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CHAPTER 12: BODY DEFENSES
Roots:
Immun = free
Lyse = to break
Phago = eat
anti = against
Macro = large
Tox = poison
Foreign Substance = anything not endemic to the body
Pathogens = harmful or disease-causing microorganisms
A. Nonspecific Defense System = immediate response to any
threat
1.
2.
3.
4.
skin
mucous membranes
inflammatory response
proteins
B. Specific Defense System (Immune System) = attacks
specific threats
1. immune cells (lymphocytes and macrophages)
2. special molecules
Nonspecific Defense
First Line of Defense
Surface Membrane Barriers:
1. Acid pH of skin and vaginal secretions – kill bacteria.
2. Stomach HCl and enzymes – kill pathogens.
3. Saliva and lacrimal fluid (tears) containing lysozymes –
kill bacteria.
4. Digestive and respiratory tract mucus traps pathogens.
5. Nonspecific
Nonspecific Defense
First Line of Defense (cont.)
Phagocytes: Cells that eat foreign particles. (Nonspecific)
1. macrophage = large phagocyte
2. neutrophils = blood born phagocyte
Use lysosomes (vacuoles with digestive enzymes) to digest
particles once they are inside the phagocyte body.
Nonspecific Defense
First Line of Defense (cont.)
Natural Killer Cells (NK cells):
1. “police” the body looking for intruders.
2. Can lyse and kill cancer and virus-infected cells.
3. Can respond to ANY intruder. (nonspecific)
biotechnologie.de
Nonspecific Defense
Inflamm = set on fire
Second Line of Defense
Inflammatory Response:
1. Nonspecific
2. Four cardinal signs of acute inflammation:
a. Redness
b. Heat
c. Swelling
d. Pain
Nonspecific Defense
Second Line of Defense
INJURY!
Damaged cells
Release inflammatory chemicals (kinins, histamine)
Blood vessels dilate
Capillaries Leak
Clotting
proteins
Increased blood flow
Edema
(fluid in tissue)
Neutrophils
Monocytes
Dead cell/pathogen
clean up
Second Line of Defense
Nonspecific Defense
Clotting
proteins
Increased blood flow
REDNESS
HEAT
Increases
metabolic
rate
Edema
(fluid in tissue)
SWELLING
More
nutrients
& O2
Dead cell/pathogen
clean up
PAIN
Fibrin
barrier
Limited
movement
HEALING
Viruses
1. Cannot make their own ATP or proteins
2. Invade and take over host body cells so they can reproduce.
3. Cells cannot save themselves, but work to save the body by
producing INTERFERONS (small proteins that go to other cells
and bind to the membrane receptors blocking virus entry.)
uk.polylooks.com
Fever = abnormally high body temperature
Pyrogens = chemicals secreted by white blood cells and
macrophages that cause a rise in body temperature.
When a fever is good:
Bacteria require iron and zinc. During a fever the liver hoards
these minerals. Fever also increases the metabolic rate which
delivers nutrients, white blood cells, etc. to the damage zone.
When a fever is bad:
If a fever gets too high it causes a “scrambling” of enzymes and
other body proteins.
http://www.youtube.com/watch?v=wGVoMMo1KW8
Immune Response
Pg 375 in text.
Antigen = receptors on the surface of cells (both harmful cells
and body cells).
Cytotoxic cell = releases destructive chemicals (cytotoxins).
Memory cell = retains information identifying pathogens that
have been fought before.
Antibodies = inactivate antigens by 3 methods:
1. neutralization = antibodies bind to bacterial exotoxins
or to viruses and block harmful effects.
2. agglutination = mismatched blood or bacteria clumps.
3. precipitation = settling out of unwanted particles.