Lymphatic/Immune/Respiratory Flashcards
what is the lymphatic system composed of?
lymphatic tissues and organs
what is lymph?
the fluid transported within lymph vessels
where does lymph originate?
as interstitial fluid surrounding tissue cells
how does lymph move into lymphatic capillaries?
passively due to pressure gradient
How much fluid entering interstitial space from capillaries does not reabsorb?
15% ~ about 3 liters a day
when does interstitial fluid become lymph?
when it enters the lymph vessels
what are the components of lymph?
water dissolved solutes small amount of protein sometimes foreign material (cell debris, pathogens & maybe metastasized cancer cells)
what are the smallest lymph vessels?
lymphatic capillaries
describe lymphatic capillaries
microscopic, closed-ended vessels that absorb interstitial fluid interspersed throughout areolar connective tissue among most blood capillary networks (except in red bone marrow and nervous system) absent within avascular tissues like epithelia
what are the similarities and differences between blood capillaries and lymph capillaries?
walls of both are composed of endothelium lymphatic capillaries are larger in diameter than blood capillaries lymphatic capillaries don’t have basement membrane & they have overlapping endothelial cells
how do overlapping endothelial cells function in lymphatic capillaries?
act as 1-way flap to let fluid enter but not exit
what are anchoring filaments?
help hold lymphatic capillary endothelial cells to nearby structures
what holds lymphatic capillaries to nearby structures?
anchoring filaments
what are lymphatic capillaries located in the GI tract called?
lacteals
what is the force that moves fluid into lymphatic capillaries?
hydrostatic pressure within the interstitial space
what prevents lymphatic capillary collapse as interstitial fluid pressure increases?
anchoring filaments
what do lymphatic capillaries merge to form?
lymphatic vessels
describe lymphatic vessels
resemble small veins have 3 vessel tunics (intima, media and externa), and have valves within lumen to prevent lymph backflow & pooling
where are lymphatic vessels found?
superficial lymphatic vessels are usually adjacent to superficial veins deep lymphatic vessels are next to deep arteries and veins
what mechanisms move lymph through the vessels?
- contraction of nearby skeletal muscles in the limbs & respiratory pump 2. pulsatile movement of blood in nearby arteries 3. rhythmic contraction of smooth muscle in walls of larger lymph vessels (trunks and ducts)
what are lymphatic organs called?
lymph nodes
where to lymphatic vessels go?
some go to lymph nodes, some feed into lymphatic trunks on bht right and left side of the body
name the lymphatic trunks
jugular trunks subclavian trunks bronchomediastinal trunks intestinal trunks lumbar trunks
what does each trunk drain?
jugular - head and neck subclavian - upper limbs bronchomediastinal - deep thoracic structures intestinal - most abdominal structures lumbar - lower limbs, abdominopelvic wall & pelvic organs
what do lymphatic trunks drain into?
lymphatic ducts (the largest lymph vessels)
how many lymphatic ducts are there?
2
name the lymphatic ducts
right lymphatic duct thoracic ducts
what do lymphatic ducts do?
convey lymph back into venous blood circulation
what is lymphedema?
swelling - an accumulation of interstitial fluid due to interference with lymphatic drainage in a part of the body
where is the right lymphatic duct?
near the right clavicle
what does the right lymphatic duct drain?
right side of the head and neck right upper limb right side of the thorax
where does the right lymphatic duct return fluid?
junction of the right subclavian vein and the right internal jugular vein
which lymphatic duct is the largest?
the thoracic duct
how big is the thoracic duct?
15-18 inches
where is the thoracic duct?
extends from the diaphragm inferiorly to junction of the left subclavian and left jugular veins superiorly
what does the thoracic duct drain?
left side of head and neck, left upper limb, left thorax, all of the abdomen and both lower limbs
what & where is the cisterna chyli?
saclike structure at the base of the thoracic duct and anterior to the L2 vertebra
what is chyle?
milky, lipid-rich lymph that drains from the small intestine and the GI tract
which trunks drain into the cisterna chyli?
left and right intestinal and lumbar trunks
What tissues and organs are lymphatic structures?
red bone marrow thymus lymph nodes spleen tonsils MALT (mucosa-associated lymphatic tissue) and diffuse lymphatic nodules
how are lymphatic system tissues and organs categorized?
