1. Chapter 26: Immunity and Health
Learning Objectives:
Understand the different ways that the body protects you against pathogens.
Describe how immunity develops after exposure to the pathogen.
Disorders related the immune system
Allergy
Red itchy bump
Cold and fever

2. The Immune System
The human immune system provides protection against an enormous variety of pathogens, including many bacteria, fungi, viruses and parasitic protists and worms.
Figure 26-3 Examples of the foreign, “non-self” microbes and viruses that can harm the body.

3. The Three Divisions of the Immune System Are Collaborative
Our immune system protects us in three ways.
Physical barriers provide the first defense against pathogens, keeping them out of the body.
Non-specific immunity is the part of the immune system that provides defense when pathogens make it past the physical barriers and into the body. These immune cells rapidly recognize and attack any and all pathogens that enter the body.
Specific immunity is the division of the immune system that deals with pathogens that have been missed by the non-specific system or cannot be overcome by that system. It recognizes specific pathogens and forms a memory of each.

4. DIVISIONS OF THE IMMUNE SYSTEM
PHYSICAL BARRIERS & SECRETIONS
- Skin
- Mucus, sweat
- Acid
- Lysozymes (saliva,tears)
- Cilia
- Ear wax
Pathogens
Innate immunity
Skin
Pathogens
NON-SPECIFIC IMMUNITY
Phagocytes
- Natural Killer Cells
-Mast cells
- Basophils
- Complement proteins
Non-specific immune system cells
Innate immunity
White blood cells
Pathogens
SPECIFIC IMMUNITY (ACQUIRED IMMUNITY)
- Lymphocytes
Acquired immunity
Specific immune system cells

5. Non-specific immunity Responding to Pathogens
Recognition followed by a call for “backup”
In response to a pathogen entering the body, immune system cells recognize and bind to molecules on the surface of the pathogen, marking the pathogen as foreign. Cytokines are then released to draw more immune cells to the site of the infection. Specialized immune cells then destroy pathogens and any infected cells.
Figure 26-8 Sometimes the security measures fail. The body recognizes and responds to invading pathogens.

6. THE WHITE BLOOD CELLS OF NON-SPECIFIC IMMUNITY
NEUTROPHILS
Phagocytic cells that ingest bacteria
Both pathogens and neutrophils are destroyed
MACROPHAGES
ingest pathogens and dead cells
Present pieces of pathogens on their surface
Pathogens
DENDRITIC CELLS
Phagocytic cells that present ingested pathogens to cells of the specific immune system
NATURAL KILLER (NK) CELLS
Kill body cells infected by viruses by making holes in the cell membranes
Also kills cancer cells
Infected cell

7. Natural Killer Cells
Natural killer (NK) cells, make holes by help of enzymes in the membranes of virus-infected cells and thus kill the virus infected cells
Figure 26-9 Attacking cancer. Natural killer cells are attaching to a cancer cell.

8. Complement Proteins
The nonspecific system can also quickly recognize and destroy invaders thanks to some circulating defensive proteins, collectively called complement proteins.
The proteins help stick to the pathogens and increase the ability of phagocytes to consume them
The proteins blast holes in the membranes of pathogens, allowing water to rush inward, and causes the pathogen to burst

9. Which describes the second line of defense?
The second line of defense includes acid secretions and skin bacteria.
The skin is the major organ of the second line of defense.
C. The second line of defense keeps most pathogens out of the body.
D. The pathogens that enter the body encounter the second line of defense
Ans: D

10. THE INFLAMMATORY RESPONSE (non-specific defense)
Macrophages 1
Cytokines
Macrophages in tissues engulf pathogens and release cytokines
Basophils in blood and mast cells in tissues release histamine
Histamine causes blood vessels to dilate causing neutrophils to exit blood
The response continues till pathogen is eliminated
Pathogens 2
Blood vessel
Mast cells 3 4
Basophils
Basophils circulate in the blood and mast cells found in tissue trigger histamine release
Histamine 5
Neutrophils 6
Inflammatory response causes redness, heat, swelling, and pain, but ultimately leads to tissue healing.
Basophils, which circulate in the ______, and mast cells, found in ______, trigger histamine release

11. Hygiene hypothesis Is Fever helpful for the immune system? A. Yes
B. No
Chemicals released by immune system cells can trigger a fever, which can inhibit pathogen growth.
Hygiene hypothesis
Exposure to germs at childhood builds immunity

12. “Complement protein” is part of a non-specific defense. What does it do?
A. prevents virus reproduction
B. forms holes in bacteria
C. attracts white blood cells to an injury
D. coats pathogens so they can’t infect cells
Ans: b

13. Specific immunity develops after exposure to pathogens
A state of long-term protection against a specific pathogen.
The memory of the specific division of the immune system results in immunity, a state of long-term protection against a specific pathogen.
There are two ways in which we can acquire immunity to a particular pathogen. The first is to become sick with the disease. The second is through a vaccine…

14. Antigens and Antibodies
An antigen is any molecule that induces a specific immune response.
The body responds to antigens by making antibodies, circulating proteins that recognize specific antigens.
Let’s investigate how the immune system recognizes and responds to pathogens.

