mass transport

• what is the function of a red blood cell?

  Transport oxygen around the body
• describe the structure of haemoglobin

  Globular

  water soluble

  Consists of four polypeptide chains, each carrying a haem group (quaternary structure).
• what is meant by affinity of haemoglobin for oxygen?

  the ability of haemoglobin to attract/bind oxygen
• what is meant by saturation of haemoglobin with oxygen?

  when haemoglobin is holding the maximum amount of oxygen that it can bind to
• what is loading/association of haemoglobin

  the binding of oxygen to haemoglobin
• what is unloading/dissociation of haemoglobin?

  When oxygen detaches or unbinds from haemoglobin
• where is oxygen loaded onto haemoglobin?

  regions of high partial pressure of oxygen (e.g. alveoli)
• where is oxygen unloaded from haemoglobin?

  regions of low partial pressure (e.g. respiring tissues)
• describe the shape of an oxyhaemoglobin dissociation curve

  sigmoid (s) shape that demonstrates that at high partial pressures, haemoglobin is almost fully saturated, and at low partial pressures, haemoglobin doesn't have a high affinity
• describe what is meant by cooperative binding

  after the first oxygen binds, the tertiary structure of haemoglobin changes shape, which makes the binding of the second and third oxygens easier but it is difficult for the fourth oxygen to bind as there are less exposed haem groups
• What is the Bohr effect?

  - High concentrations of CO2 causes the curve to shift to the right

  - the acidic CO2 changes the shape of the haemoglobin slightly - decreases affinity
• describe the position of the curve in foetal haemoglobin compared to adult haemoglobin

  -the curve shifts to the left

  - because it has a higher affinity due to high metabolic rate for growth = low PO2
• describe the position of the curve in llama haemoglobin compared to human haemoglobin

  - curve shifts to the left

  - llama have a higher affinity for oxygen because they live in high altitudes = low partial pressure of oxygen
• describe the position of the curve in small animal haemoglobin compared to human haemoglobin

  - curve shifts to the right

  - lower affinity for oxygen due to faster metabolism so more oxygen is needed for respiration
• describe the position of the curve in earthworm haemoglobin compared to human haemoglobin

  - curve shifts to the left

  - higher affinity as they live underground with a lower partial pressure of oxygen
• describe the Bohr effect and how/ why it affects the haemoglobin's affinity for oxygen

  1. CO2 enters red blood cell and reacts with water to form a carbonic acid

  2. the carbonic acid dissociates into H+ ions and HCO3- ions

  3. the HCO3 diffuses out of the cell into the plasma, whilst Cl- ions simultaneously diffuse into the cell to balance the charge change

  4. The H+ ions bind to oxyhaemoglobin, and oxygen is displaced and moves out of the cell, with reduced haemoglobin also produced

  
  

  This decreases haemoglobin's affinity for oxygen as it dissociates more readily.
• describe the advantage of the Bohr effect during intense exercise

  affinity is reduced so oxygen is unloaded more readily for aerobic respiration
• what 4 factors make a good transport system and why?

  suitable solvent- water so substances can dissolve

  a form of mass transport- rapid diffusion in bulk

  closed system that forms a branching network- distribution to whole organism

  pressure difference- mechanism to transport the medium
• what is meant by a double circulatory system?

  the blood passes through the heart twice in each circuit. There is one circuit that delivers blood to the lungs and another that delivers blood to the rest of the body
• what is the pressure of blood flow like in the lungs and why is this advantageous

  - low pressure

  - prevents damage to the capillaries

  - reduces speed of blood flow = more time for gas exchange
• what are the blood vessels that are attached to the heart?

  - vena cava

  - aorta

  - pulmonary vein

  - pulmonary artery
• what are the blood vessels that are attached to the lungs?

  -pulmonary artery

  - pulmonary vein
• what are the blood vessels that are attached to the kidney?

  - renal artery

  - renal vein
• what part of the heart do veins go to?

  atrium
• what part of the heart do arteries go to?

  ventricles
• function of the arteries


  carry blood away from the heart
• function of capillaries


  exchange metabolic materials between blood and the heart
• function of veins


  carry blood from capillaries back to the heart
• describe how the structure of the arteries are related to its function

  THICK MUSCLE LAYER - allows constriction and dilation to control volume of blood

  THICK ELASTIC LAYER - keeps blood pressure in arteries high

  THICK WALL - resists bursting under pressure
• describe how the structure of the capillaries are related to its function

  THIN LAYER OF CELLS - short diffusion distance

  HIGHLY BRANCHED- large SA for diffusion

  NARROW LUMEN- bring rbc close to cell
• describe how the structure of the veins are related to its function

  VALVES CLOSE - when muscles are at rest to prevent pooling of blood

  THIN ELASTIC LAYER - low pressure of blood so won't burst

  THIN MUSCLE- constriction + dilation can't control flow of blood to tissues
• what is an erythrocyte?


  red blood cell
• what is a leucocyte?

  white blood cell
• what is a thrombocyte?


  platelets
• what is tissue fluid?

  A watery substance containing glucose, amino acids, oxygen, and other nutrients. It supplies these to the cells, while also removing any waste materials.
• what does tissue fluid NOT contain?

  red blood cells and plasma proteins
• what is the capillary made up of?

  endothelial cells
• How is tissue fluid formed?

  arterial end of the capillary = high hydrostatic pressure due to contraction

  fluid containing oxygen, glucose and nutrients are forced out of tiny gaps in the capillary wall.

  Cells and plasma proteins are retained in the capillary as they are too big to fit through the gaps.

  The fluid is now known as tissue fluid and as it surrounds the cells allows the movement substances across the plasma membranes.
• how is tissue fluid reabsorbed?

  large molecules remain in the capillaries and lower the water potential

  the water potential is higher outside of the capillaries, so water moves into them by osmosis.

  towards the venule end of the capillaries the hydrostatic pressure is much lower; it is higher outside of the capillary, so some of the tissue fluid is forced back into the capillaries.
• what happens to excess tissue fluid?

  Excess tissue fluid passes into lymph vessels.

  
  

  Once inside, it's called lymph.

  
  

  Valvesin the lymph vessels stop lymph backflow.