The Lymphatic System and Immunity Chapter 13

Lymph and Lymph Vessels 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) Pg 338 Fig. 13.1

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. Pg 339 Fig 13.2

Lymph Nodes Filter lymph before reentering blood 2 jobs – defense and white blood cell formation Filter out bacteria and other abnormal cells by phagocytosis (vary in size from pin head to lima bean) – most are located in clusters

Prevents local infections from spreading Pg 341 – Fig. 13.4 Lymph Nodes Prevents local infections from spreading

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

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 A small lymphoid organ located in the mediastinum

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

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) (largest lymphoid organ)

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.

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. Pg 344 Fig. 13.8 Innate immunity because we are born with nonspecific defenses that do not require prior exposure.

Inflammatory Response Mediators are released Vascular Permeability Inflammatory Response Tissue Damage Occurs Blood Flow Increased # of leukocytes & mediators WBCs Page 344 Contained Destroyed Phagocytized

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 Pg 345 Table 13.1

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.

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

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. Pg 346 Fig 13.9

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 Pg 347 Fig 13.10

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