Mass transport in animals

• What is the function of the pulmonary vein?

  It transports oxygenated blood from the lungs to the left atrium.
• What is the function of the aorta?

  It transports oxygenated blood from the left ventricle to body tissues.
• What is the function of the vena cava?

  It transports deoxygenated blood from body tissues to the right atrium.
• What is the function of the pulmonary artery?

  It transports deoxygenated blood from the right ventricle to the lungs.
• What is the function of the renal artery?

  It transports oxygenated blood from the aorta to the kidneys.
• What is the function of the renal vein?

  It transports deoxygenated blood from the kidneys to the vena cava.
• What is the function of the coronary arteries?

  They transport oxygenated blood from the aorta to the cardiac muscle.
• Describe diastole

  -All the cardiac muscle is relaxed

  -Both atria fill with blood entering from the veins

  -The atrial pressure becomes greater than the ventricular pressure which opens the atrioventricular valves
• Describe atrial systole

  -The atrial muscle contracts so the volume decreases and the pressure increases, forcing the remaining blood into the ventricles

  -Ventricular pressure becomes greater than the atrial pressure, closing the atrioventricular valves
• Describe ventricular systole

  -The ventricular muscle contracts, so the volume decreases and the pressure increases, causing the semi-lunar valves to open

  -Atrial pressure is greater than the ventricular pressure so the semi-lunar valves close
• Describe and explain the structure of haemoglobin

  A protein in red blood cells made from 4 polypeptides, giving it a quaternary structure

  There is a haem group in the middle of the polypeptide, containing iron ions which bind to O2 so it can be transported
• Describe the Bohr Effect

  -CO2 produced in respiration dissolves in blood, making it more acidic

  -Tertiary structure of haemoglobin changes and now has a lower affinity for O2

  -Haemoglobin unloads more O2 which diffuses into cells for aerobic respiration

  -The dissociation curve moves slightly to the right
• Describe the 3 points of a dissociation curve

  1-A large increase in ppO2 allows the first O2 to load onto haemoglobin due to having a tight structure

  2-The first O2 changes the tertiary structure of haemoglobin, uncovering the next binding sites. The second and third O2's can now load with only a small increase in ppO2

  3-A large increase in ppO2 for the fourth O2 to load as 3/4 binding sites are now saturated
• What does a dissociation curve show if it is further left?

  -Higher affinity for O2

  -Haemoglobin can load more O2

  -It is an adaptation to lower ppO2 environments
• What does a dissociation curve show if it is further right?

  -Lower affinity for O2

  -Haemoglobin can unload more O2

  -It is an adaptation for organisms with a higher respiration rate
• Describe the formation of tissue fluid

  -As blood enters the arteriole end of the capillary, it is under high hydrostatic pressure, which originates from the contraction of the left ventricle

  -Water, glucose, amino acids and ions are forced out of the capillary and this forms tissue fluid
• Describe the reabsorption of water from tissue fluid

  -Proteins in blood plasma were too big to be forced out of the capillary so remain, therefore the venule end of the capillary has a lower water potential than tissue fluid so water is reabsorbed by osmosis

  -If there is any excess tissue fluid, a lymphatic capillary can drain it from the tissue