Flashcards in Vasculature Deck (63):
In what direction to arteries travel? veins?
arteries go from the heart
veins go to the heart
What are the exceptions to the rule of arteries (largest->smallest) and veins (smallest->largest)?
hepatic portal vein: brings blood from intestine capilary bed to liver capilary bed
Renal efferent arteriole: between glomerulus capilary and vasa recta capilary
What are the three common layers of arteries and veins?
tunica interna, tunica media and tunica externa.
Tunica intima is made up of?
endothelial cells (simple squamous), subendothelial layer and interal elastic lamina (IEL)
Tunica media is made up of?
circular smooth muscle, external elastic lamina (EEL)
Tunica externa is made up of?
connective tissue and fibroblasts.
What differs between arteries and veins in terms of the three common layers?
the width of the middle layer tunica media is much thinner in veins.
which of the three layers in arteries and veins changes with the size of the artery or vein?
tunica media (larger artery, larger tunica media)
What type of artery is the largest?
What is present in tunica media of elastic arteries? What is present in tunica externa?
collagen, elastic fibres and some smooth muscle (not very visible), thickest layer.
Blood vessels and nerves, some fibroblasts and it is loose connective tissue, this layer is thin compared to tunica media.
Muscular arteries are what sized arteries? what is unique about their tunica interna? tunica media is made up of? tunica externa?
dense wavy IEL (internal elastic lumina)
smooth muscle and collagen
collagen, elastin, fibroblasts, adipose, clear EEL (external ealstic lumina), thick layer.
EEL separates what two layers?
tunica media and tunica externa.
What are metamerioles?
bypass channels that allow for thermoregulation of blood.
Precapillary sphincters response to what?
temperature changes and internal signals i.e. vasomotor control allows for constriction if needed (for heat loss/retain)
The microvascular bed is made up of?
2. capillaries (smallest and is the ONLY palce gas exchange can occur).
3. postcapillary venules
Which are bigger generally arteries or veins?
arteries. due to reduced tunica media in veins
Small arteries normally only have how many layers of endothelium (tunica interna)? smooth muscle (tunica media)?
very few cells, usually not a full layer, can usually count.
usually only one layer of smooth muscle.
What are the three types of capillaries and where are they located?
1. continuous capillary (most common, least leaky, has pericytes, has a BM, has tight junctions, 6-7 endothelial cells in tunica interna): located in retina and iris.
2. fenestrated: has pores bridged by diaphragm, has few pericytes and sometimes has a BM, located in choroid
3. discontinous: large pores, most leaky, no pericytes, no BM, found in liver, spleen and marrow (only three places in body)
opthalamic artery enters orbit where?
within dura (dense CT that covers optic nerve) of optic nerve thru optic canal.
What is usually the first branch off the opthalamic artery?
central retinal artery.
Central retinal artery enters the dura aprx how far behind the globe?
Once the central retinal artery enters dura where does it go?
passes thru lamina cribosa (in sclera), enters disk nasal to center.
Macula is positioned how to the optic disk?
The inner retina is supplied by?
central retinal artery
collateral branches supply what?
CT surrounding optic nerve
What is unique about the eye artery system?
it is an end artery system, no connections to other arteries therefore if there is a block it could be really bad because there is no where else to go.
Photoreceptor layer gets its blood supply from?
central retinal artery gives rise to what two capillary sets?
1. superficial: ganglion cell layer
2. deep: at junction between INL (inner nuclear layer) and OPL (outer plexiform layer)
Retinal arterioles and venules are unique in that they share a common what?
tunica externa, very unique only found in eye.
What is A-V nicking?
in the eye where the artery compresses vein.
Lacrimal artery is what branch of the opthalamic? What does it supply?
second or third
lacrimal gland and lateral part of eyelid.
SPCA, some branches supply what? others supply?
others form circle of zinn (made up of CT and optic nerve head) around optic nerve and disc and supply blood to those.
LPCA run along what to the anterior portion of the globe? what do they supply?
between sclera and choroid.
ciliary body, some of conjunctiva and anterior choroid. supplies both stroma of iris and ciliary body (because connected). also forms part of major circle of iris (with anterior ciliary arteries).
