1. The Human Immune System

2. Immune System Overview
Part 1:
Functions
First & Second Lines of Defense
Part 2:
Third Line of Defense
Part 3:
Vaccinations
Autoimmune Disorders

3. What is the immune system?
The body’s defense against disease causing organisms, malfunctioning cells, and foreign particles

4. Types of Defense Non-specific Specific
Effective against any harmful agent that enters the body
Specific
Act only against certain agents and not other

5. Why do Infections Occur?
Preference for certain body tissue
Poliovirus vs. influenza vs. HIV
Portal of entry
Where the pathogen is able to gain access to body tissue
Virulence
The organism’s power to overcome its host’s defenses
Dose
The number of pathogens that are invading the body
Predisposition

6. Non-specific Defenses
Chemical & Mechanical Barriers
White Blood Cells
Phagocytes
Natural Killer Cells
Inflammation Response
Fever
Interferon

7. The First Line of Defense ~Skin~
The dead, outer layer of skin, known as the epidermis, forms a shield against invaders and secretes chemicals that kill potential invaders
You shed between 40 – 50 thousand skin cells every day!

8. The First Line of Defense ~Mucus and Cilia~
As you breathe in, foreign particles and bacteria bump into mucus throughout your respiratory system and become stuck
Hair-like structures called cilia sweep this mucus into the throat for coughing or swallowing
Don’t swallowed bacteria have a good chance of infecting you?

9. The First Line of Defense ~Saliva~
What’s the first thing you do when you cut your finger?
Saliva contains many chemicals that break down bacteria
Thousands of different types of bacteria can survive these chemicals, however

10. The First Line of Defense ~Stomach Acid~
Swallowed bacteria are broken down by incredibly strong acids in the stomach that break down your food
The stomach must produce a coating of special mucus or this acid would eat through the stomach!

11. Think of the human body as a hollow plastic tube…
The food is digested within the hole in the tube, but it never actually enters into the solid plastic material.
Tube inner surface ~Digestive System~
Tube outer surface ~Skin~
Plastic interior ~Body~

12. Escherichia coli is common and plentiful in all of our digestive tracts. Why are we all not sick?
These bacteria are technically outside the body and aid in digesting material we cannot
Only if E.Coli are introduced in an unnatural manner can they break through the first line of defense and harm us

13. The Second Line of Defense ~White Blood Cells~
If invaders actually get within the body, then your white blood cells (WBCs) begin their attack
WBCs normally circulate throughout the blood, but will enter the body’s tissues if invaders are detected

14. Where could invaders hide from phagocytes?
White Blood Cells
~Phagocytes~
These white blood cells are responsible for eating foreign particles by engulfing them
Once engulfed, the phagocyte breaks the foreign particles apart in organelles called ________
Lysosomes
Where could invaders hide from phagocytes?

15. Cell before infection…
Viruses
Viruses enter body cells, hijack their organelles, and turn the cell into a virus making-factory. The cell will eventually burst, releasing thousands of viruses to infect new cells.
…and after.
Cell before infection…

16. The Second Line of Defense ~Interferon~
Virus-infected body cells release interferon when an invasion occurs
Interferon – chemical that interferes with the ability of viruses to attack other body cells
What happens to already infected cells?

17. White Blood Cells ~Natural Killer Cells~
Natural Killer (NK) Cells recognize infected human cells and cancer cells
NK Cells will attack these infected cells, quickly kill them, and then continue to search for more cells to kill

18. The Second Line of Defense ~The Inflammatory Response~
Body’s effort to get rid of anything that irritates it or, if it is not possible, limit the harmful effects of the irritant
Injured body cells release chemicals called histamines, which begin inflammatory response
Histamines cause capillaries to dilate
Pyrogens released, reach hypothalamus, and temperature rises
Pain receptors activate
WBCs flock to infected area like sharks to blood

19. The Second Line of Defense ~Fever~
An increase in body temperature above the normal range
Can be caused by pyrogens
A fever inducing substance
Fever stimulates phagocytes, increases metabolism, and decreases certain organisms’ ability to multiply

20. Immune System Overview
Part 1:
Functions
First & Second Lines of Defense
Part 2:
Third Line of Defense
Part 3:
Vaccinations
Autoimmune Disorders

21. Immunity
New particles take longer to identify, and a person remains ill until a new antibody can be crafted
Old particles are quickly recognized, and a person may never become ill from that invader again. This person is now immune.

