PATHO: ch 13 - The Hematopoietic and Lymphatic Systems

Blood

A fluid connective tissue

Blood is composed of

Plasma and formed elements (3 formed elements)

What are the 3 formed elements

1. Erythrocytes (red blood cells)

2. Leukocytes (white blood cells)

3. Platelets

Purpose of Erythrocytes (RBCs)

Transport oxygen

What formed element is the most numerous in terms of cells?

Erythrocytes

How long do Erythrocytes survive

4 months (120 days)

Reticulocytes

Immature erythrocytes

How do Reticulocytes become mature erythrocytes

Mature in the bloodstream

What is Hemoglobin

Oxygen-carrying protein formed by the developing red cell

Hemoglobin is composed of how many subunits?

4 subunits (each consisting of heme and globin)

Heme contains what kind of atom?

an iron atom

Hematopoiesis

Formation and development of blood cells

What substances are necessary for hematopoiesis?

1. Protein

2. Vitamin B12

3. Folic Acid

4. Iron

Reticulocytes become mature…

Erythrocytes in the bloodstream

What is erythropoiesis?

The process of the body producing new red blood cells

What hormone stimulates erythropoiesis?

Erythropoietin (EPO)

What happens to worn out red blood cells?

They are removed in the spleen

How is hemoglobin degraded?

• Globin chain are broken down and used to make other proteins

• Iron is extracted and reused to make new hemoglobin

• Heme degraded and excreted as bile by liver

Anemia

Reduction in red blood cells or subnormal level of hemoglobin

What are considered raw materials?

• Iron

• Vitamin B12

• Folic acid

Etiologic classifications of anemia

1. Insufficient raw materials

2. Inability to deliver adequate red cells into circulation

3. External blood loss (hemorrhage)

4. Shortened survival of red blood cells in circulation

What would cause the inability to deliver adequate red blood cells into circulation?

1. Marrow damage or destruction (aplastic anemia)

2. Replacement of marrow by foreign or abnormal cells

Why is it bad to have insufficient raw materials

Inadequate production of red blood cells

Normocytic anemia

Normal size and appearance

Macrocytic (megaloblastic) anemia

Cells are larger than normal

What causes macrocytic (megaloblastic) anemia

• Folic acid deficiency

• Vitamin B12 deficiency

Microcytic anemia

Cells are smaller than normal

What causes microcytic anemia

Iron deficiency

Normochromic anemia

normal hemoglobin content

Hypochromic anemia

Reduced hemoglobin content

What causes hypochromic anemia

Iron deficiency

Hyperchromic anemia

Increased hemoglobin content

Hypochromic microcytic anemia

smaller than normal and reduced hemoglobin content

What causes hypochromic microcytic anemia

Iron deficiency

Signs and symptoms of anemia

• Fatigue

• Pallor (light/gray skin)

  • Especially on conjunctiva (thin, mucous membrane lining inner surface of eyelids)

• Dyspnea

• Headache

• Tachycardia (abnormally fast heart rate)

• Weakness

• Lethargy

• Exercise intolerant

Diagnostic evaluations of anemia

1. Complete blood count (CBC)

2. Blood smear

3. Reticulocytes count

4. Lab tests

5. Evaluation of blood loss from gastrointestinal tract

6. Bone marrow study

Purpose of a complete blood count (CBC)

Assesses the degree of anemia, leukopenia, and thrombocytopenia

Purpose of a blood smear

Determine if normocytic, macrocytic, or hypochromic microcytic

Purpose of Reticulocyte count

assess rate of production of new red cells

If bone marrow is functioning properly, will more or less Reticulocytes become released into the circulation?

More Reticulocytes will be released

What is iron-deficiency anemia?

• Iron absorbed from duodenum, transferrin, stored as ferritin

• Most common type of anemia

• Blood lacks sufficient amount of iron to produce hemoglobin

Pathogenesis of iron-deficiency anemia

• Inadequate iron intake in diet

  • Impaired iron absorption

• Inadequate reutilization of iron present in red cells due to chronic blood loss

Pathogenesis of iron-deficiency anemia in INFANTS

Occurs during periods of rapid growth

Pathogenesis of iron-deficiency anemia in ADOLESCENTS

Inadequate diet

How do cells of iron-deficiency anemia appear?

Hypochromic microcytic anemia (small cells and small hg content)

Iron-deficiency anemia laboratory profile

• Low serum ferritin and serum iron

• Higher than normal serum iron-binding protein

• Lower than normal percent iron saturation

Treatment of Iron-deficiency anemia

• Primary focus: learn cause of anemia

• Administer supplementary iron

Examples of iron-deficiency anemia

• Infant w/ history of poor diet

• Adults: chronic blood loss from GIT

• Women: excessive menstrual blood loss

What contains Vitamin B12?

Meat, liver, foods rich in animal protein

What contains folic acid?

Green leafy vegetables, animal protein foods

BOTH vitamin B12 and folic acid are required for…

Normal hematopoiesis and maturation of other cells (specifically DNA synthesis)

Vitamin B12 is needed for structural and functional integrity of the ________ system

Nervous

(Deficiency may lead to neurological disturbances)

Consequences of vitamin B12 or folic acid deficiency

• Cell’s can’t divide

• Enlarged RBCs (macrocytic, normochromic anemia)

• Abnormal developmen of white cell precursors and megakaryocytes: leukopenia, thrombocytopenia

What is pernicious anemia?

