Week 4 Pt 1&2 Blood vessels & Circulation Flashcards
What is the length blood vessel in an average adult human?
60,000 miles
What are the major categories of blood vessels?
Arteries, capilaries, and veins
what are the smaller arteries called?
Arterioles
Between the blood vessels, they have 3 layers EXCEPT?
capillaries
what is the innermost layer called?
tunica interna also known as tunica intima
what is the middle layer called?
tunica media
you can find what in the tunica media?
smooth muscle
what is the outermost layer called and what is another name for it?
tunica externa (tunica adventitia)
What does the tunica interna line?
the lumen
what is structure of the tunica interna?
it has endothelium, single layer of epithelial cell, and thin layer of areolar connective tissue deep to that.
Since endothelium is an epithelial tissue, what does those cells have to sit on?
a basement membrane
what layer does the capillaries ONLY have?
tunica interna
the tunica interna of an artery looks very similar to the tunica interna of a ?
vein
Why does the tunica media vary in thickness?
depending on the type of blood vessel
what are the largest arteries called?
elastic arteries
In the elastic arteries, what structures do they have?
smooth muscle and elastic tissue in tunica media
what type of artery has the thickest wall?
muscular arteries
What layer in the arteries has the thickest wall?
the tunica media is the thickest layer of the wall
what has layers that no other type of blood vessels have?
- In the elastic arteries
- the big ones such as aorta, pulmonary trunk, pulmonary arteries, iliac or common iliac arteries,
- things that are very close to the heart and receiving blood from ventricles
-branches off arteries that do that.
what are some of the layers no other blood vessels have called?
internal elastic membrane and external elastic membrane
where is the internal elastic membrane located?
deep into the basement membrane and tunica interna
where is the external elastic membrane located?
just between the outer edge of the tunica media and the beginning of the tunica externa
what does the external elastic membrane do?
lets the elastic arteries stretch a lot
what are the benefits of the elastic arteries?
it stretches and returns to its resting size
another importance of tunica media include : if you have smooth muscle, it is gonna need 2 things which is?
oxygen and autonomic innervation
smooth muscle is an autonomic ___
effector
what happens if the blood vessels are too thick for O2 to diffuse through the tunica media?
we need blood vessels to go into the tunica media of the blood vessels to supply O2 and nutrients to the smooth muscle in the wall of the blood vessels.
what is vaso vasorum?
blood vessels of blood vessels
- blood vessels that supply O2 and nutrients to the smooth muscle in the tunica media
what are the small autonomic nerves that go into the tunica media called?
nervi vasorum
what are the nervi vasorum and what does it do?
nerves of blood vessels that control whether that smooth muscle contracts or relaxes
what is the thickest layer of an artery?
tunica media
what is the thickest layer of a vein?
tunica externa
what do arteries deal with that causes the wall to be thicker?
pressure
what are veins meant to do?
to be away to get the blood back to the heart
-not meant for high pressure which is why they don’t need a thicker wall
why don’t we do much adjusting of blood pressure in the venous side of the circulation?
the arterial pressure is what matters
there’s nothing in the body that monitors venous blood pressure. T/F
True
what do the collagen fibers that stick out from the tunica externa help with in the veins?
help anchor the veins
If you have to chase a vein in the arm with a needle, what is the reason?
they are not well anchored
why do arteries have thicker walls?
handle blood that’s under higher pressure
there are more elastic fibers in the wall of artery because?
due to the thickness of the walls
what happens when you take blood out of an artery?
because of the elastic it will stay open and the lumen will stay round bc the wall is supporting it
what happens when you take blood out of a vein?
the vein will collapse bc it was the blood that was holding it open not the wall.
elastic arteries have the most elastic fibers. T/F
True
how can you tell an artery from a vein without looking at it under a microscope?
one of them is flat and one of them has an open lumen
what is vasoconstriction?
when the smooth muscle in the tunica media of an artery CONTRACTS and the lumen of blood vessel gets SMALLER due to it being in a circle
what vasodilation?
when the smooth muscle in the tunica media RELAXES and the lumen of that artery gets BIGGER
what are elastic arteries?
biggest arteries, have the second thickest wall in the artery, and also called conducting arteries.
