3.3.4 Mass transport

• label the major blood vessels, chambers, valves and septum

  A) Vena Cava

  B) pulmonary artery

  C) Aorta

  D) Pulmonary Vein

  E) right atrium

  F) left atrium

  G) left ventricle

  H) right ventricle

  I) septum

  J) bicuspid valve

  K) tricuspid valve

  L) pulmonary valve

  M) aortic valve

  
• What is the name of the blood vessel that supplies the heart muscle with its own blood supply?

  Coronary arteries
• What is the name given to the blood vessels that supply the kidneys with blood?

  Renal arteries
• The flow of blood in capillaries is much slower which is an advantage as it allows more TIME for the exchange of materials.  This allows the cells to receive more oxygen as the red blood cells pass through the tissue, allowing for increased respiration.
• How many polypeptide chains make up haemoglobin?

  4
• How many oxygen molecules can each molecule of haemoglobin carry?

  4
• What is the equation for the reversible reaction between haemoglobin and oxyhaemoglobin?

  Hb + 4O2 ⇌ Hb4O2
• Why is our circulatory system called a double circulatory system?

  Blood passes through the heart twice for each full circuit of the body.
• What is an atheroma?

  A fatty deposit or plaque that forms within the walls of arteries.
• What is an aneurysm?

  A bulge or ballooning in a blood vessel caused by a weakened wall.
•  Risk factors for cardiovascular disease:

  • Smoking
  • High salt diet (leads to high blood pressure)
  • High blood pressure
  • High blood cholesterol
  • Diabetes
• How is the composition of plasma different from that of tissue fluid?

   Tissue fluid has less proteins as they are too large to pass through the capillary wall
• Tissue fluid formation:

  1. At arterial end the hydrostatic pressure is greater than the osmotic pressure so water is pushed out of the capillary into the tissue leaving behind protein molecules (too big)
  2. This causes the water potential of the fluid in the capillaries to become more negative
  3. The loss of water to the tissue reduces the hydrostatic pressure
  4. At the venule end the osmotic pressure is now greater than the hydrostatic pressure creating a net movement of water back into the capillary by osmosis
  5. Excess fluid is returned to the circulatory system via the lymphatic system
• How does the structure of arteries relate to their function?

  Overall thickness is to stop arteries bursting under the high pressur.

  Thick muscle layer: can be contracted or dilated to control blood moving through them.

  Thick elastic layer: stretched out on each heart beat and springs back during diastole.
• How does the structure of veins relate to their function?

  Thin elastic layer: they are not at risk of bursting as the bold they carry is at low pressure.

  Thin walls: allows them to be flexible around surrounding muscles so when muscles contract they press on the veins moving the blood, valves ensure the blood gose in the right direction.
• How does structure of capillaries relate to their function?

  One cell thick walls: creates a short diffusion pathway which allows rapid exchange of substances.

  Narrow lumen: causes red blood cells to be squeezed against the capillary walls, this increases surface area for exchange of substances.
• Loading: Oxygen associating with Haemoglobin

  Unloading: Oxygen dissociating with Haemoglobin
• When there is a hight partial pressure of oxygen (hight concentration of oxygen) the haemoglobin has a hight affinity for oxygen so oxygen loads into the haemoglobin.
• When there is a low partial pressure of oxygen (low concentration of oxygen) the haemoglobin has a low affinity for oxygen so oxygen unloads from the haemoglobin.
• • Very low oxygen concentration: No oxygen has bound to the haemoglobin.  
  • Low oxygen concentrations: The polypeptide chains of haemoglobin are tightly bound together, making it difficult for the oxygen molecules to access the iron ions. 
  • High oxygen concentrations: As one molecule of Oxygen becomes bound to one haem group, the polypeptide chain opens up exposing the other 3 haem groups. This makes it easier for them to become oxygenated and the curve rises steeply. 
  • Very hight oxygen concentrations: The haemoglobin becomes saturated and the curve levels off. 
• The more carbon dioxide there is, the more readily the haemoglobin releases the oxygen.
• Diastole:

  • Both the atria and the ventricles are relaxed
  • Pressure in the vena cava and pulmonary vein is higher than in the atria so blood moves in to the atria.
• Atrial systole (contraction of the atria):

  • Atria contract, decreasing volume and increasing pressure.
  • blood moves into the ventricles
• ventricular systole (contraction of the ventricles):

  • ventricles contract, decreasing volume and increasing pressure
  • Atrioventricular valves close to prevent backflow
  • blood moves into the pulmonary artery and aorta as the pressure is lover than in the ventricles causing the semilunar valves to open
• cardiac output = stroke volume x heart rate
• stroke volume: the volume of blood pumped out of the left ventricle in one cardiac cycle
• heart rate: number of times the heart beats per minute
• Cardiac output: the volume of blood pumped out of the left ventricle in one minute
• The SAN (sino-atrial node) is where the electrical impulse starts, it is located in the right atrium. The electrical activity spreads through the wall of the atria and causes them to contract.
• The AVN (atrioventricular node) is located between the atria and ventricles, it slows the signal before it enters the ventricles allowing the atria time to contract before the ventricles.
• Thrombosis: a blood clot that builds up in the arteries or veins.
• Embolism: A blood clot that travels through the bloodstream.
• Myocardial infarction: a heart attack from a blood clot in the coronary arteries.
• Cohesion-Tension theory


  -cohesion: water is a polar molecule which enables hydrogen bonding between the molecules, making them stick together. Therefore water travels up the xylem as a continuous water column.

  -tension: when transpiration is taking place water is continuously moving out of the leaves by evaporation so water from the xylem is replacing it due to osmosis.