17-18 - Respiration Regulation & Blood Transport of Gases Flashcards
O2 requires transport proteins as it has…
Low plasma solubility
PO2 in the plasma influence the…
Saturation of haemoglobins
Factors that influence haemoglobin saturation are…
- PCO2
- PO2
- pH
- Temperature
- 2,3-BPG
The oxygen-haemoglobin saturation/dissociation curve shows rapid changes in O2 saturation % of Hb at which PO2?
Physiological tissue PO2
A small change in PO2 within the physiological range leads to a large…
Change in the amount of O2 bound to haemoglobin
Effects of exercise on the O2-Hb saturation curve (2)…
- Increase in PCO2 causes shift to the right
- Decrease in pH causes shift to the right
= decrease in O2 affinity, release of O2
A decrease in blood pH or an increase in PCO2 reduce the oxygen affinity of haemoglobin. This is known as the…
Bohr Effect
The Bohr effect occurs because _________ displace _______ from haemoglobin
The Bohr effect occurs because hydrogen ions (H+) displace oxygen (O2) from haemoglobin
Haemoglobin exists in a tense or relaxed form. The relaxed form is readily ( deoxygenated / oxygenated)
Haemoglobin exists in a tense or relaxed form. The relaxed form is readily oxygenated
The binding of H+ to haemoglobin favours which conformation?
Tense
(hence reducing O2 affinity)
An increase in temperature with shift the oxy-Hb saturation curve to the…
Right, decreasing affininty and leading O2 offloading
2-3BPG (2-3 bisphosphoglycerate) effects…
Need more O2 -> 2-3 BPG!
- Long term adaptation to O2 availability
- Interacts with beta globin chains, causing conformational change, reducing O2 affinity, increasing offload (right shift)
- Seen in anaemia, chronic lung disease, altitude (low O2), congestive heart failure
2-3BPG (2-3 bisphosphoglycerate) is produced where and when?
In erythrocytes (as a biproduct of glycolysis)
Production increases when O2 is low
CADET (or CABET), look right!
Increases in….
C O2
A cid
B/D PG 2-3
E xercise
T emp
Shift the oxygen-Hb saturation curve to the RIGHT… more dissociation!
Foetal haemoglobin is comprised of which subunits?
2x alpha, 2x gamma globins
Carbon monoxide poisining is treatable via…
Hyperbaric O2
Carbon monoxide binds tightly to Hb.
This is ( reversible / irreversible ) and has the effect of…
Carbon monoxide binds tightly to Hb.
This is reversible and has the effect of…
a) limiting saturation (curve max moves down) - competes with O2
b) increased O2 affinity (slight left shift) - tight binding hard to release remaining O2
7% of CO2 is ________________
23% of CO2 is _____________________
7% of CO2 is dissolved in the plasma
23% of CO2 is bound to haemoglobin (-> carbaminohaemoglobin)
Conversion of CO2 to hydrogen carbonate (HCO3-)
The direction of the reaction depends on the…
CO2 gradient between tissues and blood.
If PCO2tissue > PCO2blood, then CA converts CO2 + H2O = H2CO3 (which dissociates into H+ and HCO3-)
If PCO2blood > PCO2tissue, then CA converts H2CO3 back to H2O + CO2(which is expelled via lungs)
CA = carbonic anhydrase (found in RBCs)
PO2 in alveoli and aterial blood is ____ mmHg
PO2 in alveoli and aterial blood is 100 mmHg
PO2 in venous blood is ____ mmHg
PO2 in venous blood is 40 mmHg
PCO2 in venous blood is ____ mmHg
PCO2 in venous blood is 46 mmHg
PCO2 in arterial blood and alveoli is…
40mmHg
Overinflation of the lungs is prevented by the…
Heing-Breuer Reflex (triggered by stretch receptors in lung smooth muscle and signals the end of inhalation)
