LYMPHATIC SYSTEM

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LYMPHATIC SYSTEM
MACROPHAGE ATTACKING E. COLI
HUMAN T-LYMPHOCYTE
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LYMPHATIC VESSELS

• Function to pick up excess tissue/interstitial
  fluid, called LYMPH, and return it to the
  bloodstream (normally, fluids are forced out of
  capillaries at arteriole end and put back in at
  venule end, but some (about 3L/day) stays as
  interstitial fluid)
• AKA. LYMPHATICS, form a one-way system, flowing
  towards the heart

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LYMPHATIC VESSELS

• LYMPH CAPILLARIES- microscopic, blind-ended
  spider-web between the tissue cells and blood
  capillaries in the loose connective tissues of
  the body that absorb the leaked fluid very
  permeable- also allows proteins, cell debris,
  bacteria, viruses, and cancer cells in (which is
  bad b/c they can quickly travel through the body
  but good b/c lymph travels through lymph nodes
  which cleanses the lymph of debris contains
  cells that examine whats in the lymph)
• lymph is transported from lymph capillaries
  through successively larger lymphatic vessels,
  LYMPHATIC COLLECTING VESSELS, until it is finally
  returned to the venous system through one of the
  two large ducts in the thoracic region (fig.
  12.3 pg. 393)
• RIGHT LYMPHATIC DUCT drains the lymph from the
  right arm and the right side of the head and
  thorax
• THORACIC DUCT receives lymph from rest of the
  body

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LYMPHATIC VESSELS

• right lymphatic duct and thoracic duct empty the
  lymph into the SUBCLAVIAN VEIN on their own side
  of the body
• like veins of circulatory system, the lymphatic
  vessels are thin-walled, and the larger ones have
  valves is a low pressure, pumpless system lymph
  is transported by muscular and respiratory pumps
  also, smooth muscle in walls of larger lymphatics
  contracts rhythmically, helping to pump lymph
  along

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LYMPH NODES

• help protect the body by removing foreign
  material such as bacteria and tumor cells from
  the lymphatic stream and by producing lymphocytes
  that function in the immune response
• as lymph is transported towards the heart, it is
  FILTERED through the thousands of lymph nodes
  that cluster along lymphatic vessels
• large clusters are found in the inguinal,
  axillary, and cervical regions of the body
• within nodes are macrophages which destroy and
  engulf bacteria, viruses, and other foreign
  substances in the lymph before it is returned to
  the blood lymphocytes also found in nodes

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LYMPH NODES
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LYMPH NODES

• become swollen during an active infection
  swelling is result of the trapping function of
  the nodes
• vary in shape and size most are kidney-shaped
  less than 1 long surrounded by and buried in
  connective tissue
• lymph enters convex side of node through AFFERENT
  LYMPHATIC VESSELS, flows through SINUSES and
  exits from the HILUS (indented region) via
  EFFERENT LYMPHATIC VESSELS. There are fewer
  efferent than afferent vessels so flow of lymph
  is very slow (allows time for lymphocytes and
  macrophages to perform protective functions)
• lymph passes through several nodes before its
  cleaning process is complete

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LYMPH NODES
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OTHER LYMPHATIC ORGANS

• SPLEEN - located in left side of abdominal cavity
  and extends to curl around the anterior aspect of
  the stomach
• blood-rich organ that filters and cleanses blood
  of bacteria, viruses, and other debris most
  important function is to destroy worn-out RBCs
  and return some of their products to the liver
  other functions store platelets and act as a
  blood reservoir (as does the liver) in fetus,
  spleen is important hematopoietic site (only
  lymphocytes are produced by adult spleen)
• THYMUS GLAND - functions at peak levels during
  youth found low in throat overlying heart
  produces hormone thymosin and others that
  function in the programming of certain
  lymphocytes to carry out protective roles in the
  body

