The Lymphatic SystemThe Lymphatic System

February 2011February 2011

FunctionsFunctions

drains and filters protein containing drains and filters protein containing fluids from tissue which has fluids from tissue which has escaped from blood capillariesescaped from blood capillaries

transport fats from gastrointestinal transport fats from gastrointestinal tract to the bloodtract to the blood

defense – protect the body from defense – protect the body from foreign cells, microbes, cancer cellsforeign cells, microbes, cancer cells

Lymph Lymph vesselsvessels

Major Structures of the Major Structures of the Lymphatic SystemLymphatic System

Lymph (fluid)Lymph (fluid) VesselsVessels Lymph nodesLymph nodes

TonsilsTonsils AdenoidsAdenoids SpleenSpleen ThymusThymus Peyer’s PatchPeyer’s Patch AppendixAppendix

Lymph OrgansLymph Organs

Structure DetailsStructure Details

lymphlymph – clear and colorless; – clear and colorless; composed of water, lymphocytes, composed of water, lymphocytes, nutrients, hormones, and salts; nutrients, hormones, and salts; also known as intercellular or also known as intercellular or interstitial fluid. Originates in blood interstitial fluid. Originates in blood plasma.plasma.

lymph vesselslymph vessels – carry fluid; more – carry fluid; more permeable than blood capillaries.permeable than blood capillaries.

LymphLymph

Structure DetailsStructure Details lymph nodeslymph nodes – small round structures – small round structures

located in lymph vessels; they are located located in lymph vessels; they are located in clusters in the following areas: cervical in clusters in the following areas: cervical (neck), axillary (armpits), pectoral (chest), (neck), axillary (armpits), pectoral (chest), abdominal (stomach), inguinal (groin area), abdominal (stomach), inguinal (groin area), popliteal (back of leg, behind knees)popliteal (back of leg, behind knees)

FunctionFunction: they fight disease by producing : they fight disease by producing antibodies, removing bacteria or antibodies, removing bacteria or malignant cells, and filtering foreign malignant cells, and filtering foreign substances; contains large amounts of substances; contains large amounts of lymphocytes and macrophageslymphocytes and macrophages

Structure DetailsStructure Details tonsils & adenoids-tonsils & adenoids- lymph tissue located lymph tissue located

in the upper portions of the nose and throatin the upper portions of the nose and throat spleenspleen – largest lymphatic organ composed – largest lymphatic organ composed

of lymph tissue that is located in the left of lymph tissue that is located in the left upper quadrant of the abdomen upper quadrant of the abdomen

FunctionFunction: production of : production of B lymphocytesB lymphocytes; ; phagocytizes bacteria and worn out phagocytizes bacteria and worn out damaged RBC; stores and releases blood damaged RBC; stores and releases blood in case of demand in case of demand

Structure DetailsStructure Details

thymusthymus- lymph tissue; located - lymph tissue; located on top of heart, reaches on top of heart, reaches maximum size in puberty and maximum size in puberty and decreases thereafterdecreases thereafter

Function: help Function: help produce T- cellsproduce T- cells

Cells of the lymphatic Cells of the lymphatic systemsystem

macrophagesmacrophages – large phagocytic cell – large phagocytic cell (cells eats bad stuff) ((cells eats bad stuff) (like pacman like pacman chewing it upchewing it up))

lymphocyteslymphocytes – originate in the bone – originate in the bone marrow; type of white blood cell that marrow; type of white blood cell that provides immunityprovides immunity

MacrophageMacrophage

LymphocytesLymphocytes T lymphocytesT lymphocytes – (thymus dependent) 80% of – (thymus dependent) 80% of

lymphocytes are T cells.lymphocytes are T cells.