as either primary (involved in formation & maturation of lymphocytes) or secondary (house lymphocytes & other immune cells following their formation - provide the site where an immune response is initiated)
what are the primary lymphatic structures?
red bone marrow & thymus
what are the major secondary lymphatic structures?
lymph nodes, spleen, tonsils, lymphatic nodules and MALT
where is red bone marrow located?
spaces between trabeculae in spongy bone in adults –> flat bones of skull, vertebrae, ribs, sternum, ossa coxae, proximal epiphyses of each humerus and femur
what is the function of red bone marrow?
formation of all formed elements (hemopoiesis) (erythrocytes, platelets, granulocytes (neutrophils, eosinophils, and basophils), agranulocytes (monocytes and lymphocytes)
where is the thymus located?
superior mediastinum (in adults); anterior and superior mediastinum (in children)
what is the function of the thymus?
site of T-lymphocyte maturation and differentiation
where are the lymph nodes located?
along the length of lymphatic vessels; clusters are present in axillary, inguinal and cervical regions
what is the purpose of lymph nodes?
filter lymph; where immune response is initiated against a substance in the lymph
where is the spleen located?
left upper quadrant of abdomen, near 9h -11th ribs, wraps partway around stomach
what is the function of the spleen?
filters blood; where immune response is initiated against a substance in the blood; removes aged erythrocytes and platelets; serves as platelet reservoir
where are the tonsils located?
within pharynx (throat)
what is the function of the tonsils?
protect against inhaled and ingested substances
where is MALT located?
within the walls of the gastrointestinal tract, respiratory, reproductive, and urinary tracts
what is the function of MALT?
initiates an immune response against a substance that comes in contact with a mucosal membrane
what are the 2 major types of lymphocytes?
T-lymphocytes (T-cells) B-lymphocytes (B-cells)
where do t-lymphocytes complete their maturation?
in the thymus
how long does the thymus grow?
until puberty - maximum weight is 30-50 grams
what happens to the thymus after puberty?
cells begin to regress - replaced by adipose tissue
describe the thymus
2 fused lobes (thymic lobes) - each surrounded by a connective tissue capsule. trabeculae (fibrous extensions of capsule) subdivide lobes into lobules each lobule has outer cortex and inner medulla, both parts composed primarily of epithelial tissue infiltrated with T-lymphocytes in varying stages of maturation cortex has immature T-lymphocytes medulla has mature T-lymphocytes
what do epithelial cells of thymus secrete?
thymic hormones that participate in maturation of T-lymphocytes
what kind of organ is the thymus?
a lymphoepithelial organ - it has both lymphatic cells and epithelial tissue
what are secondary lymphatic structures?
structures that house lymphocytes and other immune cells
what kinds of structures are secondary lymphatic structures?
lymphatic organs or aggregates of lymphatic nodules
what is the difference between a lymphatic organ and an aggregate of lymphatic nodules?
presence or absence of a capsule composed of dense irregular connective tissue lymphatic organs have a complete capsule other lymphatic structures either have no capsule or an incomplete capsule
what are the secondary lymphatic organs?
spleen and lymph nodes
what are the secondary lymphatic nodules?
tonsils, MALT, diffuse lymphatic nodules
what are lymph nodes?
small, round or oval encapsulated structures located along the pathways of lymph vessels
what do lymph nodes do?
filter lymph and remove unwanted substances
what kinds of cells migrate from skin and mucosal membranes to a lymph node following endocytosis of foreign substances?
dendritic cells phagocytic cells that are formed in bone marrow & housed in epithelial tissue of skin & mucosal membranes
where are clusters of lymph nodes?
axillary (armpit) inguinal (groin) cervical
where do axillary lymph nodes receive lymph from?
breast, axilla, & upper limb
where do inguinal lymph nodes receive lymph from?
lower limb & pelvis
where do cervical lymph nodes receive lymph from?
head & neck
what are afferent lymphatic vessels?
bring lymph into a lymph node
what is an efferent lymphatic vessel?
drains lymph from the lymph node
What does pathogenic mean?
infectious agents that cause harm to the host
what are the 5 categories of infectious agents?
bacteria, viruses, fungi, protozoans, and multicellular parasites (and prions)
what is virulence?
the ability to cause serious illness
what are the characteristics of bacteria?
