Download Medical Microbiology Chapter 15 - Body Defenses

Medical Microbiology Chapter 15 - Body Defenses
I. Body Defenses - 3 lines of defense
A. Skin and mucous membrane - surface protection
1. low pH of skin
a. sweat glands (lactic acid)
b. sebaceous glands (fatty acids)
2. respiratory tract
a. mucous membranes and cilia - trap pathogens/dust particles, etc.
b. cilia sweep pathogens to throat
c. lysozyme in tears, saliva, nasal secretions
3. digestive tract
a. acetic digestive juices
b. alkalinity of intestines
c. mucous membranes trap pathogens
d. bacterial destruction by enzymes, phagocytes
e. pathogens excreted
f. some bacteria helpful
4. genitourinary tract
a. pathogens flushed by urination/vaginal secretions
b. women have higher incidence of bladder infections
-shorter urethra
-infrequent urination after sexual intercourse
c. vagina, bladder, urethra - slightly acetic
d. extensive antibiotic treatment can cause yeast infections
B. Circulatory Defenses - cellular and chemical
1. phagocytes - cells capable of engulfing bacteria
2. two types of phagocytes
a. fixed phagocytes
-firmly attached to liver, spleen, bone marrow, lymph nodes, and intestinal
and blood vessel linings - tissues of reticuloendothelial system (RES)
b. mobile phagocytes - leukocytes (wbc) - monocytes and neutrophils
-ingest bacteria - now called phagosome
-lysosome fuses with phagosome - called phagolysosome
-bacteria digested - degranulation
-monocyte - (wbc) - may remove cancer cells, suppress growth of
spontaneously arising tumors, and involved in tissue rejection
C. Antibodies
1. protein produced/released in response to foreign antigen (protein)
2. incubation period - time between invasion and symptoms
3. specific antibody produced for specific antigen - antibody-antigen response
4. complement
a. special proteins in plasma
b. aid antibodies
II. Immune Response and HIV (AIDS, The Disease
A. HIV destroys T-helper lymphocytes
B. CD4 - receptor on HIV - fits perfectly into receptors on T-helper cells
C. HIV RNA
1. enters cell
2. transcribed into 1 strand of complementary DNA and then another
3. HIV DNA attaches to cell's DNA and hides
4. HIV DNA comes out of hiding
a. viral RNA and proteins made
b. packaged together and bud from T-helper cell
c. T-cell count below 200 - full blown AIDS
III. Infection
A. Local infection - restricted one area
B. General infection - infection spread to other areas
1. incubation period - days to years
2. high white cell count sign of infection
C. Fever and inflammation
1. moderate fever - 1020-104 0; higher is dangerous
2. inflammation - redness, heat, edema, pain
3. pus
4. pyogenic bacteria - pathogens capable of pus formation
IV. Formation of food toxins, poisons, or exotoxins
A. Clostridium botulinum - botulism
1. nerve destruction
2. improper canning or smoking foods
3. spores
B. Staphylococcus aureus food poisoning by exotoxin
C. Clostridium tetani - destroys tissue
D. Corynebacterium diphtheriae - in throat, nose, tonsils - exotoxin circulates until
entire bloodstream is poisoned
V. Tissue Destruction
A. Tuberculosis - invades/destroys lung tissue
B. Strep - hemolysin - lyses rbc
C. Staph or Strep - leukocidin - destroys wbc