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 ThalassemiaSickle-cell anemia

Blood doping among athletes

Leukocytes The only complete cells Protect against invasion Move out of blood by diapedesis

Move through tissues by amoeboid motionFollow chemical trails by chemotaxis

Leukocytes Types

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 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 activatorformed

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

Totalarea

Velocity

Blood flow Laminar flow

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