Week 10: Respiratory 4 Flashcards
How is the pressure regulated?
passive regulation
active regulation
Describe the passive regulation of pressure.
vessels dilate easily
Describe the active regulation of pressure.
happens in the circumstance of hypoxia and chronic respiratory insufficiency
What happens during hypoxia?
Hypoxia means not enough oxygen
causes vasoconstriction to unnecessary areas of gas exchange
What happens in chronic respiratory insufficiency?
PO2 ↓
↓
vasoconstriction in lung vessels
↓
pulmonary hypertension
↓
right ventricular hypertrophy
What is the effect of gravity on the lung?
- base of the lung has larger blood flow (more effected by gravity)
- apex of the lung has smaller blood flow
Where is the volume of the alveoli smaller & less open? What is the pressure?
base of lung
-2 cm H20
Where is the volume of the alveoli larger & more open? What is the pressure?
apex of the lung
-10 cm H2O
What is the equation that tells us the diffusion of oxygen across a membrane?
VO2 = A•D• ΔP / T
What does A•D / T give us?
Diffusion capacity
What is the effect of exercise on the diffusion capacity?
↑ diffusion capacity
↑ surface area
↑ flow
more capillaries open
Does diffustion limit gas exchange in the blood?
NO
but in the tissues it does
Explain the picture
The partial pressure of the alveoli is equal to the partial pressure of arterial blood
What are the layers of which oxygen has to diffuse?
- alveolar epithelium
- apithelial basement membrane
- interstitial space
- capillary basement membrane
- capillary endothelium
In what direction does flow into the capillary occur?
from high pressure → low pressure
How long does it take for the actual gas exchange to occur?
.25 seconds
However, there is a reserve time of .75 totalseconds for gas exchange to occur in case there is a problem.
What is the graph representing the relationship between the partial pressure of O2 and Hemoglobin saturation? What are two important values?
In arterial blood the PO2 is about 90 mmHg and the hemoglobin saturation is about 97%
In venous blood the PO2 is about 40 mmHg and the hemoglobin saturation is about 75%
What is the concentratino of Hemoglobin?
2.3 mmol/l
Draw the arterial and venous HgbO2 equilibrium curves.
* venous blood has more CO2*
What causes a right shift of the HgbO2 equilibrium curve?
occurrs during exercise
(local ↑ in glycolysis occurrs)
extra amount O2 is released from Hemoglobin
- PCO2 ↑
- [H+] ↑
- 2,3 BPG ↑
- Temperature ↑
What happens in the case of CO poisoning?
- CO binds to hemoglobin with a higher affinity than oxygen
- once bound, releases slowly
- can bind at low concentration
