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Ch 31 – Section 1
Immune system
Protect body from pathogens
ANY FOREIGN PROTEIN
= antigens
Examples
Bacteria
Viruses
Fungi
Protozoa (animal-like protists)
Parasites
Vector = anything that carries a pathogen into healthy cells
Lymphoid organs
Lymph nodes
Throughout body
Filter/purify lymph before returning it to blood
99% of antigens removed
Antigens engulfed by macrophages and ‘presented’ to lymphocytes
Thymus gland
Under sternum
‘home’ of lymphocytes (T cells)
Secretes thymosin to stimulate T cell differentiation
Reduction in size with age
Lymphoid organs
Spleen
Removes abnormal blood cells
Stores./recycles Fe from RBCs
Initiates T cell and B cell response
Tonsils
Large nodules in pharynx
Ch 31 – Section 3
Immune system
Nonspecific defenses
Physical barriers (1st line of defense)
Phagocytes
NK cells
Interferon
Complement
Inflammation
Fever
Specific responses
Immune response = immunity
Cell mediated immunity = T cells
Antibody mediated immunity = B cells
Nonspecific defenses
Physical barriers (1st Line of Defense)
Integumentary system
Skin, Hair, Sweat
Mucous secretions
from all epithelial linings
White Blood Cells (2nd Line of Defense)
Phagocytes
Cells that may engulf, bind/remove, release toxins against
antigens
Nonspecific defenses
NK cells
Natural killer cells
Kill any cell with ‘abnormal’ proteins
Stick to ‘bad’ cell and secrete proteins that disintegrate its cell membrane
Attack virus infected and cancer cells
Interferon
Small proteins released infected cells to
‘warn’ healthy cells of presence of pathogens which
allows healthy cells to protect themselves from destruction
Complement 11 complement proteins
Attachment of antibodies to target cell membrane
Stimulated by attachment of pathogens to cell wall/membrane
Nonspecific defenses
Inflammation
Acute inflammatory response = immediate response to injury
*1 Release of histamines
= increased blood flow to area
*2 Clotting mechanisms cascade to isolate area and stop bleeding
*3 Local temperature rises = increased enzyme activity and
denaturing of pathogen proteins
*4 Neutrophils called to area
Phagocytize pathogens release toxins in area
Secrete cytokines to call other phagocytes to area
Nonspecific defenses
Inflammation (continued)
*5 Macrophages and eosinophils called to area increase activity
*6 more cytokines released stimulating fibroblasts to produce
scar tissue
*7 activity stimulates neural response as sense of pain causing
organism to respond
*8 specific responses initiated (cell mediated immunity)
foreign invaders ‘presented’
Nonspecific defenses
Fever
Pyrogenes stimulate hypothalamus to increase body temperature
Increased temperature = increased enzyme activity and
denaturing of pathogen proteins, stimulate White Blood Cells
Specific response
Immune response = immunity
Immunity may be:
Innate = Born with it
Acquired = As a result of exposure to antigen
or Vaccine
Ch 31 – Section 2
Immunity
Specific
Response is specific to antigen encountered
Versatile
Can respond to any antigen at any time
Memory
Memory cells remember response to initial contact with antigen
Tolerance
Ignores ‘self’ antigens
Immunity
Immunity is a result of coordinated activities of lymphocytes
Lymphocytes
T cells
Cell mediated
immunity
B cells
Antibody mediated
immunity
T cells and cell mediated immunity
T cells activated by exposure to antigen
TC cells
T cytotoxic cells
Physically and chemically attack antigens naturally on cell surface
Memory TC cells
Remember antigen for future encounter
TH cells T helper cells
stimulate B cell activity
stimulate NK cell activity
Memory TH cells
Remember antigens for future encounter
TS cells T suppressor cells
Inhibit T cell and B cell activity
B cells and antibody mediated
immunity
Produce antibodies to antigens on cell surface
B cells activated by TH cells
B cells ‘sensitized’ when encountering specific antigen
When activated TH cell encounters sensitized B cell:
B cells stimulated to produce memory cells
OR
become plasma cells
Plasma cells produce antibodies specific to antigen
Antibody–Antigen
complex
Antigen Eliminated by:
Neutralization
Prevent pathogen from attacking host cell
Agglutination/ precipitation
Large numbers of antigens ‘clump‘ together causing precipitation
Activation of complement
Attract phagocytes
Assist phagocytes in phagocytosis
Stimulate inflammation
Prevent entrance of pathogens in mucous membranes
Primary response
Secondary response
Initial exposure to antigen
Subsequent exposure to antigen
Longer response
Memory cells = quicker response
Immune Hormones
Interluekins Stimulate T cells and B cells
Enhance nonspecific defenses
Interferon Make cells and neighbors resistant to viral infection
Stimulate NK cells
Ch 31 – Sections 5 & 6
Immune
disorders
Autoimmune disease
‘self’ is not recognized
Immunodeficiency
Viral (HIV) – virus that attacks the immune system by
infecting T cells
Leukemia – cancer of the bone marrow causes abnormal WBC
Allergies
Inappropriate immune response (to nonpathogenic antigen)
Primary response to allergen not severe
secondary response = allergic reaction
Anaphylaxis = acute allergic response to allergen