Erythrocyte Physiology

Question 1

What 4 fuctions does blood do?

Answer 1

Provides O2
Removes CO2
Homeostasis
Immune response

Question 2

What is erythropoieses and where does it occur?

Answer 2

The process of producing red blood cells, occurs in bone marrow.

Question 3

How do the kidneys know when to make RBCs?

Answer 3

When O2 is low in tissues, it is low in kidneys, leading to the activation of HIFalpha

Question 4

What does HIFalpha do and what is the mechanism?

Answer 4

When O2 in tissue and kidney is low, HIFalpha accumulates (transcription factor) binds to HIFbeta in nucleus, signaling for synthesis of erythropoietin, which makes more RBC

Question 5

What occurs during microcytic anemia?

Answer 5

The RBC becomes small due to lack of Fe (needed for Hg), resulting in pallor

Question 6

What form of iron does the stomach prefer?

Answer 6

Since the stomach is acidic, it favors the Ferric (Fe3+) form

Question 7

What occurs during macrocytic anemia?

Answer 7

The RBC becomes large due to lack of vitamin B12 and folic acid (required for normal DNA synthesis)

Question 8

What is oxygen capacity?

Answer 8

The total amount of oxygen that can be carried in our blood assuming every availible heme had an oxygen bound to it

Question 9

What is the oxygen capacity of a man with 15gm Hb/100mL blood?

Answer 9

1.34mLO2/gHb (standard number) x 15g = 20.1mLO2/dL blood

Question 10

How do you find the oxygen content?

Answer 10

Take the calculated oxygen capacity and multiply by % saturation (given)

Question 11

Why do RBCs need ATP?

Answer 11

They have no organelles so cannot be produced by mtio, created by anaerobic glycolysis for:
Flexibility of membrane
ATPase
Maintain iron in Fe2+ ferrous instead of Fe3+
Prevent oxidation of Hb

Question 12

What occurs when someone has anemia (decrease RBC or Hb due to low iron/b12)?

Answer 12

Decreased oxygen capacity and content, decreased O2 to tissue, so heart will pump MORE to give more blood with O2

Question 13

What is hemochromatosis and what is it from?

Answer 13

Hemochromatosis is when there is an overload of iron in the blood. This is due to a mutation that activates Hepcidin to regulate the amount of iron

Question 14

What happens when the liver reaches its max capacity of iron?

Answer 14

Signals by HFe to hepcidin to block ferroportin so iron cannot be released into the blood

Question 15

What happens when there is a missense mutation in Hfe?

Answer 15

Hepcidin is not activated, allow ferroportin to transport all iron to bloodsteam, causing hemachromatosis

Question 16

What is polycythemia and what effects does it have?

Answer 16

It is when there are too many RBCs, leading to thicker (viscous) blood, making the heart work harder to pump blood

Question 17

What is primary polycythemia(Vera)?

Answer 17

When Bone Marrow (BM) produces too many RBCs, making blood viscous and causing heart to beat faster

Question 18

What is secondary polycythemia?

Answer 18

Due to environmental factors (high altitude), less O2 availble, leads to increase in RBC production

Question 19

What does the mneumonic CADET stand for regaurding O2-Hb curves?

Answer 19

C: CO2 (high)
A: Acidity (low pH)
D: DPG(2,3)
E: Excercise
T: Temperature
all cause Hb/O2 curve to shift to right

Question 20

What does a right shift on the O2-Hb curve represent? A left shift?

Answer 20

Right shift represents a decrease in the affinity of Hb for O2
Left shift represents an increase in affinity of Hb for O2

Question 21

What occurs when someone has methemoglobinemia?

Answer 21

Met-Hb contains Ferric Fe3+ at center which cannot bind O2. Normal Hb chains have an even HIGHER affinity for O2, so bind and do not release to tissues.

Question 22

What are the patient effects of met-Hb?

Answer 22

confusion/cyanosis