circulatory system- blood vessels Flashcards
what are the 3 different types of blood vessels
arteries
capillaries
vein
what do arteries do
carries blood under pressure away from the heart
how does the heart pump blood out
at high pressure
what are capillaries
they carry blood really close to every cell in the body to exchange substances with them
describe the artery walls
strong
elastic
thick compared to the lumen
contain thick layers of muscle to make them strong
elastic fibres to allow them to stretch and spring back
how big are capillaries
they are tiny and too small to see
what do arteries branch into
capillaries
what is 1 adaptation on a capillary
they have permeable walls so substances can diffuse in and out
what do capillaries do
they supply food and oxygen and take away waste like co2
what is the second adaptation of a capillary
their walls are usually one cell thick, this increases the rate of diffusion by decreasing the distance in which it occurs
what do veins do
they take the blood back to the heart
what do capillaries eventually do
join up to form veins
why dont the vein walls need to be as thick as the artery walls
because the blood is at a lower pressure
what are 2 adaptations of veins
they have a bigger lumen than arteries to help blood flow despite lower pressure
they have valves to help keep the blood flowing in the right direction
how can you calculate the rate of blood
volume of blood / number of minutes