prokaryotic intracellular & extracellular parasites; some produce enzymes, toxins
what are the characteristics of viruses?
not a cell; DNA or RNA is within a capsid protein obligate intracellular parasite; must enter a cell to replicate
what are the characteristics of fungi?
they are eukaryotic produce spores; release proteolytic enzymes
What are characteristics of protozoans?
they are eukaryotic intracellular and extracellular parasites that interfere with normal cellular functions
what are characteristics of multicellular parasites?
eukaryotic live within a host; grow in size with nutrients provided by the host
what are the 2 components of the immune system?
innate and adaptive
where are leukocytes formed?
in the red bone marrow
what are the different leukocytes?
1) 3 types of granulocytes (neutrophils, eosinophils, basophils) 2) monocytes (become macrophages when they exit blood vessels) 3) 3 types of lymphocytes (T-lymphocytes, B-lymphocytes, NK (natural killer) cells)
what are the primary locations that house immune cells?
lymphatic tissue select organs epithelial layers of the skin and mucosal membranes connective tissue
what immune cells are housed in lymphatic tissue?
t-cells, b-cells, macrophages, and NK cells housed in 2ndary structures of lymph nodes, spleen, tonsils, MALT & lymphatic nodules
what kind of immune cells are housed in select organs?
macrophages some named based on location (alveolar macrophages of lungs, microglia of brain) can be fixed or wandering
what kind of immune cells are located in epithelial layers of the skin and mucosal membranes?
dendritic cells (derived from monocytes) in skin, they are called epidermal dendritic cells
what kind of immune cells are located in connective tissue?
mast cells (similar to basophils) usually close to small blood vessels especially abundant in dermis of skin, mucosal linings of respiratory, digestive & urogentical tracts also housed in CT of organs
what are cytokines?
small soluble proteins produced by cells of innate & adaptive immune system - regulate and facilitate immune system activity serve as means of communication between cells control development and behavior of effector cells of immunity regulate inflammatory response of innate immunity sometimes serve as weapons to destroy cells
how does a cytokine work?
released from 1 cell & binds to receptor on target cell
what kinds of cells can cytokines act on?
the cell that released it (autocrine) a neighboring cell (paracrine) circulate in blood system to cause systemic effects (endocrine)
what is the length of a cytokine half life?
short - to prevent continuous stimulation
what are the major classes of cytokines?
interleukin - regulates immune cells tumor necrosis factor - destroys tumor cells colony-stimulating factor - stimulates leukopoiesis in bone marrow to increase synthesis of a specific type of leukocyte interferon - IFN-alpha & IFN-beta are antiviral agents. IFN-gamma is pro-inflammatory agent
what are the two categories of immunity?
innate and adaptive
what is the body’s first line of defense?
skin and mucosal membranes
what is the body’s second line of defense?
internal processes of innate immunity 1) activities of various types of cells (neutrophils, macrophages, NK cells) 2) chemicals like interferon and complement 3) physiological processes including inflammatory response & fever
what parts of the skin prevent entry of pathogens?
epidermis/dermis (physical, chemical & biological barrier) normal flora (helps prevent growth of pathogenic microbes) exfoliation (removes potential pathogens from skin surface) hyaluronic acid (located in areolar tissue of the dermis - slows migration of microbes that have penetrated the epidermis) sebaceous (oil) gland secretions - contain lactic & fatty acids (create a low pH (3-5) - interferes with growth of microbes sweat gland secretions - contain lysozyme, defensins & dermicidin (helps wash away microbes, contains antibacterial & antifungal substances)
How do the mucous membranes prevent entry of pathogens?
epithelial & connective tissue - lining of respiratory, GI & urogenital tracts (provides physical, chemical, & biological barrier) normal flora - helps prevent growth of pathogenic microbes mucus - secretion containing lysozyme, defensins & IgA (thick secretion that helps trap microbes; contains antimicrobial substances)
how does the respiratory tract prevent entry of pathogens?
nasal secretions - contain lysozyme, defensins & IgA - contain antimicrobial substances vibrissiae - hairs in nasal cavity (traps microbes in the nose) cilia - extensions of plasma membrane (sweeps mucus upward to that it can be expectorated or swallowed coughing & sneezing (mechanical elimination of microbes or other foreign substances from respiratory tract)
How does the gastrointestinal tract prevent entry of pathogens?