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OTHER LYMPHATIC ORGANS

• TONSILS - small masses of lymphatic tissue that
  ring the pharynx, where they are found in the
  mucosa job is to trap and remove any bacteria or
  other foreign pathogens entering the throat
  tonsillitis-tonsils become congested with
  bacteria and become red, swollen, and sore
• PEYERS PATCHES - resemble tonsils found in the
  wall of the small intestines prevents bacteria
  from penetrating intestinal wall
• tonsils and Peyers patches are part of a
  collection of small lymphoid tissues referred to
  as MUCOSA-ASSOCIATED LYMPHATIC TISSUE (MALT)-
  acts as a sentinel to protect the upper
  respiratory and digestive tracts from the
  never-ending attacks of foreign matter entering
  those cavities

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OTHER LYMPHATIC ORGANS
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NONSPECIFIC BODY DEFENSES

• Nonspecific body defenses (pg. 396)- responds
  immediately to protect the body from all foreign
  substances (antigens), whatever they are
• Surface Membrane Barriers- first line of defense
  is SKIN and MUCOUS MEMBRANES, which line all body
  cavities open to the exterior besides serving as
  physical barriers, these membranes produce a
  variety of protective chemicals
• Acid pH of skin secretions inhibits bacterial
  growth, and sebum contains chemicals that are
  toxic to bacteria vaginal secretions of adult
  females are also very acidic
• Stomach mucosa secretes HCl and protein-digesting
  enzymes, which kill pathogens (harmful or
  disease-causing microorganisms)
• Saliva and lacrimal fluid contain LYSOZYME, an
  enzyme that destroys bacteria
• Sticky mucus traps many microorganisms that enter
  digestive and respiratory passageways (special
  modifications cilia in resp. tract)

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NONSPECIFIC BODY DEFENSES

• Cells and Chemicals- second line of defense (pg.
  396)
• Phagocytes- ex. macrophage and neutrophil
• NATURAL KILLER (NK) cells- attack target cells
  membrane and release a lytic chemical, which
  causes the target cells membrane and nucleus to
  disintegrate
• Inflammatory response- triggered whenever body
  tissues are INJURED
• REDNESS, HEAT, SWELLING, PAIN
• when cells are injured, they release inflammatory
  chemicals, (ex. HISTAMINE KININS) that (1)
  cause blood vessels in the involved area to
  dilate and capillaries to become leaky, (2)
  activate pain receptors, and (3) attract
  phagocytes and WBCs to the area (chemotaxis)
• The inflammatory response (1) prevents the spread
  of damaging agents to nearby tissues, (2)
  disposes of cell debris and pathogens, and (3)
  sets the stage for repair

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NONSPECIFIC BODY DEFENSES

• Antimicrobial Chemicals (pg. 399)
• COMPLEMENTS- complements/enhances the
  effectiveness of both nonspecific and specific
  responses refers to a group of at least 20
  plasma proteins that circulate in the blood in an
  inactive state however, when complement becomes
  attached (FIXED) to foreign cells such as
  bacteria, fungi, or mismatched RBCs, it is
  activated, called COMPLEMENT FIXATION one result
  is formation of MEMBRANE ATTACK COMPLEXES (MAC)
  that produces lesions/holes in the foreign cells
  surface, which allows water to rush into the
  cell, causing it to burst. Activated complement
  also amplifies the inflammatory response and
  causes the membrane of the foreign cells to
  become sticky so they are easier to phagocytize,
  called OPSONIZATION
• INTERFERON- small proteins secreted by
  virus-infected cells, which help defend cells
  that are not yet invaded, by binding to their
  membrane receptors, hindering the ability of
  viruses to multiply within these cells.

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NONSPECIFIC BODY DEFENSES

• FEVER - systemic response to invading
  microorganisms WBCs release PYROGENS which
  resets the internal thermostat in the
  hypothalamus
• mild/moderate fevers BENEFICIAL because they
  cause the liver and spleen to gather up iron and
  zinc (necessary for bacteria to multiply) and
  increases the metabolic rate of tissue cells in
  general, speeding up repair processes
• high fever DANGEROUS because excess heat
  denatures/scrambles enzymes and proteins

