PHS 3342 Lecture Notes - Lecture 3: Leukocyte Extravasation, Granulocyte, Agranulocyte
28 Apr 2018
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January 12, 2018
Leukocytes
Leukocytes
Only formed elements that are complete cells
<1% of total blood volume
Protects against bacteria, viruses, parasites, toxins, and tumour cells
Granulocytes and agranulocytes
-Never Let Monkeys Eat Bananas
Need to go to the sites of invasion or tissue damage, so having them in the blood allows them to be easily
transported to where they are needed
Can leave blood (diapedesis) for immune/inflammatory response
-Histamines cause capillaries to become more leaky
-Neutrophils move slowly and roll along the capillary (margination/pavementing) in order to look for a leaky spot to
leave the capillary
-Will then leave the capillary via diapedesis
Amoeboid motion, positive chemotaxis
-Positive chemotaxis: follow a trail of increasing concentration of chemicals released by invaders
Polymorphonuclear Granulocytes
Characteristics:
-Spherical
-Larger than RBCs
-Lobed nuclei (irregularly shaped)
-Cytoplasmic granules
-Wright’s stain
-phil = granulocyte
Three kinds:
-Neutrophils (>50% WBC population): act as phagocytes (ingest and destroy bacteria) and clean up scavengers
(clean up waste in the bloodstream)
•Cytoplasm contains 2 types of granules - take up both acidic and basic dyes
•Granules contain hydrolytic enzymes (to degrade invaders) and some antibiotic-like proteins
(defensins - not specific to certain bacteria)
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Document Summary
Protects against bacteria, viruses, parasites, toxins, and tumour cells. Need to go to the sites of invasion or tissue damage, so having them in the blood allows them to be easily transported to where they are needed. Histamines cause capillaries to become more leaky. Neutrophils move slowly and roll along the capillary (margination/pavementing) in order to look for a leaky spot to leave the capillary. Will then leave the capillary via diapedesis. Positive chemotaxis: follow a trail of increasing concentration of chemicals released by invaders. Eosinophils: most important against parasitic worms (will surround them and release enzymes), also reduce severity of allergies (by phagocytosis of immune complexes: nucleus is shaped like a telephone receiver and has coarse red granules. T lymphocytes (t cells): act directly against virus-infected cells, tumour cells: directly attack invaders, produced in bone marrow, tested for immunocompetence in the thymus gland.
