Erythrocyte and its' life cycle

Question 1

3 main erythrocyte functions

Answer 1

1. Deliver oxygen to all cells/tissues of body through blood ciculation Take up oxygen in the lungs and release it it as they squeeze through capillaries. Hb responsible for red color of RBC 2. Pick up CO2 from the tissues to deliver to lungs, although most of waste CO2 transported to pulmonary capillaries as bicarbonate (HCO3-) dissolved in plasma 3. Gas exchange by diffusion through membrane

Question 2

2 secondary erythrocyte functions

Answer 2

1. When undergoing sheer stress in constricted vessels release ATP leading to vessel wall relaxation and dilation promoting blood flow 2. When Hb deoxygenated release S nitrosothiois (notroso group + Sulfur of thiol) which also dialate vessels directing blood to areas of oxygen depletion

Question 3

RBC structure

Answer 3

6-8 _ in diameter (larger than capillary diameter) and 2 _ thick. Flexible biconcave disk for greater surface area and better for gas exchange, laminar flow. Lacks nucleus (cannot be targeted by viruses) and most organelles except some mitochondria.

Question 4

Crenated RBCs

Answer 4

Happens when RBCs placed in hypertonic solution.

Question 5

Swollen RBCs

Answer 5

Happens when RBCs placed in hypotonic solution.

Question 6

RBC ghosts

Answer 6

RBCs that became so swollen in hypotonic solution that they burst and become empty membranes

Question 7

Rouleaux formation

Answer 7

Stacking of RBCs in rows in large blood vessels during inflammation when certain serum proteins are elevated

Question 8

Hemocytoblast

Answer 8

Stem of all blood cells. Large cell in red bone marrow.

Question 9

Erythropoietin

Answer 9

Hormone produced by kidneys that causes a hemocytoblast to commit to RBC line by turning it into a proerythroblast

Question 10

Proerythroblast

Answer 10

Commits cell to RBC development. Formed from hemocytoblast which turns into a basophilic erythroblast

Question 11

Correct order of Erythropoeisis (6)

Answer 11

Process takes 7 days: Hemocytoblast–>Proerythroblast–>Basophilic Erythroblast–>Polychromatophilic Erythroblast–>Orthochromatophilic Erythroblast (Normoblast)–>Reticulocyte

Question 12

Basophilic erythroblast

Answer 12

Early erythroblast. Accumulates iron and Hb which changes it from basophilic to eosinophilic.

Question 13

Polychromatophilic erythroblast

Answer 13

Late erythroblast. Has a combination of basophilia and eosinophilia.

Question 14

Orthochromatophilic erythroblast

Answer 14

AKA normoblast. Eject organelles to make a reticulocyte

Question 15

Reticulocyte

Answer 15

Leave bone marrow to circulation and mature into RBCs (make up 1% of red cells in blood)

Question 16

How are RBCs removed from circulation?

Answer 16

Lifespan is 120 days. Do not go through apoptosis. Broken down by macrophages within liver, spleen, and bone marrow (to lesser extent). Macrophages recognize membrane surface signals on aged RBCs.

Question 17

6 factors that stimulate RBC production

Answer 17

1. Hemorrhage 2. Damage to bone marrow 3. High altitude 4. Exercise 5. Hemolytic disease 6. Low Hb

Question 18

Phosphatidylserine (PS)

Answer 18

Phospholipid normally found only on inner layer of RBC membrane, but aged RBCs display it on their surface to signal macrophages

Question 19

Hemolysis (3 results)

Answer 19

10% of RBCs hemolyze with fragments engulfed by macrophages and degraded via lysosomal enzymes. 1. Iron released from heme and becomes stored or free 2. Globin broken down to AA 3. Heme degraded to bilirubin

Question 20

2 ways to control RBC concentration

Answer 20

1. Erythropoietin released in response to low blood oxygen-increases RBC production and protects cell from apoptosis 2. Testosterone increases production and effectiveness of erythropoietin

Question 21

Heinz bodies

Answer 21

Small round inclusions found within RBCs which get eliminated by macrophages (can cause Heinz body anemia)

Question 22

3 causes of Heinz bodies

Answer 22

1. Damaged hemoglobin 2. Inherited mutation 3. Chronic liver disease

Question 23

Hereditary spherocytosis

Answer 23

Congenital abnormality of spectrin in sub-membrane cytoskeleton (supports RBC shape) turning cells to spheres resulting in anemia and splenomegaly