Lecture 9 Flashcards
- What are the 3 areas where CO2 can be contained in the blood?
- what % of total CO2 is located in each area
- 30% Carbaminohemoglobin
- 60% of CO2 Transport by HCO3-
- 10% of CO2 dissolved in plasma
as pressure goes up will the amount of CO2 being dissolved go up or down?
up
How is carbon dioxide exchanged in the systemic capillaries (internal respiration)
- CO2 will enter the RBC and will bind with H20,
- carbonic anhydrase will break it down to carbonic acid and bicarbonate, and H+ (carbonic anhydrase pathway)
- bicarbonate exits the RBC (liberate bicarbonate) and will help keep pH in normal range 7.35-7.45
How is carbon dioxide exchanged at the pulmonary capillaries (external respiration)
- Once Bicarbonate gets to pulmonary capillary it will enter the RBC and go through the reverse carbonic anhydrase pathway
- so that we can break down carbonic acid and release water, CO2,
- CO2 will diffuse through pulmonary capillary wall and then it will be exhaled
what Buffers acidity of carbon dioxide
bicarbonate
What is the carbon dioxide content (ml/dl) of blood?
- Arteries- 48ml/dl
- Veins- 52ml/dl
Describe the Haldane effect on carbon dioxide carriage by the blood.
The higher the PO2, more CO2 will be liberated and less CO2 content in the blood
Explain the difference in diffusion rate between oxygen and carbon dioxide.
- CO2 is more soluble
- CO2 being carried in the blood than O2 even though the partial pressures are much higher in the arteries for O2.
Write the alveolar ventilation equation and be able to apply it to different situations of CO2 production and alveolar ventilation
Write the alveolar air equation and be able to solve it in different situations of barometric pressure, saturated water vapor pressure, fractional concentration of oxygen, and arterial partial pressure of carbon dioxide
what is hypoxemia
Hypoxemia- Less than normal arterial oxygen partial pressure PaO2
PaO2= partial pressure of oxygen in arteriole blood
- what is the usual range of PaO2?
- what does it depend upon?
- Usual range is 80 – 100 mmHg
- Depends upon altitude of residence
What are the 5 causes of hypoxemia?
1 Hypoventilation
2 Low PIO2
3 Shunt
4 V/Q mismatch
5 Diffusion impairment
which causes of hypoxemia are from decreased PAO2
- hypoventilation
- Low PIO2
What are 5 causes of hypoventilation
- look at picture for 1-4
5. anesthetic drugs
- During hypoventilation what will happen to PACO2?
- A-a O2 difference?
- Will giving pure oxygen (increasing FIO2) fix hypoxemia?
- Yes, animal will respond
during hypoventilation what will happen to
- PAO2
- PaO2
- PAO2= decrease
- PaO2= decrease
during hypoventilation what will happen to
- PACO2=
- PaCO2=
- PACO2= increase
- PaCO2= increase
- Explain why PIO2 decreases as an animal moves to higher altitudes
- Does FIO2 decrease?
- atmospheric pressure will increase which will decrease PIO2
- FIO2 stays the same!
- List the normal partial pressures of oxygen, carbon dioxide, water, and nitrogen in Inspired air
- Alveolus
- List the normal partial pressures of oxygen, carbon dioxide, water, and nitrogen in arteries
- tissues
- veins
How does an animal compensate for living at a high altitude
Increase alveolar ventilation, (hyperventilate)
Convert gas content in percent to fractional concentration and partial pressure at various total pressures (altitudes) and water vapor pressures (100% saturation)
what types of hypoxemia have an increased A-a oxygen partial pressure difference
- shunts
- V/Q mismatch
- Diffusion impairment
What are 4 things that affect pulmonary diffusion
- Alveolar Surface Area
- Driving pressure
* PA-> Pa - Membrane thickness
- Physical properties
- Solubility
- Molecular Weight (MW)
- what law is this
- What do these stand for
D – Rate of gas diffusion
∆P – Partial pressure difference (C1-C2)
A – cross-sectional area of surface
S – Solubility of gas in the fluid
X – Diffusion Coefficient, distance of diffusion path
MW– Molecular weight of gas
does CO2 or oxygen diffuse more?
CO2 diffuses 20 times faster than O2
During exercise what will happen to PaO2
decreases because it is being dropped off in the tissues
Explain how diffusion of oxygen is involved in the hypoxemia that develops in horses as they race.
- The major cause of the exercise-induced hypoxemia in the horse is a diffusion limitation.
- During exercise, the combination of rapid pulmonary blood flows coupled with a much reduced venous oxygen content have been hypothesized to cause insufficient time to achieve complete equilibration of gas exchange across the capillary–alveolar interface
