The heart

• what is the bohr effect?

  when there is a high concentration of CO2 the oxyhaemoglobin curve moves to the right, decreasing haemoglobins affinity for oxygen

  • so oxygen is more readily dissociated to respiring tissues.
  • because CO2 makes the blood more acidic, denaturing haemoglobin.
• mammels have a closed, double circulatory system
• what does closed circulatory system mean?

  blood remains in the blood vessels
• what is a double circulatory system?

  the blood passes through the heart twice in each circuit.

  • one from the heart to the lungs
  • one from the heart to the body
• what do the coronary arteries supply?

  oxygen to the heart muscle
• what carries deoxygenated blood from the body to the heart?

  vena cava
• what carries blood from the heart to the lungs?

  pulmonary artery
• what carries blood from the lungs to the heart?

  pulmonary vein
• what carries blood from the heart to the body?

  aorta
• what carries blood from the heart to the kidneys?

  renal artery
• what carries blood from the kidneys to the heart?

  renal vein
• which side of the heart pumps blood round the body?

  left (thick left ventricle)
• which side of the heart goes to and from the lungs?

  right side
• where are the semi-lunar valves?

  aorta & pulmonary artery
• where are the atrioventricular valves?

  between atria & ventricles
• what are valves for?

  to prevent the backflow of blood
• what is the septum?

  the tissue running down the middle of he heart
• describe the structure of arteries?

  -thick muscle layer

  • thick elastic layer
  • thick walls
  • no valves
• what is the muscle layer for in arteries?

  control constriction & dilation to control volume of blood
• what is the elastic layer for?

  -help maintain blood pressure as walls can recoil from heartbeat force
• what are the thick walls of arteries for?

  prevent bursting under high pressure
• describe the structure of veins?

  -thin muscle layer

  • thin elastic layer
  • thin walls
  • valves
• describe the structure of arterioles?

  -thicker muscle layer than arteries

  • thin elastic layer
  • thin wall
  • no valves
• describe the structure of capillaries?

  one cell thick, providing a short diffusion distance for gas exchange
• what are the stages of the cardiac cycle?

  diastole

  atrial systole

  ventricular systole
• describe diastole?

  -atria & ventricle muscles are relaxed

  • blood enters the atria via the vena cava & pulmonary vein.
  • increasing pressure in the atria
• describe atrial systole?

  -atria contract, increasing pressure causing the atrioventricular valves to open.

  • blood flows from atria to ventricles.
• describe ventricular systole?

  -after a short delay

  • ventricles contract, increasing pressure.
  • atrioventricular valves close
  • semi lunar valves open.
  • blood is pushed out into the aorta & pulmonary artery.
• what is the equation for cardiac output?

  Cardiac Output = Heart Rate x Stroke Volume
• what is stroke volume?

  volume of blood that leaves the heart after each beat
• what is tissue fluid?

  fluid containing water, glucose, amino acids, fatty acids, ions & oxygen which bathes tissues
• how is tissue fluid formed?

  high hydrostatic pressure in the capillaries forces out small molecules through small gaps in the capillary walls.

  • this is called ultrafiltration
• what molecules cannot pass through the gaps in the capillary walls?

  red blood cells

  large proteins

  platlets
• how is tissue fluid reabsorbed?

  -large molecules remain in the blood, lowering the water potential.

  • towards the venule end hydrostatic pressure is lower.
  • allowing water to re-enter the capillaries by osmosis.