D’YOUVILLE COLLEGE
BIOLOGY 108/508 - HUMAN ANATOMY & PHYSIOLOGY II
LECTURE # 12
BLOOD II
WHITE CELLS - INFLAMMATION/IMMUNITY
3.
Leukocytes:
• two categories, five types (figs. 17 - 9 & 17 - 10, table 17 - 2):
a. Granulocytes: obvious granules in cytoplasm; 3 granule-staining types:
• Neutrophils (polymorphonuclear cells, PMNs): faint lavender-staining
granules, nucleus usually with at least three lobes; 50 - 70% of all leukocytes;
phagocytize bacteria
• Eosinophils: coarse, crimson-staining granules, nucleus with two lobes;
2 - 5% of leukocytes; abundant in parasitic infections, allergies
• Basophils: coarse, dark blue-staining granules, nucleus with two lobes
(usually obscured by granules); less than 1% of leukocytes; similar to histamineproducing mast cells
b. Agranulocytes: no obvious granules in cytoplasm; two types:
• Lymphocytes: spherical nucleus surrounded by sparse “skin” of
cytoplasm; 25 - 30% of all leukocytes; mediators of immune responses
• Monocytes: largest of the leukocytes; kidney-shaped nucleus;
approximately 5% of leukocytes; source of tissue macrophages
• Functional Capabilities: several capabilities facilitate function:
• Margination: ability to ‘stick’ to capillary wall
• Diapedesis: squeezing through capillary wall into interstitial space
• Ameboid movement: oozing along connective tissue fibers in tissues
• Chemotaxis: movement is directed by chemical concentration gradient
• Phagocytosis: vesicle of engulfed material (phagosome) fuses with
lysosome forming phagolysosome, in which material is broken down and recycled
or stored away from rest of cytoplasm; WBC lysosomes: hydrolytic enzymes + a
variety of other defensive agents (defensins) (fig. 21 - 2)
• Leukopoiesis: like erythropoiesis, occurs in bone marrow (fig. 17 - 11)
- lymphocytes arise from lymphoid stem cell; all others arise from myeloid
stem cell, which proliferates into four different white cell lines (granulocytes +
monocytes)
- leukopoiesis is stimulated by a variety of factors: interleukins, colonystimulating factors (CSFs)
• Methods of Assessing White Cell Status of Blood:
Bio 108/508
lec. 12 - p. 2
a. White Cell Count: averages 5000 - 10,000/cu. mm. (=l.)
b. Differential Count: expressed as percentage values; see above
Bio 108/508
lec. 12 - p. 3
• White Cell Disorders: leukopenias (deficiencies of WBCs) are usually
caused by drugs; increased vulnerability to infections
- leukocytosis (elevated WBC count - approx. 20,000/l.) occurs when
infection is present; instigated by inflammations
- leukemias (500,000/l.) arise from bone marrow tumor
- infectious mononucleosis (elevated agranulocyte count) is a disease
caused by Epstein-Barr virus
4.
Inflammation: (figs. 21 - 3 & 21 - 4)
• normally beneficial response to tissue injury, infection (viruses, fungi,
bacteria)
• cardinal signs: redness (rubor), swelling (tumor), heat (calor), pain (dolor), &
altered function (functio laesa)
• local injury ---> vasoactive agents, e.g. histamine (mast cells), also
prostaglandins
a. Vasodilation: opening of arterioles to site; hyperemia (redness, warmth)
b. Capillary Permeability Increase: leakage of increased fluid from plasma
(edema – swelling, pain); ---> further fluid leakage; clotting factors among proteins
coagulate tissue fluid (“walling off” of site)
- trauma and attendant tissue damage also triggers release of chemotaxins
(white cell attractants) and leukocytosis-inducing factors (stimulate release of
leukocytes from marrow and increased leukopoiesis) ---> i. leukocyte infiltration,
ii. phagocytic response, iii. leukocytosis, e.g. neutrophilia, eosinophilia
- increased lymphatic drainage (due to edema) and containment (due to
walling off) potentiates likelihood of immune response
- pain results from tissue damage and from plasma-derived agents such as
bradykinin
- fever may induced by pyrogens released from inflammation site
• Chronic Inflammations: persistent irritant prevents resolution ---> damage
to adjacent healthy tissues; given suffix “-itis”, e.g. appendicitis, arthritis, etc.