22. Two Main Categories of Immunity
Inborn immunity – inherited along with other characteristics in a person’s genes
Acquired immunity – develops after birth
Natural
Artificial
Active
Passive

23. Inborn Immunity
Species Immunity – immunity of humans and other animals to diseases that may infect other species
Individual Immunity – a individual’s personal immunity towards specific diseases

25. Acquired Immunity
Develops during a person’s lifetime as that person encounters various specific harmful agents

26. Two Divisions of the Immune System
The efforts of the WBCs known as phagocytes and T-cells is called the cell-mediated immune system.
Protective factor = living cells
Phagocytes – eat invaders
T-cells – kill invaders

27. Types of T Cells Cytotoxic T cells – destroy foreign cells directly
Helper T cells – release substances known as interleukins that stimulate other macrophages that assist in the destruction of foreign cells
Regulatory T cells – suppress the immune response in order to prevent overactivity
Memory T cells – remember an antigen and start a rapid response if that antigen is contacted again

28. Macrophages Phagocytic white blood cells
Act as processing centers for foreign antigens
Ingest foreign proteins and break them down within phagocytic vessels

29. Two Divisions of the Immune System
The other half of the immune system is called antibody-mediated immunity, meaning that is controlled by antibodies
This represents the third line of defense in the immune system

30. The Third Line of Defense ~Antibodies~
Most infections never make it past the first and second levels of defense
Those that do are called antigens and trigger the production and release of antibodies
Proteins that latch onto, damage, clump, and slow foreign particles
Each antibody binds only to one specific binding site on the antigen, known as an antigen binding site.

31. Antigens and Antibodies
Antigen – any foreign substance that enters the body and induces an immune response
Antibody – a substance produced in response to an antigen. Manufactured by B cells.
B cells have surface receptors that bind with a specific type of antigen
Exposure to the antigen stimulates the cells to multiply rapidly and produce large numbers of plasma cells, which produce antibodies against the original antigen and release these into the blood.

32. B cells and Antibodies
Antibody (Ab) also known as immunoglobulin (Ig) is a substance produced in response to an antigen
Antibodies are manufactured by B cells
Cells must mature in fetal liver or in lymphoid tissues
B cells have surface receptors bind with specific type of antigen

33. Exposure to antigen stimulates cells to multiply and produce large numbers of plasma cells
Plasma cells produce antibodies against the original antigen and release antibodies into blood
Humoral immunity – humoral = body fluid

34. All antibodies are contained in a portion of blood plasma called gamma globulin fraction
Some antibodies produced by B cells remain in the blood and give long term immunity
Some activated B cells become memory cells

36. Antibody Production
WBCs gobble up invading particles and break them up
They show the particle pieces to T-cells, who identify the pieces and find specific B-cells to help
B-cells produce antibodies that are equipped to find that specific piece on a new particle and attach
Video - 1:58

37. Role of Macrophages
Macrophages are phagocytic WBC derived from monocytes
Act as processing centers for foreign antigens
Ingest foreign proteins such as disease organisms, and break them down within phagocytic vesicles
They then insert fragments of the foreign antigen into their plasma membrane

38. Self antigens are also known as HLA (human leukocyte antigens)
The foreign antigens are displayed on the macrophage’s surface in combination with antigens that a T cell can recognize as belonging to the “self”
Self antigens are called MHC (major histocompatability complex) antigens
Importance in cross-matching for tissue transplantation
Self antigens are also known as HLA (human leukocyte antigens)
WBCs are used in testing tissues for compatibility

39. For a T cell to react with a foreign antigen that antigen must be presented to the T cell along with the MHC proteins
A special receptor on the T cell must bind with both the MHC protein and the foreign antigen fragment

40. Activation of a helper T cell by a Macrophage

41. Activation of a helper T cell by a Macrophage – Fill in the Blanks

44. The Antigen-Antibody Reaction
The destruction of foreign cells sometimes require the enzymatic activity of a group of nonspecific proteins in the blood, together called complement.
Complement proteins are always present in the blood, but must be activated by antigen-antibody complexes or by foreign cells surfaces
Some actions of complement include:
Coats foreign cells to help phagocytes recognize and engulf them
Destroys cells by forming complexes that punch holes in plasma membranes
Promotes inflammation
Attracts phagocytes to area of inflammation

46. Naturally Acquired Immunity
Resistance to a disease through natural contact with a specific pathogen, in which case, antibodies manufactured by the infected person’s cells act against the infectious agent or its toxins.
Two types
Active Immunity
Passive Immunity

47. Active Immunity vs. Passive Immunity
You produce the antibodies
Your body has been exposed to the antigen in the past either through:
Exposure to the actual disease causing antigen – You fought it, you won, you remember it
Planned exposure to a form of the antigen that has been killed or weakened – You detected it, eliminated it, and remember it
Passive Immunity
Passive of antibodies from mother to fetus through placenta. Prolonged through breast milk.
What is this second type of exposure called?

