respiration gas transport Flashcards
what enters and leaves blood in the pulmonary circuit?
- O2 enters
- CO2 leaves
what enters and leaves blood in the systemic circuit?
- O2 leaves
- CO2 enters
textbook values
what process do gases use to move through the respiratory system?
diffusion
what are the unique features of the respiratory and circulatory systems to facilitate gas diffusion?
- Large surface area for gas exchange.
- Large partial pressure gradients.
- Gases with advantageous diffusion properties.
- Specialised mechanisms for transporting O2 and CO2 between lungs and tissues.
what are partial pressures?
the concentration of a gas within a mixture of gases
partial pressure no. s
what are the two forms in which O2 is carried in the blood?
- dissolved (smaller %)
- bound to haemoglobin (Hb)
what is the amount of O2 dissolved in the blood proportional to?
its partial pressure
where is haemoglobin found?
red blood cells
how many haem groups are in haemoglobin?
4 (two alpha and two beta polypeptide chains)
what does each haem group contain?
iron in the reduced ferrous form (Fe+++)
where is the site of O2 binding on haemoglobin?
iron
how much haemoglobin is on each rbc?
280 million per rbc
how much haemoglobin is on each rbc?
280 million per rbc
why is it necessary for binding and dissociation of O2 with Hb to be done in milliseconds?
RBCs are only in capillaries for 1 second
what factors can affect oxygen haemoglobin binding?
pH and temperature
is oxygen binding to haemoglobin reversible?
yes
when is haemoglobin almost 100% saturated?
100mmHg PO2
what partial pressure of oxygen begins to have an effect on Hb saturation?
<60mmHg PO2
what happens to Hb binding below 60mmHg PO2?
large amount of O2 is released from Hb facilitating release into tissues
how many O2 atoms can each haemoglobin molecule bind?
4
what is total O2 capacity?
211mls O2/ 1litre of blood
what is SaO2?
to the amount of O2 bound to Hb relative to maximal amount that can bind
