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Immune / Lymphatic System (Ch. 43). Why an immune system?. Attack from outside animals are a tasty nutrient- & vitamin-packed meal cells are packages of macromolecules animals must defend themselves against invaders ( pathogens ) Viruses: HIV , flu, cold, measles, chicken pox

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Presentation Transcript
why an immune system
Why an immune system?
  • Attack from outside
    • animals are a tasty nutrient- & vitamin-packed meal
      • cells are packages of macromolecules
    • animals must defend themselves against invaders (pathogens)
      • Viruses: HIV, flu, cold, measles, chicken pox
      • Bacteria: pneumonia, meningitis, tuberculosisLyme disease
      • Fungi: yeast (“Athlete’s foot”…)
      • Protist: amoeba, malaria
  • Attack from inside
    • cancers = abnormal body cells
development of red white blood cells
Development of Red & White blood cells

inflammatory response

Red blood cells

fightparasites

Leukocytes

Lymphocytes

short-lived phagocytes

60-70% WBC

develop into macrophages

1st line non specific external defense
1st line: Non-specific External defense

Lining of trachea: ciliated cells & mucus secreting cells

  • Barrier
      • Skin – sweat (acidic)
  • Traps
      • mucous membranes, cilia,hair, earwax
  • Elimination
      • coughing, sneezing, urination, diarrhea
      • Lysozyme – enzyme that breaks cell wall of bacteria in mucus, saliva, sweat, tears.
2nd line non specific patrolling cells
2nd line:Non-specific patrolling cells

bacteria

  • Patrolling cells & proteins
    • attack pathogens, but don’t “remember” for next time
      • Leukocytes
        • phagocytic white blood cells
        • macrophages, neutrophils, natural killer cells
      • inflammatory response (next slide)
        • increase in body temp.
        • increase capillary permeability
        • attract macrophages

macrophage

yeast

inflammatory response
Inflammatory response
  • Damage to tissue triggers local non-specific inflammatory response
    • release chemical signals
      • histamines & prostaglandins
    • capillaries dilate, becomemore permeable (leaky)
      • delivers macrophages, RBCs, platelets, clotting factors
        • fight pathogens
        • clot formation
  • FEVER - When a local response is not enough
    • system-wide response to infection
    • activated macrophages release interleukin-1
      • triggers hypothalamus in brain to readjust body thermostat to raise body temperature
    • higher temperature helps defense
      • inhibits bacterial growth
      • causes liver & spleen to store iron, reducing blood iron levels
        • bacteria need large amounts of iron to grow
interferon interferes with virus
Interferon – (“interferes” with virus)
  • Virus infected cells produce a group of proteins that help other cells resist viral infections.
  • Interferons inhibit the synthesis of viral proteins in infected cells and

block viral replication!

3rd line acquired active immunity
3rd line: Acquired (active) Immunity

B cell

  • Specific defense with memory
    • lymphocytes
      • B cellsand T cells
    • antibodies(B cells)
      • immunoglobulins
  • Responds to…
    • antigens(substance that triggers

a response)

        • specific pathogens
        • specific toxins
        • abnormal body cells (cancer)
how are invaders recognized
How are invaders recognized?
  • Antigens –carbs, proteins, lipids on cell surface
      • “self” antigens
        • no response from WBCs
      • “foreign” antigens
        • response from WBCs
        • pathogens: viruses, bacteria, protozoa, parasitic worms, fungi, toxins
        • non-pathogens: cancer cells, transplanted tissue, pollen

“self”

“foreign”

lymphocytes
Lymphocytes

bone marrow

  • B cells
    • mature in bone marrow
    • humoral response system
      • attack pathogens still circulating in blood & lymph (liquids)
    • produce antibodies
  • T cells
    • mature in thymus
    • Cell mediated system
  • attack invaded cells - Tens of millions of different T cells are produced, each one specializing in the recognition of one particular antigen. T cells are responsible for disease resistance.
  • We’ll hit these more in a few slides!
b cells from bone marrow
B cells (from Bone marrow)

