The Lymphatic and Immune Systems

The Lymphatic and Immune Systems

• Main structures of the lymphatic system– Lymphatic vessels

• Main components of the immune system– Lymphocytes– Lymphoid tissue– Lymphoid organs

The Lymphatic System

• Lymphatic vessels collect tissue fluid from loose connective tissue – Carry fluid to great veins

in the neck– Fluid flows only toward

the heart

Figure 20.1

Functions of Lymphatic Vessels

• Collect excess tissue fluid and blood proteins

• Return tissue fluid and blood proteins to bloodstream

Orders of Lymphatic Vessels

• Lymph capillaries - smallest lymph vessels– first to receive lymph

• Lymphatic collecting vessels– collect from lymph capillaries

Orders of Lymphatic Vessels

• Lymph nodes– scattered along collecting vessels

• Lymph trunks– collect lymph from collecting vessels

• Lymph ducts– empty into veins of the neck

Lymphatic Capillaries

• Located near blood capillaries

• Receive tissue fluid from Connective Tissue

- increased volume of tissue fluid - minivalve flaps open and allow fluid to enter

• Highly permeability allows entrance of– tissue fluid– bacteria, viruses, and cancer cells

Lymphatic Capillaries

• Lacteals

– specialized lymphatic capillaries

- located in the villi of the small intestines

- receive digested fats

- fatty lymph – chyle

Lymphatic Capillaries

Figure 20.2a, b

Lymphatic Collecting Vessels

• Accompany blood vessels

• Composed of the same three tunics as BVs

• Contain more valves than veins do – helps direct the flow of blood

• Lymph propelled by– bulging of skeletal muscles– pulsing of nearby arteries– tunica media of the lymph vessels

Lymph Nodes

• Cleanse the lymph of pathogens

• Human body contains around 500

• Lymph nodes are organized in clusters

Lymph Nodes

Figure 20.3

Microscopic Anatomy of a Lymph Node

• Fibrous capsule – surrounds lymph nodes

• Trabeculae – connective tissue strands

• Lymph vessels– Afferent lymphatic vessels– Efferent lymphatic vessels

Figure 20.4a

Lymph Node Microscopic

Anatomy

Lymph Trunks• Lymphatic collecting vessels converge

Five major lymph trunks:

• Lumbar trunks - receives lymph from lower limbs

• Intestinal trunk - receives chyle, digestive organs

• Bronchomediastinal trunks - collects lymph from thoracic viscera

• Subclavian trunks - receive lymph from upper limbs and thoracic wall

• Jugular trunks - drain lymph from head & neck

Lymph Nodes, Trunks, and Ducts

Figure 20.3

The Lymphatic

Trunks

Figure 20.6a

Lymph Ducts

• Cisterna chyli– located at the union of lumbar and intestinal trunks

• Thoracic duct– Ascends along vertebral bodies– Empties into venous circulation – Junction of left internal jugular and left subclavian veins– Drains three quarters of the body

• Right lymphatic duct – empties into right internal jugular and subclavian veins

Palpation

Mononucleosis (aka Mono or ‘the kissing disease’)

• What is it? • Mononucleosis is a

viral infection causing fever, sore throat, and swollen lymph glands, especially in the neck.

Mono

• Mononucleosis, or mono, is often spread by saliva and close contact. It is known as "the kissing disease," and occurs most often in those age 15 to 17. However, the infection may develop at any age.

Mono

• Mono is usually linked to the Epstein-Barr virus (EBV), but can also be caused by other organisms such as cytomegalovirus (CMV).

Mono

• Blood work often reveals a higher-than-normal white blood cell (WBC) count and unusual-looking white blood cells called atypical lymphocytes, which are seen when blood is examined under a microscope. Atypical lymphocytes and abnormal liver function tests are a hallmark sign of the disease.

• A monospot test will be positive for infectious mononucleosis.

• To relieve typical symptoms:

• Drink plenty of fluids.

• Gargle with warm salt water to ease a sore throat.

• Get plenty of rest.

