Erythrocyte and its' life cycle Flashcards
3 main erythrocyte functions
- 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
2 secondary erythrocyte functions
- 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
RBC structure
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.
Crenated RBCs
Happens when RBCs placed in hypertonic solution.
Swollen RBCs
Happens when RBCs placed in hypotonic solution.
RBC ghosts
RBCs that became so swollen in hypotonic solution that they burst and become empty membranes
Rouleaux formation
Stacking of RBCs in rows in large blood vessels during inflammation when certain serum proteins are elevated
Hemocytoblast
Stem of all blood cells. Large cell in red bone marrow.
Erythropoietin
Hormone produced by kidneys that causes a hemocytoblast to commit to RBC line by turning it into a proerythroblast
Proerythroblast
Commits cell to RBC development. Formed from hemocytoblast which turns into a basophilic erythroblast
Correct order of Erythropoeisis (6)
Process takes 7 days: Hemocytoblast–>Proerythroblast–>Basophilic Erythroblast–>Polychromatophilic Erythroblast–>Orthochromatophilic Erythroblast (Normoblast)–>Reticulocyte
Basophilic erythroblast
Early erythroblast. Accumulates iron and Hb which changes it from basophilic to eosinophilic.
Polychromatophilic erythroblast
Late erythroblast. Has a combination of basophilia and eosinophilia.
Orthochromatophilic erythroblast
AKA normoblast. Eject organelles to make a reticulocyte
Reticulocyte
Leave bone marrow to circulation and mature into RBCs (make up 1% of red cells in blood)
How are RBCs removed from circulation?
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.
6 factors that stimulate RBC production
- Hemorrhage 2. Damage to bone marrow 3. High altitude 4. Exercise 5. Hemolytic disease 6. Low Hb
Phosphatidylserine (PS)
Phospholipid normally found only on inner layer of RBC membrane, but aged RBCs display it on their surface to signal macrophages
Hemolysis (3 results)
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
2 ways to control RBC concentration
- Erythropoietin released in response to low blood oxygen-increases RBC production and protects cell from apoptosis 2. Testosterone increases production and effectiveness of erythropoietin
Heinz bodies
Small round inclusions found within RBCs which get eliminated by macrophages (can cause Heinz body anemia)
3 causes of Heinz bodies
- Damaged hemoglobin 2. Inherited mutation 3. Chronic liver disease
Hereditary spherocytosis
Congenital abnormality of spectrin in sub-membrane cytoskeleton (supports RBC shape) turning cells to spheres resulting in anemia and splenomegaly