• Autoimmune condition

• Vitamin B12 can’t be absorbed

  • Combines with gastric juice in stomach

• Leads to a vitamin B12 deficiency

What is the cause of Pernicious Anemia

• Autoimmune chronic gastritis

  • Gastric mucosal atrophy (thin stomach lining)

• Gastric resection and bypass

  • Lack of intrinsic factor

• Distal bowel resection or disease

  • Impaired absorption of Vitmain B12

Pernicious Anemia symptoms

• Paresthesia (pins and needles)

• Weakness

• Headaches

• Irritability

• Altered vision

• Lightheadedness

• Tinnitus (ears ringing)

• Maybe some neuropathy

Pernicious Anemia treatment

Monthly intramuscular injections of vitamin B12 during person’s ENTIRE lifetime

What is Folic Acid Deficiency Anemia?

Body has very limited stores which rapidly become depleted if not replenished continually

• Vitamin B9 deficiency

What causes Folic Acid Deficiency Anemia?

• Inadequate diet: frequent in chronic alcoholics

• Poor absorption caused by intestinal disease

• Occasionally in pregnancy - increased demand for folic acid

How is Folic Acid Deficiency Anemia diagnosed?

Presence of low serum folate

Treatment for Folic Acid Deficiency Anemia

Supplementary folic acid

What conditions depress bone marrow function (3)?

1. Bone marrow replacement anemia

2. Anemia of chronic disease

3. Aplastic anemia

What is bone marrow replacement anemia

Marrow infiltrated by tumor or replaced by fibrous tissue

What is anemia of chronic disease

Mild suppression of bone marrow function

• Chronic infection

• Some malignant tumors

What is aplastic anemia

Condition resulting from an insult to stem cells in the bone marrow resulting in destruction or inhibition of red bone marrow

What is reduced due to aplastic anemia

RBC, WBC, and platelet production is reduced

What causes aplastic anemia

• Radiation

• Chemotherapy

• Chemicals

• Autoantibodies

ALL kill stem cells

Treatment of aplastic anemia

• Blood and platelet transfusions

• Immunosuppressive drugs

• Bone marrow transplant

• In MANY cases, no specific treatment

What are hereditary hemolytic anemias?

• Genetic abnormality prevent normal survival of RBCs

• RBCs are destroyed prematurely

What causes hereditary hemolytic anemias

• Hemoglobin abnormalities (most cases)

• RBC enzyme disorders

• Glucose-6-phosphates dehydrogenase deficiency

What is sickle-cell anemia

• Defective gene codes for abnormal hemoglobin

• RBCs become sickle shaped in low-oxygen situations

What causes sickle-cell anemia

Sickle shapes RBCs

What do sickle shaped RBCs do

• Obstruct capillary flow

• Leads to tissue hypoxia

• Leads to obstruction and infarction

What populations is sickle-cell anemia prevalent in

Blacks of African origin

Sickle-cell anemia symptoms

• Recurrent infections

• Abrupt onset of pain curing crisis

  • Pain can affect any body part

  • Often involves abdomen, bones, joints, soft tissue

• Jaundice

Sickle-cell anemia treatment

• Oxygen administration

• IV fluids

• Narcotic analgesics

• Hydroxyurea stimulates bone marrow to produce hemoglobin

• CRISPR gene therapy

  • Blood stem cells start producing HBF

What is Thalassemias

Absent or fault globin chain synthesiS

What causes Thalassemias

• RBCs are thin, delicate, deficient in hemoglobin

• Microcytic, hypochromic anemia (small RBCs and reduced RBC count)

What populations are Thalassemias most prevalent in?

Those of Mediterranean descent (Greek and Italian ancestry)

What are acquired hemolytic anemias?

Normal red cells but unable to survive due to “hostile environment”

What causes acquired hemolytic anemias

1. Autoimmune Hemolytic Anemia

2. Destruction of red cells by mechanical trauma

What is autoimmune hemolytic anemia (type of acquired hemolytic anemia)

RBCs attacked an destroyed by antibodies

What is the destruction fo red cells by mechanical trauma (type of acquired hemolytic anemia)

• Passing through enlarged spleen (splenomegaly)

• In contact with some part of artificial heart vale

What is Polycythemia

Increased RBC concentration in blood

• Result of increased blood viscosity

• Increased tendency to thromboses (clotting)

Polycythemia symptoms

Headaches, dyspnea, irritability, mental sluggishness, dizziness, syncope, night sweats, weight loss, splenomegaly, clubbing of the fingers

What is polycythemia versus (primary polycythemia)

• Overproduction of red cells, white cells, and platelets

• Malignant RBCs do not require erythropoietin for growth

Primary polycythemia treatment

Marrow suppressed by drugs or radiation

What is secondary polycythemia

Increased erythropoietin production (RBCs)

What causes secondary polycythemia

• Chronic lung disease

• Congenital heart disease

• Heavy smoking

• Increased erythropoietin production by renal tumor

• Blood doping (exogenous EPO)

  • Commonly used by athletes

  • Boosts RBC count

    • Improves oxygen to muscles

    • Enhances endurance

Secondary polycythemia treatment

Periodic removal of excess blood