D6 Transport of respiratory gases Flashcards
What does the oxygen dissociation curve show?
The affinity of hemoglobin for oxygen
Describes the saturation of hemoglobin by oxygen at different partial pressures of oxygen
What determines the degree to which oxygen binds to hemoglobin?
by the partial pressure of oxygen (pO₂) in the blood
What does the significant change in saturatin over a narrow range of oygen partial pressure represent?
represents oxygen pressures surround cells are under normal metabolism
Where would low pO₂ occur?
in muscles
O₂ will dissociate from hemoglobin
Where would high pO₂ occur?
in the lungs
hemoglobin will become saturated
How is carbon dioxide transported in the blood?
carried in solution and bound to hemoglobin in the blood
In what 3 forms is carbon dioxide carried in in the blood plasma?
- Dissolved as carbon dioxide
- reversibly converted to bicarbonate (hydrogencarbonate) ions (HCO₃-) that are dissolved in the plasma
- bound to plasma proteins
What is the majority of CO2 produced by the body during cellular respiration converted to?
Bicarbonate (hydrogencarbonate) ion
* more soluble
* less toxic
What is the conversion reaction from CO2 to hydrogencarbonate ions catalysed by?
the enzyme carbonic anhydrase
What is the reaction from CO2 to hydrogencarbonate?
is reversible
How is the conversion from carbon dioxide to hydrogencarbonate ions reversible?
In the tissues
* CO2 is generated
* rection proceeds to the right
* more bicarbonate ions is generated as are H+ ions
* =Lowers pH of blood
In the lungs
* CO2 leaves the blood
* reaction proceeds to the left
* bicarbonae ion is converted to carbon dioxide
What does the Bohr shift explain?
explains the increased release of oxygen by hemoglobin in respiring tissues
What release does increased metabolism result in?
greater release of CO2 in the blood
What is the consequence of more CO2 in the blood?
lower pH of the blood
How does acidity from more CO2 in the bood from metabolism do to the Bohr Shift?
- Shifts the oxygen dissociation curve to the right
What does a shift to the right of the oxygen dissociation curve mean?
Shift to the right = increase in acidity
which results in a decreased affinity of the hemoglobin for oxygen
= greater release of oxygen from hemoglobin at the partial pressure of oxygen
How does an increase in CO2 in blood affect the release of oxygen? (i.e. when excerising)
- metabolism increase
- more CO2 released into the blood
- lower the pH
- increased accidity shifts the oxygen dissociation curve to the right
- results in a decreased affinity of the hemoglobin for oxygen
- = greater release of oxygen from hemoglobin at the same partial pressure of oxygen
- ensures that respiring tissues have enough oxygen when their need for ocygen is greatest
How is saturation of hemoglobin able to occur at lower partial pressures of oxygen in the lungs?
Because the pCO2 is lower in the lungs
How does exercise increase the rate of ventilation?
- Exercise increases metabolisms
- leads to an increase in the produciton of CO₂ (waste product of cellular respiration)
- Blood pH decrease because CO₂ dissolves in water to form carbonic acid (H₂CO₃)
- H₂CO₃ dissociated into H+ and HCO₃- (more H+ more acidic)
- Chemoreceptors in the medulla, the aorta and the carotid artery detects a change in blood carbon dioxide
- High levels of carbon diocide in the blood triggers an increase in the ventilation rate in order to rid the body of CO₂ buildup
- CO₂ diffuses into alveoli and ventilation expels it
- explains the hyperventilation in response to exercise
How are changes in the blood carbon dioxude detected in the body?
chemoreceptors in the medulla, the aorta and the arotid artery
What does high levels of carbon dioxide in the blood trigger?
increase in the ventilation rate
What does the increase in ventilation rate do?
get rids of th CO₂ buildup in the body
Ventilation expels the carbon dioxide that diffused into the alveoli
Where is the rate of ventilation regulated by?
by the respiratory centre in the medulla oblongata of the brain stem
Where is the rate of ventilation regulated by?
by the respiratory centre in the medulla oblongata of the brain stem