Lymphatic System Flashcards
Lymphatic system
network of vessels that assist in circulating body fluids away from interstitial spaces and into the bloodstream.
Pathogens
Disease causing agents
Lymphatic pathways
Lymphatic capillaries, microscopic closed ended tubes, simple squamous epithelium, interstitial fluid passes through epithelium and into the capillaries.
Lymphatic capillaries
In small intestine absorb fats and transport them to venous circulation
Tissue fluid and Lymph
Same composition as blood plasma (nutrients, gases and hormones) but no plasma proteins because they are usually too large to pass through capillaries by filtration.
Lymphatic vessels
Walls are composed of 3 layers; an endothelial lining, a middle layer of smooth muscle and elastic fibers and an outer layer of connective tissue. semilunar valves which help prevent backflow of lymph.
Lymph nodes
Filter foreign particles from lymph before returning it to bloodstream. monitor body fluids for foreign particles, along with bone marrow they are site for lymphocyte production, lymphocytes attack viruses, bacteria and parasitic cells that lymphatic vessels bring to nodes, macrophages engulf and destroy foreign substances, damaged cells and cellular debris.
Lymphatic trunks and collecting ducts
Lymph enters the venous system and becomes part of plasma before blood returns to right atrium.
Thoracic duct
Drains lymph from the intestinal, lumbar, and intercostal trunks, left subclavian left jugular and left bronchomediastinal trunks emptying them into the left subclavian vein near the junction of the left jugular vein.
Right lymphatic duct
Drains fluid from the right jugular, right subclavian and right bronchomediastinal trunks emptying them into the right subclavian vein near the junction of the right jugular vein.
Hilum
Portion of a lymph node connected to blood vessels and nerves
Lymph nodules
Compartments within the node that are partitioned by connective tissue and contain actively lymphocytes and macrophages (structural unit of a lymph node)
Lymph sinuses
Spaces in a lymph node providing a complex network of chambers and channels through which lymph circulates.
Cervical region lymph nodes
drain the skin of the scalp and face, scalp, nasal passages and pharynx.
Axillary region lymph nodes
drain the upper limbs, the wall of the thorax, the mammary glands and the upper wall of abdomen
Supratrochlear region lymph nodes
superficially on the medial side of the elbow. Drains hands and forearms
Inguinal region lymph nodes
Drain lower limbs, the external genitalia, and the lower abdominal wall.
Pelvic cavity lymph nodes
Drain pelvic region
Abdominal cavity lymph nodes
Drain abdominal viscera.
Thoracic cavity lymph nodes
Drain thoracic viscera and internal wall of the thorax.
Two other lymphatic organs whose functions are similar to those of the lymph nodes
Thymus and spleen
T lymphocytes (T cells)
Thymocytes that mature and leave the thymus and provide immunity.
Thymus
Larger in children, shrinks after puberty and is quite small in adults. Lobules contain many lymphocytes (developed in bone marrow) most of which are inactive (thymocytes- some mature into T lymphocytes and leave the thymus)
Spleen
Largest lymphatic organ. Blood reservoir houses macrophages that remove foreign particles, damaged red blood cells, and cellular debris from the blood; contains lymphocytes.
Innate defense
Include species resistance, mechanical barriers, chemical barriers ( enzyme action, interferon, and complement), natural killer cells, inflammation, phagocytosis, and fever. Respond rapidly.
Adaptive defense
More directed responses are carried out by specialized lymphocytes that recognize foreign molecules (nonself antigens) in the body and act against them. Adaptive defense are slower to respond.
Defensins
Peptides produced by neutrophils and other types of granular white blood cells in the intestinal epithelium, the urogenital tract, the kidneys, and the skin.
Collectins
Proteins that provide broad protection against bacteria, yeasts, and some viruses.
Complement
A group of proteins (complement system) in plasma and other body fluids, that interact in a series of reactions or cascade.
Mononuclear phagocytic system
Formed by monocytes, macrophages, and neutrophils. (Reticuloendothelial system)
Species resistance
Species is resistant to certain diseases to which other species are susceptible.
Immunity
Third line of defense. Based upon the ability to distinguish molecules that are part if the body (self) from those that are not (foreign)
Mechanical barriers
Skin sloughs off removing superficial bacteria. Mucous membranes lining the passageways of respiratory, digestive, urinary and reproductive systems.
Chemical barriers
Body fluids contain enzymes and chemicals that degrade pathogens. Stomach- hydrochloric acid and pepsin (protease), tears- lysozyme, skin - salt in sweat, interferons-hormone like peptide produced by cells (lymphocytes and fibroblasts)
Natural killer cells
Distinct type of lymphocyte that secretes perforins that lyse virus-infected cells and cancer cells.
