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61 Cards in this Set

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  • Back
What does the lymphatic system consist of?
Lymphatic tissues and organs & lymphatic vessels.
What are the characteristics of lymph?
excess tissue fluids carried by the lymphatic vessels
When does the fluid become lymph?
When it enters the lymph vessels.
What is the primary cause for the reabsorption of the excess fluids?
Increased osmotic pressures forces water reabsorption into the capillaries and forces it into the lymph vessels.
What are the properties of lymphatic vessels?
One way system to heart. No pump
Characteristics of lymph capillaries
Walls overlap, form flap-like minivalves that close from higher pressure intracapillary to hold fluid inside. Anchored to connective tissue by filaments.
What materials are in lymph?
H2O, blood, proteins, bacteria, viruses, cancer cells, cell debris.
What do lymph nodes do?
Filter lymph before returning it to blood. Macrophages engulf and lymphocytes provide immune response to eliminate harmful products.
Lymph node structure
Kidney shaped, <1 inch long. Cortex: outer part, contains follicles (lymphocytes here). Medulla: inner part, contains macrophages.
Flow of lymph through nodes
Enters in convex side via afferent vessels, flows thru sinuses inside, exits thru efferent lymphatic vessels. More afferent than efferent vessels.
Other lymphoid organs
Spleen, thymus, tonsils, Peyer's patches (intestinal)
What does the spleen do and its location?
Filters blood, destroys worn out cells (most important function), forms blood cells in fetus, acts as blood reservoir.
Left side of abdomen
Location and function of thymus
Located low in pharynx (throat), overlying the heart. Functions at peak levels only during childhood. Produces hormones to program lymphocytes.
What do tonsils do?
Trap and remove bacteria and other foreign materials. Tonsillitis is caused by congestion w/ bacteria.
Location and function of Peyer's patches
Found in wall of small intestines. Resemble tonsils in structure, capture and destroy bacteria in intestine.
What is the immune system also known as?
Specific body defense system, for each type of invader to the body.
What are Non-specific body defense types?
Skin, mucous membranes, specialized cells, chemicals produced by the body (lysosome,cerumen), fevers.
What are the components of the first line of defense?
Skin and mucous membranes
How does the skin protect?
Physical barrier, pH is acidic, sebum is toxic to bacteria, vagial secretions are very acidic.
How do the mucous membranes protect?
Stomach mucosa: secretes HCL & pepsin (protein digesting enzyme). Saliva & lacrimal fluid contain lysozyme. Mucus traps microorganisms.
What is the 2nd line of defense?
Specialized cells and inflammatory response.
What types of cells for defense?
Phagocytes: (macrophages, neutrophils).
Natural killer (NK) cells
How do NK cells work?
Unique lymphocytes that can fight before the immune system starts. React against any target by recognizing surface sugars. Secrete surface lytic: perforin
How does the inflammatory response work?
Tissue injury triggers, chain of events leads to protection & healing. Prevents agent spread, disposes of cell debris, sets up repairs.
What are the cardinal signs of inflammatory response
Loss of function
What is a Complement?
Group of 20+ plasma proteins. Activated when they encounter & attach to cells(complement fixation) Damage foreign cell surfaces. Has vasodilators, chemotaxis, opsonization.
What does Interferon do?
Binds to healthy cells surfaces to inhibit viruses binding. Proteins of virus-infected cells, diffuse to nearby cells and bind to membrane receptors.
Higher body temperature,pyrogens reset hypothalmus heat regulation, iron & zinc release inhibited, none for bacteria growth. Increases tissue repair speed
What is the 3rd line of defense?
The immune system, specific defenses.
Antigen specific
Recognizes and act against particular foreign substances.
Is it only a local immunity?
Systemic, has memory that recognizes and mounts a stronger attack on previously encountered pathogens.
Types of Immunity
Humoral: anti-body mediated, cells produce chemicals.
Cellular: Cell-mediated, cells target virus infected cells.
What are non-self antigens?
Any substance capable of exciting the immune system and provoking an immune response.