15. An antigen is ___ Any immune system protein
Any substance that elicits an immune response
Any cell that functions in the immune system
The ultimate product of vaccination
A particular kind of lymphocyte
Ans: B

16. A vaccine can contain the entire pathogen
(inactivated or attenuated) or
it can contain just the antigenic components or a piece of DNA that codes for a gene in the pathogen
Attenuated: weakened but live
Vaccine
Entire pathogen
antigen
DNA vaccine
Inactivated (killed)
Attenuated (weakened)

17. Small pox (Eradicated)
Edward Jenner ( )
Discovered/promoted small pox vaccine in 1796
By late 1970s small pox eradicated
jonas salk

18. Get A Flu Shot Every Year . . .
A virus, for example the flu virus inside the body, is constantly changing, to make it more resistant to its surroundings—for survival. The virus, therefore, will have a different set of antigens, when it changes, demanding different vaccines each flu season.
Figure Because the influenza virus changes so rapidly, flu vaccinations need to be given annually.

19. Lymphocytes are responsible for specific immunity
Two types of lymphocytes are
B Cells and T Cells
Both develop in the bone marrow.
T cells leave the bone marrow and continue to mature in the thymus.
B cells mature in the bone marrow.

20. Lymphocytes Fight Pathogens on Two Fronts
Humoral and cell-mediated immunity.
B CELLS Are responsible for Antibody- Mediated (humoral) Immunity
T CELLS
Are responsible for Cell-Mediated Immunity
The specific immune response system works in two ways, through a humoral response and through cell-mediated immunity. The humoral response (also called antibody-mediated immunity) protects against pathogens in body fluids, such as blood and lymph, and engages B cells. Cell-mediated immunity is accomplished by T cells and protects against invaders in body cells. These cells are only produced when the pathogen is encountered.

21. Specific Immunity Responses:
Antibody–Mediated (humoral immunity) :
B cells: antibodies produced; bind to “free antigens” and destroy pathogens.
Cell–Mediated :
Cytotoxic T cells: destroys infected body cells and tumor cells
Helper T cells: release cytokines that stimulate all lymphocytes.

22. THE PRIMARY RESPONSE TO INFECTION1
RECOGNITION
When a lymphocyte comes into contact with the antigen specific to its receptor, the cell initiates a response that leads to the destruction of the antigen.
Antigens
Antigen receptor
Lymphocyte 2
CLONAL SELECTION
The lymphocyte divides numerous times, creating two populations of cells with the same antigen specificity. 3
EFFECTOR CELLS ATTACK
Effector cells immediately take action, leading to the destruction of the antigen.
Effector cells 4
MEMORY CELL PRODUCTION
Memory cells remember the antigen so that if the body is infected with the same antigen in the future, they will be ready to respond.

23. Strength and Speed of Antibody Responses
Why is there such a difference?
Secondary response
Antibody levels
Primary response
1st Exposure to chicken pox
2nd Exposure to chicken pox
Time

24. What do B cells do? A. produce antibodies B. signal other immune cells
C. eat pathogens
D. kill infected cells
Ans: A

25. Antibody structure
All antibodies are Y-shaped, and their diversity and specificity come from variations in the top of the “Y.”
Each antibody consists of four polypeptide chains joined together: two long (also called heavy) chains and two short (or light) chains
Immunoglobins (Ig’s)
Classes: IgG, IgM, IgE, IgA, IgD

26. How Do Antibodies Work?
Antibodies function in several ways to help destroy pathogens and free-floating antigens.
phagocyte signaling
antigen clumping
prevention of cell entry
complement protein signaling

27. Preventing flu: Scientists find bacteria in Japanese pickled turnips which could boost immune system
Pickled turnip suguki has bacteria which helps make antibodies for flu
Letters in applied microbiology

28. The cowpox virus is an effective vaccine for smallpox because the ____ it elicits also recognizes smallpox virus
Antigens
Antibodies
Lysozymes
enzymes
Talk to them about how antibodies are the anitgen receptors
Ans: B

