The Lymphatic System

What Does the Lymphatic System Do? carries dissolved oxygen and nutrients to the cells. Collects cellular waste Plays an important role in the immune system.

What Is the Lymphatic System? A system of thin tubes that run through the body called lymph vessels The liquid that is inside these vessels is called lymph. Lymph comes from extracellular fluid.

Extracellular Fluid Plasma leaks out of capillaries and fills empty spaces between blood vessels and tissues. The leaked plasma is called extracellular fluid. It contains water and other substances from blood plasma as well as white blood cells.

This fluid is collected by the lymph vessels to make lymph. Lymph is: A fluid that fills the spaces between the blood vessels and body cells. It allows for exchanges between blood and body cells. -circulates in the lymphatic vessels to evacuate waste from cells

Functions of the lymphatic system To collect excess lymph and return it to blood circulation; (along with any waste that may be collected) Fight infections: carries elements of the immune system such as antibodies and white blood cells that will neutralize antigens (viruses and bacteria); Transports molecules of fat Filters the blood and lymph

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

Lymph Nodes (ganglions) Small round structures found along the 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 white blood cells

Filtering Lymph The lymph is filtered by the lymph nodes In the lymph nodes are white blood cells that attack bacteria and viruses Cancer cells often end up here

Organs That are Part of the Lymphatic System: Spleen (abdomen, left of stomach) Tonsils (mouth bordering pharynx) Thymus (beneath heart) Bone marrow (found in long bones) All these organs are filled with white blood cells that filter blood and collect harmful bacteria and viruses This is how the lymphatic system plays a role in immunity;

Filtering Blood The spleen filters the blood It destroys old worn out red blood cells It has white blood cells 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.

When the Lymphatic System Goes Wrong Elephantiasis -Happens when the lymphatic vessels are blocked due to a parasite

When the Lymphatic System Goes Wrong Lymphedema -Happens when the lymphatic vessels are blocked -This may be caused by an injury to the lymph vessels or it may be inherited

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. diapedesis is the process through which white blood cells move outside of capillaries and enter the lymphatic system to reach the site of infection. White blood cells will circle the antigens and form pseudopods Once they reach the pathogen they surround and destroy it through phagocytosis

EX: Otitis An inflammation of the ear caused by an infection. The infection is not in the blood vessels, white blood cells move out of the capillaries to fight the infection

Diapedesis Phagocytosis

Specific immunity Human body’s ability to protect itself against a particular antigen using specific antibodies 1) Natural acquisition: ex. 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

2) Artificial acquisition: being given a vaccine 2) 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!

Vaccines Were investigated by Edward Jenner in the 1700s. Later, Pasteur conducted a few experiments on fowl cholera 0ver 100 years later

Vaccines Defined A dead or weakened bacteria or virus that is injected into the blood When introduced into the body, it stimulates the immune system; which learns to protect itself from the pathogen by making specific antibodies which immunizes the individual against the 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 if in contact with the real disease.

Pathogens Pathogens are viruses and bacteria. Virus Bacteria Smallest pathogen Invade cells Few drugs to fight them To kill the virus, you must kill the cell Single cell organisms Reproduce quickly Produce toxins which destroy cells Can be killed with antibiotics

Viruses & Bacteria

Vaccines: Facts If a vaccine is administered to an entire population, epidemics can be prevented. You can get vaccinated against diseases caused by viruses, bacteria (measles, whooping cough, hepatitis B and even chicken pox. There are some vaccines recommended for children and adolescents in Québec: DTaP-Polio-Hib, MMR and others. There are some vaccines for adults: Gardasyl, influenza and others. There are some vaccines that need to be given to a person traveling in tropical countries: hepatitis A and typhoid.

Vaccine Manufacturing Attenuated vaccines are prepared from living bacteria or viruses. Manufacturers select strains that have lost their power to cause disease but are still recognized as foreign (measles, rubella, mumps etc) Inactivated vaccines are prepared from bacteria or viruses that have been inactivated or killed by chemicals, heat or UV rays. No longer pathogenic, but stimulate the immune system (typhoid, cholera, etc) Vaccines can also be prepared through genetic manipulation, where scientists replace or remove genes in viruses and bacteria that cause disease (hepatitis B) Different vaccines can sometimes have different side effects

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).