Different types of T cells – Different types of T cells – cytotoxic T cells cytotoxic T cells – – respond to foreign respond to foreign

antigens by attaching to the foreign antigenantigens by attaching to the foreign antigen (interact directly with the cells – called (interact directly with the cells – called cell-cell-mediatedmediated immunity) (Memory cells that recognize immunity) (Memory cells that recognize an antigen immediately become cytotoxic T cells.)an antigen immediately become cytotoxic T cells.)

helper T cells helper T cells – stimulate the activation and – stimulate the activation and function of other T cells and B cellsfunction of other T cells and B cells

suppressor T cells suppressor T cells – inhibit the activation and – inhibit the activation and function of other T cells and B cellsfunction of other T cells and B cells

Lymphocytes ContinuedLymphocytes Continued

B lymphocytesB lymphocytes – (bone marrow- – (bone marrow-derived) respond to foreign antigens derived) respond to foreign antigens by producing by producing antibodiesantibodies that destroy that destroy the the antigen-bearing particlesantigen-bearing particles (don’t (don’t interact directly with the cells – called interact directly with the cells – called antibody-mediatedantibody-mediated immunity) immunity)

Antibodies (immunoglobulins) – Antibodies (immunoglobulins) – destroy any cell that bearing the destroy any cell that bearing the matching antigen.matching antigen.

NK (natural killer) cellsNK (natural killer) cells NK cells recognize and destroy abnormal NK cells recognize and destroy abnormal

cells.cells. They constantly monitor normal tissues They constantly monitor normal tissues

(called immunological surveillance).(called immunological surveillance).

A single NK cell can attack bacteria in the A single NK cell can attack bacteria in the interstitial fluid, body cells infected with interstitial fluid, body cells infected with viruses or cancer cells. Abnormal cells occur viruses or cancer cells. Abnormal cells occur throughout life. Cancer arises when the throughout life. Cancer arises when the abnormal cells divide faster than the T cells abnormal cells divide faster than the T cells can kill them.can kill them.

Cells of LymphaticCells of Lymphatic

If a microbe that can cause If a microbe that can cause infection gets past your body’s infection gets past your body’s initial barriers (mechanical barrier) initial barriers (mechanical barrier) First line of defense First line of defense (skin, (skin, mucus), T cells are the army troops mucus), T cells are the army troops that do the fighting (B cells are the that do the fighting (B cells are the armed guards that hold a grudge).armed guards that hold a grudge).

Antigen vs. AntibodyAntigen vs. Antibody

Antigen – proteins, polysaccharides, Antigen – proteins, polysaccharides, lipids that are located on a cell’s lipids that are located on a cell’s surface that elicit an immune surface that elicit an immune responseresponse

Self antigens- proteins that the body Self antigens- proteins that the body cells recognize as cells recognize as “self”“self”

Non-selfNon-self- proteins that the body - proteins that the body does not recognizedoes not recognize

Continued…Continued… Antibody – protein that B cells Antibody – protein that B cells

produce in response to the presence produce in response to the presence of a non-self antigen.of a non-self antigen.

When an antibody combines with an When an antibody combines with an antigen, it renders the antigen-antigen, it renders the antigen-bearing cell/particle inactive and bearing cell/particle inactive and leads to the destruction of the cell. leads to the destruction of the cell.

Causes agglutination or massing of Causes agglutination or massing of cells together so they can be cells together so they can be destroyed. destroyed.

Agglutination of antigens with Agglutination of antigens with matching antibodiesmatching antibodies

Nonspecific Defense Nonspecific Defense

Mechanical barrierMechanical barrier: physical barrier between : physical barrier between the body and pathogen. Ex: skin, mucous the body and pathogen. Ex: skin, mucous membranes, cilia, epiglottis. membranes, cilia, epiglottis. First line of First line of defense for the body.defense for the body.

Species resistanceSpecies resistance: a given organism develops : a given organism develops diseases that are unique to it. Examples are diseases that are unique to it. Examples are mumps, gonorrhea and syphilis infect humans mumps, gonorrhea and syphilis infect humans but not other animals. but not other animals.

Disease may affect different animals Disease may affect different animals differently.differently.

Nonspecific DefenseNonspecific Defense all except mechanical barrier are all except mechanical barrier are secondsecond line of line of

defense defense chemical barrierchemical barrier: enzymes in body fluid that : enzymes in body fluid that

can damage, kill or make the environment can damage, kill or make the environment uninhabitable for the pathogen. Ex. Gastric uninhabitable for the pathogen. Ex. Gastric juice, tears, salt in sweatjuice, tears, salt in sweat

feverfever: : endogenous pyrogenendogenous pyrogen (protein) raises (protein) raises the set point in the brain for body temperature. the set point in the brain for body temperature. The higher temperature reduces the levels of The higher temperature reduces the levels of iron in the blood that the pathogen needs to iron in the blood that the pathogen needs to survive. Also, phagocytic cells attack more survive. Also, phagocytic cells attack more vigorouslyvigorously

inflammationinflammation: redness, swelling, heat, and pain : redness, swelling, heat, and pain due to a pathogen invasion, inhibits microbial due to a pathogen invasion, inhibits microbial growth. Increases blood flow through the area. growth. Increases blood flow through the area.

