Lecture 5 & 6 Flashcards
What is Henry’s Law?
Amount of Gas dissolved in a liquid is proportional to the partial pressure of that gas in the liquid
How is most of the Oxygen in the body transported?
It is bound to the Hemoglobin in RBCs
What is the Oxygen Carrying Capacity of Hemoglobin (Binding Capacity)?
Roughly 1.34 mL O2/ g of Hb
-SIDENOTE: Max would be 1.39 mL O2/g of Hb
What does 100% Capillary Saturation refer to?
It means that Hb is is fully saturated with O2 to its max carrying capacity of 1.39 mL O2/g of Hb
How do you calculate the Oxygen Saturation of Hemoglobin and what is a typical arterial blood O2 saturation?
- (O2 bound to HB/O2 Capacity) x 100
2. High 90s (around 97.5%)
What is the formula for Arterial O2 Content?
CaO2= (Hb×SaO2×1.34)+(paO2×0.003)(per 100 mL)
What is the formula for Oxygen Delivery?
DO2 = CaO2 × CO × 10 (per L)
How does pH change from the normal 7.4 to 7.0 affect Hemoglobin binding to O2?
- Acidosis (lower pH) leads to WEAKER binding and QUICKER release of O2
- Slope shifts RIGHT
How does pH change from the normal 7.4 to 7.8 affect Hemoglobin binding to O2?
- Alkalosis (increased pH) leads to BETTER binding and LESS release of O2
- Slope shifts LEFT
What are the properties of the Hb-O2 Dissociation Curve?
- Sigmoidal Shape
- Steep up to P50 (50% saturated around 26.5 mmHg)
- Flat at the top
- Shift left means bad dissociation
- Shift right means better dissociation
What are some causes of a LEFT Shift in the Oxygen Dissociation Curve (slower dissociation)?
- Alakalosis
- CO
- Low CO2 (in lung)
- Lower Temp (in lung)
- Lower 2,3-DPG (in lung)
What are some causes of a RIGHT Shift in the Oxygen Dissociation Curve (better dissociation)?
- Acidosis
- Higher CO2
- Higher Temp
- Higher 2,3-DPG
Where is effect of pH greater, at the Arterial Point or the Venous Point?
Arterial Point
Does Anemia (decreased RBCs) change the O2 saturation of Hb?
- NO, All available Hb are 100% saturated
2. The amount of Hemoglobin able to transport O2 is reduced though
Why is CO’s effect on Hb unique?
CO not only shifts the curve to the left, it also drops the max
How is CO2 transported in the body?
- 10% as gas
- Combines with H2O and dissociates into H+ and HCO3-
- 30% blood proteins like Hb
What is the Haldane Effect?
Reducing Hb helps to load CO2 in the tissue and unload the CO2 in the lung to be breathed out
What is the difference between the CO2 and the O2 Dissociation Curve?
- CO2 curve is more linear
2. Larger CO2 concentration change for smaller change in pressure
How does the lung regulate Acid made from metabolic processes and rises in paCO2?
- Lung excretes most acid in the body daily
2. Hyperventilation drops the paCO2
What is Acidosis?
- Low pH (below 7.4)
2. More H+ and less Bicarbonate
What is Alkalosis?
- High pH (above 7.4)
2. More Bicarbonate and less H+
What are the values of Ideal Arterial Blood Gas?
- pH= 7.4
- pCO2= 40 mmHg
- Bicarb (HCO3-)= 24 meq/L
- Base Excess= 0 (-1 to +1)
- paO2= 95-100 mmHg
- Anion Gap 10-15
What is the formula for Anion Gap?
Anion Gap= Sum of Cations- Sum of Anions
-(Na + K) - (HCO3 + Cl)
What are some disorders caused by an INCREASED Anion Gap?
Value ABOVE 10-15 could cause:
- Diabetic Ketoacidosis
- Lactic Acidosis
- Uremia
- Methyl Alcohol Poisoning
What are some disorders caused by an DECREASED Anion Gap?
Value BELOW 10-15 could cause:
1. Heavy Metal Poisoning
What happens in Respiratory Acidosis?
- Decrease in pH
- Increase in pCO2
- Increased Bicarbonate
What happens in Respiratory Alkalosis?
- Increase in pH
- Decrease in pCO2
- Decreased Bicarbonate
Respiratory Issues are driven by what factor?
Changes in CO2
Metabolic Issues are driven by what factor?
Changes in Bicarbonate
What happens in Metabolic Acidosis?
- Decreased pH
- Decreased pCO2
- Decreased Bicarbonate
What happens in Metabolic Alkalosis?
- Increased pH
- Increased pCO2
- Increased Bicarbonate
If the Problem is Respiratory, what is the Compensation?
Metabolic Compensation
If the Problem is Metabolic, what is the Compensation?
Respiratory Compensation