What are self-antigens?
Cells restricted to one's own body; can attack someone else's cells if placed in another person. (Organ transplants)
Allergies (hypersensitivity)
Abnormally vigorous immune response to a "perceived" threat that damages tissue to fight off something that would be harmless to body.
Lymphocytes: Types
Originate from hemocytoblasts in red bone marrow. B-lymphocytes from bone marrow. T-lymphocytes from thymus gland. Macrophages from monocytes, widely distributed in lymphoid organs.
Humoral immune response
Primary Humoral Response.
Anti-body mediated: B-lymphocyte binds to specific antigen. Event activates large number of clones to be made from the first lymphocyte.
Humoral immune response Secondary humoral response.
Most B cells become plasma cells produce antibodies to destroy antigen. Activity lasts 4+5 days Some B cells become long lived memory cells; recognizes antigen
Secondary Response does what?
Rapid response to second antigen exposure; stronger and longer lasting.
Active Immunity
B cells encounter antigens and produce antibodies. Can be naturally or artificially acquired.
Passive Immunity
Antibodies from someone else, mother/fetus or from immune serum or gamma globulin. Memory does not occur, protection from "borrowed" antibodies.
Monoclonal Antibodies
Antibodies prepared for clinical testing or diagnostic purpose. From a single cell line. Ex: Dx for pregnancy, tx for hepatitis and rabies.
Antibodies (Immunoglobulins)
Ig's: Soluble proteins secreted by B cells, carried in blood plasma. Binds specifically to an antigen.
Antibody Structure
4 amino acid chains linked by disulfide bonds; heavy chain and light chain. Specific antigen binding sites are present.
Antibody Classes
IgM: can fix complement
IgA: found in mucus
IgD: for activation of B cells
IgG: cross placental barrier
IgE: allergies involvment
Antibody Function
Inactivate antigens by:
complement fixation, neutralization, agglutination, precipitation.
Cellular Immune Response
Antigen recognition
antigens must be presented by macrophages to a T cell.
Double recognition
T cells must recognize non-self and self antigens. After antigen binding, clones form but different classes of cells produced.
Types of T cell clones
Cytotoxic T cells
Helper T cells
Suppressor T cells
Few members of each clone are memory cells.
Cytotoxic T cells
Kill infected cells, insert a toxic chemical (perforin)
Helper T cells
Recruit other cells to fight the invaders. Interact directly w/ B cells
Suppressor T Cells
Release chemicals to suppress the activity of T&B cells. Stops the immune response to prevent uncontrolled activity.
Major types of grafts
Autografts: same person graft
Isografts: from identical twin
Allografts: unrelated person
Xenografts: from different animal species.
Organ transplants and rejection
Autografts & isografts are ideal Xenografts never work
Allografts more successful w/ close tissue match.
Types of Allergies: Immediate hypersensitivity
Triggered w/release of histamine form IgE binding to mast cells. Rx w/in seconds of allergen contact. Anaphylactic shock is dangerous, systemic response.
Types of Allergies: Delayed hypersensitivity
Triggered by lymphokine release from activated helper T cells. Symptoms apppear 1-3 days after contact w/ antigen. Ex: contact dermatitis
Disorders of Immunity: Immunodeficiencies
Production or function of immune cells or complement is abnormal. May be congenital or acquired, includes AIDS.
Autoimmune Dzs
Immune system does not recognize self or non-self antigens. Antibodies & sensitized T lymphocytes attack its own tissues.
Autoimmune Examples
Mult. Sclerosis
Myasthenia Gravis
Juvenille DM
Rheumatoid arthritis,SLE, glomerulonephritis
Self Tolerance Breakdown
Inefficient lymphocyte programming; self proteins in circulation not exposed to immune system (eggs, sperm, eye lens); cross reaction - Rheumatic fever
Developmental aspects of Lymphatic System and Body Defenses
Lymphoid organs poorly developed before birth, except thymus and spleen. No functioning lymphocytes at birth, passive immunity from mother.