Human Anatomy and Physiology Blood and hemodynamics

Blood composition Plasma and formed elements Formed elements Erythrocytes, leukocytes, platelets

Blood composition Hematocrit <45% anemia (O2 delivery problems) >45% polycythemia (circulation problem)

Plasma Contents 90% water Protein (albumin acts as a buffer) Fats, amino acids, salts, gases, enzymes, hormones Narrow osmolality range

Erythrocytes Manufactured by erythropoiesis Committed cell: will form a specific cell type Erythroblasts undergo rapid mitosis Reticulocytes enter blood stream (2% of blood)

Erythropoiesis

Erythrocytes Function: gas exchange Oxy- and deoxyhemoglobin

Erythrocytes Destruction (3 - 4 months) Trapped in spleen and destroyed by macrophages Globin is recycled into amino acids Iron is used to make new RBC’s Rest of heme group converted to bilirubin Bilirubin appears in urine and feces

Erythrocyte disorders Athlete’s anemia Thalassemia Sickle-cell anemia Blood doping among athletes

Leukocytes Move through tissues by amoeboid motion The only complete cells Protect against invasion Move out of blood by diapedesis Move through tissues by amoeboid motion Follow chemical trails by chemotaxis

Leukocytes Types Abundance: Never Let Monkeys Eat Bananas Granulocytes: contain cytoplasmic granules Neutrophils, eosinophils basophils Agranulocytes: without cytoplasmic granules Lymphocytes, monocytes Abundance: Never Let Monkeys Eat Bananas

Neutrophils Characteristics Multilobed (3 - 6 lobes) nucleus Twice the size of RBC’s Phagocytose bacteria

Eosinophils Characteristics Bilobed nucleus Course granules stain deep red to crimson Twice the size of RBC’s Release digestive enzymes to kill worms (too large to be phagocytosed)

Basophils Characteristics Course, dark purple, black granules Twice the size of RBC’s Release histamine (inflammatory chemical), attract other WBC’s to the area

Lymphocytes Characteristics Large, dark purple nucleus About the size of RBC’s Act in immune response

Monocytes Characteristics Large, dark purple nucleus Three times the size of RBC’s Leave blood stream acting to phagocytose viruses and bacteria

Platelets Megakaryocytes (bone) rupture through sinusoid capillaries Enucleate, age quickly (10 days) Hemostasis

Hemostasis Phases Vascular spasm Platelet plug formation Coagulation Vasconstriction reduces blood flow Platelet plug formation Platelets swell, and adhere to each other Coagulation Blood transformed from liquid to a gel

Hemostasis Phases Prothrombin activator formed Conversion into thrombin Fibrin seals the hole RBCs and fibrin mesh

Blood typing RBC plasma membranes bear specific glycoproteins recognized by the body Glycoproteins called agglutinogens ABO blood group (A, B, AB or O) O (common), AB (least common)

Blood typing

Rh blood group Rh factor: 8 Rh agglutinogens C, D, E antigens most common Carrying Rh symbolized by + Blood groups reported together (i.e., O+)

Rheology The study of blood flow Viscosity (i.e., polycythemia)

Rheology Flow rate = 1/viscosity

Rheology Flow rate is directly proportional to differences in pressure F ∞ P1 - P2 or (∆P)

Rheology Flow rate is indirectly proportional to vessel length (F = 1/L)

Rheology Flow rate is directly proportional to the fourth power of the radius of the vessel F ∞ r4

Hemodynamics Rate of blood flow highest in smallest cross sectional areas Functional significance Total area Velocity

Blood flow Laminar flow Pulsatile (large vessels) Continuous (small vessels) Pulsatile (large vessels)

Blood flow Turbulent flow Definition (obstruction, sharp turns, high flow rate) Occurs after aortic and pulmonary valves or valves in veins

Compliance Tendency of blood vessel volume to increase as pressure increases C = ∆V/∆P P1=160 mmHg, P2=120 mmHg, V1=5 l/min. V2=3 l/min. C = 0.05 kPa-1 Are veins or arteries more compliant ?

Compliance 8X more blood 3X more elasticity 24X more compliant