1. Lymphatics and the Immune System

2. The Lymphatic System Protects us against disease
Lymphatic system cells respond to:
Environmental pathogens
Toxins
Abnormal body cells, such as cancers

3. Lymphatic System One way system: to the heart
Return of collected excess tissue fluid
Return of leaked protein
“Lymph” is this fluid
Edema results if system blocked or surgically removed

4. Lymphoid Organs Lymph nodes Spleen Thymus Tonsils
Small intestine & appendix aggregated lymphoid nodules

6. Lymph capillaries
Picks up bacteria and viruses as well as proteins, electrolytes and fluid
(lymph nodes destroy most pathogens)

7. Specific Defenses
Lymphocytes
Part of the immune response and Identify, attack, and develop immunity to a specific pathogen

8. Organization of the Lymphatic System
A fluid similar to plasma but does not have plasma proteins
Lymphatic vessels (lymphatics)
Carry lymph from peripheral tissues to the venous system
Lymphoid tissues and lymphoid organs
Lymphocytes, phagocytes, and other immune system cells
Function of the Lymphatic System
To produce, maintain, and distribute lymphocytes
Lymphocyte Production
Lymphocytes are produced
In lymphoid tissues (e.g., tonsils)
Lymphoid organs (e.g., spleen, thymus)
In red bone marrow
Lymphocyte distribution
Detects problems
Travels into site of injury or infection

9. Lymphatic collecting vessels
Lymph capillaries
Absent from bone, bone marrow, teeth, CNS
Enter lymphatic collecting vessels
Lymphatic collecting vessels
Similar to blood vessels (3 layers), but thin & delicate
Superficial ones in skin travel with superficial veins
Deep ones of trunk and digestive viscera travel with deep arteries
Very low pressure
Drain into lymph nodes

10. Up to 1 inch in size Lymph nodes: Act as filter Removes:
Purifies lymph before return to venous circulation
Removes:
Debris
Pathogens
99% of antigens
Up to 1 inch in size

11. Lymph Nodes *
Superficial groups -Cervical -Axillary -Inguinal Deep groups -Tracheobronchial -Aortic -Iliac Drainage -Superior R 1/4 of body: R lymphatic duct (green) * -The rest: thoracic duct * *

12. Macrophages on reticular fibers consume pathogens and foreign particles
Usually pathogen free lymph enters lymph trunks

13. Types of Lymphocytes T cells B cells NK cells Thymus-dependent
Bone marrow–derived
NK cells
Natural killer cells

14. T Cells
Make up 80% of circulating lymphocytes
Main Types of T Cells
Cytotoxic T (TC) cells: Attack cells infected by viruses. Produce cell-mediated immunity
Memory T cells: Formed in response to foreign substance. Remain in body to give “immunity”
Helper T (TH) cells: Stimulate function of T cells and B cells
Suppressor T (TS) cells: Inhibit function of T cells and B cells
B Cells
Make up 10–15% of circulating lymphocytes
Differentiate (change) into plasma cells
Plasma cells. Produce and secrete antibodies (immunoglobulin proteins)
Natural Killer (NK) Cells, Also called large granular lymphocytes
Make up 5–10% of circulating lymphocytes
Responsible for immunological surveillance
Attack foreign cells, virus-infected cells, and cancer cells

15. The Immune System Recognizes specific foreign molecules
Each exposure (to the same pathogen) increases the effectivity of the response
Lymphoid organs
Lymph nodes
Spleen
Thymus
Tonsils
Small intestine & appendix aggregated lymphoid nodules

16. Basic Immunology Forms of Immunity Innate Adaptive Active Passive
Present at birth
Adaptive
After birth
Active
Antibodies develop after exposure to antigen
Passive
Antibodies are transferred from another source

17. Immunity Adaptive Immunity Innate Immunity Active Immunity
Forms of Immunity
Immunity
Response to threats on an individualized basis
Adaptive Immunity
Innate Immunity
Adaptive immunity is not present at birth; you acquire immunity to a specific antigen only when you have been exposed to that antigen or receive antibodies from another source.
Genetically determinedno prior exposure or antibody production involved
Active Immunity
Passive Immunity
Develops in response to antigen exposure
Produced by transfer of antibodies from another source
Naturally acquired active immunity
Artificially induced active immunity
Naturally acquired passive immunity
Artificially induced passive immunity
Develops after exposure to antigens in environment
Develops after administration of an antigen to prevent disease
Conferred by transfer of maternal antibodies across placenta or in breast milk
Conferred by administration of antibodies to combat infection 17

18. Immune Disorders
Autoimmune disorders: A malfunction of system that recognizes and ignores “normal” antigens, (Rheumatoid arthritis)
Immunodeficiency disease: Problems with embryological development of lymphoid tissues
Viral infections such as HIV
Can result in AIDS
Allergies: Inappropriate or excessive immune responses to antigens

19. Helpful Definitions The immune system Antigen Pathogen Tolerance
Cells in our bone marrow, thymus, and the lymphatic system of ducts and nodes, spleen, and blood that function to protect us.
Antigen
Anything causing an immune response, usually foreign material but may be our own tissues.
Pathogen
Any disease causing micro-organism.
Tolerance
Non-reactivity of the immune system, usually refers to "self" but may include foreign tissue in organ transplants.
Autoimmunity
A failure of tolerance, the immune system reacts to self.
Chemokines
Molecules released by pathogens and infected tissues to attract cells of the immune system.
Cytokines
Signaling molecules released by one cell to cause a response in another. Signaling is extremely important in our immune response.
Innate immunity
Protection that is always present. Includes phagocytic (cells that eat other cells) macrophages and dendritic cells.
Adaptive immunity
Protection that arises by an immune response, including humoral immunity producing antibodies and cellular immunity.

20. Components of the immune system
Innate immune system
Response is non-specific
Exposure leads to immediate maximal response
Cell-mediated and humoral components
No immunological memory
Found in nearly all forms of life (plants & animals)
Adaptive immune system
Pathogen and antigen specific response
Lag time between exposure and maximal response
Cell-mediated and humoral components
Exposure leads to immunologic memory
Found only in jawed vertebrates

21. Innate immunity The dominant system of host defense in most organisms
Inflammation is one of the first responses
Redness, swelling, heat and pain
Chemical and cellular response
During the acute phase of inflammation, particularly as a result of bacterial infection, neutrophils migrate toward the site of inflammation in a process called chemotaxis

22. Innate immunity continued
The innate leukocytes include the phagocytes (macrophages, neutrophils, and dendritic cells), mast cells, eosinophils, basophils, and natural killer cells
These cells identify and eliminate pathogens, either by attacking larger pathogens through contact or by engulfing and then killing microorganisms
Innate cells are also important mediators in the activation of the adaptive immune system

23. Adaptive immunity
The adaptive immune system evolved in early vertebrates and allows for a stronger immune response as well as immunological memory, where each pathogen is "remembered" by its signature antigen
Antigen specificity allows for the generation of responses that are tailored to specific pathogens or pathogen-infected cells
The ability to mount these tailored responses is maintained in the body by "memory cells“
Should a pathogen infect the body more than once, these specific memory cells are used to quickly eliminate it