Pt 2 of Blood (RBCs) Flashcards
What is hematopoiesis?
The production of formed elements
- WBC and RBCs
Where does hematopoiesis take place?
In the bone marrow in a network of reticular CT
What is a Hemocytoblast?
A hematopoietic stem cell
–> The stem cell for all formed elements, and then cells become committed to a particular pathway
What is Erythropoiesis?
The formation of RBCs
What are the steps of Erythropoiesis?
- Stem cell (Hematopoietic stem cell; hemocytoblast)
- Committed cell (Proerythroblast)
- Developmental Pathway
Phase 1 - Ribosome synthesis (Basophilic erythroblast)
Phase 2 - Hemoglobin accumulation (Orthochromatic erythroblasts)
Phase 3 - Ejection of nucleus (Orthochromatic erythroblasts to a Reticulocyte) - Erythrocyte
Approximately how long does the production of RBCs take?
about 15 days
What is the difference between a reticulocyte and an RBC?
A reticulocyte is a slightly immature RBC. (in some anemias, Reticulocytes are increasingly made and are sent to the bloodstream while still immature)
What can a reticulocyte count tell you? (3)
- Provides info on the bone marrows ability to produce new RBCs
- Helps distinguish different causes of anemia
- Helps monitor bone marrow response and return of normal marrow function
Too few RBCs
Anemia
Too many RBCs
Polycythemia resulting in elevated blood viscosity
What is monitored and acts as a signal in hypoxia?
The level of O2 transport
How does the body regulate blood oxygen levels in hypoxia?
Once the body realizes smt might be wrong, the kidney (or/and liver) will release erythropoietin(EPO). This stimulates red bone marrow which increases the RBC count (starts with reticulocytes first then they mature). This allows for more O2 carrying ability of blood.
EPO stands for?
Erythropoietin
What is Erythropoietin? (1-2 days)
A glycoprotein produced in the kidneys. Stimulates RBC production.
–> important when immune system is at a low
It helps enhance maturation rate of committed RBC precursors. (more is released if–high altitude or pneumonia, increased demand, hemorrhage, insufficient Hb/RBC)
In renal failure patients what is an additional problem they face?
lack of EPO - RBCs can be 50% of normal :0. This can be helped by recombinant EPO
EPO in athletes?
Known to improve exercise performance by increasing oxygen blood transport, causing higher maximum oxygen uptake. (HEMATOCRIT from 45% to 65%)
But, Viscosity and dehydration levels rise and this can cause clotting, strokes, heart failure
What is the effect of testosterone on renal EPO production?
Testosterone stimulates the production of erythropoietin (increases iron levels.)
What is a reason why women tend to have a lower hematocrit than men?
Lower iron levels, also lower testosterone levels.
Glycoprotein
Involved in Immunity. Allows WBCs to move around the body, initiate immune responses and identify other cells
Hypoxia
Lack of Oxygen, a state in which oxygen is NOT available in sufficient amounts.
What are Erythropoiesis dietary requirements?
- Nutrients
–> Iron: 65% found in hemoglobin, the rest in liver, spleen, bone marrow.
–> B12 vitamins and folic acid: necessary for DNA synthesis for rapidly dividing cells such as developing RBCs
What is the function of Iron
helps make hemoglobin. Helps carry oxygen throughout the body
What is a fun fact about iron?
Free iron ions are toxic –> they have the ability to generate REACTIVE oxygen species. Disrupts normal cell function
What is the function of B12 and Folic acid?
B12 – Helps keep your bodys blood and nerve cells healthy
Folic Acid – produce healthy RBCs and is critical during periods of rapid growth (eg. pregnancy and fetal development)
What is the life cycle of Red Blood cells?
- Low O2 levels in blood stimulate kidneys to produce erythropoietin
- EPO levels rise in blood
- EPO and necessary raw materials in blood promote EPO in Red bone marrow
- New Erythrocytes enter bloodstream; function about 120 days
- Aged and damaged RBCs are engulfed by macrophages of spleen, liver, and bone marrow; the hemoglobin is broken down
- Raw materials are made available in blood for erythrocyte synthesis
How long is the lifespan of RBCs?
100-120 days
What is the Spleen considered?
RBC graveyard
In the spleen, what engulfs and breaksdown dying RBCs?
Macrophages
RBC breakdown
heme, iron and globin are separated
–>heme becomes yellow pigment BILIRUBIN – liver secretes this in bile into intestines -> becomes pigment UROBILINOGEN (transformed then into brown pigment – STERCOBILIN - feces)
–> globin is metabolized into amino acids - into circulation
ANEMIA (what is it, symptoms, 3 causes)
Blood has abnormally low O2-carrying capacity that is too low to support normal metabolism
Symptoms: Fatigue, pallor, dyspnea (shortness of breath), chills
Causes
1. Blood loss
2. Not enough RBCs are produced
3. Too many RBCs being destroyed
Anemias – Name the disorder!
Blood loss (1), Insufficient # of RBCs produced (4), RBCs Destruction (2)
- Hemorrhagic anemia
- a) Iron deficiency anemia
b) Pernicious anemia - autoimmune
disease
c) Renal anemia - lack of EPO
d) Aplastic anemia - Destruction or
inhibition of Red bone marrow - a) Thalassemia - one globin chain is
absent or faulty
b) Sickle-cell anemia - Mutated
hemoglobin
POLYCYTHEMIA
Abnormal excess of RBCs - increase blood viscosity causing Sluggish blood flow