saliva - secretions released into mouth from salivary glands - contain lysozyme & IgA (helps wash away microbes; contains antimicrobial substances) hydrochloric acid - produced within stomach (creates very low pH (~2) that destroys many bacteria, bacterial toxins & other microbes that enter stomach defecation & vomiting - removal of waste from digestive tract (eliminates microbes before they can be absorbed into the blood)
how does the urogenital tract prevent entry of pathogens?
urine (flow of urine flushes microbes from urinary tract) lactic acid - weak acid (produced by vagina, creates low pH that slows or prevents growth of microbes
how do secretions produced by the skin & mucous membranes prevent entry of pathogens?
lysosome - antibacterial enzyme (attacks cell wall of gram + bacteria) defensins - small proteins (create pores in the plasma membrane of microbes compromising their integrity) demicidin - small proteins produced by the skin (antibacterial agent against gram + and gram - bacteria, antifungal agent) Immunoglobulin A (IgA) - specific type of antibody present in areas exposed to the environment (binds with a specific foreign substance (antigen))
how do other secretions prevent entry of pathogens?
lacrimal fluid - fluid produced by lacrimal glands (by eye - tears) contains lysozyme & IgA (washes microbes away from surface of eyes; contains antimicrobial agents) cerumen - waxy secretions within external auditory meatus (waterproofs external auditory meatus; may trap microbes in external ear)
what is the third line of defense?
adaptive immunity
What cells are involved in innate immunity?
neutrophils, macrophages, basophils, mast cells, NK cells & eosinophils
how do neutrophils & macrophages function in innate immunity?
neutrophils - most prevalent leukocyte in blood. 1st to arrive during inflammatory response macrophages - reside in tissues throughout body - arrive later than neutrophils & stay longer both engulf unwanted substances through phagocytosis. phagosome (vesicle w/stuff) merges with lysosome –> phagolysosome –> enzymes digest unwanted stuff w/help from r O containing molecules like H2O2 –> residue released from the cell by exocytosis
How do basophils and mast cells function in innate immunity?
both are proinflammatory chemical-secreting cells basophils circulate in blood, mast cells reside in connective tissue of skin, mucosal linings & internal organs secretions increase fluid movement from the blood to an injured tissue & serve as chemotactic chemicals (attract immune cells as part of inflammatory response) both release granules –> contain histamine (increases vasodilation & capillary permeability) and heparin (anticoagulant) and eicosanoids (from plasma membrane - increase inflammation)
what does histamine do?
increases vasodilation and capillary permeability
what does heparin do?
anticoagulant
what do natural killer cells do?
destroy unwanted cells (virus-infected, bacteria-infected, tumor cells & transplanted tissue cells) formed in bone marrow, circulate in blood, accumulate in secondary lymphatic structures of lymph node, tonsils, & spleen immune surveillance (patrol body) - make physical contact w/unhealthy cells & release cytotoxic chemicals: perforin (forms transmembrane pore) and granzymes (enter through pore & initiate apoptosis)
what is apoptosis?
cellular death - involves shriveling rather than lysing - limits spread of infectious agent
what do eosinophils do?
target parasites - destroy by degranulation, releasing of enzymes & other substances that are lethal to parasite, & can release proteins that form transmembrane pore (like NK cells) participate in immune response associated with allergy and asthma & engage in phagocytosis of antigen-antibody complexes
what are two kinds of antimicrobial proteins?
interferon and complement
what are interferons?
IFN class of cytokines released from many different kinds of cells (leukocytes & fibroblasts are two) - released by virus-infected cell
what are the actions of interferon?
-binds to receptors of neighboring cells, preventing infection - triggers synthesis of enzymes that destroy viral RNA or DNA & inhibit synthesis of viral proteins -stimulates macrophages and NK cells to destroy virus-infected cells
what is complement?
