Hemoglobin & Myoglobin Flashcards
_____ is a complex of protoporphyrin IX and ferrous ion (Fe2+)
Heme
What does heme do in hemoglobin and myoglobin?
it serves to reversibly bind oxygen
Where is Myoglobin present?
Heart and skeletal muscle
What is the function of myoglobin?
reservoir of oxygen in red muscle fibers
When is the oxygen that is stored in myoglobin released?
During oxygen deprivation
Does myoglobin have a high or low molecular weight?
Low ~17,000
Where is Hemoglobin present?
in RBCs
What is the function of Hemoglobin?
it reversibly carries oxygen from lungs to peripheral tissues, and H+ and some CO2 from peripheral tissues to the lungs.
HbA has what?
2 alpha, 2 beta
HbF has what?
2 alpha, 2 gamma
HbA2 has what?
2 alpha, 2 delta
How long does embryonic hemoglobin persist?
from 15 days after fertilization until 6 weeks of embryonic life
When does HbF predominate?
from 6 weeks of fetal life; gradually falls from 30 weeks of prenatal life. At birth and up until 4-5 weeks of post natal life, HbF is the predominate type.
When completely saturated, how many oxygens do myoglobin and hemoglobin bind?
myoglobin binds one O2 and hemoglobin binds 4
In the absence of oxygen (T form), the interaction between (αβ)1- (αβ)2 is ______
tight
In the presence of oxygen (R form), the interaction between (αβ)1- (αβ)2 is ______
less tight
______ is the degree of saturation measured at different partial pressures of oxygen
Oxygen dissociation curve
2,3-BPG ______ the oxygen affinity of hemoglobin
decreases
What is 2,3-BPG’s effect on deoxyhemoglobin and hemoglobin?
it stabilizes deoxyhemoglobin and helps to release O2 from hemoglobin.
The levels of 2,3-BPG _____ in response to chronic hypoxia and helps to release O2 from hemoglobin
increase
Factors that cause a right shift (reduced affinity) to the oxygen-hemoglobin dissociation curve
- increase in 2,3-BPG
- increase in PCO2
- decrease in pH
Factors that cause a left shift (increased affinity) to the oxygen-hemoglobin dissociation curve
- decreased 2,3-BPG
- decrease in PCO2
- increased pH
- presence of CO
____ glucose levels in uncontrolled type 2 DM will increase HbA1c
Higher
What is the most abundant form of glycosylated hemoglobin?
HbA1c
What is used to monitor the long term control of blood glucose in DM?
HbA1c
What causes the release of O2 from hemoglobin?
low tissue pH and high PCO2
How does CO bind to the iron of hemoglobin?
covalently, but reversibly
Where is embryonic hemoglobin produced?
in the yolk sac
Where are the major sites of fetal erythropoiesis?
liver and some spleen
In the last few weeks before birth, what is the site of erythrocyte formation?
bone marrow
Which histidine, proximal or distal, directly interacts with Fe2+ of heme?
His F8(proximal)
Which histidine, proximal or distal, does not directly interact with Fe2+ of heme, but helps to stabilize the binding of oxygen to the ferrous ion?
His E7(distal)
10% of total CO2 produced in peripheral tissue is carried in the form of what?
carbaminohemoglobin
90% of total CO2 produced in peripheral tissue is carried in the form of what?
bicarbonate