Arteriole blood enters the eye through what 4 sets of arterioles?
1. central retinal artery (first branch of opthalamic)
2. long psoterior ciliary arteries
3. short posterior ciliary arteries
4. anterior ciliary arteries
Central retinal artery branches in which directions?
inferiorly and superiorly
nasally and temporally
macula is located in what direction compared to the disk?
central retinal artery gives rise to what two sets of capillaries?
1. superficial (ganglion cell layer)
2. deep (at junction between inner nuclear layer and outer plexiform layer)
Which to things are supplied by the lacrimal artery?
lacrimal gland and lateral palpebral artery
How many short posterior arteries? long?
What is the function of circle of zinn?
throws back arteries and arterioles to supply ON/optic disc connective tissue and optice nerve head.
Which arteries do the long posterior arteries anastomose with? together these form what?
anterior ciliary artery major arterial circle of iris.
How many anterior ciliary arteries are there? where do they branch from? how many arise from each muscle? what do the anterior ciliary arteries supply?
vessels supplying the 4 rectus muscles.
2 from each muscle except for the lateral rectus which only gives rise to one.
conjunctiva (bulbar and palpebral) and episcleral plexus.
where is the major circle of iris located? where do the anterior ciliary arteries and the posterior ciliary arteries meet?
in ciliary body NOT in iris.
anterior to iris NOT IN IT.
major circle of iris gives off what 4 sets of blood vessels? which two supply the ciliary body?
1. radial vessels (or arterioles) of iris
2. anterior ciliary arterioles
3. posterior ciliary arterioles
4. recurrent arterioles
anterior and posterior.
What is the sole blood supply of the iris? what type of capillaries are here?
continuous, cells joined by tight junctions preventing leakage.
retinal capillaries are what? choroidal?
anterior ciliary arteries are located where? what type of capillaries? blood supply for what?
run deep within ciliary stroma
blood supply for aqueous humor
posterior ciliary arteries are located where? what type of capillaries? blood supply for?
run within each ciliary process (not as deep as anterior)
blood supply for ciliary muscle
recurrent arterioles run back toward what? here they anastomose with what? what type of capillaries? what do they supply?
ora serrata where they anastomose with anterior branches of choroidal circulation from short posterior ciliary arteries.
fenestrated capillaries because dealing with choroid.
blood to the ant choroid.
what is the purpose of the cilioretinal artery? what does it supply? branches from where? what percent of the population has it?
spares central vision in cases of central retinal artery occlusion.
branches from choroid or circle of zinn to retina
which vein drains venous blood out of the iris? which veins drain the posterior uvea?
anterior ciliary vein (runs with the anterior ciliary arteries, drains all anterior uvea)
how many vortex veins per eye? where are they located?
4 (can have up to 6)
one in each quadrant of the posterior eye.
central retinal vein drains blood from? travels parallel with?
central retinal artery
the vortex veins exit how many mm posterior to the equator (middle of globe)?
superior opthalamic vein is the result of which two veins joining together? which structures does it drain blood from?
angular and supraorbital veins
inferior opthalamic vein begins as what vein? inferior opthalamic vein may form which two branches when draining?
1. empty into superior opthalamic vein then cavernous or straight to cavernous
2. AND into pterygoid plexus
the central retinal vein leaves the optic nerve how far behind the lamina cribosa? what does it travel alongside with? what does it join up with (two options)?
alongside central retinal artery (parallel)
joins superior opthalamic vein or into cavernous sinus.
what does the lateral palpebral artery supply? what does it branch from?
supplies superior and inferior eyelid (laterally) derived from lacrimal artery
what does the medial palpebral artery supply? what does it branch from? once it enters the lids, what happens?
superior and inferior eyelid (medially)
it branches into two branches forming two arches in the eye
both the lateral and medial palpberal arteries anastomose to form what?
Anterior conjunctiva artery (medial) branch of? provides vascular supply for first 1-2mm of what?
anterior ciliary artery
bulbar conjunctiva just beyond the cornea
posterior conjunctiva artery (peripheral) branches from what? (this branch supplies what?) posterior conjunctiva artery provides vascular supply to what?
peripheral arterial arch (supplies palpebral conjunctiva)
vascular supply to bulbar conjunctiva