• Take acetaminophen or ibuprofen for pain and fever.

• You should also avoid contact sports while the spleen is swollen (to prevent it from rupturing).

The Immune System

• Recognizes specific foreign molecules

• Destroys pathogens effectively

• Key cells – lymphocytes

• Also includes lymphoid tissue and lymphoid organs

Lymphocytes

• Infectious organisms attacked by inflammatory response– macrophages, then lymphocytes

• Cytotoxic T lymphocytes – Attack foreign cells directly– Binds to antigen-bearing cells– Perforates cell membrane– Signals cell to undergo apoptosis

Lymphocytes

• B lymphocytes- become plasma cells

- secrete antibodies, mark cells for destruction by macrophages

Figure 20.7

Lymphocyte Activation

• Lymphocytes originate in bone marrow

• T lymphocytes travel to the thymus gland

• B lymphocytes stay in bone marrow

• Able to recognize a unique antigen

• Gain immunocompetence– travels through blood stream– meets and binds to a specific antigen

Lymphocyte Activation

• Activating T or B cells produce– Effector lymphocytes

• Short-lived, attack immediately

– Memory lymphocytes• Wait until body encounters their antigen again

– Basis of acquired immunity– Guard against subsequent infections

Figure 20.8

Lymphoid Tissue

• Most important tissue of the immune system

Two general locations:

• Mucous membranes of digestive, urinary, respiratory, and reproductive tracts- Mucosa-associated lymphoid tissue (MALT)

• Lymphoid organs (except thymus)

Lymphoid Organs

• Primary lymphoid organs– Bone marrow– Thymus

• Secondary lymphoid organs– Lymph nodes, spleen, tonsils– Aggregated lymphoid nodules– Appendix

Figure 20.10

Lymphoid Organs

• Designed to gather, destroy infectious microorganisms

Thymus

• Immature lymphocytes develop into T lymphocytes - secretes thymic hormones - most active in childhood

• Functional tissue atrophies with age- composed of cortex and medulla- medulla contains Hassall’s corpuscles (thymic corpuscles)

• Differs from other lymphoid organs- functions strictly in lymphocyte maturation- arises from epithelial tissue

Thymus

Figure 20.11

Lymph Nodes

Functional pathway

• Lymph percolates through lymph sinuses

• Most antigenic challenges occur in lymph nodes

• Antigens destroyed – activate B and T lymphocytes

Spleen

• Largest lymphoid organ

• Two main blood-cleansing functions– Removal of blood-borne antigens– Removal and destruction of old or defective blood cells

• Site of hematopoiesis in the fetus

Spleen

• Destruction of antigens

• Site of B cell maturation into plasma cells

• Phagocytosis of bacteria and worn-out RBCs, WBCs and platelets

• Storage of platelets

• White pulp – thick sleeves of lymphoid tissue

• Red pulp - surrounds white pulp- composed of venous sinuses

- splenic cords

Spleen

Figure 20.12

Tonsils

• Simplest lymphoid organs

• Four groups of tonsils– palatine, lingual, pharyngeal, and tubal tonsils

• Arranged in a ring to gather and remove pathogens

• Underlying lamina propria consists of MALT

Palatine Tonsil

Figure 20.13

Aggregated Lymphoid Nodules and Appendix

• MALT – abundant in walls of intestines

• Fight invading bacteria

• Generate a wide variety of memory lymphocytes- aggregated lymphoid nodules (Peyer’s patches)

- located in the distal part of the small intestine

• Appendix – tubular offshoot of the cecum

Aggregated Lymphoid Nodule

Figure 20.14

Lymphoma

• Neoplasm (tumor/abnormal growth) in the lymph tissue.

• Two types: Hodgkin’s disease or non-Hodgkin’s disease.

Hodgkin’s Disease

• Malignant lymphoma which has been linked to viral infections such as EBV (Epstein-Barr virus {mono}), HIV, and exposure to wood and wood products.

• Most often occurs in young adults.

