

A

. epithelial cells

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16
Q

why is the lens in the dead sheep cloudy as oppose to transparent?

A

lens fibres proteins were denatured

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17
Q

what turns lenses to cataract in most people ?

A

exposure to ultra violet light which comes from sun causes denatures of proteins in lens fibre

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18
Q

how does lens look like when you’re looking at far ?

A

. lens is flat - doesn’t have focusing power

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19
Q

what is the black substance inside the eye?

A

. pigment called melanin which is contained inside a cell called melanocyte
. melanin can also be found in another cell melanin pigment epithelial cell

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20
Q

what is the function of melanin in eye ?

A

. absorbs uv violet / stray light
. black box effect

. light that passes through cornea and lens is picked up by photoreceptors and transduced into electrical potential - the photoreceptors don’t absorb all the light coming onto the eye and as consequence of that light can bounce around in the eye ball as stray light and melanin picks up that stray light

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21
Q

what does the amount of melanin around the iris determine ?

A
  • determines the eye colour
  • dark eye = lot of melanin at the back of the eye
  • light eye = less melanin
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22
Q

what is the function of melanin in the iris ?

A

ensures that light only enters the eye ball through pupil - thus maintaining sharp retinal image

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23
Q

what happens if you have on melanin ?

A
  • results in human albinism
  • pale skin
  • white hair
  • pink eyes - you can see the blood vessels of eye as there is no melanin in the iris or iris
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24
Q

what is special type of albinism that effects the eye ?

A

ocular albinism -
X- linked ( male only)
eyes only

25
Q

where does the lens sit ?

A
  • the lens sits directly behind the iris

- iris forms a ring around the lens

26
Q

what is function of iris ?

A
  • regulates passage of light into the eyeball
  • iris is able to dilate in dim illumination to let more light in to help you with focusing image
  • under bright illumination the iris muscle contract and produce narrower pupil to prevent light entering
27
Q

what are the two opposing tissues in the muscle of our iris ?

A

1- dilator muscle - when contracts the pupil dilates

  • smooth muscle
  • innervated by sympathetic nervous system
  • radial muscle

2 - constrictor muscle - acts as sphincter when it contracts the whole in the muscle gets smaller

  • smooth muscle
  • innervated by the parasympathetic nervous system
28
Q

what is ciliary body components ?

A
  • para plicata - most
    folded anterior part of ciliary body
  • para plana

-

29
Q

what is the function of aqueous humour ?

A
  • puts pressure in front of eye which is known as intra ocular pressure which helps the eye ball maintain its rounded shape
30
Q

what is the aqueous humour produced by ?

A
  • produced by epithelial cells that sit on the very surface of the folds of the pars plicata of the ciliary body
31
Q

what does the aqueous humour contain ?

A
  • nutrients ( oxygen )
  • molecules that cells of cornea and lens need to keep alive
  • water
32
Q

why do cornea and lens need aqueous humour to supply them with nutrients ?

A
  • cornea and lens are avascular
  • if blood vessels ran at the surface of the cornea they will refract light rays thus cornea would not be able to form a good image
33
Q

where does the aqueous humour take the metabolic waste of the lens and cornea ?

A
  • takes waste to ring of tissue that you find at a junction between the iris and the cornea
  • aqueous humour drains at the canal of schlemm
34
Q

what is the canal between cornea and iris ?

A

canal of schlemm

35
Q

what is the function of trabecular meshwork ?

A

. filters the material in aqueous humour and allows fluid to pass into the canal of schlemm

36
Q

what happens when the drain of trabecular meshwork blocks up ?

A
  • aqueous humour has difficulty passing into the canal of schlemm
  • aqueous humour builds up in the anterior part of the eye an as a consequence the intra ocular pressure of eye increases and leads to glaucoma
37
Q

what are the two types of glaucoma ?

A
  • open angle - when trabecular mesh work gets blocked and as a result inter ocular pressure increases
  • closed angle
38
Q

what is the problem with the problem with an increase in inter ocular pressure ?

A
  • the pressure tries to find an escape route and there is only one escape route which is where the optic nerves comes out at the back of the retina
  • ## optic nerve gets blown at the back of the eye ball and crushes wires that are coming from the retinal ganglion cells to the brain and hence no signals reach brain and can cause blindness
39
Q

what is the function of the blood vessels that fan out the surface of the retina ?

A
  • supply blood to neurons in the retina including the retinal ganglion cells
  • the blood vessels are known as central retinal artery and central retinal vein
40
Q

what is underneath the pars plana ?

A

ciliary muscle and extends as a ring around the eye

41
Q

what is the function of ciliary muscle ?

A
  • to regulate the shape of the lens
  • when ciliary muscle is relaxed the lens is flat because you are looking into the far distance
  • when ciliary muscle contracts it causes your lens to go rounded and can focus at near
  • controlled by the parasympathetic nervous system
42
Q

what is accommodation ?

A

the ability of the eye to change its focus from distant to near objects (and vice versa). This process is achieved by the lens changing its shape.

43
Q

what is the jelly - like substance in the posterior part of the eye ?

A

vitreous humour

44
Q

what is the function of vitreous humour ?

A
  • helps the eye ball maintain a rounded shape

- pushes the retina back into the choroid - help retina maintain a curved shape

45
Q

what type of tissue is the vitreous humour ?

A
  • connective tissue
46
Q

why is the vitreous humour transparent ?

A

light rays pass through the vitreous humour to reach the retina

47
Q

what is the inner most layer of the eye ball ?

A
  • the retina
48
Q

what is the middle layer of the eye ball ?

A
  • the choroid - laying between sclera and retina
49
Q

what is the bed of capillaries in the choroid ?

A

the bed of capillaries is right next to the retinal epithelial cells known as choriocapillaris- which supply nutrients to photoreceptors that sit at the back of retina

50
Q

what is the function of capillaries of the choroid ?

A

supply nutrients to photoreceptors that sit at back of retina ?

51
Q

what is the turquoise colour that is only present in the sheep’s eye ?

A
  • tepetum lucidum - known as eye shine
  • enhances visual sensitivity under low light conditions
  • located in the upper part of choroid
52
Q

what is the turquoise colour that is only present in the sheep’s eye ?

A
  • tepetum lucidum - known as eye shine
  • enhances visual sensitivity under low light conditions
  • located in the upper part of choroid
53
Q

where is the top part of eye looking ?

A
  • looking down because the image is inverted on retina
54
Q

where is the lower part of eye looking ?

A
  • up
55
Q

what is in the front of retina ?

A
  • cell bodies of retinal ganglion cells
56
Q

what is in the back of retina ?

A
  • cell bodies of photoreceptors ( rods and cons )
57
Q

what is behind the photoreceptors ?

A
  • single of cells known as retinal pigment epithelial
58
Q

how do retinal pigment epithelial cells look like ?

A
  • ring donuts
  • the surrounding ring is very dark and that’s where you find the melanin
  • hexagonal shape - joint together by type of junction which bridges form one cell membrane to another and that type of junction is called tight junction - so material can’t pass between them
59
Q

what is the function of retinal pigment epithelial cell ?

A
  • regulates the passage of material from the capillaries in the choroid to photoreceptors in the other side
  • black box effect

Biology Lab (5 decks)

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