HematopoiesisHematopoiesis(Blood Cell Formation)

• All blood cells differentiate from a common source, hemocytoblast stem cells in red bone marrow.

AnemiaAnemia• A decrease in the oxygen-carrying

ability of the blood. Caused by:

1) Excessive RBC destruction (hemolysis)

2) Blood loss (acute or chronic)

3) Inadequate RBC production

Hemorrhagic AnemiaHemorrhagic Anemia• Decrease in RBC

number

• Sudden hemorrhage

Hemolytic AnemiaHemolytic Anemia• Decrease in RBC

number

• Lysis of RBCs as a result of bacterial infections

Pernicious AnemiaPernicious Anemia• Decrease in RBC

number

• Lack of Vitamin B12

Aplastic AnemiaAplastic Anemia• Decrease in RBC

number

• Depression or destruction of bone marrow by cancer, radiation, or certain medications

Iron Deficiency AnemiaIron Deficiency Anemia• Inadequate

hemoglobin content in RBCs

• Lack of iron in diet or slow/prolonged bleeding which depletes iron reserves needed to make hemoglobin

Sickle Cell AnemiaSickle Cell Anemia• Abnormal

hemoglobin in RBCs

• Genetic defect leads to abnormal hemoglobin, which becomes sharp and sickle shaped.

PolycythemiaPolycythemia•Excessive or abnormal increase in the number of RBCs

•May result from bone marrow cancer or from living at high altitudes.

LeukemiaLeukemia•Excessive production of abnormal WBCs

•Bone marrow is cancerous and huge numbers of WBCs are turned out rapidly.

Infectious MononucleosisInfectious Mononucleosis•Excessive production of abnormal WBCs

Undesirable ClottingUndesirable Clotting•Thrombus – a clot that develops and persists in an unbroken blood vessel

•Embolus – if a thrombus breaks away from the vessel wall and floats freely in the blood stream

Bleeding DisordersBleeding Disorders•Thrombocytopenia results from an insufficient number of circulating platelets. Even normal movement cause spontaneous bleeding from small blood vessels.

•Hemophilia applies to several different hereditary bleeding disorders that result from a lack of any of the factors needed for clotting.

Developmental AspectsDevelopmental Aspects•Before birth there are many sites of blood cell formation including the liver and spleen among others. At seven months red marrow takes over and remains so throughout life.

•Fetal hand grasp

Developmental AspectsDevelopmental Aspects•Fetal hemoglobin has a greater ability to pick up oxygen since fetal blood is less oxygen rich than that of the mother. After birth these are replaced with RBCs with more typical hemoglobin.

•newborn

Developmental AspectsDevelopmental Aspects•If the fetal RBCs are destroyed at such a rapid rate that the immature liver cannot rid the body of hemoglobin breakdown products in the bile fast enough, the infant becomes jaundiced.

•Jaundiced baby