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  • Attack, learn & remember pathogens circulating in blood & lymph
  • Produce specific antibodiesagainst specific antigen
  • Antibodies = Proteins that bind to a specific antigen
    • multi-chain proteins (2 heavy 2 light)
    • binding region matches molecular shape of antigens
    • each antibody is unique & specific
      • millions of antibodies respond to millions of foreign antigens
what do antibodies do to invaders 4 ways they aid in immunity 15
What do antibodies do to invaders? 4 ways they aid in immunity (#15)

Y

Y

Y

Y

Y

Y

invading pathogens tagged with antibodies

macrophageeating tagged invaders

neutralize

capture

precipitate

apoptosis

vaccinations
Vaccinations
  • Immune system exposed to harmless version of pathogen
    • stimulates B cell system to produce antibodies to pathogen
      • “active immunity”
    • rapid response on future exposure
    • creates immunity without getting disease!
  • Most successful against viruses
passive immunity
Passive immunity
  • Obtaining antibodies from another individual
    • maternal immunity
      • antibodies pass from mother to baby across placenta or in mother’s milk
      • critical role of breastfeeding in infant health
        • mother is creating antibodies against pathogens baby is being exposed to
  • Injection
    • injection of antibodies (Rabies,?Ebola)
    • short-term immunity (few weeks to

months)

how is any cell tagged with antigens
How is any cell tagged with antigens?

MHC protein

T or Bcell

MHC proteins

displaying self-antigens

  • Major histocompatibility (MHC) proteins
    • proteins which constantly carry bits of cellular material from the cytosol to the cell surface
    • “snapshot” of what is going on inside cell
    • give the surface of cells a unique label or “fingerprint”

Who goes there?

self or foreign?

t cells
T cells
  • Attack, learn & remember pathogens hiding in infected cells
    • recognize antigen fragments
    • also defend against “non-self” body cells
      • cancer & transplant cells
  • Types of T cells
    • helper T cells
      • Helper T cells detect infection and get the other cells of the immune system ready to do battle. Helper T cells also tell B cells to produce antibodies.
    • killer (cytotoxic) T cells
      • attack infected body cells
    • surpressor T cells
      • Turns off when no antigen is present

T cell attacking cancer cell

hiv aids
HIV & AIDS
  • Human Immunodeficiency Virus
    • virus infects helper T cells
      • helper T cells don’t activate rest of immune system: killer T cells & B cells
      • also destroys helper T cells
  • AIDS: Acquired ImmunoDeficiencySyndrome
    • infections by opportunistic diseases
    • death usually from “opportunistic”

infections that most people can fight

      • pneumonia, cancers

HIV infected T cell

immune system malfunctions
Immune system malfunctions
  • Auto-immune diseases
    • immune system attacks own molecules & cells
      • Lupus: antibodies against many molecules released by normal breakdown of cells
      • rheumatoid arthritis: antibodies causing damage to cartilage & bone
      • Diabetes: beta-islet cells of pancreas attacked & destroyed
      • multiple sclerosis: T cells attack myelin sheath of brain &

spinal cord nerves

  • Allergies
    • over-reaction to environmental antigens
      • allergens = proteins on pollen, dust mites, in animal saliva
      • stimulates release of histamine causing sneezing, runny nose, watery eyes and even death if system drops in blood pressure (epi pen)
slide19

Make sure you can do the following:

  • Explain the interplay between the humoral (antibodies from B cells, in blood), and cell-mediated responses (helper & killer T’s, macrophages - cells) http://www.youtube.com/watch?v=1tBOmG0QMbA
  • Demonstrate how the HIV virus leads to a breakdown of the immune system.
  • Explain why a vaccine works.
  • Explain the causes of immune system disruptions and how these disruptions can lead to disruptions of homeostasis.