Erythrocytes

Question 1

Structure of Erythrocytes

Answer 1

Contain hemoglobin (Hb)

Lack of nucleus

No organelles

Small size and biconcave shape

Plasma membrane protein spectrin gives flexibility to erythrocytes to change shape as necessary

Question 2

Formation of Erythrocytes

Answer 2

1) Hematopoietic stem cell/ Hemocytoblast is transform into a proerythroblast

2) Proeyrthroblast gives rise to early erythroblasts

3) As the early erythroblast is transformed into a late erythroblast.Normoblast will synthesise the Hemoglobin and iron accumulates.The nucleus become smaller

4) When a normoblast has accumulated almost all of its hemoglobin, it ejects most of its organelles, nucleus degenerates and is pinched off to form reticulocytes

5) The entire process from hemocytoblast to reticulocyte takes about 15 days.The reticulocytes enter the bloodstream.They become fully mature erythrocytes within two days of release as their ribosomes are degraded

Question 3

Main organ for production of RBC

Answer 3

Liver

Question 4

too few erythrocytes will leads to?

Answer 4

tissue hypoxia

Question 5

too much erythrocytes will leads to?

Answer 5

increases blood viscosity

Question 6

RBC production have to depends on?

Answer 6

Hormonal controls

Adequate(足够) supplies of iron, amino acids and certain Vitamins B

Question 7

_____ stimulus for erythrocyte formation

Answer 7

Erythropoietin (EPO)

Question 8

What will increase the formation of erythropoietin (EPO)

Answer 8

Hypoxia (缺氧)

Question 9

If hypoxia which organ will produce erythropoietin

Answer 9

Kidney

Question 10

What triggers EPO formation

Answer 10

1. Reduced number of erythrocytes
2. Insufficient hemoglobin per erythrocyte

3.Insufficient oxygen

Question 11

conditions that decrease the quantity of oxygen

Answer 11

▪ Anemia

▪ Destruction of major portions of bone marrow (x-ray therapy)

▪ High altitudes (where quantity of oxygen in the air is greatly decreased)

▪ Prolonged cardiac failure & in many lung disease

Question 12

How Control of Erythrocyte Production works

Answer 12

1) oxygen level low in blood, triggers Erythropoietin (EPO) formation in kidney

2) EPO travels to the bone marrow, where it stimulates the production of red blood cells (erythropoiesis).

3) Erythropoietin (EPO) stimulates the growth and maturation of hematopoietic stem cells and early red blood cell precursors in the bone marrow, increased production of mature red blood cells.

4) more oxygen-carrying capacity is provided to the blood, helping to restore normal oxygen levels in the body.

Question 13

dietary requirements for erythropoiesis

Answer 13

amino acids

lipids

carbohydrates

iron (essential for hemoglobin synthesis)

Vitamin B12 and folic acid (Necessary for DNA synthesis for rapidly dividing cells (developing erythrocytes)

Question 14

Life span of erythrocytes

Answer 14

100-120 days

Question 15

If old RBC become rigid and fragile; hemoglobin begins to degenerate what will happen?

Answer 15

get trap in spleen and macrophages in spleen will engulf and destroy these dying RBC

Question 16

As RBC are destroyed what will happen to those molecules in the RBC

Answer 16

iron component of heme is stored for later use

Heme is degraded to bilirubin (leaves the body in feces)

The globin is broken down to amino acids, which are released to circulation

Question 17

Life cycle of erythrocytes (combined of Control of Erythrocyte Production and fate and destruction of RBC)

Answer 17

1) oxygen level low in blood, triggers Erythropoietin (EPO) formation in kidney

2) EPO travels to the bone marrow, where it stimulates the production of red blood cells (erythropoiesis).

3) Erythropoietin (EPO) stimulates the growth and maturation of hematopoietic stem cells and early red blood cell precursors in the bone marrow, increased production of mature red blood cells.

4) As erythrocytes age or become damaged, they become rigid and less flexible. They will get trap in smaller blood vessels especially in organs like spleen, macrophages in spleen will engulf and destroy these dying RBC

5)iron component of heme is stored for later use

Heme is degraded to bilirubin (leaves the body in feces)

The globin is broken down to amino acids, which are released to circulation