Specific Defense (Immunity) Specific Defense (Immunity)

ThirdThird line of defense line of defense resistance to particular pathogens or resistance to particular pathogens or

to their toxinsto their toxins cell-mediated immunity – this is cell-mediated immunity – this is

where T-cells, B-cells, and where T-cells, B-cells, and macrophages are activated. macrophages are activated.

Specific Defense (Immunity)Specific Defense (Immunity)

Antibody-mediated immunityAntibody-mediated immunity Immune responsesImmune responses

Primary immune responsePrimary immune response – B cells and T – B cells and T cells are activated and fight the pathogen. cells are activated and fight the pathogen. Anti-bodies are produced (takes 5-10 days Anti-bodies are produced (takes 5-10 days to reach detectable levels)to reach detectable levels)

Secondary immune responseSecondary immune response – Some of the – Some of the B cells activated by the primary response B cells activated by the primary response remain dormant as memory cells; if the remain dormant as memory cells; if the antigen is encountered in the future, the antigen is encountered in the future, the memory B cells immediately begin to memory B cells immediately begin to produce the antibodyproduce the antibody

Active and Passive Active and Passive ImmunityImmunity

Active immunityActive immunity – results when a person – results when a person produces an immune response to an produces an immune response to an antigen that is long-lasting antigen that is long-lasting

Occurs naturally when a person is exposed Occurs naturally when a person is exposed to a pathogen and develops a disease; to a pathogen and develops a disease; person gains resistance by initiating a person gains resistance by initiating a primary immune response.primary immune response.

The primary immune response gives The primary immune response gives immunity or a secondary immune response. immunity or a secondary immune response.

Active Immunity ContinuedActive Immunity Continued

Occurs artificially when a person receives Occurs artificially when a person receives a vaccine (bacteria or viruses that have a vaccine (bacteria or viruses that have been killed or weakened so they can’t been killed or weakened so they can’t cause a serious infection); but they still cause a serious infection); but they still contain antigens that stimulate an contain antigens that stimulate an immune response; doesn’t always last immune response; doesn’t always last for life. for life.

Still activates a secondary immune Still activates a secondary immune response.response.

Passive ImmunityPassive Immunity Occurs when a person receives antibodies Occurs when a person receives antibodies

produced by another individual; person does produced by another individual; person does not have an immune response, so immunity not have an immune response, so immunity is short-term. is short-term.

Occurs naturally when antibodies pass from Occurs naturally when antibodies pass from mother’s blood into fetal bloodstream, also mother’s blood into fetal bloodstream, also thru breastfeeding; fetus acquires immunity thru breastfeeding; fetus acquires immunity against pathogens that mother has against pathogens that mother has developed immunity against; lasts 6 months developed immunity against; lasts 6 months to a year after birth.to a year after birth.

Occurs artificially when a person receives Occurs artificially when a person receives antiserumantiserum (ready-made antibodies). (ready-made antibodies).

Types of Acquired Types of Acquired ImmunityImmunity Type Mechanism Result

Naturally acquired active immunity

Exposure to pathogens

Symptoms of disease and an immune response

Artificially acquired active immunity

Vaccine Stimulation of immune response without severe symptoms of disease

Artificially acquired passive immunity

Injections of antibodies (antiserum)

Short term immunity without an immune response

Naturally acquired passive immunity

Antibodies passed to fetus

Short term immunity for infant without immune response (lasts 6 mths to 1 yr)

Vaccines Vaccines

Mixtures of antigens (killed microbes, Mixtures of antigens (killed microbes, those that are unable to cause those that are unable to cause infection, or proteins not recognized infection, or proteins not recognized as self). as self).

