2.8.11 Blood Vessels & the Circulatory System Flashcards
The three main types of blood vessels are what?
Arteries
Veins
Capillaries
Smaller vessels that branch off from arteries are called what?
Arterioles (small arteries) and those that branch into veins are called venules (small veins)
Each vessel has a particular function which is what?
Is specifically adapted to carry out that function efficiently
Arteries carry blood at high pressure away from what?
The heart
What type of blood do arteries carry?
Oxygenated blood (except the pulmonary artery)
Arteries have walls of what structure?
Thick muscular walls containing elastic fibres
Arteries have a narrow what?
Lumen
What speed does blood flow through arteries?
Fast
The structure of an artery is what?
Thick muscular walls containing elastic fibres withstand the high pressure of blood and maintain the blood pressure as it recoils after the blood has passed through
A narrow lumen also helps to maintain high pressure
Vein key features are
Carry blood at low pressure towards the heart
Carry deoxygenated blood (other than the pulmonary vein)
Have thin walls
Have a large lumen
Contain valves
Blood flows through at a slow speed
Vein structure is
A large lumen reduces resistance to blood flow under low pressure
Valves prevent the backflow of blood as it is under low pressure
Capillaries key features are
Carry blood at low pressure within tissues
Carry both oxygenated and deoxygenated blood
Have walls that are one cell thick
Have ‘leaky’ walls
Speed of blood flow is slow
The structure of capillaries are
Capillaries have walls that are one cell thick (short diffusion distance) so substances can easily diffuse in and out of them
The ‘leaky’ walls allow blood plasma to leak out and form tissue fluid surrounding cells
As arteries get further away from the heart, they what?
They divide more and get narrower
The narrow vessels that connect arteries to capillaries are called what?
arterioles
