1. Chapter 23 Immune System

2. What You’ll Learn
You will describe how infections are transmitted and what causes the symptoms of diseases.
You will explain the various types of innate and acquired immune responses.
You will compare antibody and cellular immunity

3. 23.1 Infectious diseases Section Objectives:
Describe how pathogens are transmitted.
Explain what causes the symptoms of a disease.

4. What is an infectious disease?
Disease-producing agents such as bacteria, protozoans, fungi, viruses, and other parasites are called pathogens. (NOT all microorganisms are pathogens
main sources of pathogens are soil, contaminated water, and infected animals, including other people.

5. Reservoirs of pathogens

6. Transmission of disease
Pathogens can be transmitted to a host from reservoirs in four main ways: by direct contact, by an object, through the air, or by an intermediate organism called a vector.

7. Transmission of disease II
The common cold, influenza, and STDs are spread by direct contact.

8. Transmission of disease III
Bacteria and other microorganisms can be present on nonliving objects such as money, toys, or towels.
Transmission occurs when people unknowingly handle contaminated objects.

9. Transmission of disease IV
Airborne transmission of a disease can occur when a person coughs or sneezes, spreading pathogens contained in droplets of mucus into the air.

10. Transmission of disease V
Diseases transmitted by vectors are most commonly spread by insects and arthropods
malaria and the West Nile virus are transmitted by mosquitoes.
Lyme disease and Rocky Mountain spotted fever are diseases that are transmitted by ticks.
Flies also are significant vectors of disease.

11. What causes the symptoms of a disease?
When a pathogen invades your body, it encounters your immune system.
If the pathogen overcomes the defenses of your immune system, it can metabolize and multiply, causing damage to the tissues it has invaded, and even killing host cells

12. Damage to the host by viruses and bacteria
Most of the damage done to host cells by bacteria is inflicted by toxins.
These poisons can inhibit protein synthesis in the host cell, destroy blood cells and blood vessels, produce fever, or cause spasms by disrupting the nervous system.

13. Patterns of Diseases
Some diseases, such as typhoid fever, occur only occasionally in the United States.
On the other hand, many diseases are constantly present in the population-endemic disease. Ex. Common cold

14. Treating Diseases
1 way: An antibiotic is a substance produced by a microorganism that, in small amounts, will kill or inhibit the growth and reproduction of bacteria.
Your body also has its own built-in defense system— the immune system —that works to keep you healthy.

15. 23.2 The Immune System Section Objectives:
Identify the cells, tissues, and organs that make up the immune system.
Compare innate (nonspecific) and acquired (specific) immune responses.
Distinguish between antibody and cellular immunity.
Summarize the structure of the lymphatic system
Distinguish between passive and active immunity

16. Lines of defense Barriers 1st line: 2nd line: 3rd line:
broad, external defense
“walls & moats”
skin & mucus membranes
2nd line:
broad, internal defense
“patrolling soldiers”
phagocyte (eating) WBCs
3rd line:
specific, acquired immunity
“elite trained units”
lymphocyte WBCs & antibodies
B & T cells
Barriers
Non-specific patrol
Immune system

17. Innate Immunity
The body’s earliest lines of defense against any and all pathogens make up your nonspecific, innate immunity.

18. Nonspecific defense I
Lining of trachea: ciliated cells & mucus secreting cells
1st line of defense:
Skin Intact skin is a formidable physical barrier to the entrance of microorganisms
Body secretions mucus traps many microorganisms
Sweat, tears, and saliva all contain the enzyme lysozyme, which is capable of breaking down the cell walls of some bacteria

19. Nonspecific defense II
2nd line of defense
Inflammation (Inflammatory response) characterized by four symptoms—redness, swelling, pain, and heat; histamine released causes blood vessels in the injured area to dilate, (redness) which makes them more permeable to tissue fluid. Fluid that leaks from the vessels helps the body destroy toxic agents and restore homeostasis (swelling and pain, & heat)

20. Nonspecific defense V
Swelling
occurs
Tissue fluid moves
into injured area
After a few days, infected tissue harbors a collection of live and dead white blood cells, multiplying and dead pathogens, and body fluids called pus.
Pus formation usually continues until the infection subsides.
Eventually, the pus is cleared away by macrophages.
Phagocytes
Pus

21. Nonspecific defense III
2nd line of defense
Phagocytosis of pathogens white blood cells that destroy pathogens by surrounding and engulfing them.
Macrophages are white blood cells that provide the first defense against pathogens that have managed to enter the tissues.
Macrophage “eating” bacteria

22. Phagocytes white blood cells that eat macrophage bacteria macrophage
yeast

23. Fever When a local response is not enough
full body response to infection
raises body temperature
higher temperature helps in defense
slows growth of germs
helps macrophages
speeds up repair of tissues
Certain bacterial infections can induce an overwhelming systemic inflammatory response leading to a condition known as septic shock.
Characterized by high fever and low blood pressure, septic shock is the most common cause of death in U.S. critical care units.
Clearly, while local inflammation is an essential step toward healing, widespread inflammation can be devastating.

