transport Flashcards
what are the 3 roles of blood?
- to carry oxygen to tissues for respiration
- removes carbon dioxide from tissues
- transports dissolved substances around the body
what is diffusion alone not enough to transport dissolved substances in large organisms?
they’re too big
how much of the blood do red blood cells take up?
45%
how much of the blood does plasma take up?
55%
how much of the blood do white blood cells take up?
> 1%
how much of the blood do platelets take up?
> 1%
what are platelets involved in?
clotting the blood
what does plasma do?
transport carbon dioxide, digested food molecule, urea and hormones
how are red blood cells adapted to do their jobs?
- no nucleus so they can pack in more haemoglobin
- small + flexible so can fit in capillaries
- biconcave shape to maximise SA for oxygen diffusion
- thin, so short distance for oxygen to diffuse to centre of cell
how do arteries carry blood?
carries oxygenated blood under high pressure away from the heart
do arteries have more or less muscle and elastic tissue?
more
how do veins carry blood?
carries deoxygenated blood under low pressure back towards the heart
why do veins have valves?
to prevent the backflow of blood
do veins have more or less muscle and elastic tissue?
less
do veins have a wider or thinner lumen?
wider
how thick are capillaries and why?
1 cell thick so oxygen can diffuse across their walls
what is the pressure of the blood like in capillaries?
very low
how is your heart rate affected when we exercise?
- it increases
- so more oxygen gets into the blood and therefore more oxygen and glucose to tissues/muscles
- increased rate of aerobic respiration to release more energy for movement
- more carbon dioxide is able to be removed from the body
- if anaerobic respiration, lactic acid builds up
