Hematopoietic System

Hematopoietic System

System responsible for the production of blood cells

Plasma

Liquid part of blood that includes clotting factors

Serum

Plasma without clotting factors (after blood has clotted)

Plasma Percentage

55% of blood, contains water, salts, minerals, and proteins

Buffy Coat Percentage

1% of blood, contains white blood cells and platelets

RBC Percentage

45% of blood, contains red blood cells

Formed Elements

RBCs, platelets, granulocytes, monocytes/macrophages, lymphocytes

Granulocytes

Neutrophils, eosinophils, basophils

Monocytes/Macrophages

Derived from myeloid stem cells, involved in immune defense

Lymphocytes

B and T lymphocytes derived from lymphoid stem cells

Complete Blood Count (CBC)

Test providing info on number and characteristics of blood cells

WBC Differentiation

Percentages of each type of WBC measured in CBC

Multipotential Hematopoietic Stem Cell (Hemocytoblast)

Main stem cell giving rise to all blood cells

Myeloid Progenitor

Produces RBCs, platelets, and some WBCs

Lymphoid Progenitor

Produces NK cells, T cells, and B cells

Hematopoiesis

Formation and development of blood cells from stem cells

Cytokines

Regulatory proteins controlling stem cell proliferation and differentiation

Neutrophils

50–60% of WBCs, first responders to infection

Lymphocytes

20–30% of WBCs, defend through immune response in lymph nodes and spleen

Monocytes and Macrophages

3–8% of WBCs, present antigens to T cells, involved in chronic inflammation

Eosinophils

1–3% of WBCs, increase with allergies, parasites, asthma, release hydrolytic enzymes

Basophils

0.3–0.5% of WBCs, release histamine, anticoagulants, involved in allergic reactions

Thrombocytes

Platelets from megakaryocytes, circulate 8–9 days, form platelet plug

Red Blood Cells (RBCs)

Carry oxygen via hemoglobin; some carry CO2

Hemoglobin

Protein with 4 polypeptide chains, each with globin and heme unit

RBC Development

Erythroblast → Normoblast → Reticulocyte → Mature RBC

RBC Lifespan

120 days (4 months)

HbF

Fetal hemoglobin, strong O2 affinity

HbA

Adult hemoglobin, most common

HbS

Sickle hemoglobin, causes sickled RBCs

Erythropoiesis

Production of RBCs in red bone marrow

Red Bone Marrow Sites

Vertebrae, ribs, sternum, pelvis (in adults)

Yellow Bone Marrow Conversion

Converts back to red with severe blood loss

Erythropoietin

Hormone from kidneys that stimulates RBC production

RBC Count

Total RBCs in 1 mm³ blood

Hemoglobin Test

Measures oxygen-carrying capacity (g/100ml)

Hematocrit

Measures proportion of RBC in plasma volume

Reticulocyte Count

Measures immature RBCs, indicates RBC production rate

RBC Destruction

Occurs in spleen, iron recycled, bilirubin sent to liver

Bilirubin

Product from heme breakdown, used in bile, water soluble when conjugated

Jaundice

Yellowing due to liver not excreting bilirubin properly

Anemia

Deficiency of RBCs or hemoglobin, causing impaired oxygen carrying capacity

Nutritional Deficiency Anemia

Caused by lack of iron, B12, or B9

Iron Deficiency Anemia

Most common anemia due to poor diet or blood loss

Megaloblastic Anemia

Large, immature RBCs due to B12 or B9 deficiency

Pernicious Anemia

B12 deficiency anemia

Folic Acid Deficiency

B9 deficiency anemia

Hemolytic Anemia

RBCs are destroyed faster than they are produced

Sickle Cell Anemia

Sickled RBCs block blood flow under stress

Thalassemia

Defective globin chain synthesis

G6PD Deficiency

Enzyme deficiency causing RBC breakdown under oxidative stress

Aplastic Anemia

Bone marrow suppression by toxins, chemo, or radiation

Polycythemia

Excess RBCs in circulation

Relative Polycythemia

Dehydration leads to low plasma volume and high hematocrit

Primary Polycythemia

Bone marrow disease causing uncontrolled RBC production

Secondary Polycythemia

Hypoxia-driven increase in erythropoietin and RBCs

Polycythemia Manifestations

Splenomegaly, hypertension, venous stasis, increased viscosity

Exogenous Erythropoietin Use

Injections to stimulate RBC production, risk of polycythemia and clots

Neutropenia

Low neutrophil count from autoimmune destruction, drugs, or bone marrow issues

Felty Syndrome

RA + splenomegaly + neutropenia

Neutropenia Symptoms

Malaise, chills, fever, fatigue, weakness

Infectious Mononucleosis

Self-limited disorder with excess WBCs caused by Epstein Barr virus

Mononucleosis Symptoms

Fever, lymphadenopathy, sore throat, splenomegaly

Hemostasis

Process that prevents and stops bleeding

Thrombosis

Excess clotting leading to stroke, MI, PE, or DVT

Bleeding Disorders

Failure to clot properly

Vasoconstriction

Vessel constriction to reduce blood flow after injury

Platelet Plug Formation

vWf binds platelets to site of injury

vWf Factor

Protein from endothelium that helps platelet adhesion

Clotting Factors

Liver-synthesized factors using vitamin K

Clot Retraction

Clot contracts to stabilize

Clot Dissolution

t-PA converts plasminogen to plasmin, digests fibrin

Intrinsic Pathway

Clotting from vessel damage (slow)

Extrinsic Pathway

Clotting from external injury (fast)

Thrombocytosis

Increased platelet function causing clotting

Atherosclerotic Plaques

Promote platelet adherence and endothelial damage

PT/INR Test

Measures clotting time and standardizes results

aPTT/PTT Test

Measures anticoagulant process

Thrombocytopenia

Decreased platelets from production loss, destruction, or sequestration

ITP

Idiopathic thrombocytopenia purpura

TTP

Thrombotic thrombocytopenia purpura

vWf Disease

Low vWf levels causing abnormal bleeding

Vitamin K Deficiency

Inactive clotting factors, abnormal bleeding

Hemophilia A/B

Hereditary clotting factor deficiencies

Petechiae

Pinpoint red-purple spots from platelet deficiency

Purpura

Purple bruising from bleeding under skin

Senile Purpura

Age-related skin thinning and bruising

Hemorrhagic Telangiectasia

Dilated fragile capillaries causing bleeding

Vitamin C Deficiency

Weak collagen and vessel walls

Cushing Disease

Associated with vascular fragility