The L- atic system and immunity

1. The L-atic system and immunity Chapter 14

2. Organization of the L-atic system • Vessels L-atic vessels, or L-atics – go from peripheral tissues and end at connections to the venous system. • Fluids L – resembles plasma, but with a lower concentration of proteins • L-ocytes specialized cells that perform varied, specific functions in the body 4.L-oid tissues and organs L-oidtissues – collections of loose connective tissue and L-ocytes. These are in structures called L-oid nodules (e.g. the tonsils). L-oid organs – more complex structures, contain large numbers of L-ocytes and are connected to L-atic vessels (e.g. spleen).

3. Organization of the L-atic system • Functions of the L-atic system (454) • The production, maintenance, and distribution of L-cytes • The return of fluid and solutes from peripheral tissues to the blood. • The distribution of hormones, nutrients, and waste products from their tissues of origin to the general circulation

4. Organization of the L-atic system • L-ATIC VESSELS • Lymphatic capillaries • Thoracic duct • Right lymphatic duct Blockage of the lymphatic drainage from a limb can cause a limb to swell due to the accumulation of interstitial fluid. This is called lymphedema.

5. Organization of the L-atic system L-OCYTES • Respond to the presence of • 1) invading pathogens (e.g. bacteria, viruses) • 2) abnormal body cells (e.g. virus-infected cells, cancer cells) • 3) foreign proteins, such as the toxins produced by some bacteria • Respond through a combo of physical and chemical actions. • Specific defenses of the body are known as an immune response. • Immunity is the body’s ability to resist infection and disease through the activation of specific defenses.

6. Organization of the L-atic system L-OCYTES • Migrate throughout the body. • Have relatively long lifespans. • Roughly 80% live for 4 years. • Some live up to 20+ years. • 3 Classes: • TCells • Thymus-dependent • ~80% • BCells • Bone marrow-dependent • 10-15% • NK Cells • Natural Killer cells • 5-10%

7. Organization of the L-atic system L- NODULES • Pharynx • The 5 Tonsils • Intestines • Peyer’s patch • Appendix Tonsillitis, appendicitis

8. Organization of the L-atic system • L-OID ORGANS: • L- nodes • Thymus • Spleen

9. Organization of the L-atic system • L- NODES • Filter and purify the L- before it reaches the venous system. • At least 99% of antigens are removed. • Their detection and removal stimulates T and B cells, initiating an immune response. • THYMUS • Site of T-cell production and maturation. • Lobules • Thymosins, produced in each lobule, stimulate cell divisions and T-cell maturation. • Septae (septum; walls) • SPLEEN • Largest collection of L-oid tissue in the body. • Filters blood, not L- • Stores Fe • Removes abnormal blood cells

10. Roles of the l-atic system in body defenses 1. Nonspecific defenses  nonspecific resistance • Physical barriers • Phagocytic cells • Immunological surveillance • Interferons • Complement • Inflammation • Fever 2. Specific defenses  specific resistance • dependent on L-ocyte activity

11. Roles of the l-atic system in body defenses • Physical barriers • The skin and hair (integument) and inner linings • Secretions • Flush away microorganisms and chemical agents • Contain lysosomes (destructive enzymes), specific pH, antibodies • Phagocytic cells • First line of cellular defense • Microphages • Neutrophils and eosinophils • Macrophages • Can be free or fixed • Some have special names in some organs (e.g. microglia in CNS, Kupffer cells in and around the liver) • Can move via diapedesis or attracted/repelled via chemotaxis

12. Roles of the l-atic system in body defenses • Immunological Surveillance • Constant monitoring of tissues involving NK cells • Kill via perforins, which perforates the cell membrane in the abnormal cell • Cell escape can cause cancer cells to multiply and spread unabated • Interferons • Released by activated l-ocytes, macrophages, and virus-infected tissue cells • Example of cytokines – chemical messengers • Complement • Plasma has 11 special complement proteins • Complement activation is known to • Attract phagocytes • Stimulate phagocytosis • Destroy cell membranes • Promote inflammation

13. Roles of the l-atic system in body defenses • Inflammation • Inflammatory response • Mast cells are pivotal here • Purposes: • Temporary repair and prevent further pathogen access • Slow pathogen spread from the injury site • Mobilize defenses and aid permanent tissue repair (regeneration) • Cell death • Necrosis • Organized cell death (of injured cells) • Pus • Debris and dead cells • Accumulation in a closed space is an abscess

14. Roles of the l-atic system in body defenses • Fever • Inflammatory response • Pyrogens (fire-makers) reset the hypothalamus’ thermostat • Normally 99°-104° F • This can be beneficial – speeds up metabolism and chemical reactions

15. SPECIFIC DEFENSES: THE IMMUNE RESPONSE • Specific resistance/immunity: • Cellular/Cell-mediated • Abnormal cells • Pathogens in living cells • Humoral/Antibody-mediated • Antigens • Pathogens in fluids • Why would anti-bodies be humoral?

16. SPECIFIC DEFENSES: THE IMMUNE RESPONSE • Types of immunity • Innate • Genetic (i.e. people don’t get the same diseases as goldfish) • Acquired • Not present at birth • Arises by either means: • Active • Passive

17. SPECIFIC DEFENSES: THE IMMUNE RESPONSE • Acquired - ANTIBODIES • Active • Like preventative maintenance; you are actively seeking out protection • Appears after exposure to antigens • NATURALLY ACQUIRED • Exposure to antigens naturally • Like vocab development • INDUCED • Exposure to vaccines (immunization/vaccination) before infection • Passive • Happens to you after the fact • Mechanical xfer of antibodies to an individual • NATRUALLY ACQUIRED • Mom to baby • INDUCED • Exposure to antibodies after infection

18. SPECIFIC DEFENSES: THE IMMUNE RESPONSE 2. Properties of immunity Specificity – antigen recognition Versatility – confront any antigen at ant time Memory – memory cells Tolerance – ignores certain cells (e.g. your own cells)

19. SPECIFIC DEFENSES: THE IMMUNE RESPONSE 3. An overview of the immune response • to pathogens, abnormal cells, foreign molecules… inactivateor destroy

20. SPECIFIC DEFENSES: THE IMMUNE RESPONSE 4. T Cells and Cell-mediated immunity Cytotoxic Helper Memory Suppressor

21. SPECIFIC DEFENSES: THE IMMUNE RESPONSE 5. B Cells and antibody-mediated immunity B Cell sensitization and activation Antibody structure immunoglobulins – IgG

22. SPECIFIC DEFENSES: THE IMMUNE RESPONSE 6. Hormones of the immune system