summary of formed elements in blood

red blood cells (RBCs) or erythrocytes

4.8 million/μL in females

5.4 million/μL in males

red blood cells (RBCs) or erythrocytes

7-8 μm diameter

biconcave discs

without nuclei

live for about 120 days

red blood cells (RBCs) or erythrocytes

hemoglobin within RBCs transports most of the oxygen and part of the carbon dioxide in the blood

red blood cells (RBCs) or erythrocytes

neutrophils

eosinophils

basophils

lymphocytes (T cells, B cells, NK cells)

monocytes

5 types of white blood cells (WBCs) or leukocytes

neutrophils

eosinophils

basophils

3 granular leukocytes

lymphocyte (T cells, B cells, NK cells)

monocytes

2 kinds of agranular leukocytes

T cells

B cells

NK cells

3 kinds of lymphocytes

white blood cells (WBCs) or leukocytes

50,000-10,000 cells/µL

white blood cells (WBCs) or leukocytes

most live for a few hours to a few days

white blood cells (WBCs) or leukocytes

combat pathogens and other foreign substances that enter the body 

neutrophils 

neutrophils 

60-70% of all WBCs

neutrophils 

10-12 µm in diameter

nucleus has 2-5 lobes connected by thin strands of chromatin

cytoplasm has very fine, pale lilac granules

neutrophils 

phagocytosis

destruction of bacteria with lysozyme 

eosinophils

eosinophils

2-4% of all WBCs

eosinophils

10-12 µm diameter

nucleus usually has 2 lobes connected by a thick strand of chromatin 

large, red-orange granules fill the cytoplasm

eosinophils

combat the effects of histamine in allergic reactions

phagocytize antigen-antibody complexes 

destroy certain parasitic worms 

basophils

basophils

0.5-1% of all WBCs

basophils

8-10 µm diameter

nucleus with 2 lobes

large cytoplasmic granules appear deep blue-purple

basophils

liberate heparin, histamine, and serotonin in allergic reactions that intensify the overall inflammatory response

lymphocytes (T cells, B cells, NK cells)

lymphocytes (T cells, B cells, NK cells)

20-25% of all WBCs

lymphocytes (T cells, B cells, NK cells)

small, 6-9 µm in diameter

large, 10-14 µm in diameter

round or slightly indented nucleus

cytoplasm forms a rim around the nucleus that looks sky blue

the larger the cell, the more cytoplasm is visible

lymphocytes (T cells, B cells, NK cells)

mediate immune responses, including antigen-antibody reactions

B cells

develop into plasmocytes, which secrete antibodies

T cells

attack invading viruses, cancer cells, and transplanted tissue cells

NK cells

attack a wide variety of infectious microbes and certain spontaneously arising tumor cells 

monocytes

monocytes

3-8% of all WBCs

monocytes

10-20 µm diameter

kidney-shaped or horseshoe shaped nucleus

blue-gray cytoplasm with foamy appearance

monocytes

phagocytosis (after transforming into fixed or wandering macrophages)

platelets (thrombocytes)

platelets (thrombocytes)

150,000-400,000/µL

platelets (thrombocytes)

2-4 µm diameter cell fragments that live for 5-9 days

contain many granules but no nucleus

platelets (thrombocytes)

form platelet plug in hemostasis

release chemicals that promote vascular spasm and blood clotting