30 plasma proteins (at least) make up about 10% of serum proteins in blood - antimicrobial group of substances
what synthesizes complement proteins?
liver - continually makes & releases inactive complement proteins into the blood
how are complement proteins activated?
by an enzyme cascade in the blood
when are complement proteins activated?
when a pathogen enters the body via classical pathway (complement protein binds to an antibody that has previously attached to a foreign substance) or the alternative pathway (surface polysaccharides of bacterial and fungal cell walls bind directly with complement protein)
what mechanisms does the complement system use to protect the body?
opsonization inflammation cytolysis elimination of immune complexes
what is opsonization?
binding of protein to a portion of bacteria or other cell type that enhances phagocytosis. - binding protein is opsonin
how does complement enhance inflammatory response?
activation of mast cells and basophils and by attracting neutrophils and macrophages
how does the complement system perform cytolysis?
trigger direct killing by forming a protein channel in plasma membrane (membrane attack complex MAC) allowing influx of fluid causing cell lysis
How does the complement system mediate elimination of immune complexes?
links antigen-antibody complexes (immune complexes) to erythrocytes so they can be transported to liver and spleen where macrophages strip the complexes from erythrocytes.
what is the inflammatory response?
an immediate, local, nonspecific event that occurs in vascularized tissue against great variety of injury causing stimuli
what is the major innate immune effector response?
the inflammatory response
what are the events of inflammation?
- release of inflammatory and chemotactic factors 2. vascular changes (vasodilation, increase in capillary permeability, display of CAMs) 3. recruitment of immune cells (margination, diapedesis, chemotaxis) 4. delivery of plasma proteins
what are the chemicals of inflammation?
histamine bradykinin leukotrienes prostaglandins chemotactic factor serotonin nitric oxide alpha-1 antitrypsin C-reactive protein
describe function and source of histamine in the inflammatory response
vasodilation, increased permeability of capillaries, conversion of an inactive plasma protein (kininogen) into active peptides called kinins, released early in inflammation from mast cells, basophils and platelets
describe function and source of bradykinin in inflammatory response
vasodilation & increased permeability of capillaries, stimulates sensory pain receptors comes from plasma protein produced by the liver and other cells as kininogen; activated by tissue injury
describe function and source of leukotrienes in inflammatory response
effects are similar to histamine, released later in the inflammatory response than histamine & longer lasting source: eicosanoids produced from arachidonic acid molecules of mast cell plasma membranes
describe function and source of prostaglandins in inflammatory response
vasodilation, fever, stimulates sensory pain receptors source: eicosanoids produced from arachidonic acid molecules of mast cell plasma membranes
describe function and source of chemotactic factor in the inflammatory response
attracts immune cells, release of specific chemotactic factors attract a specific type of cell (i.e. neutrophil chemotactic factor, eosinophil chemotactic factor…) source: mast cells
describe the function and source of serotonin in the inflammatory response
similar to histamine: vasodilation, increased capillary permeability source: platelets
describe the function and source of nitric oxide in the inflammatory response
vasodilation, may inhibit mast cells and platelets source: endothelium of blood vessels
describe the function and source of alpha-1 antitrypsin in the inflammatory response
inhibits damage to connective tissue by enzymes released from destroyed phagocytes source; plasma protein formed by the liver
describe the function and source of C-reactive protein in the inflammatory response
activates complement by binding to polysaccharides on bacteria surface source: liver
what are CAMs?
cell-adhesion molecules chemicals stimulate capillary endothelium to provide molecules for leukocyte adhesion.
How do leukocytes make their way from blood to infected tissue?
margination (CAMs on leukocytes adhere to CAMs on endothelial walls of capillaries - velcro) diapedesis (cells exit blood by squeezing between vessel wall cells) chemotaxis (migration of cells along a chemical gradient - released from damaged cells)
what plasma proteins are brought to site of injury during inflammatory response?
immunoglobulins, complement, clotting proteins & kinins
what is exudate?
an effect of inflammation net movement of fluid from blood through infected or injured area then into lymph - increased fluid, protein and immune cells leaving capillaries and entering interstitial space - delivers cells & substances needed to eliminate the injurious agent & promote healing
How is exudate like washing?
increased hydrostatic pressure from fluid going to injury site, makes lymph system take up more lymph that carries with it infectious agents, dead cells, and cellular debris - monitored as it passes through lymph nodes
how long does the inflammatory response usually last?
usually slows & healing begins within 72 hours. usually lasts no longer than 8-10 days (acute inflammatory response)
what are the cardinal signs of inflammation?
