Immune SystemPrimary Function: To protect your body from pathogens.

Pathogens: Bacteria, viruses, fungus, or proteins that causes illness.

Spleen: stores lymphocytes and filters bloodThymus: where T cells matureBone marrow: where blood cells are formed

Types of ImmunityInnate Immunity:

- present before exposure to pathogens - is nonspecific

Acquired Immunity: - develops after exposure to pathogens- is very specific

Innate Immunity: ExternalSkin- physical barrier that prevents entry of pathogens- secretions from the skin cause it to be acidic enough to prevent colonization of many pathogens

Mucous membranes- Produce mucus, a fluid that traps pathogens- Can contain enzymes like lysozyme that digest the cell walls of many pathogens

Innate Immunity: External

Innate Immunity: ExternalCilia - In the trachea, ciliated epithelial cells sweep upward, preventing the microbes from entering the lungs

Figure 43.3

10m

Innate Immunity: InternalPhagocytic cells: attach to their prey using surface receptors and engulf them (endocytosis), forming a vacuole that fuses with a lysosome.

Macrophages are a type of phagocytic cell.

Innate Immunity: InternalNatural Killer cells: Attack virus-infected cells and cancer cells. Cause apoptosis (cell death) in the cells they attack.

Innate Immunity: InternalInflammatory Response: injured cells release chemicals (histamines) that cause phagocytic cells to gather at the site.

Pathogen Pin

Macrophage

Chemical signals

CapillaryPhagocytic cells

Red blood cell

Bloodclottingelements

Blood clot

Phagocytosis

Fluid, antimicrobial proteins, and clotting elements move from the blood to the site.Clotting begins.

2Chemical signals released by activated macrophages and mast cells at the injury site cause nearby capillaries to widen and become more permeable.

1 Chemokines released by various kinds of cells attract more phagocytic cells from the bloodto the injury site.

3 Neutrophils and macrophagesphagocytose pathogens and cell debris at the site, and the tissue heals.

4

Acquired ImmunityAntibodies: Proteins that recognize foreign molecules and mark them for destruction.

Acquired ImmunityB cells and T cells:

- Circulate in the blood- Made in bone marrow- B cells produce antibodies - T cells attack pathogens

Acquired ImmunityPrimary Response: B or T cells recognize the pathogen and reproduce. This creates many new cells, including memory cells.

Acquired ImmunitySecondary Response: Memory cells cause a faster, more efficient response to a pathogen

Antib

ody

conc

entr

ation

(arb

itrar

y un

its)

104

103

102

101

100

0 7 14 21 28 35 42 49 56

Time (days)Figure 43.13

Antibodiesto A

Antibodiesto B

Primaryresponse toantigen Aproduces anti-bodies to A

2Day 1: First exposure toantigen A

1 Day 28: Second exposureto antigen A; firstexposure to antigen B

3 Secondary response to anti-gen A produces antibodiesto A; primary response to anti-gen B produces antibodies to B

4

AllergiesAllergies overly sensitive response by your immune system to a molecule (allergens)Cause: Cells in your immune system release histamines that cause an inflammatory response

1

2

3

AllergenIgE

Histamine

GranuleMast cell

Infectious DiseasesAny disease caused by “germs” that can be spread from one person to another. Germs include viruses, bacteria, and fungi.

Infectious Diseases: Whooping cough

Cause: Bacterial (Bordetella pertussis) Symptoms: Severe coughing fits that can cause fractured ribs, fainting, artery tearsSpread: Direct contact with mucus from the nose/throat of infected individualsPrevention: Vaccine

Infectious Diseases: HIV/AIDS

Cause: ViralSymptoms: Initially, few, if any. May have flu-like symptoms. Over time, immune system is weakened because T cells are killed. Spread: Contact with bodily fluidsPrevention: Avoid body fluids from infected individuals

Vaccines- Improve your immune systems ability to fight off a

pathogen.- Include a weakened or killed form of the pathogen or

part of a pathogen. - Stimulates the immune system to recognize the

pathogen and create memory cells.

Infectious Diseases: Strep ThroatCause: BacterialSymptoms: Fever, sore throat with white patchesSpread: Airborne (saliva or nasal secretions)Prevention: Avoid contact with infected individuals, wash hands, keep hands away from face