Blood Vessels/Circulatory Part A Flashcards
what are blood vessels? what’s special about them?
- delivery system of dynamic structures that begin & end at the heart
- dynamic = always changing shape w/ demands
- veins, arteries, capillaries
function of arteries?
carry blood AWAY from the heart
function of capillaries?
to exchange gas, nutrients, & waste w/ body tissues
function of veins?
carry blood TOWARDS the heart
what do ALL blood vessels have?
a lumen
what is a lumen?
space inside blood vessel surrounded by the vessel wall
what are the 3 layers of the vessel wall? outside to inside
1.) tunica externa
2.) tunica media
3.) tunica intima
explain the tunica externa
where & what does it have?
- the outermost layer
- has the vasa vasorum (system of tiny blood vessels, “vessels of the vessels”)
what & where is the vaso vasorum?
- system of tiny blood vessels in the tunica externa layer of the vessel wall
- called vessels of the vessels
explain the tunica media.
what’s important about it?
- is the middle layer
- has smooth muscle
- this muscle regulates the diameter of the blood vessel, it can vasoconstrictor/vasodilate to make is smaller or bigger
explain the tunica intima
- the innermost layer
- is the inner lining of wall, just a thin little sheet
what are ALL capillaries made of? why is this important?
- all made of endothelium
- it’s thin to help exchange nutrients across the membrane faster
arteries vs. veins
which one is more elastic?
arteries are more elastic b/c they have more muscle, veins don’t
what are the 3 types of arteries?
1.) elastic
2.) muscular
3.) arterioles
describe elastic arteries
what is their nick name?
- largest arteries
- very thick walled
- they function as a pressure reservoir (has elastin in all 3 wall layers)
- nickname = conducting arteries (b/c they conduct blood from the heart to make it into smaller branches)
- found in aorta & major branches
what artery is called the conducting artery and why?
the elastic artery b/c they conduct blood from the heart to make it into smaller branches, they are the largest arteries (thick walled) to act as a pressure reservoir
describe muscular arteries
what is their nick name & why?
- has smooth muscle
- this muscle can vasodilate/vasocontract the artery to adjust blood flow
- they have vascular tone
- nickname = distributing artery b/c they deliver blood to body organs
what artery is called the distributing artery & why?
the muscular artery b/c it can adjust blood flow (muscle can vasodilate/vasocontract) to deliver blood to body organs
describe arterioles
what is their nick name?
- they regulate blood flow into capillaries (b/c arterioles are the smallest arteries)
- control blood flow into capillary beds by vasodilation/contraction
- nickname = resistance arteries b/c they can change diameters to change resistance to blood flow
what’s important about capillary layer wall cells?
the cells in the walls are connected by tight junctions w/ gaps called intercellular clefts to have things passing through
what are intercellular clefts? what’s the function?
- cells in the capillary wall that are joined by tight junctions w/ gaps
- they allow small things/fluid to pass through
describe continuous capillaries
- have continuous endothelial lining
- called continuous b/c cells are joined by tight junctions
- find these in skin b/c we don’t want big capillaries
describe fenestrated capillaries
- fenestrated means porus
- looks like swiss cheese
- great for filtration & absorption, we find these in kidneys (filtering)/intestines (absorption)
describe sinusoids capillaries
what’s unique about them?
- has huge holes, big large gaps
- good for large things to past through like proteins
- has large clefts (big giant gaps) to allow for larger molecules to pass through
- unique = have the macrophages in the wall to eat stuff
what structure in the capillary bed carries oxygenated blood?
arteriole
what structure in the capillary bed carries deoxygenated blood?
venule
capillary bed
what branches off the arteriole?
terminal arteriole
capillary bed
what is the terminal arteriole?
it branches off the arteriole that further branches into 10-20 capillaries to form the capillary bed
capillary bed
what branches off the venule?
the postcapillary venue
capillary bed
what is the function of the postcapillary venule?
so capillaries can drain into it
draw the capillary bed w/ the blood flow
how are veins formed?
when venules come together to create veins
what is the difference from veins to arteries?
- veins have thinner walls than arteries, and larger lumen (bigger space), this is why they are very good volume reservoirs
- arteries have smaller lumen have more pressure b/c they are actively pumping
- veins do not have elastin like artery
what is the nickname for veins?
capacitance vessels (called blood reservoirs)
REMEMBER: they have thin walls compared to arteries w/ big lumen (space) so they can hold more blood aka the name
capacitance = capacity
compare blood pressure in veins & arteries
blood pressure is lower in veins than arteries, so adaptions ensure return of blood to heart
