Fifth lecture. 2-White blood cells Nucleated cells. larger than RBC ’ s. Approx. 1 x 10 10 per liter. Involved in defense against pathogens.

Fifth lectureFifth lecture

2-White blood cells

Nucleated cells.

larger than RBC’s.

Approx. 1 x 1010 per liter.

Involved in defense against pathogens.

Can move through capillary wall to act locally at site of infection.

Attracted to trauma site by chemotaxis.

Neutrophils

2-White blood cells

Granuloyctes Agranulocytes

Basophils

Eosinophils

Monocytes Lymphocytes

B Cells T Cells

-

Helper T Cells

Killer T Cells

22--Leukocytes (WBCs)Leukocytes (WBCs)

Part of defense system:Part of defense system: Protect against bacteria, viruses, parasitesProtect against bacteria, viruses, parasites

Attracted to sites of infection.Attracted to sites of infection. Diapedesis & chemotaxis: leave capillary Diapedesis & chemotaxis: leave capillary

by squeezing between endothelial cells.by squeezing between endothelial cells. Ameboid movement:Ameboid movement:

Travel toward infectionTravel toward infection Originate in bone marrow.Originate in bone marrow. They are classified into:They are classified into:

A-Granulocytes A-Granulocytes B-A granulocytesB-A granulocytes

DiapedesisDiapedesis

GranulocytesGranulocytes

WBCs with granules in cytoplasmWBCs with granules in cytoplasm– Visible with LMVisible with LM

NeutrophilsNeutrophils EosinophilsEosinophils BasophilsBasophils PhagocyticPhagocytic Larger than RBCsLarger than RBCs Lobed nucleiLobed nuclei

Promyelocytes

Basophilic myelocytes

Eosinophilc myelocytes

Neutrophilic myelocytes

basophils eosinophils neutrophils

It takes about 10 days for the mature WBC’s to from the precursor cells at which they are released into the circulation.

Colony Stimulating Factors govern the rate of WBC synthesis.

Formation of granulocytes

NeutrophilsNeutrophils

60% of WBCs.60% of WBCs. half-life of 6 hours so need to half-life of 6 hours so need to

produce 100 billion per day for produce 100 billion per day for normal functionnormal function!

Lobed nucleus.Lobed nucleus. Light staining granules.Light staining granules.

– Digestive enzymes.Digestive enzymes. Function Function

– Phagocytize & destroy bacteria.Phagocytize & destroy bacteria. First cells to respond to First cells to respond to

infection.infection. Secrete antibacterial chemicals.Secrete antibacterial chemicals. Phagocytize & digest bacteriaPhagocytize & digest bacteria..

EosinophilsEosinophils

1-4% of WBCs.1-4% of WBCs. Lobed nucleus.Lobed nucleus. Eosin-staining granules.Eosin-staining granules. Phagocytize allergen-Ab complexes.Phagocytize allergen-Ab complexes. increased following allergic response.increased following allergic response. Attack parasites.Attack parasites.

BasophilsBasophils

0.5% of WBCs.0.5% of WBCs. Lobed nucleus.Lobed nucleus. Large granules stained dark Large granules stained dark

purple.purple. Release histamine and Release histamine and

heparin.heparin. Trigger inflammation.Trigger inflammation.

LymphocytesLymphocytes

A granulocyte A granulocyte 20-45% of WBCs20-45% of WBCs Spherical, dark-Spherical, dark-

staining nucleusstaining nucleus Thin rim of blue Thin rim of blue

staining cytoplasmstaining cytoplasm Each lymphocyte Each lymphocyte

recognizes and acts recognizes and acts against a specific against a specific antigenantigen

LymphocytesLymphocytes

T lymphocytes can attack foreign cells directly.T lymphocytes can attack foreign cells directly.

B lymphocytes transform into plasma cells and secrete B lymphocytes transform into plasma cells and secrete antibodies.antibodies.

Derived from lymphoblasts which divide a number

of times to form pro-lymphocytes.

Pro-lymphocytes mature into B or T lymphocytes

in lymphoid tissue i.e. thymus, spleen

MonocytesMonocytes

A granulocyteA granulocyte 4-8% of WBCs4-8% of WBCs Horseshoe shaped nucleus.Horseshoe shaped nucleus. originate from monoblasts. Life span 72 hours, Life span 72 hours, after which they migrate

to connective tissue where they remain for up to 3 months.

Migrate to spleen, liver, lungs and lymph Migrate to spleen, liver, lungs and lymph nodes where they phagocytose invading nodes where they phagocytose invading pathogens and are termed macrophages.pathogens and are termed macrophages.

33--Platelets Platelets (thrombocytes)(thrombocytes)

Not strictly speaking cells.

Really membrane bound cell fragments budded off of bone marrow cells and released in to circulation.

Rarely nucleated and only 2-4m in diameter.

Life span 10 days.

DO NOT adhere to healthy

intact

endothelium.

Fragments of Fragments of

megakaryocytes in megakaryocytes in

bone marrow.bone marrow.

Attracted to damaged places.Attracted to damaged places.

Adhere to damaged vessel walls

and exposed connective tissue to

mediate blood clotting.

33--Platelets Platelets (thrombocytes)(thrombocytes)