Transport of Blood 6b

• Explain how oxygen is loaded, transported and unloaded in a he blood by haemoglobin

  1.Haemoglobin carries O2/ has a high affinity for 02

  2.loads in lungs

  3. At high partial pressures of O2

  4. Unloads to respiring tissues

  5.at low p02
• Haemoglobin has a quaternary structure. It has more than one poly peptide chain.
• How many molecule of oxygen can haemoglobin carry?

  4
• what is the Bohr effect?

  The Bohr effect is when an increase in carbon dioxide, temperature or a decrease in pH causes a decrease in the affinity of haemoglobin for oxygen, resulting in the increased release of oxygen to the tissues. It displaces the curve to the right.
• Why is the Bohr effect important?

  During exercise, the harmful products wouldn’t be removed quick enough and not enough oxygen would reach our respirating tissues which require more due to increases respiration rates
• what is blood made up of?

  plasma, platelets, red blood cells and white blood cells
• what does blood plasma transport?

  co2, water, soluble products of digestion, glucose
• Red blood cells contain haemoglobin, which loads 02 in lungs, transports around body and unloads at respiring tissues
• red bloods are very small. this means every haemoglobin molecule is near to the cell's plasma membrane
• how does this small size of rbc help with efficient gas exchange?

  short diffusion pathway due to larger surface area to volume ratio
• red blood cells are shaped like biconcave discs
• how does the biconcave disc assist gas exchange

  increases surface area so o2 can diffuse quickly
• red blood cells have no organelles
• what is the benefit for rbc to have no organelles?

  to pack as much o2 into cell as possible- enough room to carry lots of haemoglobin and so allows for more o2 to bind
• what is tissue fluid?

  solution of water, o2, glucose and other nutrients. cells of body are bathed in tissue fluid. it is essential for efficient gas exchange of materials between blood and cells. tissue fluid is constantly being formed at arteriole end of capillaries and reabsorbed at venule end
• how is tissue fluid formed?

  at arteriole end of capillaries, the hydrostatic pressure is high ( due to contractions of left ventricle). Soluble plasma proteins in the blood reduce the water potential of the blood, creating a water potential gradient, which exerts a pulling force, opposing the loss of fluid from the capillary. However, the hydrostatic pressure is higher than the opposing water potential gradient. As a result, water and solutes are forced out of blood through the pores in capillary walls and this forms tissue fluid.
• why do some plasma proteins not leave the capillary along with the fluid?

  too large to fit through pores in capillary walls
• role of heart in formation of tissue fluid?

  contraction of left ventricle creates hydrostatic pressure which forces water and dissolved substances out of blood vessels
• as blood moves from the arteriole end to venule end of capillary, there's a fall in hydrostatic pressure, so the outward force is reduced. what causes the drop?


  the loss of tissue fluid from the capillaries. friction also as blood flows through narrow lumen
• Tissue fluid is returned by a large, inward osmotic pull at the venule end of the capillary
• Large plasma proteins remain inside the capillary
• Loss of fluid leads to low hydrostatic pressure of the blood at the venule end of the capillary
• Water potential gradient of tissue fluid is higher than the blood
• Inward osmotic pull is greater than outward hydrostatic pressure, drawing water back into the capillaries by osmosis down a water potential gradient at the venule end
• Waste products like CO2 diffuse out of cells into tissue fluid and then into capillaries along with the water at the venule end
• more fluid leaves the capillaries than is reabsorbed into them. the surplus fluid drains into lymphatic vessels. these are blind ending tubes, with valves, which eventually return to the bloodstream via the thoracic duct in the neck.
• haemoglobin is the blood pigment that has a high affinity for oxygen and readily loads oxygen where o2 concentrations are high and unloads o2 where o2 concentrations are low
• where in the body would be a) high b)low

  high in lungs. low in respiring tissues
• what does conjugated mean?

  protein bound to a non protein group
• how many polypeptide chains are there in each haemoglobin molecule?

  Four
• what is the function of the haem group ( contains Fe2+ ions)

  binds to o2
• when oxygen is bound to haemoglobin?

  oxyhemoglobin
• the amount of o2 carried by haemoglobin is known as percentage saturation
• Binding of one molecule of o2 to haemoglobin makes it easier for a second o2 molecule to bind. explain why?

  cooperative binding- binding of first 02 changes tertiary structure of haemoglobin. creates another binding site so easier for another o2 to bind
• partial pressure of oxygen can be shown as p02.
• the dissociation curve is sigmoidal in shape and displays percentage saturation of haemoglobin with 02 at varying partial pressures
• there are different forms of haemoglobin and these are related to the environmental conditions in which the animals live e.g altitude, temp, and o2 availability. different forms are also found within the same species and relate to different stages of the life cycle. like human foetal and tadpole
• Explain transport of blood in a lugworm

  lugworm (lives onthe seashore) are not very active. Most of its life it’s covered by sea water. Oxygen diffuses into the lugworm’s blood from the water and uses haemoglobin to transport it to tissues. When the tide goes out, it can’t get any oxygen so when it’s covered by a tide it extracts as much oxygen as possible. Therefore it’s fully loaded with oxygen even when there’s little available
• Transport of blood in a shrew?

  Shrews have large surface area to volume ratios (lose more heat) so have a higher metabolic rate. So shrew haemoglobin has a lower affinity for oxygen or dissociates from O2 more readily. Tissues demand more O2 due to higher respiration rates
• Does foetal Hb have a lower or higher affinity for O2 compared to adult Hb?

  Higher affinity-