Oxyhemoglobin dissociation Curve (APEX question 14) material

What is the P50? High P50 means curve shifted to the ______________ and low P50 means curve shifted to the ____________________.

The P50 is the PaO2 where hemoglobin is 50% saturated A low P50 will reflect a left shift and a high P50 will reflect a right shift in the oxyhemoglobin dissociation curve

What are causes of left shift of the oxyhemoglobin dissociation curve?

1) decreased PCO2 2) decreased 2-3 DPG 3)decreased temperature 4) decreased hydrogen= 5) increased pH 6)increased fetal hemoglobin 7)increased carbon monoxide 8)increase Methemoglobin

What are causes of right shift of the oxyhemoglobin dissociation curve?

1) increased PC02 2) increase 2-3 DPG 3) increase temperature 4) acidosis (increased hydrogen ion) 5) decreased pH

For a normal hemoglobin, what is the partial pressure of oxygen for the P50?

26.5mmHg

What is the Bohr effect? What two things are specific to the Bohr effect?

CO2 and Hydrogen ion These two molecules will cause a conformational change in the hemoglobin molecule which will facilitate it to release oxygen CO2 and hydrogen will cause hemoglobin to release oxygen

Will 2-3 DPG respond to Fetal Hemoglobin? What is the P50?

HGB F will not respond to 2-3DPG hence the left shift in the curve P50 would be 19mmHg

Will hypoxia increase or decrease 2-3 DPG production? What will this facilitate?

Hypoxia will increase 2-3 DPG production and will facilitate offloading of oxygen

What are two ways to remember left shift and right shift? (Think mnemonic)

Left: LOVE Right: RELEASE

What PaO2 does maximum oxygen loading occur at? Can we improve O2 loading if the PaO2 is above 100mmHg? What occurs?

Maximum o2 loading occurs at a PaO2 of up to 100mmHg. A PaO2 above 100mmHg will not improve oxygen loading, it will increase the amount of oxygen that is dissolved in the plasma

What does metabolic rate have to do with shifting the oxyhemoglobin dissociation curve? Will it shift the curve left or right? Why? What are things that should shift the curve this way?

Metabolic rate is a big factor in shifting the curve. Tissues that have a higher metabolic rate will consume more oxygen and will produce more CO2, hydrogen ion and heat. This will cause a right shift in the curve (rise in temperature, increase in 2-3 DPG, CO2 and hydrogen ion)

What occurs with 2-3 DPG in banked blood? Which way would the curve move?

The concentration of 2-3 DPG would decrease and this would shift the curve to the left and will reduce the amount of O2 available at the tissue level

Which way will an increase in 2-3 DPG shift the oxyhemoglobin dissociation curve?

This will maintain the curve in a slightly right shifted position

What are things that would cause a left shift again?

You should know this, some hemoglobinopatheis can cause a left shift

When is 2-3 DPG produced? What pathway is this called

2-3 DPG is produced during RBC glycolysis Called the Rapoport Luebering pathway