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SPECIFIC BODY DEFENSES

• THE IMMUNE SYSTEM
• mounts an attack against particular foreign
  substances results in highly specific resistance
  to disease called IMMUNITY
• There are three important aspects of the immune
  response
• (1) IT IS ANTIGEN SPECIFIC
• (2) SYSTEMIC
• (3) HAS MEMORY
• ANTIGEN - any substance capable of provoking an
  immune response are considered non-self our own
  cells have antigenic markers on them, but as we
  developed, our bodies took inventory of them, so
  they are recognized as self (but they would be
  antigens to other people)

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SPECIFIC BODY DEFENSES

• CELLS OF THE IMMUNE SYSTEM AN OVERVIEW
• Lymphocytes B-lymphocytes (B cells) and
  T-lymphocytes (T-cells) both start out as the
  same immature lymphocyte, differentiate depending
  on where in the body they receive
  IMMUNOCOMPETENCE (capable of responding to a
  specific antigen by binding to it) T cells arise
  from lymphocytes that migrate to the thymus,
  where they undergo a maturation process of 2 3
  days, directed by thymic hormones (thymosin and
  others). Only those with the sharpest ability to
  identify foreign antigens survive. The ones
  capable of binding strongly with self-antigens
  (thereby acting against body cells) are
  vigorously weeded out and destroyed B cells
  develop immunocompetence in bone marrow (little
  known about process)

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SPECIFIC BODY DEFENSES

• Once lymphocyte is immunocompetent, it will be
  able to react to ONE distinct antigen becomes
  immunocompetent BEFORE meeting antigens they may
  later attack, thus, it is our genes, not
  antigens, that determine what specific foreign
  substances our immune system will be able to
  recognize and resist
• After becoming immunocompetent, both T and B
  cells migrate to the lymph nodes, spleen, and
  loose connective tissue, where their encounters
  with antigens occur
• When lymphocytes bind with recognized antigens,
  they complete their differentiation into fully
  mature T and B cells.

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SPECIFIC BODY DEFENSES

• Macrophages- arise from monocytes formed in the
  bone marrow become widely distributed in
  lymphoid organs and connective tissue not only
  engulf particles, but also present fragments of
  those antigens on their surface, so
  immunocompetent T cells can recognize the
  antigen therefore act as ANTIGEN PRESENTERS
  activated T cells in turn release chemicals that
  cause macrophages to become insatiable phagocytes
  or KILLER MACROPHAGES tend to remain fixed in
  the lymphoid organs (as if waiting for antigens
  to come to them), whereas T cells circulate
  through body
• The immune systems ability to respond to
  threats depends on the ability of its cells to
• (1) recognize foreign substances in the body by
  binding to them and
• (2) communicate with one another so that the
  system as a whole mounts a response specific to
  those antigens

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SPECIFIC BODY DEFENSES

• HUMORAL (ANTIBODY-MEDIATED) IMMUNE RESPONSE
• provided by antibodies present in the bodys
  humors or fluids
• After an antigen binds to a B cells surface
  receptors, it becomes fully mature, by becoming
  sensitized/activated and undergoing clonal
  selection The lymphocyte begins to grow and then
  multiplies rapidly to form an army of cells
  exactly like itself and bearing the same
  antigen-specific receptors the resulting family
  of identical cells descended from the same
  ancestor cell is called a CLONE most clones
  become PLASMA CELLS, which produce ANTIBODIES.
  The B cells that do not become plasma cells,
  become MEMORY CELLS capable of responding to the
  same antigen at later meetings with it (where the
  immune response is much faster, more prolonged
  and more effective then the first time)

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SPECIFIC BODY DEFENSES
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SPECIFIC BODY DEFENSES

• HUMORAL (ANTIBODY-MEDIATED) IMMUNE RESPONSE
• ACTIVE IMMUNITY
• (1) naturally acquired during bacterial and viral
  infections, during which you may develop symptoms
  of the disease
• (2) artificially acquired when you receive
  vaccines- most contain dead or attenuated (living
  but extremely weakened) pathogens

