arteries
carry oxygenated blood away from the heart- branch intro arterioles that supplies blood to capillaries
capillaries
exchange vessels where gases, nutrients and wastes move between the blood within the capillaries and the interstitial fluid
list the 3 layers of blood vessel walls
- tunica intima
- tunica media
- tunica externa
Tunica Intima
- innermost layer
- endothelial cells
- flat surface to minimise friction = blood flow
Tunica Media
- smooth muscle arranged into circular arrangement
- changes diameter of blood vessels via constriction
Tunica Externa
- outermost later
- protects and reinforces the vessel wall
- anchors it to surrounding structures
Elastic Arteries
- thick walled arteries near the heart
- largest diameter
- aka conducting arteries
Muscular Arteries
- branch off of elastic arteries
- thicker tunica media
- constrict/dilate to distribute blood
- aka distributing artieries
Arterioles
- branch off of muscular arteries
- smallest artery
- can alter lumen diameter
- aka resistance vessels
continuous capillaries
- most common
- least permeable
- tunica intima
- contain vesicles that transport fluids and larger substances
fenestrated capillaries
- same as continuous but have pores
- more leaky
- larger volumes rapidly cross capillary walls
- found in kidneys etc
sinusoidal capillaries
- leakiest of capillaries
- largest intercellular clefts and fenestrations
- allows large proteins to cross
- found in liver and bone marrow
Capillary Bed
a network of 10 - 100 capillaries which receives blood from an arteriole and drains into a postcapillary vein which is connected to a vascular shunt
how is blood flow into a capillary bed controlled
pre capillary sphincter
- controlled by local conditions eg too much co2 will remain dilated to allow for oxygen
veins
carry blood away from the capillary bed and towards the heart
