Blood supply to the eye and adnexa Flashcards

1
Q

GIve 6 reasons there is a blood supply to the eye

A

-provides oxygen, nutrients and water
-removes carbon dioxide and metabolic wastes
-hormones
-to mediate the immune system response
-to maintain a constant pH and temperature
-source of pressure

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2
Q

What is the common carotid and what does it consist of?

A

the main artery that supplies blood to the head and neck

theres a left and a right carotid artery and each divides into the internal carotid and the external carotid

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3
Q

what is the infraorbital artery?

A

a branch of the external carotid that provides blood supply to the eye

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4
Q

what is the circle of Willis? What arteries does it contain?

A

the cerebral arterial circle that provides alternative passages for blood flow in case another gets blocked. It contains
-the internal carotid arery
-the middle cerebral artery
-the basilar artery
-vetebral artery

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5
Q

what is the ophthalmic artery?

A

a branch of the internal carotid that provides blood supply to the adnexa

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6
Q

what are the main branches of the ophthalmic artery?

A

-posterior ciliary arteries ( short and long)
-lacrimal artery
-central retinal artery
muscular arteries that branch to form:
-anterior ciliary arteries
-supraorbital artery
-medial palpebral arteries

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7
Q

for the central retinal artery,
what structures does it go through and what is it accompanied by?

A

-goes through the optic nerve behind the eye and the central optic disk
-accompanied by the central retinal vein

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8
Q

how does the central retinal artery supply blood to the optic nerve?

A

via collateral branches

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9
Q

what forms the blood-retina barrier?

A

endothelial cells of retinal capillaries and retinal pigment epithelial cells capillaries via tight junctions by zonula occludens

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10
Q

what is autoregulation in the retina?

A

the maintenance of constant blood flow despite the changes in intraocular pressure and systemic blood pressure controlled by metabolism

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11
Q

how does the Bruch’s membrane change with age?

A
  1. it thickens
  2. it causes decreased permeability
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12
Q

how is dry AMD diagnosed?

A

staining of the large drusen in the retina as a result of the bruch’s membrane allowing for extracellular debris

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13
Q

what supplies the choroid with blood?

A

posterior ciliary arteries

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14
Q

what supplies the iris and ciliary body with blood?

A

anterior ciliary arteries as they anastomose with the branches of the long posterior ciliary arteries

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15
Q

what do the short posterior ciliary arteries supply?

A

posterior choroid, optic nerve, pia matter of the optic nerve and in some cases the inner retina

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16
Q

what do the long posterior ciliary arteries supply?

A

ciliary body, anterior choroid and major arterial circle of the iris

17
Q

what are the two muscular arteries and what do they supply?

A

-lateral superior artery supplies, lateral rectus, superior rectus, superior oblique and levator muscle
-medial inferior artery supplies, medial rectus, inferior rectus and inferior oblique

18
Q

what does the lacrimal artery pass through and what does it supply?

A

passes through the lacrimal gland and supplies the lacrimal gland, conjunctiva and the lids , it anastomoses the medial palpebral artery

19
Q

which arteries provide blood supply for the photoreceptors?

A

the short posterior ciliary arteries and long posterior ciliary arteries

20
Q

which arteries provide blood supply for the majority of retinal ganglion cells in our eyes?

A

the central retinal arteries

21
Q

what does the central retinal artery branch off?

A

the ophthalmic artery

22
Q

Give two reasons for the need of a dual blood supply to the retina

A

-the blood supply in the inner retina is only enough for the retinal ganglion cells, intermediary neurones and muller cells. As the outer retina has high oxygen requirements, the nutrients need to have a separate blood supply
-as photoreceptors are metabolically active in the dark producing ATP hence use up alot of oxygen supplied from the choroid and so causing the conc of o2 to steeply decrease from the choroid towards the inner segment layer where it is close to zero meaning no o2 can diffuse into the inner retina

23
Q

which arteries provide branches that supply the optic nerve?

A

-the central retinal artery
-the short posterior ciliary arteries