Human mass transport Flashcards
Need for mass transport systems in large multicellular organisms
Needed to carry substances ( gases, glucose, amino acids act) between exchange surfaces and around the body
- most cells too far away from exchange surfaces to maintain a suitable stable composition of tissue fluid
- maintain of final diffusion gradients- to allow diffusion into/ out of cells ( eg in large network cap surrounding alveoli to enable efficient diffusion of oxygen)
Pulmonary circulation
Re-oxygenating blood
Pulmonary artery- lungs- CO2 out O2 in- back to heart via pulmonary vein
Systemic circulation
Circulation of oxygenated blood around the whole body- aorta
What does it mean to have a double closed circulation system?
Double- blood passes heart twice in one complete circulation
closed- pulmonary and systemic separate- no mix of de ox and ox blood
Explain the Bohr effect
Increasing rate of respiration
Increase concentration of CO2 in the blood
Lower pH, changes tertiary structure of haemoglobin
Reduces it affinity for oxygen
More readily unloads and dissociates with oxygen at the lower pp of O
Provides more oxygen to respiring cells
Shifts the dissociation curve to the RIGHT
What would cause a left ward shift in the oxygen dissociation curve ?
An increase in affinity for oxygen
More readily loads and associates with oxygen at lower pp of oxygen
Example: foetal haemoglobin
Formation of tissue fluid
At arteriole end blood has high hydrostatic pressure
Forces fluid and small molecules like glucose amino acids out of the blood into spaces surrounding cells
Large molecules remain in the blood like proteins too large to leave
Return of tissue fluid
As the blood passes along the capillary fluid leaves and hydrostatic pressure reduces
Water potential decreases
Osmotic pressure becomes greater than hydrostatic at the venule end
Water moved back into the capillary via osmosis down the water p gradient
Any excess fluid is collected by the lymphatic system
