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LYMPHATIC AND IMMUNE SYSTEMS (THE ADAPTIVE IMMUNE DEFENSES OF THE BODY: T…
LYMPHATIC AND IMMUNE SYSTEMS
ANATOMY OF THE LYMPHATIC SYSTEM
The lymphatic systems is composed of both lymph vessels and lymphatic tissues and organs.
Lymphatic tissues and organs are organized into:
Primary Structures
are involved in the formation and maturation of lymphocytes.
Thymus
--- Site of T-lymphocyte maturation and differentiation that is superior mediastinum.
Red Bone Marrow
--- Spaces in spongy bone within certain bones that form all formed elements (erythrocytes, leukocytes, and platelets).
Secondary Structures
are NOT involved in lymphocyte formation but house lymphocytes and other immune cells following formation. Provide site of immune response initiation.
Lymph nodes
--- Clusters along the length of lymphatic vessels that filter/monitor lymph.
Axillary
Inguinal
Cervical
Spleen
--- Located in the left upper quadrants of the abdomen and functions as a filter of blood by removing "worn out" erythrocytes and platelets, as well as serving a s a platelet reservoir.
Tonsils
--- structure within the pharynx which protects against inhaled and ingested substances.
Lymph Vessels
Lymphatic Ducts
convey lymph back into the venous blood circulation
R. Lymphatic duct
--- Drains lymph from the upper right quadrant of the body (right side of the head and neck, right upper limb, and right side of thorax) and returns the lymph back into the junction of the R. subclavian vein and the R. internal jugular vein.
Thoracic duct
--- Drains lymph from the rest of the body.
Lymphatic trunks
Bronchomediastinal trunks
-- drain lymph from deep thoracic structures
Intestinal trunks
-- drain lymph from most abdominal structures.
Jugular trunks
-- drain lymph from both the head and neck
Lumbar trunks
-- remove lymph from the lower limbs, abdominopelvic wall, and pelvic organs.
Subclavian trunks
-- remove lymph from the upper limbs, breast and superficial thoracic wall
Lymphatic vessels
--- larger structures created by the forming of lymphatic capillaries and directly connect with lymph nodes.
Contains valves within lumen that prevent lymph backflow (network is a low pressure system)
ANTIGENS AND ANTIBODIES
What are antigens?
The foreign substance that binds to antibodies in order to activate an immune response.
What are antibodies?
Proteins made in the body; immunoglobin
The function of antibodies:
Neutralization
: surround a pathogen so much that they neutralize it.
Agglutination
: Clumping caused by the binding of antigens to more than one cellular antigen.
Precipitation
: cross-link soluble, circulating antigens to form antigen-antibody complexes. Precipitate out of the body and then engulfed by macrophages.
Complement fixation
: Binding of specific complement proteins and activating the classical pathway. Stimulate opsonization, inflammation, cytolysis, and elimination of immune complexes.
Antibody monomer:
Variable region: contain the antigen binding site.
Constant region: contains the Fc region which is the portion of the antibody that determines the biological functions of the antibody
IgA
Found in areas exposed to the environment
Actions include: neutralization and aggluitnation
IgD
B-lymphocyte receptor
identifies when immature B-lymphocytes may be ready for activation to participate in adaptive immunity.
IgE
Formed in response to allergic reactions
found in the blood
activate mast cells in basophils
IgM
Found mostly in blood (monomer is B-cells)
Actions include:
Neutralization
agglutination
complement binding
IgG
Major class of immunoglobin.
Comprises 75 - 85% of antibody in the blood and is the predominant antibody in the lymph, cerebrospinal fluid, serous fluid, and peritoneal fluid
Actions include:
neutralization (viruses, bacteria, toxins)
agglutination
precipitation
complement activation
opsonization
NK cell activation
Composed of two heavy chains and two light chains (polypeptides) held together by disulfide bonds that make an antibody monomer.
THE INNATE IMMUNE DEFENSES OF THE BODY
Surface barriers
--- first line of defense
Skin --- Epidermis (Stratified squamous epithelial) and dermis (areolar and dense irregular connective tissue) provide a physical, chemical and biological barrier for body surface.
Mucous membranes --- secretions containing lysozyme, defensins, and IgA; they are antimicrobial.
Internal Defenses
--- 2nd line of defense
Phagocytes
--- This includes:
Mast Cells
: reside in connective tissue of the skin, mucosal linings, and various internal organs; proinflammatory chemical secreting cells (granules).
Basophils - circulate in blood.
Eosinophils
: target parasites by way of enzymes or other substances
Neutrophils
: most prevalent leukocyte in the blood and first to arrive during inflammatory response.
Kupffer cells
: specialized macrophages that constitute 80-90% of the tissue macrophages present in the body.
Microglia
: type of glial cell located in the brain and spinal cord that are the first and main form of immune response in the CNS.
Fever
--- Pyrogens stimulates a high metabolism that causes damage to pathogens
NK cells
--- Natural killer cells that initiate a non-specific response to cells (pathogens and one's body cells) when activated by viruses. They secrete perforins (cytotoxic chemical that creates holes in a cell; apoptosis by granzymes), histamines (vasodilation), and cytokines.
Antimicrobial proteins
--- Includes:
Complement
: proteins C1 - C9 that link to antibodies, or factors B, D, and P that link to glycocalyx (sugar-coating).
Inflammation - complement increases the inflammatory response through activation of mast cells and basophils and by attracting neutrophils and macrophages.
Cytolysis - C5 - C9 trigger direct killing of a target by forming a protein channel in the plasma membrane of a target cell (membrane attack complex).
Opsonization - binding of a protein to a portion of bacteria pr other cell type that enhances phagocytosis.
Elimination of immune complexes - compliment links antigen/antibody to erythrocytes and are transported to liver and spleen.
CRP
(from liver): binds to pathogen to mark it for destruction by macrophages.
Interferon
: cytokine (released by leukocytes and fibroblast) makes neighboring cells resistant to viral reproduction and is non specific.
Inflammation
--- A response to an infection, which causes dilation of blood vessels, redness, pain, swelling and releases leukocytosis-inducing factors.
Quick protection; defenses we are born with
THE ADAPTIVE IMMUNE DEFENSES OF THE BODY: B LYMPHOCYTES (HUMORAL RESPONSE)
B Lymphocytes create antibodies, as well as tag pathogens so that T-cell may identify them and attack that specific pathogen.
When they encounter antigens they make plasma proteins, which produce antibodies (memory B-cells).
Antigen molecule structure: proteins and some nonprotein molecules
Effective against antigens outside of cells
General effector response is to synthesize and release antibodies.
Does not require antigen presenting cells
THE ADAPTIVE IMMUNE DEFENSES OF THE BODY: T LYMPHOCYTES (CELLULAR RESPONSE)
Requires antigen-presenting cells
Antigen molecule structure: proteins digested into peptide fragments
Effective aginst antigens within cells.
The general effector response is the release of cytokines for activating other immune cells or for destroying infected cells.
T-cells are activated by an antigen and stimulate macrophages to hunt and destroy pathogens.
Dendritic cells present antigens to T and B cells to find the right match to begin cloning process.
Made in Red bone marrow and mature in thymus