48. Artificial Immunity The use of a vaccination or immunization
Preventative measure designed to provide protection in anticipation of invasion by a certain pathogen
Reduce virulence of pathogen before it is administered
People who are immunosuppressed and pregnant woman should not receive vaccines

49. Immune System Overview
Part 1:
Functions
First & Second Lines of Defense
Part 2:
Third Line of Defense
Part 3:
Vaccinations
Autoimmune Disorders

50. Do Now: Matching Active Immunity Passive Immunity Macrophage
Memory T-Cell
Cytotoxic T- Cell
Remember antigens of foreign invaders for future
Body creates antibodies to fight disease
Destroy foreign invaders
Phagocytic white blood cells
Antibodies given, such as through placenta

51. Vaccine
Antigens are deliberately introduced into the immune system to produce immunity
Because the pathogen has been killed or weakened (attenuated), minimal symptoms occur
Have eradicated or severely limited several diseases from the face of the Earth, such as polio and smallpox

52. How long does active immunity last?
It depends on the antigen
Some disease-causing pathogens multiply into new forms that our body doesn’t recognize, requiring annual vaccinations, like the flu shot
Booster shot - reminds the immune system of the antigen
Others last for a lifetime, such as chicken pox

53. Do we get all the possible vaccines we can?
Although the Center for Disease Control (CDC) recommends certain vaccines, many individuals go without them
Those especially susceptible include travelers and students
Consider the vaccine for meningitis, which is recommended for all college students and infects 3,000 people in the U.S., killing 300 annually
Link

54. Think the flu is no big deal?
Think again…
In 1918, a particularly deadly strain of flu, called the Spanish Influenza, spread across the globe
It infected 20% of the human population and killed 5%, which came out to be about 100 million people

55. Passive Immunity You don’t produce the antibodies
A mother will pass immunities on to her baby during pregnancy - through what organ?
These antibodies will protect the baby for a short period of time following birth while its immune system develops. What endocrine gland is responsible for this?
Lasts until antibodies die
Thymus
Placenta
Why doesn’t the mother just pass on the WBCs that “remember” the antigens?

56. Passive Immunization
May be necessary for a person who receives a large dose of virulent organisms and has no established immunity to them
Administration of an immune serum or antiserum
Gives short-lived, but effective protection against the invaders in he form of an artificially acquired passive immunity.

57. Immune Disorders ~Allergies~
Immune system mistakenly recognizes harmless foreign particles (allergens) as serious threats
Launches immune response, which causes sneezing, runny nose, and watery eyes
In serious instances anaphylaxis may occur. This involves breathing problems, swelling of the throat and tongue, edema, and decreased blood pressure with cardiac shock
Anti-histamines block effect of histamines and bring relief to allergy sufferers

58. Transplantation
Grafting to a recipient of an organ or tissue from an animal or other human to replace an injured or incompetent part of the body
Rejection syndrome caused by antigen-antibody reaction
Try to find donor that matches most of the recipients antigens
Recipients need to take drugs that suppress and immune response to the transplanted tissue

59. Autoimmunity Refers to an abnormal reactivity to one’s own tissues
Immune system reacts to body’s own antigens, described as “self,” as if they were foreign antigens, “or “nonself.”
Examples
Rhuematoid arthritis
Multiple sclerosis
Lupus erythematosus
Type I diabetes

60. Immune Deficiency Diseases
Involves some type of failure of the immune system

61. Aquired Immune Deficiency Syndrome
Caused by the Human Immunodeficiency Virus
Discovered in 1983
Specifically targets and kills T-cells
Because normal body cells are unaffected, immune response is not launched

62. AIDS ~The Modern Plague~
The HIV virus doesn’t kill you – it cripples your immune system
With your immune system shut down, common diseases that your immune system normally could defeat become life-threatening
Can show no effects for several months all the way up to 10 years

63. AIDS ~The Silent Spread~
Transmitted by sexual contact, blood transfusions, contaminated needles
As of 2007, it affects an estimated 33.2 million people

64. Immune System & Cancer
People with AIDS and other immune deficiencies develop cancer at a higher rate than normal. Suggests that cancer cells most likely form continuously in the body, but immune system recognizes them as “nonself” and kills them.
Immune surveillance – cell-mediated immunity process of overseeing “nonself” particles in the body to destroy. Declines over time.

65. Multiple Myeloma
Cancer of the blood-forming cells in bone marrow, mainly the plasma cells that produce antibodies.
Causes loss of resistance to infection, anemia, bone pain, and weakening of the bones, owing to the production of a factor that accelerates loss of bone tissue.
Treated with chemotherapy