Major Functions of Lymphatic System 1. Production, storage, maintenance & distribution of Lymphocytes 2. Maintenance of normal blood volume 3. Fat absorption in GI- tract

Composed of Lymph – Fluid that resembles plasma but contains a much lower concentration of suspended proteins Lymphatic vessels – Begin in peripheral tissues and end at connections to veins Lymphoid tissues and organs Lymphocytes

Lymphatic Vessels= Lymphatics lymphatic capillaries Originate as pockets Have large diameters and thinner walls than blood capillaries Allow passage of fluids, solutes, viruses, bacteria, and cell debris Lymphatic vessels Flow toward trunk Pumped by muscle contraction separate from blood circulation Valves prevent back flow Types Superficial Deep

Lymph capillaries converge become collecting vessels and end up as either thoracic duct Drains upper quadrant: Drains rest of body

largest

Bone Marrow: Lymphopoiesis Lymphocytes are also produced in thymus, spleen, and tonsils

Thymus “T-cell academy” Only lymphoid organ that does NOT fight antigens Blood thymus barrier Involution after puberty

Largest lymphoid organ Soft and very blood rich white White pulp- Red pulp- blood sinusoids white White pulp- lymphoid tissue Major Functions: 1.Initiation of Immune response to antigens in blood 2.Removal of aged and defective RBCs 3.Repository for new RBCs 4.Iron salvaging, storage and recycling Spleen Fig 23-17

Lymph Nodes ~ 500 Bean-shaped Situated along collecting vessels Contain lots of lymphocytes

Distribution of Lymph nodes Superficial clusters – cervical, axillary, poplitealaxillary – palatable Deep clusters – large intestinelarge intestine – nonpalatable

1 2 2 Connective tissue dominated by Lymphocytes Found beneath epithelial lining of respiratory, digestive & urinary tracts Example: the 5 tonsils Lymphoid Nodules

Immune System - trigger inflammation - attract eater cells such as macrophages to the area - coat intruders so that eater cells are more likely to devour them - kill intruders The first part of the immune system that meets invaders such as bacteria is a group of proteins called the complement system. These proteins flow freely in the blood and can quickly reach the site of an invasion where they can react directly with antigens - molecules that the body recognizes as foreign substances. When activated, the complement proteins can

PHAGOCYTES This is a group of immune cells specialized in finding and "eating" bacteria, viruses, and dead or injured body cells. There are three main types Granulocyte Macrophage Dendritic cell

GRANULOCYTES Often take the first stand during an infection They attack any invaders in large numbers, and "eat" until they die. The pus in an infected wound consists chiefly of dead granulocytes. A small part of the granulocyte community is specialized in attacking larger parasites such as worms.

Macrophages "big eaters“ Slower to respond to invaders than the granulocytes, but they are larger, live longer, and have far greater capacities Macrophages also play a key part in alerting the rest of the immune system of invaders. Macrophages start out as white blood cells called monocytes. Monocytes that leave the blood stream turn into macrophages.

Dendritic Cells "eater" cells and devour intruders, like the granulocytes and the macrophages help with the activation of the rest of the immune system also capable of filtering body fluids to clear them of foreign organisms and particles

Lymphocytes White blood Originate in the bone marrow but migrate to parts of the lymphatic system such as the lymph nodes, spleen, and thymus Surface receptors enable them to recognize foreign substances Two main types of lymphatic cells – T cells – B cells.

T cells T cells come in two different types – Helper cells – killer cells T cells are produced in the bone marrow and later move to the thymus where they mature.

Helper T cells Main regulators of the immune defense Activate B cells and killer T cells Become activated by antigen presentation on macrophage or dendritic cell than has consumed a pathogen Receptor of a helper T cell recognizes the antigen and starts to divide and to produce proteins that activate B and T cells as well as other immune cells.

Killer T cells specialized in attacking cells of the body infected by viruses and sometimes also by bacteria or cancer cells. has receptors that are used to search each cell that it meets for tiny traces of the intruder, antigen on their surface. – If a cell is infected, it is swiftly killed.

B cells search for an antigen matching its receptors and connects to it triggering signal to get proteins produced by helper T cells to become fully activated B cells start to divide and produce two new cell types – plasma cells – B memory cells. B cells on the attack!

Plasma cells specialized in producing antibodies, that will respond to the same antigen that matched the B cell receptor. – Antibodies are released from the plasma cell so that they can seek out intruders and help destroy them. – Plasma cells produce antibodies at an amazing rate and can release tens of thousands of antibodies per second.

