Blood• Cells in the body are fixed within tissues and

must have nutrients and oxygen brought to them and waste removed.

• The blood is classified as a fluid matrix connective tissue– The cells and cell fragments are the formed

elements and the matrix of the blood is fluid (plasma).

– Formed elements make up about 45% and plasma 55% of the total blood volume.

– Blood volume: 4-5 L in females, 5-6 L in males.

Blood Functions• Distribution and transportation

– Respiration

– Nutritive

– Excretory

– Negative Aspects

• Regulation and Maintenance

– Hormonal regulation

– Thermoregulation

– pH / acid-base balance

– Fluid volume

• Protection

– Clotting

– Immunity

Major Components of the Circulatory System

• Two divisions: Cardiovascular and lymphatic systems.– Cardiovascular: Heart, blood vessels

• Heart• Vessels

– Lymphatic: lymphatic vessels and lymphoid tissues in spleen, thymus, tonsils, and lymph nodes.

• The fluid portion of the blood (plasma) passes through the capillary walls under hydrostatic pressure (interstitial fluid).

• Some interstitial fluid returns to the blood and some enters the lymphatic system

– Lymphatic vessels carry interstitial fluid now called lymph back to the venous blood.

– Lymph nodes along the way filter and cleanse the blood before it is returned.

Erythrocytes• Structure

– Biconcave, anucleate– 4.8 million/mm3 in

women. – 5.4 million/mm3 in men.– 7.5 um in diameter

• Components– Hemoglobin– Lipids, ATP, carbonic

anhydrase• Function

– Transport oxygen from lungs to tissues and carbon dioxide from tissues to lungs

Hemoglobin

• Consists of: – 4 globin molecules: 2 alpha and 2 beta chains

• 280 million per RBC.• Transport carbon dioxide (carbonic anhydrase involved), nitric

oxide.

– 4 heme molecules: Transport oxygen• Iron is required for oxygen transport

Erythropoiesis

• Production of red blood cells

– Stem cells proerythroblasts early erythroblasts intermediate late reticulocytes

• Erythropoietin: Hormone to stimulate RBC production

Hemolytic Anemia

Anemias • Result of either a decrease in hemoglobin / RBC or in the

number of RBCs.

• Symptoms: pale, lethargic, shortness of breath, tired.

• Aplastic anemia: inability of red bone marrow to produce RBCs

• caused by: damage to Red bone marrow, Iron of Folate deficiency

• Pernicious anemia - Vitman B12 deficiency

• Hemorhagic anemia - results from loss of blood

• Hemolytic anemia - erythrocytes rupture or are destroyed at an increased rate.

• Thalasemia - defective hemoglobin production

Malaria

Sickle cell anemia

Formed Elements• Red blood cells (erythrocytes)• White blood cells (leukocytes)

– Granulocytes• Neutrophils

• Eosinophils

• Basophils

– Agranulocytes • Lymphocytes

• Monocytes

• Platelets (thrombocytes)

Production of Formed Elements

• Hematopoiesis or hemopoiesis: Process of blood cell production

• Stem cells: All formed elements derived from single population– Proerythroblasts: Develop into red blood cells– Myeloblasts: Develop into basophils,

neutrophils, eosinophils– Lymphoblasts: Develop into lymphocytes– Monoblasts: Develop into monocytes– Megakaryoblasts: Develop into platelets

Hematopoiesis

Neutrophil

• Appearance– 2-5 lobes – 10-12 um– 54-62% of white cells

• Characteristics– Fights bacterial and

fungal infections– Contains peroxidases and

defensins– Numbers increase with

meningitis and appendicitis

Eosinophil

• Appearance– Bilobed nucleus– Red granules– 11-14 um– 1-3% of white blood cells

• Characteristics– Fights parasitic infections.– Releases anti-

inflammatory chemicals.– Secretes enzymes that

break down clots.

Basophils

• Appearance– Two indistinct lobes– Blue-purple granules– 10-12 um– Less than 1% of WBC

• Characteristics– Release histamine– Chemoattractant for other

WBCs– Releases heparin to

prevent clots.Basophil Eosinophil

Monocyte

• Apearance

– Nucleus round, kidney or horseshoe shaped

– 12-20 um

– 3-9 % of WBC

• Characteristics

– Transforms into macrophages

Lymphocyte

• Appearance– Round nucleus– 6-14 um– 25-33% of WBC

• Characteristics– Found in lymphoid tissue– Provides specific immune

response• T - lymphocytes

• B - lymphocytes

Leukocytes

Hemostasis

• Arrest of bleeding• Events preventing excessive blood loss

– Vascular spasm: Vasoconstriction of damaged blood vessels

– Platelet plug formation – Coagulation or blood clotting

Thrombocytes

• Cell fragments pinched off from megakaryocytes in red bone marrow

• Important in preventing blood loss

– Platelet plugs

– Promoting formation and contraction of clots

Platelet Plug Formation

Coagulation

• Stages

– Activation of prothrombinase

– Conversion of prothrombin to thrombin

– Conversion of fibrinogen to fibrin

• Pathways

– Extrinsic

– Intrinsic

Clot Formation

Fibrinolysis

• Clot dissolved by activity of plasmin, an enzyme which hydrolyzes fibrin

Blood Grouping

• Determined by antigens (agglutinogens) on surface of RBCs

• Antibodies (agglutinins) can bind to RBC antigens, resulting in agglutination (clumping) or hemolysis (rupture) of RBCs

• Groups– ABO and Rh

ABO Blood Groups

Agglutination Reaction

Rh Blood Group

• First studied in rhesus monkeys• Types

– Rh positive: Have these antigens present on surface of RBCs

– Rh negative: Do not have these antigens present

• Hemolytic disease of the newborn (HDN)– Mother produces anti-Rh antibodies that cross

placenta and cause agglutination and hemolysis of fetal RBCs

Erythroblastosis Fetalis

Diagnostic Blood Tests

• Type and crossmatch

• Complete blood count

– Red blood count

– Hemoglobin measurement

– Hematocrit measurement

• White blood count

• Differential white blood count

• Clotting

Blood Disorders

• Erythrocytosis: RBC overabundance

• Anemia: Deficiency of hemoglobin

– Iron-deficiency

– Pernicious

– Hemorrhagic

– Hemolytic

– Sickle-cell

• Hemophilia

• Thrombocytopenia

• Leukemia

• Septicemia

• Malaria

• Infectious mononucleosis

• Hepatitis