video - blood vessels

• what are blood vessels?


  the tubes that run through the transport system and in which blood is transported.
• what does transporting blood in vessels allow?

  this allows it to be pumped at high pressure, delivering nutrients and removing waste more effectively.
• how is it a closed system?

  the vessels are completely shut off from the tissues. The blood in the tubes stays in the tubes the whole way around the circuit.
• how many types of vessel are there in the circulatory system?


  there are 5 types of vessel.
• what does the heart send blood out into?


  the heart sends blood out into arteries.
• what do a arteries always do?


  arteries always go away from the heart.
• what happens as arteries get smaller?


  arteries get smaller and become arterioles.
• what happens as arterioles get smaller?


  arterioles get smaller and become capillaries.
• what type of vessel is where exchange happens?


  exchange happens in the capillaries.
• what do capillaries rejoin up to form?

  capillaries rejoin up to form venules.
• what happens as venues form together to form bigger vessels?


  they form veins.
• what do veins do?


  veins brining blood back to the heart.
• what are each vessels adaptations based on?


  how far the vessel is from the heart.
• what is the pressure of the blood like in the arteries and why?


  the blood pressure in the arteries is very high because the heart isn't far away.
• are veins far from the heart?


  yes as they've gone around the whole body.
• what do all vessels have in common?

  all vessels have a smooth and thin inner layer of cells called the endothelium.
• why is the blood in the arteries such high pressure?


  because the heart has just pumped it out.
• how do arteries cope with the blood pressure?


  they have very thick walls.
• what are artery walls like?


  artery walls have thick layers of elastic tissue and smooth muscle encased in a thick outer layer of collagen.
• why is elastic tissue important?


  elastic tissue is important as it can expand and contract so can absorb shock forces.
• what does smooth muscle do for the artery?


  smooth muscle helps to keep the artery open and controls the diameter.
• what does collagen do for the artery?


  collagen helps to withstand forces and keep the artery strong.
• what is collagen?


  a tough abundant protein
• how are arterioles similar and different to arteries?


  • arterioles have a similar structure to arteries.
  • they're smaller and have thinner muscle and elastic layers.
• why do arterioles have a different structure to arteries?


  because the pressure drops going from artery to arterioles as the blood makes contact with the wall and friction slows the blood down.
• how can arterioles control their diameter?


  the smooth muscle that is around the arteriole can constrict to limit the vessel's diameter, as the muscle constricts the diameter decreases.
• why is it important that arterioles can control their diameter?


  important in controlling blood flow
• what are capillary walls like?


  capillary walls are very thin, made of only the endothelium.
• what DOESNT the capillaries have compared to the other vessels?


  capillaries have no outer layers or muscles or elastic tissue.
• why are capillaries very thin?


  so we can have oxygen going out to cells and oxygen coming in at the alveoli.
• what is the lumen like in capillaries?


  the lumen is very narrow
• why is the lumen of the capillary narrow?


  so they can squeeze red blood cells against the endothelium to important transfer of oxygen. Short diffusion distance.
• how do the capillaries avoid damage?


  the blood has increased resistance due to being squeezed against the vessel walls, now lots of the blood is in contact with capillary walls. This slow down blood flow, reduces the pressure and so saves damage. Blood pressure drops, flow drops so damage to walls and leakage is reduced.
• what do veins do?


  veins carry low pressure blood back to the heart
• what has happens to the blood before the veins take it back to the heart?

  the blood has undergone all exchange it needs and so now needs to go back to the heart as its now full of carbon dioxide and oxygen needs replenishing. Some nutrients are gone too.
• what is the blood pressure like in the veins? why?


  the blood pressure drops so much at the capillaries and there is no pump at the capillaries so pressure stays very low in the veins. This low pressure blood goes from the venules to the veins.
• what are the walls of the veins like?


  the walls aren't thick (bc they don't need to withstand much blood pressure) but has a very wide lumen to maximise blood flow.