Lecture 5B Flashcards
Oxygen is carried in blood in what two forms?
Dissolved in plasma (1.5%)
Bound to hemoglobin (98.5%)
Hemoglobin increases the Oxygen carrying capacity of blood by???
70X
In hemoglobin, Iron is in what state to bind oxygen?
Ferrous state (Fe2+)
Normal adult hemoglobin is sometimes called what?
a2b2 (alpha 2 beta 2)
What 5 things in blood can influence hemoglobin saturation at a given Po2
- Temperature
- Blood pH
- Pco2
- BPG (2,3-bpg)
- DPG (2,3-dpg)
2,3-BPG is produced how?
By RBCs as they break down glucose by glycolysis. 2,3-BPG binds reversibly with hemoglobin.
A shift to the right in a Hemoglobin-O2 dissociation curve means what?
- Occurs when the affinity of hemoglobin for O2 is decreased.
- P50 is increased, and unloading of O2 from arterial blood to the tissues is facilitated
- For any level of Po2, the % saturation of hemoglobin is decreased
What 3 things Shift the dissociation curve to the right?
- Increased Pco2 or decreases in pH
- Increased Temperature
- Increased 2.3-DPG
The Bohr effect is associated with what factors of oxygen dissociation?
When the increase in Pco2 or decrease in pH decrease the affinity of hemoglobin for O2 and facilitates the unloading of O2 in the tissues.
When the tissues produce more Co2 for example during exercise, what happens to the pH?
The pH is decreased. (BOHR EFFECT)
How does 2,3 DPG or BPG work?
It binds to the beta chains of deoxyhemoglobin and decreases the affinity of hemoglobin for O2
Explain the relationship of chronic hypoxemia and 2,3-DPG
The adaptation to chronic hypoxemia (living at high altitude) includes increased synthesis of 2,3-DPG, which binds to hemoglobin and facilitates the unloading of O2 in the tissues
A shift to the left in the dissociation curve means what?
- Occurs when the affinity of hemoglobin for O2 is increased
- P50 is decreased and unloading of O2 from arterial blood into the tissues is more difficult
- For any level of Po2, the % saturation of hemoglobin is increased
What 3 things shift the dissociation curve to the left?
- Decreased Pco2 or increased pH
- Decreased temperature
- Decreased 2,3-DPG
T or F, Even though CO competes for O2-binding sites on hemoglobin, the affinity of hemoglobin for O2 is much greater than CO
False, Affinity of hemoglobin for CO is 200x its affinity for O2.
What happens in Carbon Monoxide Poisoning?
- CO occupies O2-binding sites on hemoglobin, thus decreasing the O2 concentration of blood.
- In addition, bind of CO to hemoglobin increases the affinity of remaining site for O2, causing a shift of the curve to the left. DRAW the CURVE
What is Hypoxemia?
Decrease in arterial Po2
WHat is Hypoxia?
Decreased O2 delivery to the tissues
O2 content of blood depends on what?
- Hemoglobin concentration
- O2-binding capacity of hemoglobin
- % saturation of hemoglobin by O2
What 3 things may cause Hypoxia?
Decreased Cardiac Output
Decreased O2-binding capacity of hemoglobin
Decreased arterial Po2
What is Anemic Hypoxia?
Reflects poor O2 delivery resulting from too few RBCs or from RBCs that contain abnormal or too little hemoglobin
What is Ischemic (stagnant) Hypoxia?
Results when blood circulation is impaired or blocked.
- Congestive heart failure may cause body-wide ischemic hypoxia, whereas emboli or thrombi block oxygen delivery only to tissues distal to the obstruction.
What is Histotoxic Hypoxia?
Occurs when body cells are unable to use O2 even though adequate amounts are delivered.
- Consequence of metabolic poisons such as cyanide
What is Hypoxemic Hypoxia?
Indicated by reduced arterial Po2
