Chapter 2: RBC Formation, Metabolism, and Destruction

Question 1

What are the characteristics of mature RBC?

Answer 1

1. Has no nucleus
2. Has no mitochondria
3. Alive

Question 2

What is erythropoiesis?

Answer 2

Term used to describe the process of RBC production

Question 3

Where does erythropoiesis occur?

Answer 3

In distinct anatomical sites called erythropoietic islands

Question 4

What is the fxn of macrophage in erythropoiesis?

Answer 4

It serves to supply the developing RCs w/ Fe for hgb synthesis

Question 5

Each erythropoietic island (in connection to erythropoiesis) consists of what?

Answer 5

Consists of a macrophage surrounded by a cluster of erythroblasts

Question 6

How many % does nucleated cells account in erythroid cells in normal bone?

Answer 6

5 - 38%

Question 7

Where does erythropoiesis occur?

Answer 7

In distinct anatomical sites called erythropoietic islands

Question 8

What is tissue hypoxia?

Answer 8

Literally means decrease in O2 content within the tissues

Question 9

What are the purposes of tissue hypoxia?

Answer 9

1. Produces a dramatic increase in the production of EPO
2. Primary stimulus for the production of RBCs
3. # 1 trigger why stem cells produce RBCs

Question 10

Explain how tissue hypoxia triggers the stem cells to produce RBCs

Answer 10

Situation where O2 (w/c is needed to consume GLU -> what will happen is GLU + O2 -> ending is CO2 + H2O: CO2 is formed from the consumed GLU; w/c is discarded) in the tissues decrease -> low O2 will be detected by the kidneys -> kidney will produce EPO (w/c is a type of hormone: hormone is a chemical messenger [communication between organs to achieve a normal status in the body] | w/c will pass through the bld -> hence, the hormone will pass through all organs because it is present in the bld) -> EPO targets BM (specifically the stem cells [specifically CFU-E and BFU-E]) -> BM will produce many RBCs (1 RBC has many hgb: hgb can bind O2 -> if there are many RBCs, it means that there are many O2) -> since there are many O2, tissue hypoxia will be resolved (the body will now return to its normal state) -> at some point, overload of O2 in the tissues will occur w/c is not normal because it will result to hyperventilation (only homeostasis [balanced / regulated / normal state] must be achieved in the body) -> negative feedback mechanism will happen (w/c aims to decrease O2 because it is too much) -> since there is overload of O2 in the tissues -> it will be detected by the kidneys -> kidneys will decrease EPO -> w/c will be detected by BM -> resulting to decreased RBC production -> since RBC is decreased, only few O2 will be delivered into the body -> achieving homeostasis

Other feedback mechanism that can happen is positive feedback mechanism (where it increases O2 more | it only happens if a female gives birth -> a female gives birth due to oxytocin: w/c is a hormone that makes the muscles contract to give birth)

Question 11

Explain erythropoietic islands

Answer 11

Inside the RBCs, there is nurse (w/c is a type of macrophage) w/c is surrounded by large nucleated cells (w/c are normoblasts: normoblasts are also known as NRBCs: cells w/ nucleus; exs are pronormoblasts, basophilic normoblast, polychromatophilic normoblast, and orthochromic normoblasts [PBPO]) -> macrophage have many Fe and the NRBCs surrounding it wants to have Fe (this phenomenon where NRBCs sucks Fe from the nurse cell is called as suckling pig phenomenon): w/c will be used for the production of hgb (because hgb has Fe) -> becomes RBC (w/c needs Fe for hgb)

This whole phenomenon is called as erythroid islands

Question 12

What are the characteristics of nucleated RBCs (NRBCs)?

Answer 12

1. Immature RBCs
2. Still maturing to become RBC
3. Still has nothing much hgb
4. Will only take 4 - 5 days in this stage
5. Must not be present in the circulation
   => instead, these must only be seen in the BM -> if NRBCs are present in the circulation, pt may have leukemia | only polychromatic erythrocyte and erythrocyte must be seen in the circulation

Question 13

What are the exs of NRBCs?

Answer 13

1. Pronormoblast
2. Basophilic normoblast
3. Polychromatophilic normoblast
4. Orthochromic / orthochromatic normoblast

PBPO

Question 14

True or False

After time, the nucleus of NRBCs will be removed w/c is called as polychromatophilic erythrocytes

Answer 14

True

Question 15

What stain is used to stain polychromatophilic erythrocytes?

Answer 15

Wright’s stain

Question 16

How many days is the maturation of polychromatophilic erythrocytes in the BM?

Answer 16

2.5 days

Question 17

What are the general characteristics of a cell?

Answer 17

1. Has nucleus
2. Has cytoplasm
3. Has cell membrane

Question 18

What is erythron?

Answer 18

Refers to all of the stages of erythrocyte development emcompassing the earliest precursor cells in the BM to the mature RBCs in the circulating, peripheral bld and the vascular areas of organs such as the spleen

Question 19

What are the basic substances needed for normal erythrocyte and hgb production?

Answer 19

1. Amino acids (PRO)
2. Fe
3. Vit B12
4. Vit B6
5. Folic acid
6. Trace minerals
   a. Cobalt
   b. Nickel

Amino acids + Fe + 2 vits + 2 trace minerals

Question 20

What are the building blocks of PROs?

Answer 20

Amino acids

Question 21

What is the purpose of Fe (as a basic substance needed for normal erythrocyte and hgb production)?

Answer 21

For hgb

Question 22

What is the characteristic of folic acid?

Answer 22

Member of B2 complex