Transcript Lymphatic System

Mrs. Penley
• The fluid that leaves capillaries and goes into tissues
• It flows TOWARDS the heart only
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Valves in lymph vessels
Smooth muscle contractions
Pressure changes
Contraction of skeletal muscles
• Filters
• Remove foreign materials
• Contain lymphocytes (T cells)
http://www.youtube.com/watch?v=RO6qmpApyDM
• Contain macrophages
http://www.youtube.com/watch?v=7WGyq82oMkM
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Act as antigen presenters
Engulf foreign particles
Secrete monokines
Considered “big eaters” of immune system
• The study of immunity
• An antigen is any substance that causes your immune system to
produce antibodies against it.
• An antigen may be a foreign substance from the environment
such as chemicals, bacteria, fungi, viruses, or pollen grains.
• An antigen may also be formed within the body, as with
bacterial toxins or tissue cells.
• Antibodies are large Y-shaped proteins.
• They are recruited by the immune system to identify and neutralize
foreign objects like bacteria and viruses.
• Each antibody has a unique target known as the antigen present on
the invading organism.
• This antigen is like a key that helps the antibody in identifying the
organism. This is because both the antibody and the antigen have
similar structure at the tips of their “Y” structures.
• Just like every lock has a single key, an antibody has a single antigen
key. When the key is inserted into the lock, the antibody activates,
tagging or neutralizing its target.
• The production of antibodies is the main function of the humoral
immune system.
• http://www.news-medical.net/health/Antibody-What-is-anAntibody.aspx
• Antibodies are composed of a light chain protein and a heavy
chain protein that come together and form a Y-shaped structure.
• The base of the Y is a conserved region that all antibodies have
in common, while the tips of the forks of the Y are unique to
each antibody.
• The tips react with the antigen, while the conserved base
interacts with the immune system.
• Five types of antibodies are formed in the body: IgG, IgM, IgA,
IgD and IgE (notice they spell MADGE)
• Immunoglobulin G (IgG) is the most abundant circulating antibody, making up
80% of the total antibodies and 75% of that found in serum.
• It contains a single antibody protein complex, with two heavy chains and two
light chains.
• IgG is the second type of antibody synthesized in response to an infection and is
the only antibody that can pass through the wall of small blood vessels to access
antigens present in the extracellular spaces.
• It is also the only antibody capable of crossing the placenta in humans, where it
confers the mother's immunity onto the fetus and newborn.
• This immunity protects a baby for the first 6-12 months of its life and allows it
time for its own immune system to mature.
• IgG is particularly effective at attacking extracellular viruses and protein toxins
and is also capable of activating the classic pathway of the complement
cascade. It helps to prevent the systemic spread of infection and facilitates
recovery from many infections.
• Finally, IgG is the antibody that serves as an efficient handle for phagocytes
• IgM is the largest antibody, with five Y structures being joined by their Fc
regions in a circular configuration.
• A J chain (another polypeptide) links the five antibodies together. IgM is
present in serum, making up about 10 % of antibodies in the blood.
• The presence of its ten antigen reactive sites helps agglutinate or clump
antigens (see the explanation of this term in the next section), making it
easier for the immune system to eliminate them.
• IgM is more efficient than IgG at activating the complement pathway.
• IgM is synthesized by plasma cells early in a primary infection and is very
important in slowing or stopping the spread of a pathogen during the initial
stages of an illness.
• IgM is also found on mature B cells in a monovalent form, where it serves as
a receptor.
• IgA is present in serum, mucus, saliva, tears, sweat and milk.
• Two subclasses with different heavy chains are made, IgA1 and IgA2.
IgA1 is synthesized in the bone marrow and makes up most of the
serum IgA.
• IgA2 is synthesized by B cells present in MALT (mucosa-associated
lymphoid tissue). NOTE: MALT includes your tonsils & Peyer’s
patches
• IgA in breast milk interferes with the colonization of the GI tract by
harmful microorganisms in the first few months of life. The mother's
IgA in the GI tract of newborns keeps these pathogens at low
populations, preventing them from causing serious disease, but still
allowing the stimulation of the infant's own immune system. The
newborn thus develops its own immunity while being partially
protected by the mother. IgA molecules do not activate the classical
complement pathway, but may activate the alternative complement
pathway.
• IgE is a monomeric antibody that accounts for only 0.002 % of the
total serum antibodies.
• Almost all IgE is bound to tissue cells, especially mast cells and
eosinophils in various parts of the body.
• Contact of IgE with antigen leads to release of a set of signal
molecules from the mast cells, which effectively recruits various agents
of the immune response to fight the infection.
• IgE and MALT serve to detect penetrating pathogens and amplify the
immune response in an area leading to the repulsion of the invader.
• Antigen reactions with IgE are also responsible for atopic allergic
reactions (e.g., hives, asthma, hay fever etc.)
