LI 1
Describe the general functions of the lymphatic system
Lymphatic system picks up excess fluid from interstitial spaces and eventually back to the blood.
Describe how tissue fluid and lymph form, and explain the function of lymph.
Tissue fluid is formed when leftover water/dissolved substances leave the capillaries via filtration because the capillary blood pressure forces water and small molecules from the plasma. (Simple terms: Filtration of the plasma exceeds resorption, resulting in tissue fluid)
Lymph is formed when an accumulation of tissue fluid increases the tissue fluid hydrostatic pressure, allowing tissue fluid to enter lymphatic capillaries
Lymph transports foreign particles such as bacteria and viruses to lymph nodes
What is the body's third line of defense?
Immunty
Describe the major lymphatic pathways.
*Lymphatic capillaries -> Afferent lymphatic vessels -> Lymph node -> Efferent lymphatic vessels -> Lymphatic trunk -> Collecting duct -> Subclavian vein
Explain how lymphatic circulation is maintained.
Muscular activity moves lymph through lymphatic vessels. (Skeletal muscle contractions, breathing movements) (*Valves prevent backflow)
Describe a lymph node and its major functions.
Lymph nodes are bean shaped enlarged regions that are located in groups or chains along lymphatic vessels. (masses of b/t cells)
Main functions of lymph nodes include: filtering lymph and getting rid of bacteria before it returns to the blood, monitor body fluids, centers for lymphocyte production
Discuss the locations and functions of the spleen.
The spleen is in the upper left abdominal cavity, inferior to the diaphragm. (DRAW THIS!)
The spleen filters blood and removes damaged blood cells and bacteria. *Its the body's largest lymphatic organ, similar to a large lymph node but it contains BLOOD instead of lymph.
Distinguish between innate (nonspecific) and adaptive (specific) defenses.
Innate: guard against MANY types of pathogens, responds quickly (include species resistance, mechanical barriers, chemical barriers, NK cells, inflammation, phagocytosis, &fever)
Adaptive: respond only against CERTAIN pathogens, respond slowly (specialized lymphocytes that secrete cytokines or antibodies)
Discuss the locations and functions of the thymus.
The thymus is located behind the sternum and anterior to the aorta.
It secretes thymosins that influence T-lymphocyte maturation. The T-lymphocytes leave the thymus to provide immunity.
*Shrinks in size as person matures* ADD 100 POINTS IF YOU CAN ANSWER WHY THIS HAPPENS!
Explain how two major types of lymphocytes are formed and activated, and how they function in immune mechanisms
*T/B-cells
T-cells are produced in the bone marrow and mature in the thymus. They are activated once they encounter antigen presenting cells. Once activated, T-cells react directly with antigen-bearing cells. They also synthesize and secrete cytokines that enhance cellular immune responses.
B-cells are produced and mature in the bone marrow. When the B-cell encounters an antigen that matches its receptors, it binds and becomes activated. Some B-cells differentiate into plasma cells that secrete antibodies (these travel through body fluids and destroy antigens) Memory B-cells remain dormant but respond to future encounters with the antigen.
Discuss the actions of the five types of antibodies.
IgG: found in tissue fluid/plasma, defend against bacterial cells, viruses, toxins
IgA: in exocrine glands (breast milk, saliva, tears, nasal fluid, bile etc.)
IgM: in plasma when food antigens or bacteria is present, activates complement, contains Anti-A & B
IgM: on surface of most B lymphocytes, functions in B cell activation
IgE: (EMILY) on surfaces on basophils and mast cells, associated with allergic reactions
List seven innate body defense mechanisms, and describe the action of each mechanism.
Species resistance: A species is resistant to a disease that affects other species
Mechanical barriers: Prevent entry of certain pathogens by providing a physical separation between pathogens and internal tissue
Chemical barriers: Chemicals that kill certain pathogens
Inflammation: Stop spread of pathogens and infection by redness, swelling, heat and pain
NK cells: Small group of lymphocytes, defend body by secreting perforins and substances that promote inflammation
Phagocytosis: Engluf and digest pathogens, foreign particles, and debris
Fever: Provides hostile environments for pathogens by increasing internal temperature
Distinguish between active and passive immunity.
Active immunity is gained through antigen exposure, its an immune response that occurs in the body, antibodies and memory b cells are produced. LONG LASTING
Passive immunity is gained by receiving antibodies, no antigen contact & no immune response, no memory b cells produced, SHORT TERM IMMUNITY
Explain how allergic reactions, tissue rejection reactions, and autoimmunity arise from immune mechanisms.
Allergic reactions: person becomes sensitized by producing IgE antibodies in response to the presence of the allergen, IgE attaches to mast cells and basophils which release histamine and prostaglandin. Allergy mediators cause mucus production, vasodilation, and bronchoconstriction resulting in inflammation.
Tissue rejection: this can occur when a recipient's immune system doesn't recognize the transplanted tissue and reacts with foreign antigens on its surface.
Autoimmunity: when a body loses the ability to distinguish between self and non-self antigens, it turns against its own body. May develop from viral infection, faulty T-cell production or reaction to a nonself antigen that closely resembles a self antigen.
Distinguish between primary and secondary immune responses.
Primary: initial encounter, activation of B/T-cells, antibodies appear in plasma 5-10 days after exposure, IgM & IgG are released into blood, help destroy antigens for weeks
Secondary: rapid, long lasting response to re-exposure to an antigen, accomplished by memory T/B-cells, memory b-cells proliferate (make more) in 1-2 days and last for months to years