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what is resistance?
ability to ward off pathogens that produce disease
what is susceptibility?
lack of resistance
what is nonspecific or innate immunity?
present a birth and includes defense mechanisms that provide general protection against invasion by a wide range of pathogens
what does immunity involve?
activation of specific lymphocytes that combat a particular pathogen or other foreign substance
what does the lymphatic system consist of?
lymph fluid flowing within lymphatic vessels, structures and organs containing lymphatic tissue, and bone marrow
where is lymphocyte production?
in bone marrow
what is the comparison of interstitial fluid and lymph?
the same but differ in location
what are the functions of the lymphatic system?
drain interstitial fluid
return leaked plasma proteins to the blood
transport dietary fats
protect against invasion by nonspecific and specific immune responses
how do lymphatic vessels begin?
as blind ended lymph capillaries in tissue spaces between cells
where does interstitial fluid drain into?
lymphatic capillaries, thus forming lymph
what do lymph capillaries merge to form?
lymphatic vessels, which convey lymph in and out of lymph nodes
where are lymphatic capillaries found?
throughout the body except in avascular tissue, the CNS, portions of the spleen, and red bone marrow
how do lymphatic capillaries differ from blood capillaries?
they have a slightly larger diameter and have overlapping endothelial cells which work as a one way valves for fluid to enter the lymphatic capillary
what do anchoring filaments attach?
endothelial cells to surround tissue
what is the lacteal?
a lymphatic capillary in the villus of the small intestine that functions to transport digested fats from the small intestine into blood
what are the principal lymph trunks formed from the exiting vessels of lymph nodes?
lumbar, intestinal, bronchomediastinal, subclavian, and jugular trunks
what is the thoracic duct?
it begins as a dilation called cisterna chyli and is the main collecting duct of the lymphatic system
where does the lymphatic duct receive lymph?
from the left side of the head, neck, and chest, the left upper extremity, and the entire body below the ribs
where does thoracic duct drain lymph?
into venous blood via the left subclavian vein
where does the right lymphatic duct drain lymph from?
from the upper right side of the body
where does the right lymphatic duct drain lymph to?
venous blood via the right subclavian vein
where does interstitial fluid drain into?
lymph capillaries
what is the passage of lymph
arteries and blood capillaries (blood)
interstitial spaces (interstitial fluid)
lymph capillaries (lymph)
lymphatic vessels
lymph trunks
thoracic duct or right lymphatic duct
subclavian veins
what does causes lymph flow?
milking action of skeletal muscle contractions and respiratory movements
what aids lymph flow?
lymphatic vessel valves to prevent backflow of lymph
what are the primary lymphatic organs?
those in which cells become immunicompetent (capable of mounting an immune response) and the red bone marrow (B cells) and the thymus gland (T cells)
what are the secondary lymphatic organs?
lymph nodes and spleen
what are secondary lymphatic tissues?
lymphatic nodules
where do most immune responses occur?
in secondary lymphatic organs and tissues
what is the thymus gland?
it lies between the sternum and the heart and functions in immunity as the site of T cell maturation
what is the thymus after puberty?
it is large in the infant and is largely replaced by adipose and areolar connective tissue
what are lymph nodes?
encapsulated oval structures located along lymphatic vessels
what do lymph nodes contain?
T cells, macrophages, follicular dendritic cells, and B cells
how dose lymph enter nodes?
through lymphatic vessels and exits through efferent lymphatic vessels
what happens to foreign substances?
filtered by lymph nodes and are trapped by nodal reticular fibers
macrophages destroy some and cells by phagocytosis
lymphocytes bring about the destruction of other cells by immune responses
what are lymph nodes the site of?
poliferation of plasma cells and T cells
why is the knowledge of lymph nodes and the direct of lymph flow importnat?
for diagnosis and prognosis of the spread of cancer by metastasis; many cancer cells are spread by way of the lymphatic system, producing clusters of tumor cells where they lodge
what is the spleen?
largest mass of lymphatic tissue
found in the left hypochondriac region between fundus and the diaphragm
consists of white (lymphatic tissue) and red pulp
what do the spleens T lymphocytes directly attack and destroy?
antigens in blood via primarily cytolysis
what do the spleens B lymphocytes develop into?
antibody producing plasma cells and the antibodies inactivate antigens in blood
how do macrophages destroy antigens in blood
by phagocytosis
what does the red pulp consist of?
venous sinuses filled w/ blood and splenic cords consisting of RBCS, macrophages, lymphocytes, plasma cells, and granulocytes
what do macrophages remove?
worn out or defective RBCs, WBCs, and platelets by phagocytosis
what is the red pulp involved in?
the production of blood cells during the second trimester of pregnanct
where is the spleen often damaged?
in abdominal trauma; splenectomy may be required to prevent excessive bleeding
what are lymphatic nodules?
oval shaped concentrations of lymphatic tissue
where are lymphatic nodules?
scattered throughout lamina propria of mucous membranes lining the GI tract, respiratory airways, urinary tract, and reproductive tract
what type of lymphatic tissue or lymphatic nodules?
mucosa associated lymphatic tissue (MALT)
what are peyers patches?
lymphatic nodules in the ileum of the small intestine
what are tonsils?
multiple aggregations of large lymphatic nodules embedded in a mucous membrane at the junction of the oral cavity and the pharynx
what do lymphatic nodules include?
pharyngeal (adenoid), palatine, lingual tonsils
how are lymphatic nodules situated?