• IgD is found on the surface of B-lymphocytes and together with
monomeric IgM, serves as antigen receptor for the activation of
B cell as described previously.
• IgD is monovalent (one site of attachment).
• The complement pathway consists of a series of over thirty
proteins in plasma that are part of the immune response.
• Activation of the complement system lyses bacterial cells, forms
chemotactic peptides by attracting immune cells, and increases
phagocytotic clearance of infecting cells.
• Picture on next slide
• Let’s take a breather and do a little thoughtful Ed activity here.
• Compare and Contrast T-cells and B-cells
• B cell and T cell are lymphocytes responsible for the third line of defense in
your body. Basically defending your body from invading antigens (i.e.
germs).
The main difference between the two are:
- B cell are responsible for the antibody-mediated response while T cells are
responsible for cell-mediated response.
- B cell produced in bone marrow. T cell produced in bone marrow & lymph
nodes.
- When detected antigen, B cell undergoes clonol expansion and create
different B cell, some are memory B cell which remembers the germ. Most
become plasma cells which produces antibody (germ killer) to fight the
antigen.
- T cell's main role is to destroy infected cells and cancer cells and to
coordinate acquired immune response.
• Note: Antigen presentation is necessary for the activation and cloning of
T-cells.
• Each B cell and T cell is specific for a particular antigen. What
this means is that each is able to bind to a particular molecular
structure.
• They are integral membrane proteins.
• They are present in thousands of identical copies exposed at
the cell surface.
• They are made before the cell ever encounters an antigen.
• They are encoded by genes assembled by the recombination of
segments of DNA.
• B cells get immunocompetence (the ability to develop an
immune response following exposure to an antigen) in the BONE
MARROW
• AND
• Lymphocytes that are able to mount an immune response are
called immunocompetent
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They complement fixation
Precipitation
Agglutination
Neutralization
• Complement fixation. Antibodies IgM and IgG bind to enemy
cells and change shape, exposing their complement-binding
sites
• This initiates the binding of complement to the enemy cell
surface and leads to inflammation, phagocytosis, immune
clearance, and cytolysis
• Complement fixation is the primary mechanism of defense
against foreign cells such as bacteria and mismatched
erythrocytes.
• It makes it easier for phagocytes to ingest and destroy
bacteria.
• a similar process in which antibodies link antigen molecules (not
whole cells) together.
• This creates large Ag–Ab complexes that are too large to
remain dissolved in solution.
• These complexes can be removed by immune clearance or
phagocytized by eosinophils in the connective tissues.
• It is effective not only in mismatched blood transfusions, but
more importantly as a defense against bacteria.
• An antibody molecule has 2 to 10 binding sites; thus, it can bind
to antigen molecules on two or more enemy cells at once and
stick them together
• This immobilizes microbes and antigen molecules and prevents
them from spreading through the tissues.
• Only certain regions of an antigen are pathogenic—for
example, the parts of a toxin molecule or virus that enable
these agents to bind to human cells.
• Antibodies can neutralize an antigen by masking these active
regions (i.e. The antibodies bind to specific sites on bacteria
toxins and block their “bad” effects) .
• The migration of phagocytes and WBCs (white blood cells) to
an inflamed area along a chemical gradient
• Q: When would this happen?
• Skin & mucous membranes
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Fever
Inflammatory response
Intact skin
Natural killer cells (these are not to be confused with T or B
cells) http://www.youtube.com/watch?v=HNP1EAYLhOs
• The inflammatory response is the body's natural response that
occurs immediately following tissue damage.
• It's main functions are to defend the body against harmful
substances, dispose of dead or dying tissue and to promote the
renewal of normal tissue.
• Pain (due to chemicals released by damaged cells).
• Swelling or Edema (due to an influx of fluid into the damaged
region).
• Redness (due to vasodilatation- the widening of blood vessels
and bleeding in the joint or structure).
• Heat (due to an increase in blood flow to the area).
• Loss of function (due to increased swelling and pain).
http://www.youtube.com/watch?v=_bNN95sA6-8
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Dilate the blood vessels
Capillaries become leaky
Attract phagocytes
Activate natural pain receptors
• Artificially acquired active immunity
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Spleen
Tonsils
Thymus
Peyer’s Patches
• The spleen destroys worn out red blood cells.
• It is located in the upper far left part of the abdomen, to the
left of the stomach.
• The spleen varies in size and shape between people, but it’s
commonly fist-shaped, purple, and about 4 inches long.
• The spleen also helps fight certain kinds of bacteria that cause
pneumonia and meningitis
• Enlarged Spleen (Splenomegaly): An enlarged spleen, usually caused by
viral mononucleosis (“mono”), liver disease, blood cancers (lymphoma and
leukemia), or other conditions.
