BloodBy: Dr. Holly Nash-Rule

Functions of blood• Distribution/transport - nutrients, wastes,

gases, etc.

• Communication, i.e., hormones

• Prevention of fluid loss – hemostasis, osmosis

• Maintenance of pH

• Disease/ infection fighting

• Heating/Cooling

Blood Circulation

• Powered by the pumping action of the heart

• Functions of blood

• Carries respiratory gases, nutrients, and hormones

• Helps body regulate temperature

• Blood volume

• Males: 5–6 liters

• Females: 4–5 liters

Composition of Blood

• Contains cellular and liquid components

• A specialized connective tissue

• Blood cells—formed elements

• Plasma—fluid portion and fibrinogen

• Hematocrit—measure of % RBC

• Males: 47% ± 5%

• Females: 42% ± 5%

Major Components of Whole Blood

Withdraw blood and place in tube.

Plasma

55% of whole bloodLeast dense component

Buffy coat

Leukocytes and platelets<1% of whole blood

Erythrocytes

45% of whole bloodMost dense component

Centrifuge theblood sample.

Formedelements1 2

Blood Plasma• Straw-colored, sticky fluid portion of blood

• Approximately 90% water

• Contains over 100 kinds of molecules

• Ions—Na+ and Cl–

• Nutrients—Sugars, amino acids, lipids, wastes, and proteins

• Three main proteins

• Albumin, globulins, and fibrinogen

Formed Elements• Blood cells

• Erythrocytes, leukocytes, and platelets

• Staining of blood cells

• Acidic dye—eosin; stains pink

• Basic dye—methylene blue; stains blue and purple

Erythrocytes

LymphocyteNeutrophils

Photomicrograph of a human blood smear

Platelets Monocyte

Erythrocytes• Oxygen-transporting cells—7.5 µm in

diameter (diameter of capillary 8—10mm)

• Most numerous of the formed elements

• Females: 4.3–5.2 million cells/cubic millimeter

• Males: 5.2–5.8 million cells/cubic millimeter

• Have no organelles or nuclei

Erythrocytes• Are packed with oxygen-carrying

hemoglobin

• Hemoglobin molecule bears four oxygen molecules

• Each O2 molecule bears an iron molecule

• Results in the oxidation of iron atoms of hemoglobin molecules

• Gives blood its red color

Erythrocytes• Pick up O2 at lung capillaries

• Release O2 across other tissue capillaries

• Structural characteristics contribute to respiratory function

• Biconcave shape 30% more surface area

• 97% hemoglobin

• Lack mitochondria

•Do not consume O2 they pick up

Erythrocyte

Leukocytes—White Blood Cells (WBCs)• 4,800–11,000/cubic millimeter

• Protect the body from infectious microorganisms

• Function outside the bloodstream in loose connective tissue

• Circulating leukocytes leave the capillaries

• Originate in bone marrow

Leukocytes—White Blood Cells (WBCs)

• Two types of leukocytes

• Granulocytes

• Agranulocytes

•Girls Never Eat Bananas

•Around Long-armed Monkeys

Relative Percentages of the Different Types of Leukocytes

Formedelements

Platelets

Leukocytes

Erythrocytes

DifferentialWBC count(All total 4,800–10,800/l)

Neutrophils (50–70%)

Lymphocytes (25–45%)

Eosinophils (2–4%)

Basophils (0.5–1%)

Monocytes (3–8%)

Agranulocytes

Granulocytes

Granulocytes• Neutrophils—most

numerous WBC

• Phagocytize and destroy bacteria

• Nucleus—has two to six lobes

• Granules pick up acidic and basic stains

• Eosinophils—compose 1–4% of all WBCs

• Play roles in

•Ending allergic reactions, parasitic infections

• Granules pick up mostly acidic stain

Granulocytes

Granulocytes• Basophils—about 0.5% of

all leukocytes

• Nucleus—usually two lobes

• Function in inflammation mediation

• Granules secrete histamines

•Granules pick up mostly basic stain

Agranulocytes

• Lymphocytes—compose 20–45% of WBCs

• The most important cells of the immune system

• Nucleus—stains dark purple

• Effective in fighting infectious organisms

• Act against a specific foreign molecule (antigen)

Agranulocytes• Two main classes of lymphocyte

• T cells—attack foreign cells directly

• B cells—multiply to become plasma cells

• Secrete antibodies

Agranulocytes

• Monocytes—compose 4–8% of WBCs

• The largest leukocytes

• Nucleus—kidney shaped

• Transform into macrophages

•Phagocytic cells

Platelets• Cell fragments

• Break off from megakaryocytes

• Function in clotting of blood

Blood Cell Formation

• Hematopoiesis—process by which blood cells are formed in red marrow

• 100 billion new blood cells formed each day

Bone Marrow as the Site of Hematopoiesis• Bone marrow—located within all bones

• Red marrow—actively generates new blood cells

• Contains immature erythrocytes

• In adults, red marrow is located

• Between trabeculae of spongy bone of axial skeleton

• Appendicular girdles

• Proximal epiphyses of humerus and femur

Bone Marrow as the Site of Hematopoiesis

• Yellow marrow—dormant

•Contains many fat cells

• Located in the long bones of adults

Cell Lines in Blood Cell Formation

• All blood cells originate in bone marrow

• All originate from one cell type

• Blood stem cell (pluripotential hematopoeitic stem cell)

• Lymphoid stem cells

•Give rise to lymphocytes

• Myeloid stem cells

•Give rise to all other blood cells

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Proerythroblasts

Megakaryoblasts Myeloblasts

Monoblasts

The End