• Most common symptom is painless, swelling of the lymph nodes in the neck, armpit, or groin. Other symptoms include fatigue, unexplained fever, night sweats, and indigestion.

Hodgkin’s Disease

• Diagnosis• Often shows up on a

CAT scan.• Confirmed by biopsy.

• Treatment usually includes chemotherapy and radiation.

Non-Hodgkin’s Lymphoma

• Patients with HIV/AIDS or those who have received immune suppressive therapy are at higher risk for developing non-Hodkin’s lymphoma.

• Same presenting symptoms as Hodgkin’s and treatment is similar.

Chemotherapy

• Works by killing fast-growing cancer cells. Unfortunately, chemo can't always tell the difference between cancer cells and fast-growing healthy cells, including RBCs and WBCs.

Chemotherapy

• Nurses will wear special gloves and gowns when preparing and giving you chemotherapy drugs. Additionally, pharmacists prepare the drugs in areas with special ventilation systems. Special procedures are used for disposing of materials after mixing and administrating the drugs. There are separate plastic containers to dispose of sharp items, syringes, IV tubing and medication bags.

Radiation

 Cancer treatment that uses high doses of radiation to kill cancer cells and stop them from spreading. 

Immunity

• The ability of the body to defend itself against infectious agents, foreign cells, and even abnormal body cells, such as cancer.

• Immunity can be acquired, like when you get chicken pox and then you are protected from getting it again.

• Immunity can be artificially acquired like when you get a vaccination.

Nonspecific Immunity

• Innate-you are born with it.

• Provides immediate and general protection against invaders.

Nonspecific Immunity

• Physical and chemical barriers:

• Intact skin is a physical barrier

• Skin also produces chemical barriers to infection (sweat, tears, oil) .

• Mucus membranes produce mucus which trap foreign material and form a barrier to invaders.

• Cilia sweep out debris and impurities.

Nonspecific Immunity

• Phagocytosis: Leukocytes (WBC) can destroy infectious agents “cell eating.”

• Natural Killer Cells: Type of WBC that recognizes body cells with abnormal membranes. Cell membranes can become altered from cells being infected with foreign invaders like viruses.

Nonspecific Immunity

• Fever: When phagocytes destroy invaders, they release a substance that raises the body temperature. Fever aids the immune system by stimulating phagocytosis, increasing metabolism.

Nonspecific Immunity

• Interferon: Group of substances that boost the immune system.

• First found in flu cells infected with the flu virus and was named for its ability to interfere with viral multiplication.

• Virus-infected cells and other agents produce interferon.

Nonspecific Immunity

• Inflammation

1500 B.C. Egyptians used dried myrtle to relieve back pain. In 200 B.C. Hipprocrates prescribed willow tree bark to relieve fever and pain. Today the active ingredient in aspirin, acetylsalicylic acid, is derived from a related anti-inflammatory chemical (salicylic acid) found in myrtle leaves and willow tree bark.

Nonspecific Immunity

• Inflammation:

• The signs and symptoms of inflammation are redness, swelling, heat, and pain.

• Protective tissue response to injury or invaders. Blood vessels dilate to increase blood flow (hyperemia) to the area. That causes the heat and redness.

Inflammation

Nonspecific Immunity• Inflammation: As blood flow increases,

more leukocytes reach the area. The damaged tissue releases a substance called histamine that causes the capillary walls to become more permeable (“leaky”). This increased permeability enables plasma and leukocytes to move out of the blood vessels and into the tissues (exudate). This is what causes pain (exudate pressure on the nerve endings) and swelling.

Nonspecific Immunity

• Inflammation: Bacterial infections may cause inflammation. The toxin-producing bacteria triggers an inflammatory response. The bone marrow and lymph nodes release large quantities of leukocytes. So an increase in a WBC (white blood cell count) can indicate a inflammatory response.

Specific Immunity

• Acquired-protects against particular identified foreign agent and develops in response to that agent.

• Once established against a foreign agent, specific immunity is able to respond to future exposures to that same agent.

Specific Immunity• Specific immunity or the immune system is

connected to the body via the lymphatic system.

