circulatory system cognito

• movement of blood?

  vena cava - right atrium - right ventricle - pulmonary artery - lungs - pulmonary vein - left atrium - left ventricle - aorta - rest of body
• which part of heart has thicker walls and why?

  left ventricle has thicker walls as it pumps for whole body
• Double circulatory system

  A system in which blood passes twice through the heart on one complete circuit of the body
• what are pacemaker cells and where are they found

  pacemaker cells produce small electrical impulses and are found in the right atrium
• atria and ventricles seperated by?

  valves
• what are coronary arteries

  Arteries that branch off the aorta & surround the heart, ensuring that it gets all the oxygenated blood it needs
• what is an artificial pacemaker

  A device that uses electrical impulses to regulate the beating of the heart or to reproduce the rhythm of the heart beat.
• heart during pumping:

  1) walls of atria contract and blood is released into ventricles

  2) walls of ventricles contract and blood is pushed out of heart. blood flows into the now relaxed atria
• Structure and function of capillaries

  Capillaries are the smallest of the three blood vessels.

  
  

  The role of capillaries is to exchange nutrients and waste products with the tissues.

  
  

  Capillary walls are permeable, meaning substances are able to move through them.

  
  

  Their walls are also only one cell thick which means a short distance for diffusion.

  
  

  Capillaries carry blood at a low pressure and have a lower rate of flow than arteries.
• Structure and function of arteries

  Arteries are large and carry blood at a very high pressure.

  Artery walls have a thick middle layer, containing both muscle and elastic tissue.

  
  

  The muscle tissue provides strength, and allows the arteries to direct blood flow.

  
  

  The elastic tissue allows the arteries to stretch and recoil.

  
  

  Compared to their walls, arteries have a relatively narrow lumen, which keeps the blood pressure high.
• examples of nutrients that are exchanged between the blood in the capillaries and the body tissues?

  glucose, amino acids
• examples of waste products that are exchanged between the blood in the capillaries, and the body tissues?

  carbon dioxide, urea
• Structure and function of veins

  The role of veins is to carry blood from the body (or lungs) back to the heart.

  
  

  Veins are a similar size to arteries, but they have relatively thin walls and a relatively wide lumen

  
  

  This is because they carry blood at a much lower pressure.

  
  

  Veins also contain valves to prevent the blood from flowing backwards.
• Coronary heart disease

  1. Coronary arteries branch out of the aorta and supply oxygenated blood to the heart muscle.

  
  

  2. In coronary heart disease, layers of fatty material build up inside the coronary arteries, causing the lumen to get narrower.

  
  

  3. This reduces the flow of blood through the coronary arteries, resulting in a lack of oxygen and nutrients for the heart muscle.

  
  

  4. This can cause chest pain as the heart muscle is starved of oxygen, and in severe cases, can cause a heart attack.
• fatty material that builds up in heart is known as

  fatty plaques
• treatments for coronary heart disease:

  - stents to keep the coronary arteries open

  
  

  - statins to reduce blood cholestrol levels and slow down the rate at which fatty materials build up.
• benefits of stents when treating chd

  - last long time

  - almost immediate effect

  - surgery quick
• how do statins help treat chd

  - decrease ldl cholestrol

  - increase hdl cholestrol
• disadvantages of statins for chd

  - risk of kidney failure and headaches

  - can take a while to see positive effects

  - need to take pills every day
• two problems caused by faulty valves

  - not enough blood getting through

  - valves cant stop blood going backwards
• what can you replace faulty valves with

  - mechanical valves

  - biological valves
• treatments for heart failure


  - biological heart (can be rejected, hard to find donor)

  - artificial heart (often used as a temporary fix)