circulatory system-blood vessels Flashcards
why do arteries have thick walls?
to withstand pressure
direction of blood flow for all
a-away from heart
v-to heart
c-arteries to veins
why do capillaries have one cell thick walls?
so the walls are permeable and to decrease diffusion distance, increasing rate of diffusion
why do veins have thin walls?
they only carry low pressure blood
what are arteries made of and why?
muscular walls to make them strong to resist high pressure, elastic fibres that stretch when the surge of blood passes through and then recoil in between to keep blood flowing and withstand high pressure
how does blood travel in veins and arteries?
veins-smoothly
arteries-in surges, when the heart beats
what diffuses in and out of capillaries?
food in and waste products out
what do arteries branch into?
capillaries
what do capillaries join to form?
veins
what do capillaries do?
carry blood close to every cell to exchange substances
why do veins have the biggest lumen?
to help blood flow, enable low pressure
why do veins have valves?
blood moves slow with low pressure so valves keep it flowing in the right direction and prevent its backflow
capillaries
carry blood through the body tissues, allowing oxygen, nutrients, and waste products, to be exchanged between tissues and the blood
give 2 nutrients that are exchanged between the blood in the capillaries
amino acids
glucose
give 2 waste products that are exchanged
carbon dioxide
urea
what is the only artery that doesn’t carry oxygenated blood?
plumonary
which is the only vein that carries oxygenated blood?
pulmonary
3 types of blood vessels
-arteries
-veins
-capillaries
function of arteries
carry blood away from heart
function of veins
carry blood towards heart
function of capillaries
enable transfer or substances between the blood and tissues
why do capillaries have a narrow lumen?
blood moves slowly meaning more time for diffusion
how do you calculate the rate of blood flow?
volume of blood/number of minutes
two ways arteries are adapted for their function
-thick muscle layer
-thick elastic layer
three ways capillaries are adapted for their function
-walls one cell thick
-walls permeable
-narrow lumen
two ways veins are adapted for their function
-wide lumen
-valves