• Specific immunity is based on the ability to recognize and respond to foreign elements that triggers the immune response (anitgens).

• The specificity of acquired immunity is its ability to recognize these different antigens.

Specific Immunity

• Specific immunity against antigens includes humoral and cell-mediated immunity.

• Humoral includes antibodies. (B cells)

• Cell-mediated includes activated lymphocytes. (T cells)

• Acquired immunity includes both antibodies and activated lymphocytes.

Cell Mediated-Immunity(T cells)

T lymphocytes (several types):

*Cytotoxic (CD8)-”Killers”-release poison into ‘bad’ cell. Important in killing cells that have been invaded by virus. Also can destroy cancer cells.

*Helper (CD4)-Boost, stimulate other cells.

*Memory-rapid mobilization to repeat offender

*Suppressor-dampen immune response.

Humoral Immunity (B cells)

Plasma cells (Immunoglobulins)

IgG-neutralizes toxins, bacteria, viruses

IgM-protects newborns

IgA-localized protection at mucosal surface

IgE-Allergy

IgD-Activates B lymphocytes

Memory cells

Viral Infection

Bacterial Infection

Hypersensitivity (Allergies)

• Some diseases result from an individual’s immune response, which causes tissue damage and destruction rather than immunity. The immune phenomena are destructive rather than defensive in an individual who is hypersensitive or allergic to an antibody.

• Can be local (like a welt) or systemic (like anaphylaxis).

Hypersensitivity (Allergies)

• Abnormal sensitivity to allergens result in the overproduction of IgE.

• IgE (immoglobulin from B cells) attaches one end to a cells called basophils and mast cells; its other end points away, where IgE can bind to the allergens.

• When allergens enter the body and bind to the IgE antibodies, the cells break down and release chemicals.

Hypersensitivity

• Histamine is one of the chemicals released.

• Histamine causes dilation of the blood vessels, making them leak plasma into the tissues. This tissue fluid causes edema (swelling). Examples: nasal congestion, welts, hives.

• Treatment would include anti-histamine medications.

Hives

Hypersensitivity• Anaphylaxis is systemic reaction which

follows the same underlying cellular mechanisms of a local reaction but on a ‘global’ scale. The cell permeability is body wide causing low blood pressure (hypotension) and shock. Smooth muscle contraction in the airway may cause respiratory distress.

• Epinephrine, glucocorticoids, or cortisone are used to reduce the immune response.

Autoimmunity

• The immune system response normally recognizes the difference between the individual’s own tissues and those of invaders; this is known as tolerance.

• When tolerance fails, an autoimmune disease is the result.

• Autoimmunity occurs when individuals develop antibodies (called autoanitbodies) to their own tissues or self-anitgens.

Lupus• Chronic inflammatory disease. It is an

autoimmune disease.• 90% are women.• Affects many different body systems

including joints, skin, kidneys, blood cells, heart, and lungs.

• Causes: Exact cause is unknown. Likely due to a combination of factors including genetics and exposure to a certain unknown trigger.

Lupus

Signs and Symptoms: extreme fatigue, headaches, painful or swollen joints, fever, anemia, edema, pleurisy, butterfly-shaped rash across cheeks and nose, sun- or light-sensitivity (photosensitivity), hair loss, abnormal blood clotting, fingers turning white and/or blue when cold (Raynaud’s phenomenon), mouth or nose ulcers….

ALMOST EVERY SYMPTOM IN OTHER WORDS!!!!!

Lupus• With all those symptoms, how do you

diagnosis Lupus?• It’s hard. Lupus is known as “the great

imitator,” because its symptoms mimic so many other illnesses. The doctor will look for signs of inflammation, your lab results, medical history, and family history. Test results can suggest Lupus, but may be positive or negative depending upon inflammation at the time.

Lupus

• How is it treated?

-Corticosteroids (prednisone, methylprednisolone, hydrocortisone)

-Monoclonal antibodies

-Aspirin

People with lupus are generally treated by a rheumatologist (specializes in diseases of the joints and muscles).

