O2 and CO2 unloading Flashcards
Does Hb unload the same amount of O2 to all tissues?
No. Hb doesn’t unload the same amount of O2 to all tissues- some need more O2, eg if exercising, some less, eg at rest.
What 4 factors adjust the rate of O2 unloading into tissues?
Ambient PO2 (in tissue)
Temperature
Bohr Effect
BPG
How does the ambient PO2 of tissue impact the unloading rate of O2?
Since an active tissue consumes O2 rapidly, the PO2 remains low. At low PO2 HbO2 releases more O2
How does thetemperatuire of tissue impact the O2 unloading rate?
Active tissue are warmer than less active tissues
Warmer tissues promote O2 unloading (extract more O2 from blood passing by)
What is the Bohr effect?
↑ PCO2 and/or ↑H+ concentration (↓pH) weaken the HbO2 bond- so more O2 unloading
How does the Bohr effect work?
Active tissues make more CO2. We shift the equation to the right, so it raises the H+ concentration and ↓blood pH
H+ weakens the bond between Hb and O2 and therefore promotes O2 unloading.
The effect of pH on Hb saturation is the _____effect
Bohr
RBCs must get their energy needs through anaerobic pathways, and one of the intermediate steps in this pathway is _____.
BPG
What happens with an increase of BPG in the RBC?
The higher the concentration of BPG in the RBC the greater the release of O2 from Hb
What 4 things increase the BPG concentration?
Thyroid hormones
Growth hormone
Epinephrine
Testosterone
What is the Haldane effect?
Low HbO2 enables the blood to transport more CO2
O2 is going out to tissues and is replaced with CO2
What 2 mechamisms cause CO2 unloading?
1- HbO2 does not bind CO2 as well as HHb does
2- HHb binds more H+ ions than HbO2 does, and by removing H+ ions from solution, HHb shifts the equation to the right (removing CO2)
CO2 → H2O → H2CO3 → HCO3- + H+
A high _______ rate keeps oxyhemoglobin levels relatively low, and thus allowing more CO2 to be transported by the above two mechanisms
metabolic
As more CO2 enters the systemic bloodstream it causes the O2 to disassociate from Hb, this is the ____ effect . Which in turn, allows more CO2 to combine with the Hb, which is the ______ effect.
Bohr
Haldane
Gas exchange not only requires good ______ of the alveolus, but also good ______ of its lung capillaries.
ventilation
perfusion
What is perfusion coupling?
The ability to match ventilation and perfusion to each other is critical
Airflow matches bloodflow
Arterioles respond to ____; Bronchioles respond to _____. (gasses)
PO2
PCO2
If part of a lung is blocked by mucus, tumor, what happens to the blood flow?
It will be redirected.
Because if it’s poorly ventilated there is little point of sending blood there
Poor alveolar ventilation results in low ___and high ____ levels in the alveoli. (gasses)
O2
CO2
If ↑ PO2 then blood vessels will _______ to bring more blood to O2
vasodilate
Rising PCO2 causes local ________, to eliminate excess CO2
bronchodilation
If airflow through bronchioles is lower than normal, then there is rising _____ level.
PCO2
COPD tends to reduce pulmonary ________ and _____ capacity
compliance
vital
Any disease in which there is long-term obstruction of airflow and substantial reduction in pulmonary ventilation is called ….
COPD
What are the two major COPDs?
Emphysema
Chronic bronchitis
What are the normal causes of COPD?
They are almost always caused by cigarette smoking, but occasionally from air pollution or occupational exposure to airborne irritants
What happens with emphysema?
Destruction of alveolar walls (type I cells)
What happens with chronic bronchitis?
The cilia are immobilized and reduced in number
At the same time, goblet cells enlarge and produce excess mucus in bronchial mucosa
This thick mucus provides a growth medium for bacterial
