12- Respiratory system 3 Flashcards
3 factors that affect the transport of gases
partial pressure, pH and temperature
is oxygen or carbon dioxide more soluble in water?
carbon dioxide
6 factors affecting O2 binding to and dissociation from haemoglobin
Oxygen partial pressure Acidity (pH) Carbon dioxide partial pressure Temperature 2,3-bisphosphoglycerate (BPG) Foetal haemoglobin
what is the most important factor that determines how much oxygen combines with haemoglobin (Hb)?
oxygen partial pressure (PO2)
where is PO2 higher and lower?
In the pulmonary capillaries, the PO2 is high.
In the tissue capillaries, PO2 is lower.
the greater the PO2, the more/less oxygen will combine with Hb?
more
what is the Bohr effect?
the ability for haemoglobin to act as a buffer for hydrogen ions
As acidity increases (pH decreases), the affinity of haemoglobin for O2 (increases/decreases)?
decreases
O2 dissociates faster = more available for working muscles
what effect does carbon dioxide partial pressure (PCO2) have on Hb and O2?
As carbon dioxide (CO2) enters the blood, much is converted to carbonic acid (H2CO3) which increases hydrogen ions (H+) and decreases pH, causing release of O2 from Hb
as body temperature increases, what happens to Hb?
haemoglobin releases O2 more readily
what is 2,3-biphosphoglycerate (BPG) ?
a substance formed in red blood cells during glycolysis
what does BPG do to the affinity of haemoglobin for O2
BPG decreases the affinity of haemoglobin for O2
how does foetal hemoglobin differ from adult haemoglobin?
in structure and in its affinity for O2
it has a higher affinity for oxygen because it binds BPG less strongly and can carry more O2 to offset the low oxygen saturation in maternal blood in the placenta.
how does carbon monoxide poisoning happen?
carbon monoxide has a 200 times higher affinity for haemoglobin than oxygen, so it binds to Hb and blood loses its ability to bind O2
3 ways CO2 is carried in blood?
Dissolved CO2 (7%) Carbaminohaemoglobin (23%) combined with the globin part of Hb molecule Bicarbonate ions (HCO3-) (70%) - CO2 + H2O combine to form carbonic acid that dissociates into H+ and a bicarbonate ion