Blood = specialized connective Blood = specialized connective tissuetissue

Cells = 45% of bloodCells = 45% of blood– Erythrocytes (red blood cells, RBCs)Erythrocytes (red blood cells, RBCs)– Leukocytes (white blood cells, WBCs)Leukocytes (white blood cells, WBCs)– Platelets (cell fragments)Platelets (cell fragments)

Plasma = 55% of bloodPlasma = 55% of blood

- extracellular matrix of blood;- extracellular matrix of blood;

5-6 Liters total blood volume in adult 5-6 Liters total blood volume in adult

Functions of BloodFunctions of Blood

Gaseous transport – RBCs carry Gaseous transport – RBCs carry oxygen and carbon dioxideoxygen and carbon dioxide

Transport of metabolites and Transport of metabolites and regulatory molecules (hormones)regulatory molecules (hormones)

Homeostatic regulation of body Homeostatic regulation of body temperature, osmotic balancetemperature, osmotic balance

Transport of cells and antibodies for Transport of cells and antibodies for defense and immunitydefense and immunity

Erythrocytes (red blood cells)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

ErythrocytesErythrocytes

Biconcave disk shape provides large Biconcave disk shape provides large surface area relative to volume; good for surface area relative to volume; good for gas exchangegas exchange

Shape maintained by bendable Shape maintained by bendable cytoskeletoncytoskeleton

Normal adult RBC

Sickle cell anemia

No mitochondria.Energy needs met by anaerobic fermentation

Red Blood Cell Physiology

Hematocrit - % of whole blood volume that is RBCs

men: 42 – 52%women: 37 – 48%

Typical RBC count:men: 4.6 – 6.2 million/mm3

women: 4.2 – 5.4 million/mm3

Erythrocyte Membrane Organization

Antiporter: Cl- in;HCO3- out

Structure of Hemoglobin (HbA)

Typical Hb concentrations:

men: 13 - 18 g/dLwomen: 12 – 16 g/dL

The Life and Death ofEryhrocytes

Correction of Hypoxemia by a Negative Feedback Loop

Sickle Cell Anemia (HbS)Inherited

Point mutation in gene for Hb -chain

Deoxygenated HbS rigid, fragile RBCs anemia

Increases blood viscosity

RelativeRelative Sizes of Blood Cells Compared Sizes of Blood Cells Compared to RBCs (7-8 to RBCs (7-8 m diameter)m diameter)

Leukocytes (White Blood Leukocytes (White Blood Cells)Cells)

Neutrophil Eosinophil Basophil Monocyte Lymphocyte

Granulocytes Agranulocytes

- Numerous secretory vesicles in Numerous secretory vesicles in cytoplasmcytoplasm

- Nucleus has 2 or more lobes- Nucleus has 2 or more lobes

- Do NOT have Do NOT have abundant abundant secretory vesiclessecretory vesicles

- Single-lobed Single-lobed nucleusnucleus

Neutrophils: 60-70% of circulating Neutrophils: 60-70% of circulating leukocytesleukocytes

Nucleus has 3-5 lobesNucleus has 3-5 lobes

Phagocytosis & destruction of bacteriaPhagocytosis & destruction of bacteria

Motile: exit the blood stream early Motile: exit the blood stream early in response to bacterial infections.in response to bacterial infections.

Granules contain lysozyme and other antimicrobial Granules contain lysozyme and other antimicrobial enzymes, collagenase plus others.enzymes, collagenase plus others.

In females, the nucleus has a drumstick (Barr body), In females, the nucleus has a drumstick (Barr body), contains the condensed, inactivated second X contains the condensed, inactivated second X chromosome.chromosome.

Eosinophils: 2-4% of circulating Eosinophils: 2-4% of circulating leukocytesleukocytes

bi-lobed nucleusbi-lobed nucleus

Eosinophilic granules (red/pink)Eosinophilic granules (red/pink) contain histaminasecontain histaminase

AllergicAllergic & inflammatory reactions & inflammatory reactions and and parasitic infectionsparasitic infections

Counteract the effects of basophils in allergic reactionsCounteract the effects of basophils in allergic reactions

Often found at sites of chronic inflammation, Often found at sites of chronic inflammation, commonly in respiratory or digestives tractscommonly in respiratory or digestives tracts

Basophils: <1% of circulating Basophils: <1% of circulating leukocytesleukocytes

Bilobed nucleusBilobed nucleus

Basophilic granules (blue/black) Basophilic granules (blue/black) obscure the nucleusobscure the nucleus

Secrete Secrete histaminehistamine (vasodilation) (vasodilation) and and heparinheparin (anti-coagulant) (anti-coagulant)

Involved in allergic and inflammatory reactionsInvolved in allergic and inflammatory reactions

Lymphocytes: 20-25% of circulating Lymphocytes: 20-25% of circulating leukoctyesleukoctyes

Agranulocyte Agranulocyte

Variable in size, 6-18 Variable in size, 6-18 m in diameterm in diameter

Single, round, heterochromatic nucleusSingle, round, heterochromatic nucleus

Function in immunityFunction in immunity 2 classes, indistinguishable morphologically2 classes, indistinguishable morphologically

– B cells: produce antibodiesB cells: produce antibodies– T cells: mature in thymus, cell-mediated immune T cells: mature in thymus, cell-mediated immune

responseresponse

Monocytes: 3-8% of circulating Monocytes: 3-8% of circulating leukocytesleukocytes

Agranulocyte Agranulocyte

Largest circulating WBCLargest circulating WBC

Large indented nucleusLarge indented nucleus

Stay in circulation a few daysStay in circulation a few days then migrate into the tissues and differentiate into then migrate into the tissues and differentiate into

macrophagesmacrophages

As macrophages, phagocytize and destroy dead As macrophages, phagocytize and destroy dead cellscells

Platelets (Thrombocytes)Platelets (Thrombocytes) Anucleated cell fragmentsAnucleated cell fragments 2 2 m diameter m diameter 10-day life span10-day life span Main function: blood Main function: blood

clottingclotting

Produced by Produced by megakaryocytes megakaryocytes

in bone marrow: bud off in bone marrow: bud off

cytoplasm to form platelets.cytoplasm to form platelets.Bone marrow capillary

Platelets

Differential White Blood Cell Differential White Blood Cell Count:Count:

Neutrophils > Eosinophils > Basophils Monocytes >Lymphocytes >

Never Let Monkeys Eat Bananas