The Lymphatic System The Lymphatic System The Lymphatic

The Lymphatic System

The Lymphatic System

The Lymphatic System � Carries essential nutrients to the cells � Collects cellular waste � Plays an important role in the immune system of the body

Lymph �A fluid that fills the spaces between the blood vessels and the body cells (interstitial fluid) � Derived from blood, mainly plasma � Made up mostly of water and circulates in the lymphatic vessels

Functions of the System � To collect excess lymph and return it to the blood circulation, along with any waste that may be collected � To carry elements of the immune system such as antibodies and WBC that will neutralize antigens (viruses & bacteria) � To transport molecules such as fats

Lymphatic Vessels � Similar to blood vessels, they are located near them � They carry lymph and return it to the blood by emptying it into two subclavian veins near the heart (right vein for upper body, left vein for lower body) � Lymph circulates as a result of the contracting of the muscles on the lymphatic vessels (like blood in veins).

Lymph Nodes AKA Ganglions � Small round structures found along lymph vessels � Found in 4 areas: � Groin, neck, armpits, abdomen � During an infection such as tonsillitis or the flu, lymph nodes swell and harden � Lymph is filtered by lymph nodes, which are filled with white blood cells that attack bacteria and viruses � They make WBC

Organs of Lymphatic System � Spleen: in abdomen � Tonsils: in mouth � Thymus: underneath heart � Bone marrow: in long bones � These organs are filled with WBC that filter blood and collect harmful bacteria and viruses

Spleen � The spleen filters blood. It destroys old worn red blood cells. It has WBC that attack viruses and bacteria

The Immune System � Includes vessels and organs of the lymphatic system as well as other structures or cells, such as white blood cells, which help to protect the body � Immunity: ability of the human body to protect itself against foreign antigens � Antigens are viruses, bacteria, abnormal cells or any other substances that can trigger a reaction of the immune system � Antibody: substance produced by certain white blood cells and that is able to neutralize a specific antigen

Non-Specific Immunity � Human body’s ability to protect itself against a wide range of antigens (white blood cells) � Skin acts as a barrier and is one of the mechanisms of non-specific immunity � Your lymph nodes or glands become swollen when you are sick because they are working to make cells to fight infections. � White blood cells move outside of capillaries through a process called diapedesis and enter the lymphatic system to reach the site of infection, the white blood cells will circle the antigens and form pseudopods � Once they reach the pathogen they surround and destroy it through phagocytosis

Diapedesis

Phagocytosis

Specific Immunity � Human body’s ability to protect itself against a particular antigen using specific antibodies � Immunity can be acquired in two ways: �Natural acquisition: being exposed to an infection like chicken pox. � Cells of immune system have a memory of the antibodies produced by white blood cells to fight against the antigen causing the infection. If the antigen enters the body again, body can produce the specific antibodies quicker, and the person will not develop the illness again

Specific Immunity � Immunity can be acquired in two ways: � Artificial acquisition: being given a vaccine. Vaccines contain dead/weakened antigens which trigger the production and memory of antibodies without causing the illness. Vaccinated person has immunity to that illness if they would encounter it. � **Vaccines do not cure you of diseases – you need to be vaccinated BEFORE getting sick!

Basically… � General � Specific immunity is like an on-going security system immunity is like someone’s picture being posted and being banned from entering a building

Vaccines � Substance that, when introduced into an organism, stimulates the immune system; which then manufactures specific antibodies and immunizes the individual against a given disease. � What are they used for? � To protect the health of the people that receive them which will prevent them from developing diseases with dangerous consequences � How does it work? � They contain antigens (bacteria, viruses, virus fragments, etc. ) that are weakened and cannot transmit disease. The body still produces antibodies to eliminate these antigens that will be effective against the real disease.

Vaccines � Cowpox and Smallpox – The First Vaccine � Herd Immunity � Vaccines before travelling to certain countries � Refreshing vaccines

The Difference between Antibiotics and Vaccines � Antibiotics cure disease by killing or injuring bacteria � Although antibiotics are useful in a wide variety of infections, it is important to realize that antibiotics only treat bacterial infections. � Antibiotics are useless against viral infections (for example, the common cold) and fungal infections (such as ringworm).