BS - Blood Retina Barrier - Week 3 Flashcards
Name the two circulatory systems.
Cardiovascular
Lymphatic
Name the three components of the cardiovascular system.
Heart
Pulmonary
Systemic
Name the 5 components of the systemic circulation.
Arteries Arterioles Capillaries Venules Veins
Which of the following vessels have valves?
Arteries
Veins
Lymphatic vessels
Veins
Lymphatic vessels
Name the innermost layer of a blood vessel.
Give its alternate name, and describe the number of cell layers, shape, type, and association with tissue (2).
Tunica intima (or interna) Is a single layer of flattened squamous endothelial cells, with underlying connective tissue called internal elastic lamina (endothelial side). A basement membrane is found in between.
Name and describe the middle layer of a blood vessel. What kind of tissue is it?
Tunica media
Circumferentual smooth muscle cells with underlying connective tissue called external elastic lamina (endothelial side).
Name and describe the outermost layer of a blood vessel. What kind of tissue is it?
Tunica adventitia (or externa) Fibroelastic tissue.
Define the lumen and endothelium of a blood vessel.
Consider the innermost cell layer. The side facing inside the vessel is the lumen. The side facing outward is the endothelium.
What do endothelial cells line? What are they connected by (2)?
Blood vessel lumen. Connected by tight/gap junctions.
Name 2 things that can cause damage to the lumen.
Diabetes
Nicotine use
Where are pinocytotic vesicles found, and what is their function? What does this allow for?
Found in endothelial cells, allowing the passage of fluid across cells from the blood. Allows the lumen to act as a selective filter.
What kind of nerves supply blood vessels?
Unmyelinated fibres
What does the tunica media mostly consist of?
Fenestrated lamellae of elastin
Describe the vasa vasorum of elastic arteries.
Very thicc
Needs its own blood supply
Where are elastic arteries typically found?
All arteries close to the heart like the aorta and its branches, common iliac trunk, and the pulmonary trunk.
What are elastic arteries, and where are they typically found?
Distributing arteries.
Most arteries from the aorta
Name 3 distinguishing features of muscular arteries.
- Internal elastic lamina is prominent and undulates.
- Thick tunica media composed mostly of smooth muscle cells, 40 layers
- Sparse vasa vasorum in the tunica adventitia
Define an arteriole (2).
Artery with a diameter of <0.1mm
Width of the wall is approximately equal to the lumen
What is the tunica intima like in arterioles?
No internal elastic lamina, except in larger arterioles.
What is the tunica media like in arterioles?
1-3 layers of smooth muscle cells.
True or false
Arterioles have an external elastic lamina
False, they do not
What is the tunica adventitia like in arterioles?
Very little
What layer composes a capillary?
Only the tunica intima with no internal elastic lamina.
What cell composes a capillary?
One layer of endothelial cells.
Where are pericytes found?
Located on the outside of capillaries and venules.
Name the three types of capillaries.
Continuous
Fenestrated (2 types)
Non-continuous/sinusoidal
Describe the structure of fenestrated capillaries (2), fluid movement within, and where in the eye its found.
- Thin walls
- Fenestrations covered by a complete basal lamina
- Large fluid movement
- Found in the choroid and ciliary body
Describe the structure of continuous capillaries (2), how molecular movement within occurs, and where in the eye its found.
- Continuous with no holes, and a complete basal lamina
- Endothelial cells have tight junctions
- Big molecules - active transport
- Small molecules - diffusion
- Found in the retina and iris
Describe the structure of dis-continuous capillaries (2) and where in the eye its found.
- Large and tortuous
- Fenestrated with incomplete basal lamina covering holes
- Not found in the eye
True or false
Veins outnumber arteries
True
Which vessel holds the most blood, and how much?
Veins, holding 70%
Are vein walls thick or thin?
Thin
Are the layers within a vein wall distinct?
No, theyre indistinct
What is the diameter range of venules?
0.02 - 0.2mm
What are the walls of venules similar to?
Capillaries
What happens to pericytes on venules as diamter increases?
They are replaced by smooth muscle.
What diameter do medium veins have?
<1cm
Which kind of vein is responsible for draining most of the body.
Meedium veins
Describe the tunica intima of medium veins.
Has endothelial cells, may not have an elastic lamina
Describe the tunica media of medium veins.
Smooth muscle in loosely organised collagen and fibroblasts
Describe the tunica adventitia of medium veins.
Thickest part of the wall, composed of collagen, elastic fibres, and a few smooth muscle cells
Name 6 large veins.
Vena caeva Pulmonary Portal Renal Jugular Iliac
Describe the tunica intima, media, and adventitia of medium veins.
Tunica intima and media are the same as medium veins.
Tunica adventitia is very wide and has longitudinal smooth muscles.
What is the vasa vasorum of large veins like?
Extensive
What is the blood-olcuar barrier highly permeable to?
Lipid soluble molecules, including O2 and CO2
What is the blood-olcuar barrier not permeable to?
Water and small water soluble molecules
What keeps the cell barrier continuous?
Tight junctions
Name 4 diseases that can compromise the blood-ocular barrier.
Diabetes
Arterial hypertension
Giant cell arteritis
Anterior uveitis
Does the iris have an epithelium?
No
Why does the iris have a blood-ocular barrier?
To prevent blood and aqueous humour from mixing. No leakage of HRP, good barrier to macromolecules.
True or false
HRP doesnt leak into the ciliary stroma
False, it does
What percentage concentration of protein is the ciliary stroma compared to plasma?
75%
Does the ciliary stroma have a blood-ocular barrier?
No
Are ciliary stroma vessels fenestrated?
Yes
True or false
The ciliary epithelium is a blood-aqueous barrier.
True
Name three kinds of uveal inflammation, and what umbrella condition they fall under.
Iritis
Cyclitis
Choroiditis
-Fall under uveitis
What are three symptoms of uveitis?
Red eye
Pain
Photophobia
What are three signs of uveitis in the anterior chamber?
Cells (inflammatory)
Flare (protein)
Iris vessel leakage
What happens to IOP during uveitis, and explain why.
Lower IOP, due to reduced aqueous humour production in iritis.
What happens to HRP during uveitis? Name 4 reasons why.
It leaks from the ciliary body.
- Tight junctions are damaged
- Separated vascular endothelial cells
- Part of the inflammatory process
- Allows white blood cells to enter to deal with injury/infection
Name 4 consequences as a result of a loss of tight junctions.
Decreased aqueous humour production
Decreased aquaporin permeability
Decreased cell pH
Decreased IOP
How is the integrity of the blood-retinal barrier tested clinically?
Fluorescein angiography (NaFl)
Give the clearance time for the following during fluorescein angiography: Choroidal Arterial Arterial-venous Venous Late
Choroidal - 10 secs Arterial - 10-12 secs Arterial-venous - 13-15 secs Venous - 16-20 secs Late - 30 secs
Does HRP leak from choroidal vessels?
Yes
Does HRP leak from retinal vessels?
No
True or false
The choriocapillaris is fenestrated on both sides.
False, it is fenestrated only on the RPE side
Name the two retinal blood supplies.
Inner retina
Choroid
Name the blood retinal barrier at the inner retina.
Endothelial cell tight junctions in vasculature
Name the blood retinal barrier at the outer retina.
Tight junctions between retinal pigment epithelial cells
