BIOL 235 Chapter 22: Immune System, question and answer, A+ content

BIOL 235 Chapter 22: Immune System, question and answer, A+ content What is resistance? ability to ward off damage or disease through body defences What is susceptibility? vulnerability or lack of resistance to disease What is innate immunity ? - non-specific, present at birth defence - First line (physical and chemical barriers of skin) and second line of defence (fever, inflammation, antimicrobials) What Is Adaptive Immunity (specific immunity) acquired ability to recognize and destroy a pathogen Involves lymphocytes (B & T cells) What is lymph? excess interstitial fluid carried by lymphatic vessels What is lymphatic tissue? - specialized form of reticular connective tissue that contains large numbers of lymphocytes What are the functions of the lymphatic system? - Drain excess interstitial fluid - Transport dietary lipids - Carry out immune responses What are lymphatic capillaries? close-ended vessels that weave between tissue cells and blood capillaries unite to form lymphatic vessels have greater permeability than blood capillaries ** What are lacteals? Intestinal lymphatic vessels carry dietary lipids into lymphatic vessels and then into blood What is chyle? lymph from the digestive system containing lipids creamy white in colour Where does the lumbar trunk drain lymph from? lower limbs, lower abdominal wall, kidneys, adrenal glands, wall & viscera of the pelvis Where does the intestinal trunk drain lymph from? The stomach, intestines, pancreas, spleen, part of liver Where does the Bronchomediastinal trunk drain lymph from? The thoracic wall, lung, heart Where does the subclavian trunk drain lymph from? upper limbs Where does the jugular trunk drain lymph from? head and neck What is the cisterna chyli? a dilation at the beginning of the thoracic duct anterior to the second lumbar vertebrae What is the thoracic duct? main channel through which lymph from the majority of the body is returned to the venous system receives lymph from the LEFT side of the body Where does the thoracic duct drain its lymph into? Into venous blood at the junction of the left internal jugular and left subclavian veins What is the right lymphatic duct? Drains lymph from the right jugular, subclavian & bronchomediastinal trucks drains lymph from upper RIGHT side of the body Where does the right lymphatic duct drain its lymph into? Junction of the right internal jugular and right subclavian veins How is lymph formed ? When more interstitial fluid (blood plasma) is filtered out of blood capillaries than reabsorbed, the excess fluid drains into lymphatic vessels = lymph What is the flow of lymph? Blood capillaries - Interstitial spaces - lymph capillaries - lymph vessels - lymph trunks - lymph ducts - junction of internal jugular & subclavian veins What are the two pumps that aid return of venous blood to the heart & maintain flow of lymph? Respiratory Pump Skeletal Muscle Pump What is the Respiratory pump? Pressure changes created during inhalation, lymph flows from higher pressure (abdominal region) to lower pressure in the thoracic region Pressure reverses during exhalation: lymphatic valves prevent back flow of lymph What is the skeletal muscle pump? "Milking action" of skeletal muscle contractions compress lymphatic vessels thus forcing lymph toward the heart What are the primary lymphatic organs? The red bone marrow, thymus gland site where stem cells divide and become immunocompetent What are the secondary lymphatic organs ? lymph nodes, spleen, lymphatic nodules site where most immune responses occur What is the thymus gland? Bilobed organ in the mediastinum (between the sternum and aorta) site where immature T cells from the red bone marrow migrate to proliferate and mature Largest at puberty and then overtime atrophies What are Hassall's corpuscles? clusters located in the medulla of the thymus, serve as sites of T cell death What are the characteristics of a lymph node? Bean shaped filters made of dense connective tissue located along lymphatic vessels Trabeculae that divide the node into compartments, support and a route for blood vessels Contains a cortex(double layered) and medulla What is included in the outer cortex of a lymph node? Contains lymphatic nodules: egg shaped aggregates of B cells Contains mostly secondary lymphatic nodules (form from a response to an antigen) What are secondary lymphatic nodules site of plasma cell and memory B cell formation When B cells in a primary lymphatic nodule recognize an antigen, primary nodule develops into a secondary lymphatic nodule What is included in primary lymphatic nodules B cells What is included in the inner cortex of a lymph node? T cells and dendritic cells that enter the node from other tissues (dendritic cells present antigens to T cells causing their proliferation) No lymphatic nodules What is included in the medulla of a lymph node? Contains B cells, antibody producing plasma cells that have migrated out of the cortex, and macrophages What are afferent lymphatic vessels ? direct lymph inward into the lymph node carry toward What are efferent lymphatic vessels? vessels leading lymph out of a lymph node wider and fewer in number What is the hilum? slight depression on the lymph node site where vessels enter and leave the node What are lymph node sinuses? lymph enters a series of irregular channels inside the node, containing branching reticular fibres, lymphocytes, macrophages What is the largest mass of lymphatic tissue in the body? The Spleen What is the white pulp of the spleen? lymphatic tissue containing mostly lymphocytes and macrophages What is the red pulp of the spleen? contains blood-filled venous sinuses 3 functions: removal by macrophages of dead worn out RBCs, storage of platelets, production of RBCs during fetal life What are lymphatic nodules? masses of lymphatic tissue that are NOT surrounded by a capsule scattered throughout mucus membranes of the GI, respiratory, urinary, reproductive tracts What are lymphatic nodules also referred to as? mucosa-associated lymphatic tissue (MALT) Where is the pharyngeal tonsil located? posterior wall of nasopharynx Where are the palatine tonsils located? at posterior end of oral cavity commonly removed in a tonsillectomy Where are the lingual tonsils located? base of tongue What layer of skin provides first line of defence against pathogens ? The epidermis: physical and chemical barrier shedding of this layer helps remove microbes as well What is in sebum that helps inhibit growth of certain bacteria and fungi? The unsaturated fatty acids makes skin very acidic (pH 3-5) What is the second line of defense? includes inflammation, antimicrobial substances, phagocytes, natural killer cells, fever What are interferons and what do they do? - Proteins produced by virus infected macrophages, lymphocytes, fibroblasts - diffuse to uninfected neighbour cells and induce synthesis of antiviral proteins (interfere with viral replication) - ONLY stop replication, CANNOT prevent viruses from penetrating hosts What is the complement system? group of serum proteins found in blood plasma & on plasma membranes when activated: complement or enhance immune reactions ex: cytolysis, promote phagocytosis, contribute to inflammation What are iron-binding proteins? inhibit growth of certain bacteria by reducing amount of available iron ex: hemoglobin, transferrin, lactoferrin, ferritin What are antimicrobial proteins (AMP)? short peptides with broad spectrum antimicrobial activity Also can attract mast and dendritic cells Ex: dermicidin, defensins, thrombocidin * microbes exposed to AMPs don't appear to develop resistance What are natural killer cells (NK)? lymphocyte that destroy tumor cells and a wide variety of viruses release granules containing toxic substances non specific defence found in: blood, spleen, red bone marrow, lymph nodes What is perforin? Protein produced by NK cells creates perforations on a target cells membrane causing cytolysis (ECF flows inside target cell causing it to burst) What are the two types of phagocytes? neutrophils and macrophages What are the five stages of phagocytosis? 1. Chemotaxis 2. Adherence 3. Ingestion (pseudopods and phagosome) 4. Digestion (lysosomes fuse with phagosome) 5. Killing (oxidative burst - superoxide, hypochlorite and peroxide)