LYMPHATIC SYSTEM The body has a second transportation system, which consists of a network of lymphatic vessels and lymphoid organs. Called the lymphatic system, it has two major functions. First, it ensures that blood volume stays the same. Each day, some 51 pints (24 liters) of fluid leave the blood as it passes through the tissues. Most returns to capillaries, but some 6- 8 pints (3-4 liters) remains.

This surplus, now called lymph, drains into lymphatic vessels and is emptied back into the bloodstream. Second it plays a major part in body defense. It contains cells, also found in the blood, called lymphocytes and macrophages, which form the immune system the body’s most powerful defense against disease.

LYMPHATIC SYSTEM Functions: LYMPH – fluid that goes between capillary blood and tissues. LYMPH VESSELS – transport excess tissue fluid back into circulatory system. LYMPH NODES – produce lymphocytes, filter out harmful bacteria. SPLEEN – produces lymphocytes and monocytes, blood reservoir, recycles old red cells. Thymus gland – produces T-LYMPHOCYTES

LYMPH Straw-colored fluid (similar to plasma) INTERSTITIAL FLUID or tissue fluid because it is in the spaces between cells Composed of H2O, lymphocytes, some granulocytes, O2, digested nutrients, hormones, salts, CO2 and urea. NO red blood cells or protein molecules (too large) Carries digested food, O2 and hormones to cells Carries wastes back to capillaries for excretion Since the lymphatic system has no pump, skeletal muscle action squeezes lymph along Valves prevent backward flow

LYMPH VESSELS Closely parallel veins Located in almost all tissues and organs that have blood vessels

LYMPH CAPILLARIES The smallest vessels in the lymphatic system, lymph capillaries form a branching network of dead-end tubes that, like blood capillaries, pass between tissue cells. The thin walls of the lymph capillaries have tiny flaps that act like one-way swinging doors letting in excess tissue fluid – which has passed out of, but not returned to, blood capillaries – but not allowing it to flow back out into the tissues. This clear, watery fluid, now called lymph, is carried onward into the larger lymphatic vessels

Tissue lymph enters small lymph vessels which drain into larger vessels called lymphatics – they flow into one of two large, main lymphatics – the THORACIC DUCT and right lymphatic duct.

THORACIC DUCT gets lymph from left side of chest, head and neck, abdominal area and lower limbs  left subclavian vein  superior vena cava  heart. Lymph flows only in one direction – from body organs to the heart.

LYMPH NODES Tiny, oval shaped - size of pinhead to size of almond Located alone or grouped Site for lymph production and filter for screening out harmful substances If substance can’t be destroyed, node becomes inflamed

Occur along lymph vessels like beads on a string. Lymph nodes filter lymph as it passes through them. Surrounded by a tough capsule, the spaces, or network of fibers that support macrophages and lymphocytes. These fibers slow the flow of lymph passing through while macrophages engulf and destroy bacteria, cancer cells, and debris, and lymphocytes launch their immune defenses. During infections, lymph nodes may swell up and become tender, a condition known as “swollen glands”

TONSILS Masses of lymphatic tissue that produce lymphocytes and filter bacteria – they get smaller in size as person gets older ADENOIDS – tonsils on upper part of the throat

A ring of five tonsils (2 at the back of mouth, 2 at the back of tongue, & one in the upper throat) protect the entrance to the digestive & respiratory systems from bacteria carried in food and air. Bacteria migrate into the tonsils where they are trapped inside deep “crypts” & destroyed by lymphoctyes.

SPLEEN Sac-like mass of lymphatic tissue Upper left abdominal cavity, just below diaphragm Forms lymphocytes and monocytes Filters blood Stores large amounts of RBCs – contracts during vigorous exercise or loss of blood, to release RBCs Destroys or removes old or fragile RBCs

THYMUS GLAND Upper, anterior thorax, above the heart Thymus is also considered an endocrine gland

The two lobed thymus gland carries out its most important functions in the early years of life. It trains lymphoctyes to be effective as part of the body’s immune system. Unspecialized lymphocytes arrive in the blood from bone marrow. They mature in the thymus, becoming capable of attacking specific pathogen, then leave as T-cells (thymus-dependent) to be sent to lymphoid organs, blood and lymph

Immunity The body’s ability to resist bacterial invasion and disease. 2 general types – natural and acquired.

NATURAL IMMUNITY – at birth, inherited and permanent. Includes: Unbroken skin sweat together with sebum produced by sebaceous glands, protects the skin. Both substances have antiseptic properties Mucus and tears tears produced by glands in the eyelids wash away dirt & contain an antiseptic substance Blood phagocytes WBC that engulf & destroy invading organisms. Two types: neutrophils & macrophages. Neutrophils circulate in the blood before being transferred to the tissues, where they seek out organisms. Macrophages also start in the bloodstream, where they are known as monocytes, before moving to the tissues where they become macrophages. Some macrophages stay in one place; others travel around looking for invading organisms. All phagocytes flow around organisms, wrapping them within a membrane that fuses with granules called lysosomes. These granules contain strong chemicals that digest the organisms, producing harmless substances that pass out through the cells’ membrane.

Local inflammation This is the familiar warm, reddish, tender swelling that appears after an injury. At the site of the damage, tissue cells release histamine & other chemicals. They make the blood vessels wider, so that extra blood arrives, and more leaky, so that fluid passes into the tissues, aiding repair and making the area, swollen, and warm. These chemicals also attract phagocytes that destroy pathogens.

