The Immune System The Immune System Biology 2201: Unit III: Section Five

What is the immune system? The system of the body which protects us from pathogens, like bacteria and viruses. It helps to maintain homeostasis by recognizing and destroying harmful organisms that could possibly interfere with human health. Biology 2201: Unit III: Section Five

The Immune System The thymus is a specialized organ of the immune system. Within the thymus, T-cells, critical to the adaptive immune system, mature. Each T cell attacks a foreign substance which it identifies with its receptor. Lymph nodes act as filters or traps for foreign particles and are important in the proper functioning of the immune system. They are packed tightly with the white blood cells called lymphocytes and macrophages. The spleen synthesizes antibodies in its white pulp and removes antibody-coated bacteria and antibody-coated blood cells by way of blood and lymph node circulation. Biology 2201: Unit III: Section Five

How does the immune system work? White blood cells (WBC) make up the immune system. When a pathogen enters the body, our WBCs try to destroy it. WBC & Platelets = 1% of blood Biology 2201: Unit III: Section Five

How does your immune system know a pathogen is present? The Immune System How does your immune system know a pathogen is present? Pathogens produce antigens. Antigens may be proteins, carbohydrates, nucleic acids or lipids, but are different from the body. Since they are different, the body notices. An antigen is any substance which provokes an adaptive immune response. An antigen is often foreign or toxic to the body (for example, a bacterium) which, once in the body, attracts and is bound to a respective and specific antibody. That is to say, an antigen is a molecule that also induces an immune response in the body Biology 2201: Unit III: Section Five

How does your immune system get rid of the pathogen? Antigens trigger the formation of antibodies. An antibody is a protein produced by the body's immune system when it detects harmful substances. Antibodies attach to the antigen, and mark it to be destroyed by WBCs.

Each type of antibody is unique and defends the body against one specific type of antigen Antigen-antibody complex fits together like a lock and key

The Immune System Biology 2201: Unit III: Section Five

Question How would the body respond to the presence of pollen in a non-allergic person?

Answer Pollen = antigen When pollen enters the nose, antibodies are produced to attach to the pollen. This antigen-antibody complex is now marked to be destroyed. Therefore the person does not have an allergic reaction. Video: http://www.youtube.com/watch?v=KpNFAEbLcvk

Question How would the body respond to the presence of pollen in an allergic person?

Answer Pollen = antigen When pollen enters the nose, an antibody is produced which is hypersensitive to the antigen. This means the antibody-antigen response is greater than it needs to be. It causes histamine to be released, which causes an allergic reaction (swelling) Video: http://health.howstuffworks.com/diseases-conditions/allergies/allergy-basics/allergy.htm

What is the difference between an antibody in a non-allergic person and an antibody in an allergic person? Use a drawing to explain. In a non-allergic person, the cell has fewer antibodies present on the surface. The immune system is normal Cell of allergic person – lots of antibodies present on the mast cell (which contains histamines). This immune system is hypersensitive

How does our immune system protect our body? The Immune System How does our immune system protect our body? First Line of Defense: Physical and Chemical barriers that help to prevent the entry of pathogens Ex: skin, mucous lining of respiratory and digestive tracts, chemicals in tears and sweat Biology 2201: Unit III: Section Five

Second Line of Defense –the Inflammatory Response The Immune System Second Line of Defense –the Inflammatory Response This occurs when invaders get past first line of defense (ex: a splinter in your finger) Damaged cells release chemicals (histamines) which cause surrounding tissue to become red, swollen, and sore (inflammation) Biology 2201: Unit III: Section Five

WBCs called macrophages engulf (eat) pathogens by phagocytosis The Immune System WBCs called macrophages engulf (eat) pathogens by phagocytosis The lymph nodes swell at site of infection as they filter out bacteria Body temperature rises (fever) These changes in the body are designed to destroy any pathogen that got past the first line of defense. Biology 2201: Unit III: Section Five

The Immune System Biology 2201: Unit III: Section Five

Third Line of Defense – Specific Immune Response The Immune System Third Line of Defense – Specific Immune Response Involves special kinds of WBCs called Lymphocytes There are 2 types of Lymphocytes: 1. T-cells 2. B-cells These cells help destroy the pathogen Biology 2201: Unit III: Section Five

What is the difference between T-cells and B-cells?

What is the difference between B-cells and T-cells? The Immune System What is the difference between B-cells and T-cells? B-Cells Mature in the Bone marrow Used in the production of antibodies. When they encounter a new antigen, plasma cells and memory cells are formed. The memory cell remembers the antigen and which antibody to use The plasma cell makes the antibodies Biology 2201: Unit III: Section Five

Mature in the Thymus gland (by heart) The Immune System T-cells Mature in the Thymus gland (by heart) Used in identifying antigens and releasing chemicals which attract macrophages to destroy the antigen. They recognize viral infections and tumor cells Biology 2201: Unit III: Section Five

The Immune System Biology 2201: Unit III: Section Five

The Immune System What is immunity? Immunity means the body has built up antibodies and memory cells so that it can respond quickly in the future if the pathogen invades the body. Biology 2201: Unit III: Section Five

What are the two types of immunity? The Immune System What are the two types of immunity? Natural or Passive Immunity you get this from having the infection yourself you can get it when you’re a baby from your mother (breast-feeding) Biology 2201: Unit III: Section Five

Comes from vaccines that contain weakened or dead pathogens The Immune System 2. Artificial immunity Comes from vaccines that contain weakened or dead pathogens The body builds up antibodies in response Biology 2201: Unit III: Section Five

When the body’s own immune system attacks body tissue. The Immune System Autoimmune Disorders When the body’s own immune system attacks body tissue. The actual cause of this disease is unknown. inherited. Biology 2201: Unit III: Section Five

MS (multiple sclerosis) When the immune system destroys the myelin covering of nerve cells. There is no cure, but medication to suppress the immune system is taken

The Immune System Rheumatoid arthritis The immune system attacks the bone and tissue of joints in the body, which causes pain, stiffness and swelling. Treatment: Anti-inflammatory medication Biology 2201: Unit III: Section Five

HIV/AIDS When the Helper T Cells, are attacked by the HIV virus The Immune System HIV/AIDS When the Helper T Cells, are attacked by the HIV virus This destroys the immune system. Biology 2201: Unit III: Section Five

The Immune System Organ Transplants Foreign organs are considered antigens by the body’s immune system. The immune response is activated, which can cause the body to reject the organ. Immuno-supressant drugs may be given, but this can increase the risk of infection. Biology 2201: Unit III: Section Five