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SPECIFIC BODY DEFENSES

• HUMORAL (ANTIBODY-MEDIATED) IMMUNE RESPONSE
• PASSIVE IMMUNITY
• antibodies are not made by your plasma cells,
  they are acquired from an immune human or animal
  donor since your B cells were never challenged,
  memory does not get made and protection ceases
  when the antibodies break down
• (1) conferred naturally on fetus when mothers
  antibodies cross the placenta and enter the fetal
  circulation, and after birth through
  breastfeeding baby is protected from all the
  antigens to which the mother is currently being
  exposed to
• (2) conferred artificially when one receives
  immune serum (poisonous snake bits, botulism,
  rabies, tetanus- because these diseases will kill
  a person before active immunity can be
  established) or gamma globulin (given after
  exposure to hepatitis)
• scientists also use monoclonal antibodies,
  produced by descendants of a single cell and
  exhibiting specificity for one antigen, for
  research, clinical testing for diagnostic
  purposes, and treating certain cancers

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SPECIFIC BODY DEFENSES

• HUMORAL (ANTIBODY-MEDIATED) IMMUNE RESPONSE
• Antibodies- AKA IMMUNOGLOBULINS (Igs) - produced
  by plasma cells specific for a particular
  antigen
• Antibody classes MADGE
• IgM can fix complement first one released to
  plasma from plasma cells potent agglutinating
  agent
• IgA AKA. secretory IgA found mainly in mucus
  and other secretions that bathe the body
  surfaces plays major role in preventing
  pathogens from gaining entry into the body
• IgD important in activation of B cell
• IgG most abundant Ig in blood plasma only one
  that can cross the placental barrier (proving
  passive immunity to fetus) can fix complement
• IgE binds to basophils, triggering release of
  histamine, mediating inflammation and certain
  allergic responses

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SPECIFIC BODY DEFENSES

• HUMORAL (ANTIBODY-MEDIATED) IMMUNE RESPONSE
• Antibody function inactivate antigens by
  complement fixation, neutralization,
  agglutination, and precipitation
• Neutralization- occurs when antibodies bind to
  specific sites on bacterial exotoxins (toxic
  chemicals secreted by bacteria) or on viruses
  that can cause cell injury, thus blocking the
  harmful effects of the exotoxin or virus
• Precipitation- occurs when so much agglutination/
  clumping occurs that the antigen-antibody complex
  settles out of solution

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SPECIFIC BODY DEFENSES
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SPECIFIC BODY DEFENSES

• CELLULAR (CELL-MEDIATED) IMMUNE RESPONSE
• Provided by T-lymphocytes activated to form
  clones with a recognized antigen
• Unlike B cells, T cells cannot bind with free
  antigens, they must be presented by a
  macrophage
• 4 kinds of T-cells
• Cytotoxic/Killer T-cells
• Specialize in killing virus infected, cancer, or
  foreign graft cells
• Bind and insert toxic chemical into plasma
  membrane of target cell (ruptures)
• Helper T-cell
• directs or manages the immune system once
  activated, circulate through body and recruit
  other cells to fight invaders
• Release cytokine chemicals (lymphokines)
  indirectly rid body of antigens by stimulating
  killer T B cells to grow and divide, attracting
  other protective WBCs to the area, and enhancing
  microphage activity

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SPECIFIC BODY DEFENSES

• 4 kinds of T-cells
• Cytotoxic/Killer T-cells
• Helper T-cell
• Suppressor T-cells
• Release chemicals that suppress the activity of
  both T and B cells
• Vital for bringing the immune response to a halt
  after antigen is destroyed
• Helps prevent uncontrolled or unnecessary immune
  activity
• Memory T-cells
• Cells that remain after other T cells die off
  (most only last a few days)
• Provide immunological memory for each antigen
  encountered and enable the body to respond
  quickly to subsequent invasions

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SPECIFIC BODY DEFENSES
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SPECIFIC BODY DEFENSES
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SPECIFIC BODY DEFENSES

• ORGAN TRANSPLANT AND REJECTION
• 4 Different Grafts
• Autografts
• Isografts
• Allografts
• Xenografts
• After transplant, patient needs to take
  immunosuppressant drugs so they wont reject
  transplanted tissue
• Problem since immune system is suppressed, body
  is more susceptible to foreign agents such as
  bacterial and viral infections
• http//en.wikipedia.org/wiki/Organ_transplant

