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I. Ocular Physiology > Retinal/Choroid Vascular Physiology (F) > Flashcards

Retinal/Choroid Vascular Physiology (F) Flashcards

1
Q

What is the vasculature that forms from the optic nerve head? 1. What do the vertical sprouts from the superficial plexus give rise to? 2

A
  1. primary vascular plexus

2. inner capillary plexus

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2
Q

Where do long and short posterior ciliary arteries first coalesce?

A

mesenchymal meshwork adjacent to the primitive RPE

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3
Q

When does substantial interarterial anasamosing occur during development?

A

4th month

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4
Q

What does the ophthalmic artery split into that supply the eye?

A
  1. central retinal artery (CRA, 2)

2. ciliary arteries (CA, 3)

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5
Q

What artery provide oxygen and nutrients to the inner retina?

A

central retinal artery

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6
Q

What arteries providesoxygen and nutrients to the RPE and outer retina (photoreceptors)?

A

ciliary arteries

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7
Q

Are retinal vessels innervated? 1. Is the choroid? 2

A
  1. no

2. yes

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8
Q

What is the percentage of O2 is delivered to the retina by the choroid? 1. Percentage of glucose? 2. Percentage of blood flow? 3

A
  1. 65%
  2. 75%
  3. 4%
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9
Q

What is the percentage of O2 is delivered to the retina by the choroid? 1. Percentage of glucose? 2. Percentage of blood flow? 3

A
  1. 65%
  2. 75%
  3. 4%
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10
Q

How is the foveola nourished?

A

through choroid only

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11
Q

What cells are tight junctions found in regards to the blood vessels of the retina?

A

endothelial cells

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12
Q

What is the superficial glia sheathed by? 1. What are the inner plexuses sheathed by? 2

A
  1. astrocytes

2. Muller cells

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13
Q

Are blood vessels of the choriocapillaris fenestrated?

A

yes

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14
Q

What are transported via transcellular mechanisms in the RPE?

A

nutrients and vitamin A

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15
Q

What mediates glucose transport (transcellularly) into retinal vasculature endothelial cells? 1. Where are these located? 2

A
  1. GLUT1

2. luminal and abluminal membranes

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16
Q

What are the major complications are associated with pathology of the inner retina and inner blood-retinal barrier?

A
  1. Loss of pericytes, and capillaries
  2. Increased tortuosity of retinal capillaries
  3. Microaneurysms
  4. Plasma protein leakage
  5. Neovascularization (advanced)
17
Q

What is it called when the retina of premature infants are exposed to excess O2?

A

retinopathy of prematurity

18
Q

What is it called when the retina of premature infants are exposed to excess O2?

A

retinopathy of prematurity (abnormal vascularization)

19
Q

What is 90% of total glucose utilized by retina converted to?

A

lactate

20
Q

Does the retina have higher metabolism in the light or dark?

A

dark

21
Q

What is blood flow in the retina and choroid a function of?

A

muscular tonus of the arterioles and the state of contraction of the pericytes (because no sphincters)

22
Q

What does an increase in lactate lead to?

A

Vasodilatory response

23
Q

What does an increase in lactate lead to?

A

Vasodilatory response

24
Q

What determines if light induces vasodilation or vasoconstriction?

A

presence of nitric oxide

25
Q

What is a reduction in blood oxygen that preferentially affects the outer retina?

A

hypoxia

26
Q

What does hypoxia cause in the retina? 1. How does it do this? 2

A
  1. Causes vasodilation in the retina and increases blood flow
  2. Due to release of retinal lactate and endothelium derived nitric oxide
27
Q

What does hyperoxia cause in the retinal arterioles? 1. In the choroid? 2. What mediates these responses? 3

A
  1. Causes vasoconstriction of the retinal arterioles
  2. Choroidal blood flow does not change with increase in pO2
  3. ET-1 receptors (endothelin -1) in the retina
28
Q

What does hypercapnia cause in the retina? 1. In the choroid? 2. What mediates these responses? 3

A
  1. Causes vasodilation in the retina and increases blood flow and decrease pH
  2. increases blood flow in the choroid
  3. endothelial release of prostaglandins and Nitric oxide
29
Q

What does hypercapnia cause in the retina? 1. In the choroid? 2. What mediates these responses? 3

A
  1. Causes vasodilation in the retina and increases blood flow and decrease pH
  2. increases blood flow in the choroid
  3. endothelial release of prostaglandins and Nitric oxide
30
Q

What is is the mean blood pressure in the ophthalmic artery minus the blood pressure in the central retinal vein called?

A

mean perfusion pressure driving blood through the retina

31
Q

What does high IOP cause in the retina?

A
  1. Inner retina pO2 is unaffected due to autoregulation

2. Outer retina blood flow and pO2 decreases

32
Q

What are the metabolic components that are tone relaxing? 1. Tone contracting? 2

A
  1. lactate, prostaglandins, and nitric oxide

2. Endothelin-1

33
Q

What are the two mechanisms of production of nitric oxide (and where do each exist)?

A
  1. NOS1 (expressed in retinal neurons = ganglion, amacrine, horizontal, muller, photoreceptors, RPE)
  2. NOS3 (endothelial cells of the retina and choroidal vessels and pericytes of the retinal capillaries, and endothelium of optic nerve head)
34
Q

Where is Endothelin-1 expressed in the eye?

A

endothelium, retinal neurons, astrocytes, and pericytes

35
Q

What are prostaglandins mediated by?

A

adenyl cyclase and inhibition of calcium flux in smooth muscle cells

36
Q

What are prostaglandins mediated by?

A

adenyl cyclase and inhibition of calcium flux in smooth muscle cells

37
Q

What does sympathetic innervation do to the choroidal blood flow? 1. What is it mediated by? 2. What is it stimulated by? 3

A
  1. reduces choroidal blood flow
  2. vasoconstrictive alpha-receptors in smooth muscle cells
  3. neurotransmitter neuropeptide Y (NPY)
38
Q

What does parasympathetic innervation do to the choroidal blood flow? 1. What is it mediated by? 2. What is it stimulated by? 3

A
  1. increases choroidal blood flow
  2. vasodilation
  3. acetyl choline, vasoactive intestinal peptide (VIP), PACAP, and NO
39
Q

What acts as a modulator of synaptic transmission in vasodilation in the retina and choroid?

A

adenosine

I. Ocular Physiology (20 decks)

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