Gas Transport Flashcards
what is gas diffusion
movement of gas throughout the respiratory system occurs via diffusion
what are some anatomical and physiological properties that facilitate gas diffusion
- large surface area for gas exchange
- large partial pressure gradients
- gases with advantageous diffusion properties
- specialised mechanisms for transporting oxygen and carbon dioxide between lungs and tissues
what is total pressure
the sum of the partial pressures or tensions of a gas
what is the barometric pressure at sea level
760 mmHg
what is Pgas
partial pressure of a gas
what is Fgas
fraction of a gas
what does partial pressure equal
Fgas in gas mixture times by barometric pressure
what are the two forms of oxygen being carried in the blood
dissolved
bound to haemoglobin
describe how dissolved oxygen is measured
clinically in an arterial blood sample
how much of oxygen in the blood is dissolved
only a small percentage
what is the amount of oxygen dissoved in the blood proportional to
partial pressure
how many ml of oxygen per 100ml of blood for each mmHg of PO2
0.003
how many litres of oxygen in the blood when the arterial blood has a partial pressure of 100mmHg
3ml
is the transport of oxygen in the dissolved form adequate for the body’s requirements
no
what is the typical partial pressure of oxygen in the blood for healthy individuals
100mmHg
which artery is usually used to provide a sample for calculating partial pressure
radial
what does the amount of oxygen dissolved in the blood determine
the partial pressure of oxygen in the blood
what is the minimum tissue requirement of oxygen at rest
250ml of oxygen a minute
how many litres of blood per minute at rest cardiac output
5 litres
what are the tissue requirements for oxygen during strenuous exercise
3000 ml oxygen per minute
what is haemoglobin
major transport molecule for oxygen found in red blood cells
describe the structure of haemoglobin
four heme groups joined to globin proteins.
two alpha and two beta chains
what is heme
iron porphyrin compound
what is found in each heme group
iron in reduced ferrous form Fe+++
what is the site of oxygen binding in haemoglobin
each ferrous molecule in the heme groups
how many haemoglobin molecules per red blood cells
280 million