The Lymphatic System

Functions of Lymphatic System Drain fluid back into the bloodstream from tissues Filters lymph Filters the blood Fights infections As the blood circulates, fluid leaks out into the body tissues. This fluid is important because it carries food to the cells and waste products back to the bloodstream. The leaked fluid drains into the lymph vessels. It is carried through the lymph vessels to the base of the neck where it is emptied back into the bloodstream. This circulation of fluid through the body is going on all the time.

The Lymphatic System Lymph- clear fluid that circulates around the body tissues Contains high number of white blood cells Includes- lymph nodes, spleen, thymus, tonsils, and adenoids

Lymph Nodes Located in armpits, groin, neck, abdomen, pelvis and chest Filter the lymph as it passes through White blood cells attack any bacteria or viruses If cancer cells break away from a tumour, they often become stuck in the nearest lymph nodes. This is why doctors check the lymph nodes first when they are working out how far a cancer has grown or spread

White Blood Cells and Antibodies White blood cells produce antibodies- proteins used by immune system to identify and neutralize foreign invaders Antibodies prevent invaders from entering or damaging cells by binding to them; stimulate removal of invader by other cells; trigger destruction of invader by stimulating immune responses Antibodies specific to antigens

Spleen Filters blood to take out worn out red blood cells- Red blood cells are replaced by new ones made in the bone marrow Filters out bacteria, viruses, and other foreign particles White blood cells in spleen attack bacteria and viruses as they pass through

Thymus Small gland under breastbone Helps produce white blood cells Most active in teenagers and shrinks in adulthood

Tonsils and Adenoids Two glands at back of throat Protects entrance to digestive system and the lungs from bacteria and viruses

Vaccines Immunity booster to a certain virus Can be to prevent or improve the effects of a future infection Can be therapeutic ex. Vaccines against cancer

Types of Vaccines Can be dead or inactivated organisms or purified products of them Containing killed microorganisms Containing live modified organisms Containing inactivated toxic compounds ex. Tetanus fragmented

Developing Immunity Immune system recognizes vaccines as foreign, destroys them, ‘remembers’ them Upon entry of virus, immune system recognizes foreign invaders, neutralizing and destroying cells infected by them

Efficacy of Vaccines Vaccines do not guarantee complete protection from a disease Sometimes the immune system does not respond properly or at all ex. low immunity due to diabetes, steroid use, HIV infection

Typical Vaccinations Polio Hepatitis A,B Tetanus Diphtheria Chicken pox

In class work P.196 Questions 16 & 17