- blood vessels that receive blood that’s directly getting pumped from the heart or very close branches
examples of elastic arteries
aorta, pulmonary trunk, pulmonary artery, common iliac, and common carotid
what are the functions of the elastic arteries?
to stretch when stroke volume is pushed into them.
- aorta is not getting steady flow of blood from right ventricle and it has to stretch to accept 75ml SV
what happens when you stretch an elastic artery?
the elastic fibers that are getting stretched stores energy and that energy is used to help push blood forward as elastic artery returns to its resting size
-due to no constant BP
what structures are muscular arteries and what is it called?
distributing arteries
- gastric arteries
- brachial arteries
- femoral arteries
the wall of the muscular arteries are what?
the thickest walls of any artery and bc the wall is so thick, the lumen is smaller than the lumen in the elastic artery
the muscular arteries are responsible for?
delivering blood to the specific regions of the body whereas the elastic ones have the job of receiving blood that’s coming out of the heart.
what are arteriole arteries?
smallest artery that connect to capillaries.
- don’t have much tunica externa
-walls are not very thick
what are arteriole arteries responsible for?
determining where blood goes and the main spot for blood pressure control
when its cold and you don’t want to lose the heat in the surface of the body ___
we constrict the arterioles in the skin and dilate arterioles in the core making it easier to go to the core
what are the three categories of capillaries?
continuous capillaries, fenestrated capillaries, and sinusoids
why are capillaries the only blood vessels with a wall thin enough?
to allow exchange
what are continuous capillaries?
most common
- least permeable
- simple squamous epithelium
- complete basement membrane on the outside of capillary
- space between the cells called intercellular cleft
where can you find continuous capillaries?
lungs, skeletal muscle, skin, and some types of connective tissues
when something has to move from capillary from outside and into the capillaries, what are the two diff pathways?
- to diffuse through basement membrane and simple squamous epithelium
- to go in the space between the cells called intercellular cleft: small size (intercellular cleft are not very big so the things that can leave/enter capillary are also not very big)
what are fenestrated capillaries?
- intercellular clefts between the cells are bigger than the ones in continuous capillaries: medium size
- holes in the cells called fenestration’s
- complete basement membrane around capillary
- more permeable than continuous capillary
- work like strainers (if smtn wants to enter or exit, it can pass through intercellular clefts and diffuse through basement membrane and simple squamous epithelium or fenestrations)
where can you find fenestrated capillaries?
organs where we have things moving in and out
- kidneys (tend to have stuff moving out)
- small intestine (where we have stuff moving in cuz we’re absorbing it)
what are sinusoids?
- have an INCOMPLETE basement membrane
- really big intercellular clefts
- have bigger fenestrations than in fenestrated capillaries: big size
- bigger diameter than fenestrate/continuous capillaries
- very windy ( things get stuck in turns if not flexible)
Where can you find sinusoids?
liver, spleen, and bone marrow
benefits of sinusoids having really big intercellular clefts?
it makes it easier for diapedetic WBC to move in and out of the blood stream
benefits of bigger fenestrations
allow us to move things out of blood or into the blood that are bigger than what we would add in most places.
Where would plasma proteins go through and why?
sinusoids because it is made by liver and need to be put in the blood
How do you filter out the older RBC in a windy sinusoid?
When RBC get old, they lose flexibility causing them to not make sharp turns and they get stuck
what do the capillaries connect?
the arterioles to the venules
you can find capillaries in most places in something called ____
capillary bed
what structures are in a capillary bed?
short connecting structures called metarterioles
what are precapillary sphincter?
band of smooth muscle that adjusts flow into capillaries
what happens when a pre capillary sphincter is closed?
blood goes form metarteriole into venule without any blood going to the capillaries
- blood can’t go anywhere, roads are blocked
- the more that have closed, less blood that goes through capillary bed and the less oxygen and nutrients we will delivery in waste area and fewer waste product we will pick up to get out
what happens when precapillary sphincter is open?
blood can get out of arteriole and go into smaller capillary areas
what is a metarteriole?
when precapillary sphincter is open
what is it called when all precapillary sphincter is closed?
thoroughfare channel