How antibodies work When the Y-shaped antibody finds a matching antigen it attaches to it – The attached antibodies serve marker cell for the macrophage. – Each branch of the Y-shaped antibody can bind to a different antigen, so while one branch binds to an antigen on one cell, the other branch could bind to another cell - in this way pathogens are gathered into larger groups that are easier for phagocyte cells to devour. Antibodies also neutralize toxins and incapacitate viruses, preventing them from infecting new cells.

Memory cells Produced by the division of B cells These cells have a prolonged life span and can thereby "remember" specific intruders. The second time an intruder tries to invade the body, B and T memory cells help the immune system to activate much faster.

Play Immune System Defender s/medicine/immunity/ s/medicine/immunity/

HIV-Human Immunodeficiency Virus “HIV invades the helper T cells to replicate itself. HIV Virus T-Cell HIV Infected T-Cell New HIV Virus

HIV is a Retrovirus A RNA virus that is replicated in a host cell via the enzyme reverse transcriptase to produce DNA from its RNA genome. The DNA is then incorporated into the host's genome by an integrase enzyme.

HIV Transmission HIV enters the bloodstream through: – Open Cuts – Breaks in the skin – Mucous membranes – Direct injection

HIV Transmission Common fluids that are a means of transmission: – Blood – Semen – Vaginal Secretions – Breast Milk

HIV in Body Fluids Semen 11,000 Vaginal Fluid 7,000 Blood 18,000 Amniotic Fluid 4,000 Saliva 1 Average number of HIV particles in 1 ml of these body fluids

Routes of Transmission of HIV Sexual Contact:Male-to-male Male-to-female or vice versa Female-to-female Blood Exposure: Injecting drug use/needle sharing Occupational exposure Transfusion of blood products Perinatal: Transmission from mom to baby Breastfeeding

Window Period This is the period of time after becoming infected when an HIV test is negative 90 percent of cases test positive within three months of exposure 10 percent of cases test positive within three to six months of exposure

HIV Infection and Antibody Response InfectionOccurs AIDS Symptoms ---Initial Stage Intermediate or Latent Stage Illness Stage--- Flu-like Symptoms Or No Symptoms Symptom-free < ----

AIDS Acquired Immunodeficiency Syndrome HIV is the virus that causes AIDS Disease limits the body’s ability to fight infection A person with AIDS has a very weak immune system No Cure

Stage 1 - Primary Short, flu-like illness - occurs one to six weeks after infection no symptoms at all Infected person can infect other people

Stage 2 - Asymptomatic Lasts for an average of ten years This stage is free from symptoms There may be swollen glands The level of HIV in the blood drops to very low levels HIV antibodies are detectable in the blood

Stage 3 - Symptomatic The symptoms are mild The immune system deteriorates emergence of opportunistic infections and cancers

Stage 4 - HIV  AIDS The immune system weakens The illnesses become more severe leading to an AIDS diagnosis

Opportunistic Infections associated with AIDS Bacterial – Tuberculosis (TB) – Strep pneumonia Viral – Kaposi Sarcoma – Herpes – Influenza (flu)

Opportunistic Infections associated with AIDS Parasitic – Pneumocystis carinii Fungal – Candida – Cryptococcus

Anonymous Testing No name is used Unique identifying number Results issued only to test recipient Anonymous

Confidential Testing Person’s name is recorded along with HIV results – Name and positive results are reported to the State Department and the Centers for Disease Control and Prevention Results issued only to test recipient

Blood Detection Tests Enzyme-Linked Immunosorbent Assay/Enzyme Immunoassay (ELISA/EIA) Radio Immunoprecipitation Assay/Indirect Fluorescent Antibody Assay (RIP/IFA) Polymerase Chain Reaction (PCR) Western Blot Confirmatory test

Urine Testing Urine Western Blot – As sensitive as testing blood – Safe way to screen for HIV – Can cause false positives in certain people at high risk for HIV

Oral Testing Orasure – The only FDA approved HIV antibody. – As accurate as blood testing – Draws blood-derived fluids from the gum tissue. – NOT A SALIVA TEST!

Antiretroviral Drugs Nucleoside Reverse Transcriptase inhibitors – AZT (Zidovudine) Non-Nucleoside Transcriptase inhibitors – Viramune (Nevirapine) Protease inhibitors – Norvir (Ritonavir) h8lZ4sZFw&feature=related