RESP 4 Flashcards
What is the % of hemoglobin saturated with O2 in the pulmonary veins (SvO2)?
75%
What is the % of hemoglobin saturated with O2 in the pulmonary arteries (SaO2)?
97%
___ of O2 reversibly binds to
hemoglobin inside of the RBC
98%
___ of total oxygen content is
dissolved in plasma
2%
Iron must be in __________ state to bind O2
ferrous (Fe2+)
The amount of oxygen bound to Hb depends on:
- Plasma PO2
- Number of binding sites in RBCs depends on the Hb amount per RBC
What is CaO2?
ml of O2carried by oxyhemoglobin plus ml of O2 carried dissolved in plasma
What is the average CaO2?
19.782 ml O2/ 100 ml blood
What is positive cooperativity?
At a high PO2, hemoglobin’s affinity for O2 is highest.
The lower the PO2, the ____ likely O2 will dissociate from hemoglobin.
more
2,3-BPG binds to Beta subunits of deoxy HB and ________ its O2 affinity
decreases
What is the bohr effect?
Oxyhemoglobin Dissociation Curve Shifts to the RIGHT
What does a right shift in the Oxyhemoglobin Dissociation Curve cause?
- DECREASED affinity between hemoglobin and oxygen
- oxygen is MORE likely to dissociate
from Hemoglobin.
When do levels of 2,3-BPG increase?
- exercise
- hypoxia from high altitude
- pregnancy
- chronic lung disease
What causes a right shift in the Oxyhemoglobin Dissociation Curve?
- increased hydrogen ions (lower pH)
- increased CO2
- increased temperature
- increased BPG
What does a left shift in the Oxyhemoglobin Dissociation Curve cause?
- INCREASED affinity between oxygen and hemoglobin
- oxygen is LESS likely to dissociate from hemoglobin
What causes a left shift in the Oxyhemoglobin Dissociation Curve?
– Decreased PCO2
– Increased pH
– Decreased temperature
– Decreased 2,3-BPG
Carbon Monoxide has a ______ greater affinity for Hemoglobin than Oxygen.
250X
CO bound to hemoglobin _______ Hb’s affinity for O2.
increases
- left-ward shift
What is the treatment for carbon monoxide poisoning?
- Pure oxygen
- 5% CO2
What are the variants of hemoglobin?
- Methemoglobin
- Hemoglobin F (fetal hemoglobin)
- Hemoglobin S (sickle cell)
How does fetal hemoglobin differ from HbA?
- left shift
- no B chains
- higher affinity for oxygen
How is methemoglobin different from HbA?
- Heme with Fe3+ does not bind O2 as readily (reduced
affinity) - Causes any heme groups in the same Hb molecule with heme in the Fe2+ state to have have higher affinity for bound O2 ➔ net effect is reduced O2 delivery to the tissues
What causes methemoglobin to form?
- Ferrous to ferric
- occur due to G6PDH deficiency or upon exposure to some local anesthetics
