Lymphatic System By Jenna Hanson and Rachel Gaddis

Word Bank: tonsils spleen thymus lymph node Lymph vessels

What is the lymphatic system?  The lymphatic system is a collection of cells and biochemicals that travel in lymphatic vessels, and the organs and glands that produce them.  The lymphatic system is also known as the immune system.

What does the lymphatic system do?  Transports fluids  Carries away excess fluid from interstitial spaces  Destroys foreign particles (Immunities)  Destroys toxins and cancerous cells

Lymphocytes  Type of white blood cell (leukocyte)  Two types: T-cells and B-cells  Determines immune response *Lymphocytes must be activated in order to respond to antigens!*

T and B cells

Lymph Nodes  Contain large numbers of lymphocytes and macrophages that fight invading organisms  Vary in diameter from 1/25 to 1 inch  Located along lymphatic vessels  Approximately lymph nodes in the adult human body

Lymphatic Pathways  Prevent backflow of lymph  Begin as lymphatic capillaries  Turn into larger lymphatic vessels

Spleen (Superior abdomen, Upper left quadrant)

Functions of the spleen  Filters blood (immune system)  Helps to fight certain kinds of bacteria  Recycles red blood cells

Thymus (Thoracic Cavity, between lungs, connects w/ trachea )

Functions of the thymus  Transform lymphocytes into T-cells  T-cells in the thymus help to fight disease and infection *The thymus grows less functional with age and is eventually replaced almost entirely by adipose (fat) tissue*

Lymph Movement

Body Defenses  Innate (nonspecific)  Species resistant: the development of diseases unique to that organism.  Mechanical barriers: Prevent entry of infectious agents, in areas such as the respiratory, urinary and reproductive systems (Skin and mucus membranes, and sweat).  Chemical barriers: Enzymes in body fluid that provide the barrier to the pathogens. Lymphocytes produce hormone like peptides called interferons. (Viruses/ tumor cells).  Fever: the raise in temperature cause the spleen and liver to take away iron in the blood which is needed for bacteria/fungi as the temp rises.  Inflammation: blood flow to region of infection increases to isolate and destroy the infection, however this is painful

Body defenses cont.  Adaptive (Specific)/ Immunity  Antigens: Usually located on cells surface; with the help of lymphocytes detect foreign antigens.  Lymphocyte Origins: During fetal development, release lymphocytes into the circulation with later turn to T and B cells.

Types of antibodies  Immunoglobulin G (IgG): in plasma and tissue fluids, effective against bacteria, viruses and toxins.  Immunoglobulin A (IgA): Found in exocrine gland secretions (breast milk, tears, nasal fluid, gastric juices, intestinal juice, bile and urine).  Immunoglobulin M (IgM): Develops in blood plasma in response to contact with certain antigens in food or bacteria.  Immunoglobulin D (IgD): Found on surface of most B cells. Important in activating B cells.  Immunoglobulin E (IgE): Found in exocrine secretions. Associated with allergic reactions.

Immune Responses  Primary response:  Cells release antibodies (IgM, then IgG)  Antibodies are then transported to blood and throughout body  Secondary response:  Following a PR, B cells produce a ‘memory’ cell.  More vigorous of a response than PR.

Autoimmune responses  Sometimes, the immune system accidentally produces autoantibodies, T cells that attack and damage tissues and organs.  The condition of cells attacking oneself is called autoimmunity Common auto immune disorders  Type 1 Diabetes  Rheumatoid arthritis  Lupus

Allergic Reactions  Allergic responses are immune attacks against a non-harmful substance  Allergic reactions can vary from inflammation and fever to the closing of the throat, resulting in inability to breathe. Common allergens:  Peanuts  Grass  Dairy (Lactose intolerance)  Shellfish

Diseases  Multiple Sclerosis (MS):  Causes pain, blindness, weakness, poor coordination, and muscle spasms  Immune system destroys myelin sheaths in neurons, damaging nerve tissue  Can be suppressed but no treatment  AIDS: Acquired Immune Deficiency Syndrome.  Virus that weakens the immune system  Final stage of HIV  Often Flu like symptoms  Life-threatening  Transmitted through sexual intercourse, contaminated needles, birth and receiving infected blood (transfusion)  No treatment