bio 7.1 - Arteries, Capillaries, Veins

arteries

function:

• carry blood away from heart

• very elastic

• stretch and recoil after ventricles eject blood from heart

• carry oxygen rich blood (not always)

leads into:

• branch out into arterioles

structure:

• thick, muscular, elastic walls

location:

• found deep along bones

veins

function:

• transport blood back to the heart

structure:

• thin walls, contain valve which prevent backflow of blood

• without them, blood would get stuck in legs and feet

location:

• often on surface and surrounded by skeletal muscles

blood comes from:

• very small veins which collect blood from capillaries called venule

capillaries

function:

• connect arteries to veins

structure:

• very thin walls

• 1 cell passes through at a time

• ten capillaries make the thickness of 1 hair

location:

• found everywhere within a few cells from each other

how they work:

• they have muscles that can dilate and constrict the vessel

arterioles and venules

• same features as arteries and veins but on a smaller scale

• arterioles leading to specific organs and regions have sphincter muscles

• when triggered they can dilate or constrict to regulate blood pressure by increasing and decreasing blood flow to particular capillary bed

• afferent arterioles: incoming arteriole

• efferent arterioles: outgoing arteriole