NORMAL ERYTHROPOEISIS

Question 1

Properties of red cells

Answer 1

• carry O2

- high surface area/ volume ratio allows efficient GAS exchange

Question 2

What makes it more flexible?

Answer 2

• no nucleus

- no mitochondria

Question 3

Consequences of high Hb

Answer 3

• HIGH oncotic pressure/ oxygen rich env

Question 4

Probs with no nucleus and no mitochondria?

Answer 4

• can’t divide (limited cell lifespan)

- limitied to glycolysis

Question 5

Probs with high SA/V ratio?

Answer 5

• need to keep water out

Question 6

What makes the RBCs flexible?

Answer 6

• protein spars/ anchors

Question 7

What ensures water is KEPT out of the RBCS?

Answer 7

• having Na+/K+ pumps

- more sodiums out and potassiums in

Question 8

Describe the structure of Hb?.

Answer 8

• 2 Alpha and 2 Beta chains

- heme gr. (flat molecule with iron in the centre)

Question 9

What state is the iron in, in the Hb?

Answer 9

• Fe2+ state (ferrous??)

Question 10

Which state of IRON does not bind to oxygen?

Answer 10

• Fe3+

Question 11

What is the fxn o fHb?

Answer 11

• oxygen delivery
• acts as a BUFFER for H+
• CO2 transport

Question 12

How is the red cell prodn moderated?

Answer 12

• kidney has an oxygen sensor built in
• they sense a RELATIVE lack of oxygen
• —–erythropoietin is produces; acts on the erythroid precursors to make more rbcs

Question 13

Where are RBCs broken down?

Answer 13

• in the SPLEEN and LIVER

- avg. lifespan is 120days

Question 14

What is HEME broken down into?

Answer 14

• into bilirubin

- is conjugated and excreted in BILE (which colors faeces and urine)

Question 15

What occurs with AGED red cells?

Answer 15

• taken up by marcophages

Question 16

When krebs cycle is not working, what is formed?

Answer 16

LACTIC acid

Question 17

What is Hb called if it becomes oxidized?

Answer 17

-methemoglobin

Question 18

What does superoxide dismutase do?

Answer 18

• converts superoxide to hydrogen peroxide

Question 19

What does glutathione do?

Answer 19

• protects us from Hydrogen peroxide by reacting with it to form WATER and an oxidized glutathione prod.

Question 20

What is the HEXOSE MONOPHOSPHATE shunt?

Answer 20

• BY PASSES normal pathway
• –makes NADPH
• –therefore maintains GSH levels (preventing oxidative damage) ——limits G6PD acitivity

Question 21

When does the cell swell?

Answer 21

• high chloride levels in the RBCs

Question 22

How does CO2 get from the tissues to the lungs?

Answer 22

• 60% gets there as BICARBONATE

10% dissolved in solution

Question 23

Wht Hb is seen in the fetus? -

Answer 23

HbF (2 alpha and 2 gamma units)

Question 24

What pathway is ACITVATED in ANEMIA?

Answer 24

Rapapoport-Lubering Shunt
(involving 2,3-biphosphoglycerate) —–they INTERFERE with the Hb and alter the position of the heme groups (making it harder for oxygen to be bound to the molecule)