Administered orally, nasally, Administered orally, nasally, inoculation - not for life – usually inoculation - not for life – usually repeated. repeated.

Immune System Concerns Immune System Concerns

Three types of immune system Three types of immune system disorders …disorders … Autoimmune DisordersAutoimmune Disorders AllergiesAllergies Immunodeficiency DiseaseImmunodeficiency Disease

Autoimmune Disorders –Autoimmune Disorders –

a. Your system attacks your own self a. Your system attacks your own self cellscells

b. Occurs when bacteria/virus causes T b. Occurs when bacteria/virus causes T cells to attack body’s own macrophage. cells to attack body’s own macrophage. Eventually killer T cells start to view Eventually killer T cells start to view other cells in the body as foreign other cells in the body as foreign

c. Examples: Lupus, Rheumatoid c. Examples: Lupus, Rheumatoid Arthritis, Multiple SclerosisArthritis, Multiple Sclerosis

Allergies –Allergies –

a. Allergens cause the system to have a a. Allergens cause the system to have a hypersensitivity reaction which causes hypersensitivity reaction which causes an excessive immune response. Severity an excessive immune response. Severity can change year to year and some start can change year to year and some start late in life – genetics can predispose late in life – genetics can predispose people to allergiespeople to allergies

b. Delayed reaction allergy results from b. Delayed reaction allergy results from repeated exposure to antigens repeated exposure to antigens

Allergies ContinuedAllergies Continued

c. IgE antibodies cause the release of c. IgE antibodies cause the release of histamine …. Initiating allergic histamine …. Initiating allergic reactions which can damage the reactions which can damage the tissues in the bodytissues in the body

d. dilation of blood vessels, increased d. dilation of blood vessels, increased vascular permeabilty, swelling, vascular permeabilty, swelling, contract of bronchial and smooth contract of bronchial and smooth muscles, increased mucous productionmuscles, increased mucous production

Allergies ContinuedAllergies Continued

e. the result is severe inflammation- hives, e. the result is severe inflammation- hives, hay fever, asthma, or gastric disturbanceshay fever, asthma, or gastric disturbances

f. some are seasonal and others are year f. some are seasonal and others are year round (food)round (food)

g. A severe allergic reaction (sudden g. A severe allergic reaction (sudden breathing difficulty) is anaphylaxis can cause breathing difficulty) is anaphylaxis can cause anaphylactic shock which can lead to death – anaphylactic shock which can lead to death – treatment is an epinephrine injection or treatment is an epinephrine injection or tracheotomy. Symptoms of an anaphylactic tracheotomy. Symptoms of an anaphylactic shock: hives, vomiting, diarrhea, face, tongue shock: hives, vomiting, diarrhea, face, tongue and larynx swelland larynx swell

Immunodeficiencies Immunodeficiencies

(acquired immunodeficiency syndrome) is (acquired immunodeficiency syndrome) is caused by HIV (human immunodeficiency caused by HIV (human immunodeficiency virus. HIV targets helper T cells, which virus. HIV targets helper T cells, which makes a person infected unable to fight makes a person infected unable to fight against this virus. against this virus.

Over time, the person is deficient in helper Over time, the person is deficient in helper T cells T cells immunodeficiency. It is acquired immunodeficiency. It is acquired (rather than induced) via lifestyle choices (rather than induced) via lifestyle choices (unprotected sex, intravenous drug use) (unprotected sex, intravenous drug use) or events (blood transfusions)or events (blood transfusions)

ImmunodeficienciesImmunodeficiencies

initial symptoms- weakness, recurrent initial symptoms- weakness, recurrent fever, night sweats, swollen glands, fever, night sweats, swollen glands, weight loss (similar symptoms of the flu)weight loss (similar symptoms of the flu)

latency period- 5-10 years person feels latency period- 5-10 years person feels well, immune system struggles with well, immune system struggles with growing HIV invading cellsgrowing HIV invading cells

AIDS (third stage)-opportunistic infection. AIDS (third stage)-opportunistic infection. Those infected don’t die from AIDS, they Those infected don’t die from AIDS, they die due to the flu, pneumonia, etc die due to the flu, pneumonia, etc because their immune system is so because their immune system is so weak, they can’t fight anymore.weak, they can’t fight anymore.