1. Blood = specialized connective tissue
Cells = 45% of blood
Erythrocytes (red blood cells, RBCs)
Leukocytes (white blood cells, WBCs)
Platelets (cell fragments)
Plasma = 55% of blood
- extracellular matrix of blood;
5-6 Liters total blood volume in adult

2. Functions of Blood
Gaseous transport – RBCs carry oxygen and carbon dioxide
Transport of metabolites and regulatory molecules (hormones)
Homeostatic regulation of body temperature, osmotic balance
Transport of cells and antibodies for defense and immunity

3. Erythrocytes (red blood cells)
Most numerous blood cells
Transport O2 and CO2 via
hemoglobin
No nucleus, mitochondria, ER,
ribosomes in mature RBCs.
All expelled during development.
120-day life span; destroyed by macrophages in spleen and bone marrow.
- The only cell in blood stream that
remains in blood stream

4. Erythrocytes
Biconcave disk shape provides large surface area relative to volume; good for gas exchange
Shape maintained by bendable cytoskeleton
Normal adult RBC
Sickle cell anemia

5. Red Blood Cell Physiology
Typical RBC count:
men: – 6.2 million/mm3
women: 4.2 – 5.4 million/mm3
Hematocrit - % of whole blood volume that is RBCs
men: 42 – 52%
women: 37 – 48%
No mitochondria.
Energy needs met by anaerobic fermentation

6. Erythrocyte Membrane Organization
Antiporter: Cl- in;HCO3- out

7. Structure of Hemoglobin (HbA)
Typical Hb concentrations:
men: g/dL
women: 12 – 16 g/dL

8. The Life and Death of
Eryhrocytes

9. Correction of Hypoxemia by a Negative Feedback Loop

10. Sickle Cell Anemia (HbS)
Inherited
Point mutation in gene for Hb b-chain
Deoxygenated HbS  rigid, fragile RBCs  anemia
Increases blood viscosity

11. Relative Sizes of Blood Cells Compared to RBCs (7-8 mm diameter)

12. Leukocytes (White Blood Cells)
Granulocytes
Agranulocytes
Lymphocyte
Neutrophil
Eosinophil
Basophil
Monocyte
Numerous secretory vesicles in cytoplasm
- Nucleus has 2 or more lobes
Do NOT have abundant secretory vesicles
Single-lobed nucleus

13. Neutrophils: 60-70% of circulating leukocytes
Nucleus has 3-5 lobes
Phagocytosis & destruction of bacteria
Motile: exit the blood stream early
in response to bacterial infections.
Granules contain lysozyme and other antimicrobial enzymes, collagenase plus others.
In females, the nucleus has a drumstick (Barr body), contains the condensed, inactivated second X chromosome.

14. Eosinophils: 2-4% of circulating leukocytes
bi-lobed nucleus
Eosinophilic granules (red/pink)
contain histaminase
Allergic & inflammatory reactions
and parasitic infections
Counteract the effects of basophils in allergic reactions
Often found at sites of chronic inflammation, commonly in respiratory or digestives tracts

15. Basophils: <1% of circulating leukocytes
Bilobed nucleus
Basophilic granules (blue/black)
obscure the nucleus
Secrete histamine (vasodilation)
and heparin (anti-coagulant)
Involved in allergic and inflammatory reactions

16. Lymphocytes: 20-25% of circulating leukoctyes
Agranulocyte
Variable in size, 6-18 mm in diameter
Single, round, heterochromatic nucleus
Function in immunity
2 classes, indistinguishable morphologically
B cells: produce antibodies
T cells: mature in thymus, cell-mediated immune response

17. Monocytes: 3-8% of circulating leukocytes
Agranulocyte
Largest circulating WBC
Large indented nucleus
Stay in circulation a few days
then migrate into the tissues and differentiate into macrophages
As macrophages, phagocytize and destroy dead cells

18. Platelets (Thrombocytes)
Anucleated cell fragments
2 mm diameter
10-day life span
Main function: blood clotting
Produced by megakaryocytes
in bone marrow: bud off
cytoplasm to form platelets.
Bone marrow capillary
Platelets

19. Differential White Blood Cell Count:
Neutrophils >
Lymphocytes >
Monocytes >
Eosinophils >
Basophils
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