RG Circulatory System

• What type of system is the circulatory system?

  A mass transport system
• What do multicellular organism need and why?

  they have a low surface area: volume ratio so they need a specialised transport system to carry raw materials from specialised exchange organs to their body cells- this is the circulatory system
• What is the circulatory system made up of?

  heart and blood vessels
• What does the heart do?

  Pumps blood through blood vessels to reach different parts of the body
• What are the FOURtypes of blood vessels that the heart pumps the blood through?

  arteries , arterioles, veins, capillaries
• What does blood transport round the body?

  respiratory gases, products of digestion, metabolic waste and hormones
• How many circuits are there?

  2
• What does one circuit do?

  Takes blood from the heart to the lungs, then back to the heart
• What does the other circuit do?

  Takes the blood around the rest of the body
• What does the heart have?

  Its own blood supply- the left and right coronary arteries
• what does the circulatory system contain?

  A pump (heart), vessels (arteries, capillaries etc) and a medium (blood) to transport substances around body
• Define double circulatory system?

  Blood is confined to vessels and passes twice through the heart for each complete circuit of the body (to the lungs and tissues)
• What is the heart?

  • a muscular organ that lies in the THORACIC CAVITY behind the STERNUM
  • Operates continuously + tirelessly throughout the life of the organism
  • Made of 4 chambers- left and right atria and left and right ventricle
• Define atria?

  The upper chambers of the heart which are thin-walled and elastic and stretches as it collects blood
• define ventricles?

  Lower chambers of the heart which have a thick muscular wall as it has to contract strongly to pump blood some distance, the left side to rest of body (So has thicker muscular wall) and right side to LUNGS
• Define VENA CAVA?


  A vein connected to RIGHT ATRIUM and brings deoxygenated blood back from the tissues of the body (EXCEPT the LUNGS)
• Define PULMONARY ARTERY?


  An artery connected to the right ventricle which carries deoxygenated blood to the lungs where its oxygen is replenished and its carbon dioxide is removed
• Define PULMONARY VEIN?


  A vein which is connected to the left atrium and brings oxygenated blood back from the LUNGS
• Define AORTA?

  An artery which is connected to the left ventricle & carries oxygenated blood to all parts of body EXCEPT LUNGS
• define AV vavles?


  valves found between atrium and ventricle which prevent the backflow of blood into atria when the ventricles contract and the ventricular pressure exceeds atrial pressure

  • left =the bicuspid
  • right = the tricuspid
• Define SL valves?


  The valves found in the aorta and pulmonary artery which prevent the backflow of blood into ventricles when the pressure in these vessels exceeds that in the ventricles
• define coronary artery?


  The blood vessels which branch off the aorta and supply the heart muscle with oxygenated blood
• Define myocardial infarction ?

  blockage of the coronary arteries leads to this. aka heart attack
• briefly describe diastole?


  stage of cardiac cycle when the atria and ventricles are relaxed
• define atrial systole?


  The stage of the cardiac cycle when the atrial walls contract, forcing the remaining blood into the ventricles from the atria. ventricle walls then remain relaxed