Human Anatomy and Physiology

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Human Anatomy and Physiology

• Blood and hemodynamics

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Blood composition

• Plasma and formed elements
• Formed elements
• Erythrocytes, leukocytes, platelets

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Blood composition

• Hematocrit
• lt45 anemia (O2 delivery problems)
• gt45 polycythemia (circulation problem)

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Plasma

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

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Erythrocytes

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

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Erythropoiesis
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Erythrocytes

• Function gas exchange

Oxy- and deoxyhemoglobin
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Erythrocytes

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

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Erythrocyte disorders

• Athletes anemia
• Thalassemia

Sickle-cell anemia
Blood doping among athletes
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Leukocytes

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

Move through tissues by amoeboid motion
Follow chemical trails by chemotaxis
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Leukocytes

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

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Neutrophils

• Characteristics
• Multilobed (3 - 6 lobes) nucleus
• Twice the size of RBCs
• Phagocytose bacteria

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Eosinophils

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

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Basophils

• Characteristics
• Course, dark purple, black granules
• Twice the size of RBCs
• Release histamine (inflammatory chemical),
  attract other WBCs to the area

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Lymphocytes

• Characteristics
• Large, dark purple nucleus
• About the size of RBCs
• Act in immune response

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Monocytes

• Characteristics
• Large, dark purple nucleus
• Three times the size of RBCs
• Leave blood stream acting to phagocytose viruses
  and bacteria

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Platelets

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

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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

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Hemostasis

• Phases
• Prothrombin activatorformed
• Conversion into thrombin
• Fibrin seals the hole

RBCs and fibrin mesh
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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)

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Blood typing
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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)

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Rheology

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

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Rheology

• Flow rate 1/viscosity

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Rheology

• Flow rate is directly proportional to differences
  in pressure
• F 8 P1 - P2 or (?P)

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Rheology

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

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Rheology

• Flow rate is directly proportional to the fourth
  power of the radius of the vessel
• F 8 r4

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Hemodynamics

• Rate of blood flow highest in smallest cross
  sectional areas
• Functional significance

Total area
Velocity
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Blood flow

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

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Blood flow

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

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Compliance

• Tendency of blood vessel volume to increase as
  pressure increases
• C ?V/?P
• P1160 mmHg, P2120 mmHg, V15 l/min. V23 l/min.
• C 0.05 kPa-1
• Are veins or arteries more compliant ?

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