ACQUIRED IMMUNITY – body’s reaction to invaders PASSIVE ACQUIRED IMMUNITY Acquired artificially by injecting antibodies to protect from a specific disease Immediate immunity Lasts 3-5 weeks Used when someone exposed to measures, tetanus, infectious hepatitis Mother provides newborn with some passive immunity

ACTIVE ACQUIRED IMMUNITY Lasts longer, two types NATURAL ACQUIRED IMMUNITY – result of having had and recovered from a disease. For example, a child who had measles will usually not get it again – child’s body has manufactured antibodies.

ARTIFICIAL ACQUIRED IMMUNITY – comes from being vaccinated IMMUNIZATION – artificial resistance to a particular infection by artificial means Antigen injected into a person to stimulate production of antibodies

Disorders of the Lymphatic System ADENITIS – swelling in the lymph glands TONSILLITIS In childhood, they may become infected, enlarged, and cause difficulty swallowing Surgery done in extreme cases

LYMPHADENITIS enlargement of the lymph nodes, occurs when infection is present and body is attempting to fight off the infection.

HODGKIN’S DISEASE cancer of the lymph nodes, painless swelling of lymph nodes is early symptom. Rx – chemotherapy and radiation

INFECTIOUS MONONUCLEOSIS Caused by virus Frequently in young adults and children Spread by oral contact (kissing)

Symptoms – enlarged lymph nodes, fever, physical and mental fatigue,  leukocytes Rx – bedrest

HYPERSENSITIVITY When the body’s immune system fails to protect itself against foreign material, and instead, the antibodies formed irritate certain body cells. An abnormal response to a drug or allergen.

An ALLERGEN is an antigen that causes allergic responses. (Examples of allergens – ragweed, penicillin, bee stings, foods, etc.)

ANAPHYLAXIS severe, sometimes fatal allergic reaction Antigen-antibody reaction stimulates a massive secretion of histamine Symptoms – breathing problems, headache, facial swelling, falling blood pressure, stomach cramps, and vomiting Rx – adrenaline

AIDS/HIV Acquired Immunodeficiency Syndrome Caused by HTLV-III (human T- lymphotrophic virus type III) Commonly caused HIV or Human immunodeficiency virus. Affects not only homosexual males but all populations The patient with AIDS cannot fight off cancers and most infections.

Between October 1980 and May 1981, five young, previously healthy homosexual men were treated for a pneumonia caused by a parasite, Pneumocystis carinii. Before this, P. carnii pneumonia occurred only in immunosuppressed patients, especially those receiving cancer therapy. At the same time, a rare and unusual blood vessel malignancy called Kaposi’s sarcoma was being diagnosed with increasing frequency in young homosexual males. In 1981, twenty-six cases of Kaposi’s sarcoma had been diagnosed in young homosexual males. These cases were an early indication of an epidemic of a previously unknown disease. Later, it was called the Acquired Immunodeficiency Sybndrome. (AIDS). It is said to be the third leading cause of death in young people.

Three responses to HIV infection: AIDS ARC (AIDS-related complex) Asymptomatic infection Screening tests for HIV/AIDS are available

Screening tests Blood tests for presence of antibodies does not reach detectable levels until 1-3 months after infection Tests: ELISA- enzyme linked immunosorbent assay (detects antibodies but not the virus itself) Western Blot confirms the ELISA results

AIDS Most severe type of HIV infection Subject to OPPORTUNISTIC INFECTIONS – a healthy person would fight off these infections, but a person with AIDS has a compromised immune response.

Opportunistic infections Kaposi sarcoma Cervical cancer Parasitic infections (some pneumonias) Fungal infection – candidiasis Viral infections – herpes simplex, hepatitis B Higher risk for TB & syphilis

Symptoms of AIDS Prolonged fatigue Persistent fevers or night sweats Persistent, unexplained cough Thick coating in throat or on tongue Easy bruising, unexplained bleeding Appearance of purple lesions on mucous membranes or skin that don’t go away Chronic diarrhea Shortness of breath Unexplained lymphadenopathy Unexplained weight loss, 10 pounds or more, in less than 2 months

AIDS-RELATED COMPLEX (ARC) Has HIV but not AIDS and develops other conditions such as: Chronic diarrhea Chronic lymphadenopathy Unexplained weight loss If life threatening opportunistic infections develop, then individual is said to have AIDS ASYMPTOMATIC INFECTION - Has HIV but no symptoms. High-Risk Groups for AIDS – EVERYONE who participates in risky behaviors.

Transmission by: Sex with someone who is HIV positive Sharing needles with infected IV drug users At birth from infected mother

Cannot be spread by: Casual contact Through air, feces, food, urine or water Coughing, sneezing, embracing, shaking hands and sharing eating utensils Prevention: Avoid risky behaviors Standard precautions

STANDARD PRECAUTIONS Guidelines to be used in patient care setting Must be used when there is contact with blood, any body fluid (except sweat), mucous membranes and non-intact skin.

Handwashing – the single most effective way to prevent infection. Wash hands after touching body fluids, even if gloves are worn. Wash hands immediately after removing gloves, between patient contacts. Use a plain (non-antimicrobial) soap Wash for a minimum of 10 seconds Gloves – worn when touching blood, body fluids, etc. Mask, eye protection, face shield and gown – during patient care activities that may generate splashes or sprays of blood, body fluids, etc. Patient care equipment and linens – handle with care, don’t let it touch your or clothing, clean or discard appropriately.

Occupational Health and Bloodbourne Pathogens Beware of needles! Never recap used needles. Dispose of all needles and sharp objects in sharps container. Use mouthpieces, resuscitation bags, or other ventilation devices as alternative to mouth-to- mouth resuscitation. A patient who contaminates the environment should be in a private room or relatively isolated area.

The AIDS Patient Sometimes treated as outcasts Healthcare worker should be supportive Use of gloves for normal patient contact is not necessary