Lupus

• Prognosis: There is no cure for lupus, and some people do die. However, people with non-organ threatening aspects of lupus can look forward to a normal life-span if they follow their treatment plan.

Lupus

Immune Deficiency

• AIDS (acquired immunodeficiency syndrome) destroys the individual’s immune system. This makes a person remarkably susceptible to infection.

• What causes it? It is caused my the human immunodeficiency virus (HIV). HIV is a retrovirus; that is, it carries its genetic information as RNA rather than DNA.

AIDS• The virus (HIV) infects primarily helper or

CD4 lymphocytes. The virus replicates within the lymphocytes, killing them and spreading them to others. The lymphocytes normally activate B-lymphocytes; so this basically cripples the body’s immune system. The body then is more susceptible to infections and tumors that could easily be controlled by a healthy immune system.

AIDS

• How do I get it? It is transmitted via contaminated body fluids, including blood, semen, vaginal secretions, and breast milk. It can be transmitted by unprotected anal, oral, or vaginal intercourse; birth; breast feeding; and the sharing of needles.

AIDS

AIDS

• Many people don’t develop signs or symptoms immediately after HIV infection. The length of the asymptomatic period may last from months to many years. The long latency period increases the risk of spreading the disease because the infected person is unaware they have it.

AIDS

• The virus continues multiplying, infecting and killing CD4 lymphocytes. Once the immune symptom is weakened enough the person will develop signs and systems. Eventually, a threshold is crossed a person moves from being HIV-infected to having AIDS. (CD4 count less that 200).

AIDS

• How is it diagnosed?

• HIV anitibodies are detected with the enzyme-linked immunosorbent assay (ELISA).

• AIDS is usually diagnosed by CD4 count less than 200. Healthy people have CD4 count of 1000.

AIDS Opportunists

• Kaposi's sarcoma is a type of cancer that mainly affects the skin, mouth, and lymph nodes.  

• Due to weakened immune systems, people with HIV are more likely to develop certain cancers.

AIDS Opportunists

• Candidiasis (Thrush) is a fungal infection of the mouth, throat, or vagina. CD4 cell range: can occur even with fairly high CD4 cells.

• Cytomegalovirus (CMV) is a viral infection that causes eye disease that can lead to blindness.CD4 cell range: under 50.

Thrush (Candidiasis)

AIDS Opportunists

• Herpes simplex viruses can cause oral herpes (cold sores) or genital herpes. These are fairly common infections, but if you have HIV, the outbreaks can be much more frequent and more severe. They can occur at any CD4 cell count.

Herpes Simplex Virus

AIDS Opportunists

• Pneumocystis pneumonia (PCP) is a fungal infection that can cause a fatal pneumonia. CD4 cell range: under 200. Unfortunately this is still a fairly common in people who have not been tested or treated for HIV.

PCP Pnuemonia

AIDS

• How is it treated? Drug treatment started shortly after infection increases the chances the immune system will not be destroyed by HIV. There is no cure for AIDS, but anti-HIV medications are used to control the replication of the virus and progression of the disease.

AIDS Medication

• Highly active antiretroviral therapy (HAART)-combines three or more anti-HIV medications in a daily regimen. Target HIV replication and entry. (Altripla, Travada, Vreead, etc)

Comfort Care/Hospice• Comfort care is usually

terminally ill and have DNRs; we provided hydration (PO/IV), pain medication, O2 therapy, medications that pt can tolerate taking. In other words, do what you can to make them comfortable until they pass.

Vaccinations

• Provides artificial immunity.

• Two types: Active and Passive.

• Active: Person forms anitbodies (given a weakened or attenuated organism or deactivated organism).

Vaccinations

• Passive: What happens when a person is exposed to a serious disease like hepatitis, tetanus, or rabies and has no immunity built up?

• It would take too long to build up antibodies in response to the disease, so the person is given passive immunity……doses of preformed antibodies (usually from a horse) are given to the person. Breast milk is considered passive.