Flashcards in Carbon Dioxide Transport and Control of Respiration Deck (15):
What are the 4 factors that affect the binding of O2 to heme?
What is a right shift in the oxyhemoglobin dissociation curve?
Shift in the original dissociation curve, causing more O2 to be dissociated due to the increase in pH
What is the Bohr effect?
In the presence of CO2 or protons (H+), hemoglobin has a decreased affinity for O2
-aka: more H+ causes the blood to become more acidic, lowering pH or if the level of CO2 increases in the blood O2 will want to dissociate from hemoglobin
What does CO2 turn into when released from body into the blood?
Combines with water to make carbonic anhydrase(H2CO3) and then quickly converts to bicarbonate(HCO3) and H+
What happens when O2 levels are high?
Hemoglobin wants to bind O2
What happens when CO2 is high in the blood and pH is low at tissues?
Hemoglobin no longer wants to bind to O2, so O2 dissociates from the oxyhemoglobin
What happens when O2 dissociates from oxyhemoglobin?
O2 can leave the blood and enter the cells of the tissues for use
What are the 3 ways in which CO2 carried in the blood?
1. Dissolved form: 7% because CO2 is better at dissolving in plasma
2. Carbamino form: 23% CO2 binds to globing subunits
3. Bicarbonate form: 70% bicarbonate formed in the blood with the help of carbonic anhydrase which speeds up the reaction
How is ventilation regulated?
Nervous system adjusts pulmonary ventilation and consequently alveolar ventilation to match O2 demands and CO2 production
-Does this through a negative feedback loop
describe the 6 steps to the negative feedback that regulates ventilation
1. Set Point: Normal PO2 and PCO2 values
2. Integrating Centre: Respiratory centre in the medulla
3. Effector: Respiratory muscles (diaphragm and intercostals)
4. Response: Alter pulmonary ventilation
5. Stimulus/Controlled Variables: PO2 and PCO2 levels
6. Receptors: Chemoreceptors sense blood chemical levels
What are chemoreceptors?
Special receptors that respond to changes in the chemical composition of the blood or other fluid around the receptors
What are the 2 kinds of chemoreceptors?
Peripheral chemoreceptors in aortic arch and carotid body (outside CNS). Signal transmission to respiratory centre based on blood PO2 PCO2 and pH levels detected in carotid bodies and aortic arch
Central chemoreceptors located in the medulla
How does the regulation of ventilation by central chemoreceptors differentiations from peripheral receptors?
Not directly affected by CO2, H+ and O2 in the blood. There is a chemosensitive area in the medulla that is highly sensitive to H+
-Central only responds to pH
Why can't CO2rxn be sensed in the blood at the central receptor?
Because of the BBB, conversion of CO2--> H+ and HCO3 requires a channels/transported to get the end products across the BBB.