strategically to protect against invasion of foreign substances and participate in immune responses by producing lymphocytes and antibodies
where do lymphatic vessels develop from?
lymph sacs which develop from veins; mesoderm
where do lymph nodes develop from?
lymph sacs that become invaded by mesenchymal cells
what is the first line defense?
skin and mucous membranes
what is innate immunity (nonselective resistance?
a wide range of body responses against a wide range of pathogens (disease producing organisms) and their toxins that is present at birth
what do mechanical protection include?
the intact epidermis layer, mucous membranes, the lacrimal apparatus, saliva, mucus, cilia, epiglottis, flow of urine; defecation and vomiting
where is chemical protection localized?
on the skin, in loose connective tissue, stomach, and vagina
what does the skin produce?
sebum which has low pH due to presence of unsaturated fatty acids and lactic acid
what is lysozyme?
enzyme component of swear that also has antimicrobial properties
what does gastric juice do?
render the stomach nearly sterile due to its low pH (1.5-3.0) kills many bacteria and destroys most of their toxins; vaginal secretions are slightly acidic too
what is the second line of defense?
the internal defenses
what does the internal defenses include?
internal antimicrobial proteins, phagocytic and natural killer cells, inflammation and fever
what are interferons (IFNs)?
proteins produced from lymphocyte and macrophage cells infected w/ viruses
once released from virus infected cells, IFN diffuses to uninfected neighboring cells to synthesize antiviral proteins that interfere w/ or inhibit viral replication
what comprises the complement system?
a group of about 20 proteins present in blood plasma and on cell membranes
what happens when the complement system is activated?
the proteins “complement” or enhance certain immune, allergic, and inflammatory reactions
what do iron binding proteins do?
remove iron from the body fluids thereby inhibiting microbial growth
what are anti microbial substances?
peptides that produce anti microbial activity and attract dendritic and mast cells
what are natural killer (NK) cells?
lymphocytes that lack the membrane molecules and identify T and B cells
what do natural killer cells do?
to kill a wide variety of infectious microbes
what do Natural killer cells sometimes reslease?
perforins that insert into the plasma membrane of a microbe and make the membrane leaky so that cytolysis occurs
what are phagocytes?
cells specialized to perform phagocytosis and include neutrophils and macrophages
what are the 3 phases of phagocytosis?
chemotaxis, adherence, ingestion
what happens after phagocytosis is accomplished?
a phagolysosome forms and the lysosome in phagolysosome along w/ lethal oxidants produced by the phagocyte quickly kills many types of microbes
what are some reasons why a microbe may evade phagocytosis?
capsule formation
toxin production
interference with lysozyme secretion
microbes ability to counter oxidants produced by phagocytes
when does inflammation occur?
when cells are damaged by microbes, physical agents, or chemical agents; injury may be viewed as stress
how is inflammation characterized?
redness, pain, heat, swelling; loss of function depending on the site and extent of injury
what are the 3 basic stages of inflammation?
vasodilation and increased permeability of blood vessels
phagocytic migration
tissue repair
what substances contribute to inflammation?
histamines, kinins, prostglandins, leukotrienes, complement
what happens after phagocytes engulf damaged tissue and microbes?
they eventually die, forming a pocket of dead phagocytes and damaged tissue and fluid called pus
pus must drain out the body or it accumulates in a confined space, causing an abscess; ulcer forms when tissue sloughs off
what causes fever?
infection from bacteria and their toxins, and viruses; high temp inhibits some. microbial growth and speeds up body reactions that aid repair
what is immunity?
ability of the body to defend itself against specific invading agents
what are antigens?
substances recognized as foreign by immune responses
what are the distinguishing properties of immunity?
specificity and memory
where do T and B cells derive from?
stem cell in bone marrow
what happens in to B cells in bone marrow?
they complete their development, becoming immunocompetent
what do T cells develop from?
pre-T cells that migrate to the thymus where they become immunocompetent under the influence of thymic hormones
what happens before T cells leave the thymus or B cells leave bone marrow?
they acquire several distinctive surface proteins, some function as antigen receptors, molecules capable of recognizing specific antigens
what is cell mediated immunity?
destruction of antigens by T cells
what are cell mediated immunity effective against?
intracellular pathogens like fungi, parasites, viruses; some cancer cells and foreign tissue transplants; CMI always involved attacking cells
what does antibody mediated (humoral) immunity refer to?
the destruction of antigens by antibodies; works against antigens dissolved in body fluids and extracellular pathogens like bacteria, the multiply byt rarely enter body cells.
what do pathogens provoke?
both types of immune response
what is clonal selection?
the process where an immune cels proliferates and differentiates in response to a specific antigen
what are the 2 major types of cells that result from clonal selection?
effector cells and memory cells
what are effector cells?
cells that do the work to destroy antigens and include: cytotoxic T cells, helper T cells, and plasma cells (clone of B cells)
what are memory cells?
have long life spans and provide a faster second invasion response by proliferating and differentiating into effector cells
what are antigens?
chemical substances that are recognized as foreign by antigen receptors when introduced in the body; both immunogenic and reactive
how does an antigen get into lymphatic tissue?
by entering an injured blood vessel and being carried to the spleen, penetrating the skin and entering lymph vessels leading to lymph nodes, or penetrating mucous membranes and lodging in mucosa associated lymphoid tissue
what type of molecules are antigens?
large and complex proteins but are sometimes nucleoproteins, lipoproteins, glycoproteins, and certain large polysaccharides
what specific portion of antigen molecules trigger immune responses?
antigenic determinants or epitopes
