Download Body Defenses

Body Defenses
Physical Barriers
• Skin – intact
a. Bacteriostatic secretions
b. Normal flora inhibits other organisms
c. Sloughing of epithelium
Physical Barriers
• Mucous membranes – intact
a. Lines all orifices except ears
b. Bactericidal properties
c. Slightly acidic pH
Physical Barriers
• Reflexes
a. Gagging, vomiting
b. Blinking
c. Sneezing
Antimicrobial Substances
• Genitourinary/ reproductive tracts
a. Slightly acidic pH
b. IgA and enzymes produced
c. Unidirectional peristalsis
ACID
a. Stomach acid is too acidic for most pathogens
ENZYMES
a. Inhibit or kill organisms
i tears
ii also in phagocytes
Physical Barriers
• Normal Flora
1. Prevents invading organisms from
adhering to host cells by covering binder sites.
2. Consume available nutrients
3. Produce compounds that are toxic to
other organisms.
Body Defenses
Second line: innate immunity
Inflammation
• Inflammatory Response:
• Local or systemic
Signs
• Erythema
– Due to the dilation of blood vessels
• Swelling
– Due to extra fluid in the area
• Heat
– Due to dilation of blood vessels (increased blood flow)
• Pain
– Extra fluid presses on nerves
Inflammation
• Temperature elevation
As body temperature rises, organism growth
declines and allows other defense
mechanisms to work.
Increases enzyme reactions and phagocytic
action.
Body Defenses
Third line of defense- Immune
response
Humoral Immune Response
• Involves the actions of antibodies
• Antibodies:
– Proteins also known as Immunoglobulins
– Tremendous Diversity—there are thought to be
millions (1015) of different specific antibodies
– Examples of immunoglobulins: IgA, IgE
Types of antibodies
Immune Response
• Antibody production
1. Stimulated by presence of an
organism/antigen
2. Systemic
3. Has memory – May allow reproduction for
future exposure to same organism/antigen
Plasma Cells
• Secrete loose antibodies into the
bloodstream
– Like antibody factories 
• Plasma cells have a lot of ribosomes and
Rough ER– WHY?
– Antibodies are proteins  these are the
organelles needed for protein synthesis
Immunity
• Passive Immunity- Someone else makes
antibodies
a. Natural – from mother
-placenta
-Mother’s milk/colostrom-most may be
digested, but may provide some protection
b. Artificial- made by mother
-Hepatitis A immunoglobulin
Immunity
• Active Immunity- You make the antibodies
a. Natural – Have disease
b. Artificial – Immunization/vaccination
Describe the types of Vaccines
1) Contain these things to activate antibody
production:
a) Living, attenuated pathogens – polio
b) Killed pathogens – pertussis, influenza
c) Extracts of pathogens (eg a capsule)
2. Contain these things to activate antitoxin
production
a) Attenuated toxins or toxoids – tetanus, diphtheria
Allergies
• When the immune system “overreacts” or
becomes hypersensitive to certain antigens
• Most allergies involve the actions of IgE
antibodies
Allergic Response
1. Allergen introduced, and IgE produced
a) VIDEO
2. Histamine release, which leads to:
a) Mucus production
b) Bronchoconstriction
c) Airway inflammation
d) Swelling
e) VIDEO again
Anaphylaxis
• Severe, systemic allergic reaction
-Bronchioles constrict
-Increased mucus production blocks airway
-Edema: swells airway and may cause a loss
of volume from circulatory system to cause
hypotension
-can occur suddenly
-death can occur within minutes
Common allergens/antigens
• Inhalants
– pollen
• Foods
– peanuts
• Drugs
– penicillin
• Contact
– grass
Treatment
• Something to open the bronchioles
• Something to prevent more release of
histamine
• Fluid to increase blood pressure or
vasopressor (constrict vessels)
• Oxygen
• Steroids for inflammation if necessary to
decrease inflammation
Cell-Mediated Response
• Involves the action of Cytotoxic T Cells
• Eliminates infected cells, cancer cells, and
transplanted cells
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Rejection Syndrome
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Following transplantation of organs
Normal to reject foreign substances
Cross matched to match as closely as possible
Anti-inflammatory drugs are given (patient is
immunosuppressed)