Blood Vessel Flashcards
Blood Vessel layers
Tunica Interna: innermost layer
Tunica Media: Middle layer, smooth muscle and elastic fibers
Tunica Externa: outtermost layer
Blood Vessel vs. Artery
Artery has large tunica media, smooth muscle,
Artery has more elastic layers
Veins tend to have a larger lumen and main structural feature is the valve, prevents backward flow of blood
Cappilaries
One cell thick, endothelium
Surrounded by basement membrane.
Tight and continuous or have holes in them, all depends on where they’re on the body
Arteries
Carry blood away from the heart to the tissues
walls are elastic, allowing them to absorb pressure
Because of smooth muscle, they can regulate in diameter( vasoconstriction)
Types of ateries
Elastic Arteries
Muscular arteries
Anastomoses
Where branches of arteries fuse and move out in different directions
supply the same body region
Capillaries
Smallest blood vessels connect arterial outflow and venous return
One cell thick & composed of basement membrane
permit the exchange of nutrients
Found everywhere
Microscopic vessels that connect arterioles and venues
Tunica media and tunica externa
Types of capillaries
Three types
Continuous: tight junctions but you can move fluids in between cells, endothelial cells
Fenestrated: Found in kidney and parts of DT, allows some proteins and larger molecules to move out of the blood vessels. have fenestrations or pores
Sinusoid:Wider and more winding, Allow for large plasma proteins to move in and out and some cells too, found in liver and spleen primarily
Veins
Veins have little smooth muscle, very thin walls
Have valves
same 3 layers: but
Tunica internal thinner than arteries and with little smooth muscle
and the tunica externa is the thickest layer
Valves fold on tunica international forming cusps
Blood distribution
Largest portion of the blood is in the veins and venues,aka blood resiviors. 64%
Heart 7%
Pulmonary 9%
Capillaries 7%
arteries and arterioles 13%
Venoconstruction reduces volume of blood in reservoirs and allows greater blood volume to flow where needed
Capillary exchange
The movement of substances between blood and interstitial fluid
Substances cross capillary walls by :
Diffusion
Transcytosis
Bulk flow: movement of fluid under pressure
Bulk flow
Passive process in which large number of ions molecules or particles in a fluid move together in the same direction
Based on pressure gradient
More important for regulation of relative volumes of blood and interstitial fluid
Filtration
Pressure driven movement of fluid and solutes from blood capillaries into interstitial fluid
Reabsorbtion
Pressure driven movement of fluid and solutes from interstitial fluid into capillaries
blood flow
Volume of blood flowing through any tissue at a given time
What are the five main types of blood vessels
Arteries arterioles capillaries venules veins
Tunica interna
Inner lining in direct contact of blood
Active role in vessel related activities
Tunica media
Muscular and connective tissue layer
Smooth muscle regulates diameter of lumen