Quiz 5 Flashcards
What is cellular respiration?
Intracellular processes using oxygen to generate ATP + CO2 + H2O
What is external respiration?
Movement of gases between atmosphere & cells
What are the types of external respiration?
- Ventilation
- Gas exchange in the pulmonary circuit
- Gas transport in the blood
- Gas exchange in the systemic circuit
What are the functions of external respiration?
-support cellular respiration
-regulation of pH via retention or elimination of CO2
What is alveolar ventilation (Va)?
Volume of fresh air that reaches alveoli per minute
What is hyperventilation?
Increase Va
What is hypoventilation?
Decreased Va
What are the 2 outcomes if ventilation is inadequate?
-Hypoxia = insufficient O2 availability to cells
-Hypercapnia = elevated CO2 levels
What does gas exchange (diffusion) require at lungs & tissues?
A gradient in partial pressure.
What is partial pressure (Pgas)?
Pressure of a single gas
What is Dalton’s Law?
Total pressure exerted by mixture of gases = sum of pressures exerted by individual gases
At sea level what is the Patm?
760 mmHg
What happens to Pgas and Patm at different altitudes?
Pgas & Patm change, but % gas in atmosphere is constant
What is the normal Po2 in our alveoli?
100 mmHg
What is the normal Pco2 in our alveoli?
40 mmHg
What happens to alveolar Po2 & Pco2 if we hypoventilate?
PO2 Decr. & PCO2 Incr.
What happens to alveolar Po2 & Pco2 if we hyperventilate?
PO2 Incr. & PCO2 Decr.
In peripheral tissues what is the PO2?
40 mmHg
In peripheral tissues what is the PCO2?
46 mmHg
What are the factors that increase alveolar gas exchange?
- Incr. partial pressure gradient
- Incr. surface area
- decr. diffusion distance
What are conditions that decrease alveolar gas exchange?
-Decr. surface area
- Decr. partial pressure gradient
- Incr. diffusion distance
What is Henry’s Law?
Movement of gas from air to liquid is proportional to:
1. Solubility
2. Pressure Gradient
What is the Law of mass action?
-Incr. Plasma PO2 causes incr. in binding
-Decr. in plasma PO2 causes decr. in binding and more release O2
What does the amount of O2 bound to Hb depend on?
-% saturation of Hb due to Po2
-Number of O2 binding sites (# of RBCs & Hb content per RBC)
What is the oxyhemoglobin saturation curve?
Shows % of available binding sites occupied determined by plasma Po2
Why is the shape of the oxyhemoglobin saturation curve important?
Sigmodial “S” shape important for delivering O2 to active tissues
What does a right shift curve in the oxyhemoglobin saturation curve mean?
Right-shifted curve occurs in active or chronically hypoxic tissues and increases O2 delivery to cells
What is a right shift curve in the oxyhemoglobin saturation curve caused by?
-Incr. PCo2
-Decr. pH (due to more lactic acid)
-Incr. temperature
-Incr. 2,3-BPG
What is 2,3-BPG?
A molecule that is a byproduct of cellular metabolism in chronically hypoxic cells
What are the 3 ways CO2 is transported in the blood?
- Dissolved in plasma: 7%
- Bound to hemoglobin: 23%
- Converted to bicarbonate: 70%
What is the law of mass action for bicarbonate?
-Hypercapnia –> right shift –> incr. H+ = acidosis
-Hypocapnia –> left shift –> decr. H+ = alkalosis
