B5 Blood Vessels Flashcards
List the three main types of blood vessel
Arteries
Capillaries
Veins
What do arteries do?
Carry blood away from the heart
What do capillaries do?
These are involved in the exchange of materials at the tissues
What do veins do?
Carry the blood to the heart
What are arteries walls like?
Strong and elastic
Why are artery walls strong and elastic?
Because the heart pumps the blood out at high pressure.
What is the lumen?
The hole down the middle of the blood vessel
Complete this sentence
The walls of arteries are …… compared to the size of the lumen.
Thick
What do arteries contain to make them strong?
Muscle
What do arteries contain to allow them to stretch and spring back?
Elastic fibres
Complete the sentence
The capillaries are really ……
Tiny
What are networks of capillaries in tissue called?
Capillary beds
What do capillaries do?
They carry the blood really close to every cell in the body to exchange substances with them.
Why do capillaries have permeable walls?
So substances can diffuse in and out
What do capillaries supply?
Food and oxygen
What do capillaries take away?
Waste like CO2
Why are capillary walls usually only one cell thick?
Thin walls increase the rate of diffusion by decreasing the distance over which it occurs.
Why are vein walls thinner than artery walls?
The blood in them is at a lower pressure.
Why do veins have a bigger lumen than arteries?
To help the blood flow despite the lower pressure.
What helps to keep the blood in veins flowing in the right direction?
Valves
What are the muscle and elastic fibres like in veins?
Thin layers of elastic fibres and smooth muscle
Describe how veins are adapted to carry blood back to the heart (2 marks)
They have big lumen to help the blood flow despite the low pressure (1 mark)
And they have valves to keep the blood flowing in the right direction (1 mark)
Explain how capillaries are adapted to their function. (3 marks)
Networks of capillaries carry blood to every cell in the body to exchange substances with them (1 mark)
They have permeable walls, so that substances can easily diffuse in and out of them (1 mark)
Their walls are only one cell thick, which increases the rate of diffusion (1 mark)