Inflammation
A tissue response to injury that helps prevent the spread of infectious agents into nearby tissues.
Phagocytosis
Cells in lymph, blood, spleen, liver, or bone marrow engulf foreign material. Injured tissue secretes chemicals that attract phagocytes (chemotaxis), neutrophils engulf smaller particles, monocytes give rise to macrophages which become fixed in tissues or attach to the inner walls of lymph and blood vessels. Engulf large particles
Fever
Elevated body temperature inhibits microbial growth and increases phagocytic activity.
Antigens
Molecules that elicit an immune response.
Hapten
A smaller molecule that cannot by itself stimulate an immune response combines with a larger one, which makes it able to do so.
B lymphocytes or B cells
Humoral immune response
Clone
Genetically identical cells originating from division of a single cell.
Antigen presenting cell
Accessory cell, macrophages, B cells, and several other cell types can be antigen-presenting cells.
Major histocompatibility complex (MHC) or human leukocyte antigens (HLA)
Antigens that help T cells recognize that an antigen is foreign, not self. Class I MHC antigens are in cell membranes of all body cells except red blood cells. Class II MHC antigens are on the surfaces of antigen presenting cells, thymus cells, and activated T cells.
Cellular immune response
Activated T cells that interact directly with the antigen presenting cell.
Cytokines
T cells (and some macrophages) that synthesize and secrete polypeptides which enhance certain cellular responses to antigens.
Colony stimulating factors
Stimulate bone marrow to produce lymphocytes
Interferons
Block viral replication, stimulate macrophages to engulf viruses, stimulate B cells to produce antibodies, attack cancer cells.
Interleukins
Control lymphocyte differentiation and growth.
Tumor necrosis factor
Stops tumor growth, releases growth factors, causes fever that accompanies bacterial infection, stimulates lymphocyte differentiation.
Helper T cell
Releases cytokines that cause the B cell to proliferate. (Clones)
Cytotoxic T cell
Attack cancer cells and cells infected with virus that have non-self antigens on their surface. Becomes activated when antigen receptor on T cell binds to antigen. T cell proliferates into clone cells. T cells bind to antigen and release perforin ( protein that cuts holes in the tumor or virally infected cells)
Memory T cells
Provide for future immune protection.
Plasma cells
Produce and secrete large globular proteins
Polyclonal response
Immune response that may include several types of antibodies manufactured against a single microbe or virus.
Immunoglobulin G (IgG)
Defends against bacteria, viruses, and toxins. Activates complement
Immunoglobulin A (IgA)
Defends against bacteria and viruses
Immunoglobulin M (IgM)
Antigens on RBC’s activates complement
Immunoglobulin D (IgD)
Cell activation
Immunoglobulin E (IgE)
Inflammation and allergic response, antibody is attached to mast cells. Binding of antigen causes mast cell to release histamine. Histamine causes inflammation.
Phagocytosis
Attracting macrophages and neutrophils. Rupturing membranes of foreign cells, altering the molecular structure if viruses.
Immune primary response
Plasma B cells produce IgM followed by IgG antibodies into the lymph, antibodies are transported into the blood and carried to the site where the antigen resides, production of antibodies continues for several weeks.
Immune secondary response
Some if the B cell clonal cells differentiate into memory cells. If a subsequent exposure to the same antigen occurs these cells enlarge, proliferate and produce IgG against the antigen. Memory T cells also help to fight the antigen. Infection may not produce symptoms. Follicle cells in lymph nodes can retain B cells for a very ling time.
Type I allergic reactions
Immediate reaction occurs within 5 min. Inherited tendency to produce too much IgE in response to an antigen ( ex. Bee sting or penicillin) release of histamine, prostaglandin D2 and leukotrienes can produce anaphylactic reaction.
Type II allergic reaction
Antibody dependent, occurs within a few hrs, antigen to specific cell causing phagocytosis and complement mediated lysis of the antigen (ex. Mismatched blood transfusion)
Type III allergic reactions
Immune complex reactions
Type 4 allergic reactions
Delayed reaction allergy- occurs within 48 hrs, sensitization to allergen over repeated exposure activates T cells and macrophages (ex. Poison ivy and cosmetics)
Type 5 allergic reactions
Transplants- isograft (identical twin), autograft (self), allograft (same species), xenograft (different species)
Type 6 allergic reactions
Autoimmune disease- antibodies attack their own tissue.
CD4 helper T cell
Target of HIV