redness (increased blood flow) heat (increased blood flow & increased metabolic activity in the area) swelling (increased fluid loss from capillaries into interstitial space) pain (stimulation of pain receptors from compression & chemical irritation by kinins, prostaglandin & substances released by microbes) loss of function
what is pyrexia?
fever - abnormal elevation of body temperature of at least 1degree C
what are pyrogens?
interleukin 1, interferons, toxins produced by infectious agents (fever producing substances)
what do pyrogens target?
hypothalamus
what do pyrogens do?
target hypothalamus –> causes release of prostaglandin E2 –> raises temperature set point of hypothalamus
what are the stages of fever?
onset stadium defervescence (can be cyclical until pathogen is eliminated or controlled)
what happens during onset of fever?
hypothalamus stimulates blood vessel vasoconstriction in dermis of skin to decrease heat loss. person shivers to increase heat production through muscle contraction body temperature rises person may experience chills —> shivering
what happens during fever stadium?
elevated temperature is maintained. Metabolic rate increases. liver and spleen bind zinc and iron (minerals needed by microbes) to slow microbial reproduction.
what happens during fever defervescence?
temperature returns to its normal set point. hypothalamus no longer stimulated by pyrogens, prostaglandin release decreases. hypothalamus stimulates mechanisms to release heat from body –> vasodilation of blood vessels in skin and sweating. person may be flushed & skin warm to touch.
what are the benefits of fever?
inhibits reproduction of bacteria and viruses, promotes interferon activity, increases activity of adaptive immunity, accelerates tissue repair
when is a fever significant?
when it is above 100 degrees
what constitutes chronic inflammation?
when it continues for longer than 2 weeks.
what is the difference between acute inflammation and chronic inflammation?
acute is characterized by neutrophil presence, chronic is characterized by cells that arrive later, like macrophages and lymphocytes
what are risks of high fever?
changes in metabolic pathways and denaturation of body proteins may occur seizures may occur at sustained temperatures above 102 irreversible brain damage with sustained temps above 106, and death likely when temp reaches 109.
what is the difference between the first line of defense and the second line of defense in innate immunity?
first line - preventing entry of infectious agents second line - nonspecific cellular and molecular defenses for protecting the body (fever, inflammation)
which response is faster, innate or adaptive immunity?
innate immunity
what is the immune response?
lymphocytes formed and products they secrete in the body’s defense after contact with an antigen.
how long does it take to develop and immune response?
several days
what is the body’s third line of defense?
adaptive immunity
what are the two types of immune response?
cell-mediated immunity (response involving T-lymphocytes) humoral immunity (response involving B-lymphocytes that develop into plasma cells to synthesize and release antibodies)
compare cell-mediated immunity with humoral immunity
cell-mediated: T-lymphocyte effective against antigen within cells requires an antigen-presenting cell humoral B-lymphocyte effective against antigen outside of cells does not require antigen-presenting cells
what is the molecular structure of an antigen?
usually a protein or a large polysaccharide i.e. parts of infectious agents like protein capsid of viruses, cell wall of bacteria or fungi, bacterial toxins, tumor antigens
what is an antigenic determinant?
specific portion of an antigen to which the components of the adaptive immune system bind. - typically, each antigen has several antigenic determinants.
what is an autoimmune disorder?
when the body’s immune system reacts to self-antigens as if they were foreign
what happens to foreign antigens?
they bind with the body’s immune components because they are different in structure from the body’s own molecules
what is another name for antigenic determinant?
epitope
what is an immunogen?
an antigen that induces an immune response
what is immunogenicity?
the ability to cause an immune response
what is a hapten?
a substance that is too small to function as an antigen alone, but when attached to a carrier molecule in a host, then they become antigenic
how do T-lymphocytes & B-lymphocytes differ from other immune cells?
they have a receptor complex (about 100,000 per cell) - each complex will bind with one specific antigen
what is a TCR and a BCR?
t-cell receptor - antigen receptor of a t-lymphocyte and b-cell receptor - antigen receptor of a b-lymphocyte
which lymphocyte can make direct contact with an antigen?
b-lymphocytes
what do t-lymphocytes have that B-lymphocytes do not?
additional receptor molecules called co-receptors facilitate interaction with a cell presenting antigen
what are the 2 major types of t-lymphocytes?
helper t-lymphocytes and cytotoxic t-lymphocytes