Hematopoiesis

Blood Cell Production

The formation of blood or all types of blood cells in the living body.

in red bone marrow in lymph tissue

Hematopoiesis -

erythrocyte

Erythropoiesis - The formation or production of red blood cells only.

Red blood cellor

erythrocyte

Note the loss of the nucleus

Your baseline production of red blood cells represents about 20% of your total capacity and is the amount of production that normally occurs just to keep you healthy.

Facts:1. 25 trillion r.b.c. per person2. r.b.c. live ~120 days

What are we trying to find?Question:

Answer: r.b.c./sec (r.b.c. per second)

So, how many red blood cells die and must be replaced each second in your body?

How can this be done?

That’s right ladies and gentlemen. You guessed it!!

It’s a Math Problem!!!Yeah!!!!

Additionally needed facts:(things you already know)

3. 1 day = 24 hours4. 1 hour = 60 minutes5. 1 minute = 60 seconds

Let’s begin!!

25 trillion = 25,000,000,000,000 = 2.5 x 1013

1 2 3 4 5 6 7 8 9 10 11 12 13

How can this number be converted to scientific notation?

2.5 x 1013 r.b.c. x

120 days 1 day x

24 hrs 1 hr x

60 min1 min =

60 sec

Now remember your basic algebra!(We called it “conversion factor” math in

Chemistry!)2.5 x 1013 r.b.c. x

120 days 1 day x

24 hrs 1 hr x

60 min1 min =

60 sec2.4 x 106 r.b.c.

or2,400,000 r.b.c.

or2.4 million r.b.c.

After birth, erythropoiesis takes place in the red bone marrow in the ends of some long bones such as the femur and humerus, and in the red marrow of the ribs, vertebrae, sternum, pelvic girdle, and portions of the skull.

The need for new red blood cell production is monitored by receptor sites for blood oxygen concentration located in the kidneys (and some in the liver).

Erythropoietin targets the red bone marrow and stimulates the production of red blood cells. The more hormone, the more red blood cells made. The production of red blood cells will continue until the production of erythropoietin stops.

Any drop in the oxygen content of the blood will cause the kidney to secrete an enzyme that acts on a non-nutrient plasma protein to for a key hormone called erythropoietin.

1. Severe blood loss – greater than 20% of blood volume. This results in fewer r.b.c. to carry oxygen. A “normal” cell count (hematocrit) can be restored in 3 to 4 weeks.2. Anemia – this is a deficiency in the oxygen-carrying component of the blood, measured in the unit volume concentrations of hemoglobin, red blood cell volume, or red blood cell number.

Causes of prolonged oxygen depletion in blood are:

(reasons for erythropoietin to be produced)

Over 400 different types of anemia are known. Most are rare, all are important so here they all are:

Here are a few of the more common and important:

Just Kidding!!

2. Aplastic anemia – A form of anemia in which the capacity of the bone marrow to generate red blood cells is defective, caused by bone marrow disease or exposure to toxic agents, such as radiation, industrial chemicals, or drugs (such as chemotherapy drugs).

Iron deficiency anemia – A form of hypochromic anemia due to a lack of sufficient iron in one’s diet.hemorrhagic anemia – A form of hypochromic anemia due to a loss of iron from chronic bleeding.

1. Hypochromic anemia – A form of anemia characterized by a decrease in the concentration of corpuscular (r.b.c.) hemoglobin.

3. Megaloblastic anemia – A form of anemia characterized by many large, immature and dysfunctional erythrocytes (megaloblasts) resulting from a deficiency of vitamin B12 and/or folic acid.

Pernicious anemia – A type of anemia caused when antibodies are directed against parietal cells in the gastric glands of the stomach which produce intrinsic factor. Intrinsic factor is required for vitamin B12 absorption, so impaired absorption of vitamin B12 can result. This is more commonly found in older adults.

4. Hemolytic anemia – a form of anemia resulting from the destruction of red blood cells due to abnormally high fragility caused by certain infectious agents and in certain inherited blood disorders.

Sickle cell anemia – A chronic, often fatal inherited anemia resulting in abnormal hemoglobin which causes characteristic crescent-shaped red blood cells that can easily rupture.

Thalassemia (Cooley’s anemia) – A genetic defect that results in synthesis of an abnormal hemoglobin molecule. The blood cells are vulnerable to mechanical injury and die easily.

Causes of prolonged oxygen depletion in blood continued:

(reasons for erythropoietin to be produced)

1. Severe blood loss2. Anemia

3. Clogging of blood vessels – this reduces the blood flow to areas of the body and cuts the amount of oxygen per unit time.

Reviewing the first two:

Continued:

4. Reduction in atmospheric oxygen – moving to a high altitude region produces an increase in red blood cell production because there is less oxygen in the air. This is a form of natural blood “doping”.

Artificial blood doping can be achieved by taking drugs that stimulate red blood cell production and are currently banned by all major sporting organizations.

Causes of prolonged oxygen depletion in blood are:

(reasons for erythropoietin to be produced)

In summary:

1. Severe blood loss2. Anemia3. Clogging of blood vessels4. Reduction in atmospheric oxygen