Hemoglobin Flashcards
hemoglobin oxygen-hemoglobin dissociation curve
Each alveolus is surrounded by a network of capillaries. What kind of blood does the pulmonary arteries bring to the capillaries?
(carries blood away from the heart)
Deoxygenated blood
- high levels of CO2
- low levels of O2
Each alveolus is surrounded by a network of capillaries. What kind of blood does the pulmonary veins bring to the capillaries?
(carries blood toward the heart)
Oxygenated blood
- high levels of O2
- NO levels of CO2
In the respiratory system, is ATP required for gas transfer (O2 and CO2) between the alveoli and blood?
NO, because both gases are moving down their concentration gradients.
How is oxygen transported by the blood?
Binds to the protein hemoglobin (Hb).
What is hemoglobin?
A protein that carries oxygen in the blood.
What gives blood its characteristic red color?
Heme groups
(They are prosthetic groups and without heme groups, hemoglobin is inactive.)
When does an enzyme or protein exhibit cooperativity?
When there are multiple binding sites or subunits.
One subunit can undergo a conformational change, which either enhances or reduces the activity of the other subunits.
Is hemoglobin (Hb) affected by positive or negative cooperativity?
Positive cooperativity
Why is there a sigmoidal shape for an oxyhemoglobin dissociation curve?
Because hemoglobin exhibits positive cooperativity.
Explain positive cooperativity in hemoglobin.
*Think of the party example*
One O2 molecule binds to a heme group and causes a conformational change in the shape of Hemoglobin. This allows other O2 molecules to bind more easily in succession.
What is the composition of hemoglobin (Hb)?
4 subunits connected together, each with a heme group
Each subunit has a heme group that contains 1 iron atom in its center. It is the iron core that binds to oxygen.
What is the composition of myoglobin?
1 subunit with 1 heme group
What is the main difference between the oxygen carrying capacity of hemoglobin and myoglobin?
Basically where do they carry oxygen?
Hemoglobin: carries oxygen in the blood
Myoglobin: carries oxygen in the muscles
How many oxygen molecules can a single hemoglobin (Hb) molecule carry?
4 oxygen molecules
(1 in each heme group)
How many oxygen molecules can a single myoglobin molecule carry?
1 oxygen molecule
(1 heme group binds 1 oxygen molecule)
The majority of CO2 that enters the blood is absorbed and converted into carbonic acid which then dissociates. What does carbonic acid dissociate into?
- bicarbonate ion (HCO3-)
- hydrogen ion (H+)
What is the equation for the bicarbonate buffer system in blood?
If an oxyhemoglobin dissociation curve shifts towards the left, what kind of affinity does hemoglobin have for oxygen?
Hemoglobin has an increased affinity for oxygen.
“_l_eft _l_oads O2 at the tissues”
If an oxyhemoglobin dissociation curve shifts towards the right, what kind of affinity does hemoglobin have for oxygen?
Hemoglobin has decreased affinity for oxygen.
“_r_ight _r_ids O2 into the tissues”
[Mnemonic]
CADET, face right!
(how to remember which factors shift the oxygen-hemoglobin dissociation curve/Bohr effect to the right)
CADET, face right!
- pCO2
- Acidity (↓ pH, ↑ [H+])
- 2,3- BPG (diphosphoglycerate)
- Exercise
- Temperature
An increase (NOT decrease) in ALL of these will shift the curve to the right.
How do RBCs produce ATP?
Via anaerobic glycolysis
RBCs have an enzyme called bisphosphoglycerate mutase. What is the function of this enzyme?
Converts 1,3-BPG (from glycolysis) to 2,3-BPG.
What effect does 2,3-BPG have on adult hemoglobin (HbA)?
Binds allosterically and decreases HbA’s affinity for oxygen.
This causes a _r_ight shift in a oxyhemoglobin dissociation curve because HbA _r_ids of oxygen at the tissues.
2,3-BPG ONLY binds to adult hemoglobin (HbA), but not to fetal hemoglobin (HbF). What effect does this have on HbF?
HbF can bind to oxygen and therefore has a higher affinity for oxygen than maternal HbA.