24. Nonspecific defense IV
Phagocytosis of pathogens
If the infection is not stopped by the tissue macrophages, another type of phagocyte, called a neutrophil is attracted to the site.
If the infection is not stopped by tissue macrophages and neutrophils - Monocytes

25. Nonspecific defense VI
Protective proteins:
Interferons are proteins that protect cells from viruses.
Complement: help attract phagocytes to foreign cells and help destroy foreign cells
Natural Killer cells: type of white blood cell that destroy the body's own infected cells, may attack cells that form tumors

26. The lymphatic system a network of lymphatic vessels and organs
The lymphatic system becomes a crucial battleground during infection
a network of lymphatic vessels and organs
It returns tissue fluid to the circulatory system
It fights infections
Lymph nodes are key sites for fighting infection
They are packed with lymphocytes and macrophages

27. Acquired Immunity
Defending against a specific pathogen by gradually building up a resistance to it
This acquired immune response enables these white blood cells to inactivate or destroy the pathogen.
Acquired immunity involves the production of two kinds of immune responses: antibody immunity and cellular immunity ~
your 3rd line of defense

28. Acquired Immunity SPECIFIC IMMUNITY IMMUNE RESPONSE
a recognition system that distinguishes “self” from “non-self”
responds to foreign molecules called antigens
Stimulates the body to make antibodies:
specific defensive proteins which help to counter antigens in various ways

29. How are invaders recognized?
Antigens
chemical name tags on the surface of every cell
“self” vs. “invader”
one of your own cells
disease-causing virus
disease-causing bacteria
antigens say: “I belong here”
antigens say: “I am an invader”
antigens say: “I am an invader”

30. 3rd line of defense Lymphocytes ~type of white blood cell that carry out the immune response
B lymphocyte
Two kinds
B cells secrete antibodies that attack antigens (antibody immunity)
T cells attack cells infected with pathogens (cellular immunity)

31. B cells & antibodies B cells Patrolling B cells Memory B cells
white blood cells that attack invaders in blood
mature in Bone marrow
Patrolling B cells
make antibodies against invader immediately
Memory B cells
remembers invader
can make antibodies quickly the next time
protects you from getting disease more than once

32. Antibodies
Proteins made by B cells that tag invaders in the blood so macrophages can eat them
tag says “this is an invader”  gotcha!
biological “handcuffs”
antibody attaches to antigen of invader Y
invading germs tagged with antibodies
B cells releasing antibodies Y Y
macrophage eating tagged invaders

33. Antibody Immunity
An antibody molecule has antigen-binding sites specific to the antigen
Do not posses the power to destroy antigens directly, tag and mark them for destruction by a variety of mechanisms

34. B cells immune responseY Y
B cells
release antibodies
patrol blood
forever
invader (foreign antigen) Y Y
“reserves”
memory B cells Y
B cells
recognition Y Y
10 to 17 days

35. T cells T cells mature in Thymus Helper T cells Killer T cells
sound the alarm for rest of immune system
Killer T cells
destroy infected body cells
Memory T cells
remembers invader & reacts against it again quickly
Where’s that?

36. Attack of the Killer T cells
Killer T cells destroy infected body cells
T cell binds to invaded cell
secretes perforating protein
punctures cell membrane of infected cell
cell bursts
Killer T cell
vesicle
Perforin punctures cell membrane
cell membrane
cell membrane
invaded cell

37. You need trained assassins to kill off these infected cells!
What if the attacker gets past the B cells in the blood & infects some of your cells?
You need trained assassins to kill off these infected cells! T
Attack of the Killer T cells!

38. Cellular Immunity Infected cells Perforin Pathogen engulfed by Foreign
antigen
Infected cell lyses
Macrophage
Cytotoxic T cell
Displays antigens
on surface and
stimulates T cell
Attacks infected
cell
Stimulates
Cytotoxic T cell
Helper T cell

39. Immune response invader skin skin invaders in body invaders in blood
invaders infect cells
macrophages
B cells
helper T cells
T cells
patrolling B cells
memory B cells
memory T cells
killer T cells Y
antibodies Y
antibodies

40. Passive and Active Immunity
Acquired immunity to a disease may be either passive or active.

41. Passive Immunity
Passive: short term, antibodies passed on, not stimulated by antigens,
acquired naturally by placenta or breast milk or
artificially acquired by a shot

42. Active Immunity
Active: long term, conferred by actual encounter with infection (naturally acquired) or vaccination *(artificially acquired)
* vaccine~ substance consisting of weakened, dead, ,or parts of pathogen or antigen that when injected , stimulates the immune system

43. 23.3 Noninfectious disorders
Section objective:
Describe categories od noninfectious disease

44. Noninfectious disorders
Genetic disorders
Caused by the inheritance of genes that do not function properly
ex: sickle cell anemia, hemophilia, cystic fibrosis

45. Noninfectious disorders
Degenerative diseases~ result of a part of the body wearing out ex: degenerative arthritis
Metabolic diseases~ results in an error in a biochemical pathway
Cancer~ abnormal cell growth

46. DISORDERS OF THE IMMUNE SYSTEM
Allergies are overreactions to certain environmental antigens called
allergens : Ex. Animal dander, dust mites, pollen
release of histamine causes symptoms: sneezing, increased mucus production in the nasal passages, and redness.
Antihistamines can relieve symptoms

47. DISORDERS OF THE IMMUNE SYSTEM
Rheumatoid arthritis
Autoimmune diseases
immune system also can mistakenly attack the body’s own tissues
Examples: Rheumatic fever, Type I Diabetes, Multiple Sclerosis, Rheumatoid arthritis, Lupus

48. DISORDERS OF THE IMMUNE SYSTEM
HIV on a lymphocyte
Immunodeficiency diseases
Immune components are lacking, and infections recur
Ex: Acquired immune deficiency syndrome (AIDS)
SCIDS

49. AIDS HIV (Human Immunodeficiency Virus) the virus that causes AIDS
HIV is transmitted mainly in blood and semen
HIV kills helper T-cells and leads to AIDS

50. Attacking transplanted tissue.
T cells and antibodies also can attack transplanted tissue, such as a transplanted kidney, that comes from a source outside the body.