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SPECIFIC BODY DEFENSES

• DISORDERS OF THE IMMUNE SYSTEM
• Allergies (Hypersensitivities)
• Abnormally vigorous immune response in which the
  immune system causes tissue damage as it fights
  off a perceived threat that would otherwise be
  harmless to the body
• Immediate or acute hypersensitivity
• Usually occurs within seconds of exposure
  lasts about half hour
• Histamine is released runny nose, watery eyes,
  itching reddened skin (hives), asthma,
• Rare, but sometimes body-wide (systemic allergic
  response) called anaphylactic shock occurs when
  allergen gets directly into bloodstream causes
  vasodialation, drop in blood pressure, shock, or
  even death treated with epinephrine (epi-pens)

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SPECIFIC BODY DEFENSES

• DISORDERS OF THE IMMUNE SYSTEM
• Delayed hypersensitivities
• Take 1-3 days, lymphokines are released instead
  of histamine so corticosteroid drugs are used
  instead of antihistamines
• Examples allergic contact dermatitis skin
  contact with poison ivy, some heavy metals, and
  certain cosmetic deodorant chemicals

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SPECIFIC BODY DEFENSES

• DISORDERS OF THE IMMUNE SYSTEM
• Immunodeficiencies
• Includes both congenial and acquired conditions
  in which the production or function of immune
  cells or complement is abnormal
• Severe combined immunodeficiency disease (SCID)
• Deficit of both B T cells afflicted children
  have no protection against pathogens of any type
• Treatments include bone marrow transplants and
  umbilical cord blood for stem cells without
  treatment, must live behind plastic barrier
  (bubble)
• Acquired immune deficiency syndrome (AIDS)
• Cripples immune system by interfering with
  activity of helper T cells

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SPECIFIC BODY DEFENSES

• DISORDERS OF THE IMMUNE SYSTE
• Autoimmune disorders
• When immune system loses ability to tolerate
  self-antigens begins attacking itself
• Multiple sclerosis (MS) destroys white matter
  (myelin sheath) of brain spinal cord

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SPECIFIC BODY DEFENSES

• DISORDERS OF THE IMMUNE SYSTEM
• Autoimmune disorders - Myasthenia gravis
• Impairs communication between nerves skeletal
  muscles

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SPECIFIC BODY DEFENSES

• DISORDERS OF THE IMMUNE SYSTEM
• Autoimmune disorders Graves disease
• Thyroid gland produces excessive amounts of
  thyroxine

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SPECIFIC BODY DEFENSES

• DISORDERS OF THE IMMUNE SYSTEM
• Autoimmune disorders type I diabetes mellitus
• Destroys pancreatic beta cells, resulting in
  deficient production of insulin
• http//diabetes.niddk.nih.gov/dm/pubs/diagnosis/bm
  i_tbl.pdf

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SPECIFIC BODY DEFENSES

• DISORDERS OF THE IMMUNE SYSTEM
• Autoimmune disorders systemic lupus
  erythematosus (SLE)
• A system disease that occurs mainly in young
  females and particularly affects the kidneys,
  heart, lungs, skin

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SPECIFIC BODY DEFENSES

• DISORDERS OF THE IMMUNE SYSTEM
• Autoimmune disorders glomerulonephritis
• Severe impairment of kidney function

http//www.healthsystem.virginia.edu/uvahealth/pe
ds_urology/glomerul.cfm
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SPECIFIC BODY DEFENSES

• DISORDERS OF THE IMMUNE SYSTEM
• Autoimmune disorders rheumatoid arthritis (RA)
• Systemically destroys joints

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SPECIFIC BODY DEFENSES

• DEVELOPMENTAL ASPECTS
• Lymphatic vessels bud from veins of the blood
  vascular system by the 5th week
• Stem cells for immune system arise from the
  spleen liver during the first month of
  development. Afterwards, the bone marrow takes
  over this function
• Ability to recognize foreign substances is
  controlled by our genes and nervous system
• As we age, immune system loses efficiency and we
  become more prone to disease