29. Antivenom given to patients of snake bites is a passive type of immunity
True
False
Ans: A

30. offers immediate protection)
Passive Immunity
(short term
offers immediate protection)
Antibodies produced by the mother is passed to the baby through breast milk and protects the baby for the first few months of life.
Antibody injections

31. Active Immunity (exposed to the pathogen) Artificial
(long term; body makes own antibodies) Natural
(exposed to the pathogen)
Artificial
(Achieved with vaccines)

32. T Cells provide cell mediated immunity
Two types of T cells
Cytotoxic T cells (killer T cells)- effectors of the cell mediated response; they directly kill cells infected with pathogens.
2. Helper T cells - do not directly kill infected cells but, instead, stimulate other immune cells.
required in the stimulation of B cells to produce antibodies and of cytotoxic T cells to kill infected cells

33. The specific immune response involves a T cell-mediated response, because antibodies just aren’t enough.
Here’s an example of how Helper T cells and cytotoxic T cells work together to recognize and respond to pathogens (Figure 26-26):
Presentation and recognition An antigen-presenting cell displays digested particles of a virus to a helper T cell that recognizes the viral antigen being presented.
Activation Binding to the antigen-presenting cell causes the helper T cell to produce cytokines, activating cytotoxic T cells (as well as the B cells of the humoral response).
Clonal expansion Both helper T cells and cytotoxic T cells undergo clonal expansion, producing vast amounts of memory and effector cells with specificity for the viral antigen.
Maturation Other cytokines produced by the helper T cells make the cytotoxic T cells mature and ready to fight the pathogen.
Destruction Mature cytotoxic T cells circulate throughout the body, destroying cells infected with the specific viral antigen.

34. How Do Cytotoxic Effector Cells Fight the Internal Pathogen?
They kill the infected cell.
They use proteins (perforins) to destroy the cell membrane or promote apoptosis, or programmed cell death.

35. “Cytotoxic” or “Killer” T-cells bind to infected cells and releases perforin that lyse (rupture) the infected cell

36. Helper T cells activate other cells
Killer
T cell
attacks
infected
cells
Interleukin-2
stimulates
cell division
and activates
other cells
Helper T cell
Interleukin-2
APC
secretes
antibodies
B cell
Interleukin-1
activates helper T cell

37. Activated helper T cells secrete IL-2 which helps
● make more effector helper T cells and memory helper T cells ● activate B cells ● activate killer T (cytotoxic T) cells
Interleukin 2 (IL-2) therapy
IL-2 is a drug (protein) approved by FDA for kidney cancer
Made by genetically engineered bacteria
Immunotherapy for cancer cells
Provenge® for prostrate cancer (dendritic cells)
Vaccines for cancer:
HPV: Human Papilloma Virus causes cervical cancer
Hepatitis virus: increases risk of liver cancer

38. This cell alerts the specific immune system by presenting pieces of the pathogen on its cell membrane.
Neutrophil
Macrophage
mast cells
natural killer (NK) cells
Basophil
Answer: B

39. Immune system disorders
Autoimmune diseases: Rheumatoid arthritis, type I diabetes, Multiple sclerosis (MS)
Immunodeficient disease: SCID (bubble boy), Hodgkin’s disease (type of cancer), AIDS
Allergies
Cancer

40. Autoimmune diseases
Type 1 diabetes is an autoimmune disorder in which cytotoxic T cells destroy one’s own pancreatic cells.
Healthy pancreatic cells
Multiple sclerosis: Immune cells destroy the Myelin sheath surrounding the nerve cell
Cytotoxic T cells
Multiple sclerosis is the result of an autoimmune attack on the insulation that surrounds the nerve fibers of the brain and spinal cord.
Rheumatoid arthritis: cartilage cells are destroyed in joints

41. IMMUNE SYSTEM DEFICIENCY: HIV
AIDS
B cell
Without helper T cells, B cells and cytotoxic T cells cannot be activated.
Helper
T cell
Common pathogens that are normally kept at bay in a healthy individual lead to serious illness and, ultimately, death.
Cytotoxic T cell
Common pathogens

42. HIV selectively targets Helper T cells; when too many helper T cells are lost, killer T cells and B cells are less active. This results in weak immune system and AIDS

43. Allergies are an inappropriate immune response to a harmless substance
Allergens introduce a humoral response
Allergies are an inappropriate immune response to what should be a harmless substance.
Allergens are antigens that causes an allergic response
An allergic reaction begins with a normal humoral response. Antibodies bind to mast cells in response to the allergen. Allergens then stick to these antibodies, triggering a histamine response, and inflammation ensues—hence, the allergic reaction. Taking an antihistamine can alleviate some allergies by blocking the inflammatory effects of histamine.