Midterm Chapter 17 & 18 Flashcards
Describe the structure of the respiratory membrane including tissues present.
simple squamous epithelium lining the alveoli, endothelium of the pulmonary capillary walls and fused basement membrane
What is the pressure in the pulmonary trunk?
25/8 mmHg
What is the flow rate of blood through the pulmonary circuit?
5L/min
Explain why the pressure in the pulmonary circuit is much lower than the systemic circuit. Explain what would happen if the pressure was the same.
the lower pressure allows for effective contact between the blood and the respiratory structures of the lung, and thus to make possible gas exchanges with the outside air.
If the pressure were the same then the lung would be considerably wetter than it is, and the exchange of gases across the layer of fluid outside the capillary would be slowed.
What is the partial pressure of oxygen in the alveoli?
100mmHg
What is the partial pressure of oxygen in the venous blood?
40mmHg
What is the partial pressure of CO2 in the alveoli?
40mmHg
What is the partial pressure of CO2 in venous blood?
45mmHg
List the 4 main gases found in atmospheric air. Which are the 2 that make up most of our atmosphere? What percent of the air does each contribute?
O2 = 21% CO2 = 0.03% N2 = 80% H2O = variable
Is O2 or CO2 easier to exchange? Why?
O2 because it has a larger pressure gradient
Explain what lung compliance is. Why is compliance important?
the ability to stretch “ease of filling”
-important because lungs need to be able to expand to fill with air.
Explain what elasticity is. Why is elasticity important?
the ability to recoil
-important because lungs need to be able to return to their resting position in able to move inhaled air out of the lungs.
The protein that carries O2 in the blood is what? How many O2 molecules does one of these proteins carry?
Hemoglobin
Each hemoglobin carries 4 oxygen molecules
What are the 2 ways that O2 is carried in the blood? For each list the percent carried in this way.
- Dissolved in plasma ~1%
2. Binds to hemoglobin ~99%
What is the most important factor that determines whether O2 is being bound to or released from hemoglobin?
The partial pressure of O2 determines binding/unbinding.
low PO2 = unbinding: example - Lungs PO2 = 100mmHg = binding / Tissue PO2 = 40mmHg = unbinding
With respect to the blood, explain what percent saturation is.
A measure of how much oxygen the blood is carrying as a percentage of the maximum it could carry.
What are the three major factors (other than PO2) that influence O2 binding/unbinding? Describe the mechanism behind the change in affinity that hemoglobin has for O2.
- Decrease in pH = increase in H+ = extra unloading - the Hydrogen binds to the hemoglobin causing the O2 to unbind.
- Increase in Temp = increase in MR = extra unloading - Increase temp causes increase movement which causes more instability and the O2 unbinds
- Increase in CO2 = extra unloading - CO2 binds to the hemoglobin causing the CO2 to unbind
List the three ways that CO2 is transported in the blood. For each list the percent of the CO2 that is carried in that way.
- Simply as CO2 ~10%
- Bound to hemoglobin ~ 20%
- Bicarbonate ions in plasma ~70%