• Ruptured spleen: The spleen is vulnerable to injury, and a ruptured spleen
can cause serious life-threatening internal bleeding and is a life-threatening
emergency. An injured spleen may rupture immediately after an injury, or in
some cases, days or weeks after an injury.
• Sickle cell disease: In this inherited form of anemia, abnormal red blood cells
block the flow of blood through vessels and can lead to organ damage,
including damage to the spleen. People with sickle cell disease need
immunizations to prevent illnesses their spleen helped fight.
• Thrombocytopenia (low platelet count): An enlarged spleen sometimes stores
excessive numbers of the body’s platelets. Splenomegaly can result in
abnormally few platelets circulating in the bloodstream where they belong.
• The tonsils (palatine tonsils) are a pair of soft tissue masses
located at the rear of the throat (pharynx).
• Each tonsil is composed of tissue similar to lymph nodes,
covered by pink mucosa (like on the adjacent mouth lining).
Running through the mucosa of each tonsil are pits, called
crypts.
• Acute tonsillitis: A bacteria or virus infects the tonsils, causing swelling and a
sore throat. The tonsil may develop a gray or white coating (exudate).
• Chronic tonsillitis: Persistent infection of the tonsils, sometimes as a result of
repeated episodes of acute tonsillitis.
• Peritonsillar abscess: An infection creates a pocket of pus next to the tonsil,
pushing it toward the opposite side. Peritonsillar abscesses must be drained
urgently.
• Acute mononucleosis: Usually caused by the Epstein-Barr virus, “mono” causes
severe swelling in the tonsils, fever, sore throat, rash, and fatigue.
• Strep throat: Streptococcus, a bacterium, infects the tonsils and throat. Fever
and neck pain often accompany the sore throat.
• Enlarged (hypertrophic) tonsils: Large tonsils reduce the size of the airway,
making snoring or sleep apnea more likely.
• Tonsilloliths (tonsil stones): Tonsil stones, or tonsilloliths, are formed when this
trapped debris hardens, or calcifies.
• http://www.entusa.com/tonsils_adenoid_surgery.htm
• Note: not for the queasy
• This organ programs T cells and functions at its highest in youth
• The thymus is a small organ in your upper chest, under your
breastbone.
• Before birth and during childhood, the thymus helps the body
make a type of white blood cell.
• These cells help protect you from infections.
• Lymphatic tissue found in the walls of the small intestine
• Peyer's patches are areas of specialized tissue in the lower
area of the small intestine that work to distinguish friend from
foe as food passes through the gastrointestinal tract.
• Sensitized cells inside these areas identify antigens and decide
whether they are harmless, associated with foods that the
person is consuming for nutrition, or harmful, and linked with
organisms like bacteria that could try to colonize the body.
• As food passes by, the antigens in the food are presented to the
tissue and it determines whether it recognizes them and how
they are classified.
• In addition to recognizing antigens and triggering the
appropriate response, the Peyer's patches can also learn to
identify new antigens, storing this information for future
reference to make the immune system more effective.
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Pneumonia
Tetanus
Polio
Meaasles
• Grave’s Disease http://www.webmd.com/a-to-zguides/understanding-graves-disease-basics
• Rheumatoid arthritis http://www.webmd.com/rheumatoidarthritis/guide/rheumatoid-arthritis-basics
• Multiple sclerosis http://www.webmd.com/multiplesclerosis/default.htm?names-dropdown=RI
• Type I Diabetes Mellitus
http://www.webmd.com/diabetes/types-of-diabetes-mellitus
• Also known as “PYREXIA”
• Fevers are caused by chemicals called pyrogens flowing in the
bloodstream.
• Pyrogens make their way to the hypothalamus in the brain,
which is in charge of regulating body temperature.
• When pyrogens bind to certain receptors in the hypothalamus,
body temperature rises.
• One common pyrogen is called Interleukin-1 (IL-1). IL-1 is
produced by white blood cells called macrophages when they
come into contact with certain bacteria and viruses.
• IL-1 has multiple purposes, one of which is to signal other white
blood cells, called helper T cells, into action.
• Average body temperature is about 98.6°F or 37°C, and
temperatures above 100.4°F or 38°C are generally considered
to be febrile.
• Fevers…….
• Speed up the repair process
• Increases metabolic rate (this is why your heart rate gets faster)
• Denature proteins
Stimulate liver and spleen to gather zinc and iron
• The process that neutrophils use to get across the capillary walls
is called diapedesis
• Cells infected by viruses secrete the protein interferon to protect
nearby cells
• Lymph from the left arm goes back into the heart through the
thoracic duct
• Your genes determine the ability of your being able to
recognize foreign substances.
• The lymphatic organs on a diagram
• Lymph capillary, lymph node, valve, blood capillary, and vein
on a diagram