T he Lymphatic System and Immunity

1. The Lymphatic Systemand Immunity Chapter 13

2. Lymph and Lymph Vessels • Lymph • a specialized fluid formed in the tissue spaces that is transported by of specialized lymphatic vessels to eventually reenter the circulatory system. • Movement of lymph is one way • Have one way valves (like veins)

3. Lymph and Lymph Vessels • Lymphatic capillaries • permit excess tissue fluid and some other substances such as dissolved protein molecules to the leave the tissue spaces.

4. Lymph Nodes • Filter lymph before reentering blood • 2 jobs – defense and white blood cell formation • Filter out bacteria and other abnormal cells by phagocytosis

5. Lymph Nodes Prevents local infections from spreading

6. Lymph Nodes Afferent lymph vessels Efferent lymph vessels Carry lymph out of the node • Carry lymph to the node

7. Thymus Composed of lymphocytes – largest at puberty Source of lymphocytes before birth Especially important in the maturation or development, of specialized T lymphocytes (T cells). Thymus completes most of its work early in childhood and is replaced largely by fat and connective tissue – involution

8. Tonsils • Masses of lymphoid tissue • Located in the mouth and back of the throat • First line of defense from exterior

9. Spleen • Located in the upper left quadrant of the abdomen – protected by the lower ribs • Filters blood, destroys worn out RBC’s, and salvages iron found in hemoglobin • Serves as a reservoir for blood – very rich blood supply (1 pint)

10. IMMMUNE SYSTEM • The body’s defense mechanisms protect us from disease-causing microorganisms, from foreign tissue cells that may have been transplanted into our bodies, and from our own cell when they have turned malignant or cancerous.

11. Nonspecific Immunity • Is maintained by mechanisms that attack any irritant or abnormal substance that threatens the internal environment. In other words, general protection • Often called innate immunity • Ex: skin, tears, mucous membranes, etc…. • Inflammatory response – a set of nonspecific responses that often occurs in the body.

12. Mediators are released Vascular Permeability Inflammatory Response Tissue Damage Occurs Blood Flow Increased # of leukocytes & mediators WBCs Contained Destroyed Phagocytized

13. Nonspecific Immunity • Includes protective mechanisms that confer very specific protection against certain types of invaders. • Involves the memory and ability to recognize and respond to certain harmful substances or bacteria – called adaptive immunity

14. Specific Immunity • Can be either natural or artificial • Natural – is not deliberate and occurs in everyday living • Artificial – is called immunization and is deliberate exposure of the body to a potentially harmful agent.

15. Specific Immunity Active Passive When immunity to a disease that has developed in another individual or animal is transferred to an individual who was not previously immune. • When an individuals own immune system responds to a harmful agent, regardless of whether that agent was naturally or artificially encountered.

16. IMMUNE SYSTEM MOLECULES • Antibodies – protein compounds that are normally present in the body. • Have combining sites and combine with antigens • Antigens are often protein molecules imbedded in the surface membranes of invading or diseased cells. • In general, antibodies produce immunity by changing the antigens so that they cannot harm the body.

17. IMMUNE SYSTEM MOLECULES • Complement Proteins • Complement is that name used to describe a group of protein enzymes normally present in an inactive state in the blood. • Complement cascade – basically drill holes in foreign cells causing them to die

18. IMMUNE SYSTEM CELLS • Phagocytes – Neutrophils, Monocytes, and Macrophages • Lymphocytes – T-lymphocytes and B-lymphocytes