1. Lymphatic System and Immunity

2. Function of the Immune System
Fight off infection by keeping foreign (not suppose to be there) cells OUTSIDE the body and by making cells that kill those bad cells if they get in.

3. Lymphatic Pathways
Lymphatic capillaries – microscopic, closed – ended tubes, thin walls make it possible for fluid to enter the lymphatic capillaries
Fluid = lymph
Lymphatic vessels – similar to veins but thinner
Large lymphatic vessels lead to lymph nodes then lead to lymphatic trunks

4. Lymph Nodes
Lymphocytes and Macrophages – fight invading microorganisms
Hilum – where blood vessels and nerves join
Nodule – masses of lymphocytes and macrophages
Sinus – allow for lymph circulation

5. Lymph Nodes Located throughout the body, not found in the CNS.
Functions:
Filter potentially harmful particles from lymph before returning it to the bloodstream
Immune surveillance –
(Lymphocytes attack what is brought to the nodes, macrophages engulf and destroy foreign substances, damaged cells, and debris)

6. Thymus and Spleen Thymus Spleen Shrinks after puberty
Produces T cells which provide immunity
Secretes Thymosin which stimulates the maturation of T cells
Spleen
Contains many macrophages which filter foreign particles and damaged RBCs from the blood

7. Types of Defenses
Pathogen – (disease causing agent) which causes infection.
Nonspecific - guards against everything equally; does not pick and choose
Specific - targets individual (one type of) invaders

8. First Line of Defense Skin & mucous membrane secretions sweat tears
pH 3-5
tears
washing action
mucus
traps microbes
saliva
anti-bacterial = “lick your wounds”
stomach acid
pH 2
anti-microbial proteins
lysozyme enzyme
digests bacterial cell walls

9. Second line of defense
Fever – high body temp. causes liver and spleen seize iron (bacteria and fungi require more iron as the temp. increases so their growth is decreased) and phagocytic cells work more vigorously with increased temps.
Inflammation – increases blood volume, infected cells release chemicals that attract WBCs to engulf pathogens
Phagocytosis – millions of WBCs released (neutrophils and monocytes)

10. Third line of defense - SPECIFIC
Antigens – chemical that stimulates cells to produce antibodies
T cells
Origin: Red bone marrow, mature in the thymus
Function: provide cell mediated immunity in which T cells interact directly with the antigens
B cells
Origin: Red bone marrow
Function: provide antibody mediated immunity in which B cells interact indirectly, producing antibodies that destroy the antigen

11. Specific Defense: Humoral Immunity (B Cells)
B cells recognize antigens
B cells make antibodies
Antibodies recognize and bind (connect) to antigens to kill/inactivate them
Memory B cells also made to help fight off future invasions faster

12. Specific Defense: Cell-mediated immunity
The Last Line
If the pathogen gets by all other defenses and into the cell, this is how to solve the problem:
Killer T cells track down and destroy cells with antigens inside
Memory T cells are made to recognize antigen if it invades again

13. Specific Defenses
T cell activation
B cell activation

14. Types of Antibodies
IgG – effective against bacteria, viruses, and toxins
IgA – found in breast milk, tears, nasal fluid, gastric and intestinal juices, bile, and urine (stops bacteria from adhering to host cells and from forming colonies on mucous membranes)
IgM – develops in blood plasma (anti-A, anti-B)
IgD – activating B cells
IgE – appears in exocrine gland secretions associated with allergic reactions

15. How Antibodies Work!

16. Antibody Actions
Direct Attack – antibodies combine with antigens and cause them to clump together or they form insoluble substances.
Antibodies cover the toxic parts of antigen molecules and neutralize their effects.

17. Immune Responses Primary Immune Response Secondary Immune Response
B cells and T cells are activated after first encountering antigens
Antibodies are released and transported throughout the blood
Secondary Immune Response
Memory B cells and memory T cells are produced

18. Types of Acquired Immunity
Active immunity – a person produces an immune response
Naturally acquired active immunity – a person is exposed to a pathogen and develops a disease
Vaccine – artificially acquired active immunity
Passive immunity – a person receives antibodies produced by another individual
Artificially acquired passive immunity – antiserum
Naturally acquired passive immunity – maternal blood into the fetal bloodstream provides the baby with immunities from the mother for about 6-12 months

19. Allergic Reactions
Allergens – antigens that trigger allergic responses
Allergic reactions can damage tissues
Delayed – reaction allergy activate T cells
Immediate – reaction allergy activate B cells

20. Transplants
Danger – the recipients immune cells may recognize the donor’s tissues as foreign and attempt to destroy the transplanted tissue = tissue rejection reaction
Resembles cell-mediated response
Immunosuppressive drugs – reduce rejection of transplanted tissues by interfering with the recipient’s immune response, it suppresses the formation of antibodies and the production of T cells = weakened immune system!

21. Autoimmunity Autoimmunity = attack against self
The immune system fails to distinguish self from nonself, producing autoantibodies and cytotoxic T cells that attack and damage tissues and organs

22. Scenario 1: Non-specific
Its Monday. The teacher has moved your seat. Your new neighbor smells like he hasn’t showered in weeks. In the middle of lecture your neighbor falls asleep and unfortunately, his body slumps over onto yours. His drool and snot gets all over your arm.
Describe your body’s first line of defense.

23. Scenario 2: Specific
Its Tuesday. Thanks to your first line of defense you have survived David the Drooler. But, unfortunately for you, Melvin was absent the day his kindergarten teacher discussed not walking around with scissors. During an activity Melvin trips over someone’s soccer equipment bag and stabs you right in the arm with a pair of scissors! Oh no! The scissors are loaded with germs! The germs have clearly gotten past your first line of defense.
Describe your body’s second line of defense.

24. Cartoon Creation
YOU (individually) will turn in a cartoon depicting the different types of cells in your immune system.
Half = Specific; other half of the room = non-specific