Midterm #2 Flashcards
also called white blood cells
leukocytes
only formed elements that are complete cells, with nuclei and the usual organelles
leukocytes
form a mobile army that helps to protect the body from damage by bacteria, viruses, parasites, toxins, and tumour cells
leukocytes
special characteristic of leukocytes
able to slip out of capillary blood vessels
diapedesis
ability of leukocytes to slip out of capillaries
what uses signals to prompt WBCs to leave the bloodstream at certain locations
cell adhesion molecules displayed by endothelial cells forming the capillary walls at sites of inflammation
how do leukocytes move through the tissue space once out of the bloodstream
through a process called amoeboid motion
positive chemotaxis
leukocytes follow the chemical trail of molecules released by damaged cells or other leukocytes and pinpoint areas of tissue damage and infection and gather there in large numbers to destroy foreign substances and dead cells
leukocytosis
WBC count over 11 000 cells/µL
(normal response to an infection in the body)
what are the 2 major categories that leukocytes are grouped into and what are they based on?
grouped based on structural and chemical characteristics
granulocytes and agranulocytes are the 2 categories
rank leukocytes from most abundant to least abundant
neutrophils
lymphocytes
monocytes
eosinophils
basophils
“never let monkeys eat bananas”
3 types of granulocytes
neutrophils
eosinophils
basophils
properties of granulocytes
- roughly spherical
- larger
- lobed nuclei
- much shorter-lived than erythrocytes
- membrane-bound cytoplasmic granules stain specifically with Write’s stain
most numerous WBC (50-70% of population)
neutrophils
twice as large as erythrocytes
neutrophils
cytoplasm contains very fine granules that are difficult to see
neutrophils
cytoplasm takes up both basic and acidic dyes and together give the cytoplasm a lilac colour
neutrophil
lysosomes
neutrophil granules that contain hydrolytic enzymes
defensins
smaller neutrophil granules that contain a potent ‘brew’ of antimicrobial proteins
polymorphonuclear leukocytes
neutrophil nuclei that have 3-6 lobes
the body’s bacteria slayers
neutrophils
when do neutrophil numbers increase explosively?
during acute bacterial infections
which leukocyte is chemically attracted to sites of inflammation and are active phagocytes
neutrophils
how do neutrophils ingest bacteria and some fungi?
enclose them in a vesicle called a phagosome
what is a respiratory burst?
- a method by which neutrophils can kill bacteria
how does s respiratory burst work?
- cells metabolize oxygen to produce potent germ-killer oxidizing substances such as bleach and hydrogen peroxide
- defensin containing granules merge with the microbe containing phagosome and form peptide ‘spears’ that pierce holes in the membrane of the ingested ‘foe’ and the bacterium lyses
makeup 2-4% of leukocytes and are about the size of neutrophils
eosinophilis
describe the granules found in eosinophils
- large, coarse granules that stain from brick-red to crimson with acid dyes pack the cytoplasm
- lysosome-like and filled with a unique variety of digestive enzymes but unlike lysosomes, they lack enzymes that specifically digest bacteria
the most important role of eosinophils
lead the counter-attack against parasitic worms that are too big to be phagocytized
where do eosinophils reside?
in the loose connective tissues and when they encounter a parasitic worm, they gather around and release the enzymes from their cytoplasmic granules onto the parasites surface, digesting it away
have complex roles in many other diseases including allergies and asthma
eosinophils
contribute to tissue damage that occurs in many immune processes but are important modulators of the immune response
eosinphils
rarest WBC (0.5-1%)
basophils
cytoplasm contains large, coarse, histamine containing granules that have an affinity for the basic dyes and stain purplish black
basophils
inflammatory chemical that acts as a vasodilator and attracts other WBCs to the inflamed site
histamine
nucleus is usually U or S-shaped with 1 or 2 constrictions
basophils