Human Biology 3.2

1. Human Biology 3.2 The immune system defends the body.

2. Many systems defend the body from harm. Can enter the body through food, drink, and air Have constant contact with Disease causing agent Pathogen Can enter through the skin

3. The integumentary system stops most pathogens from entering the body, except through a cut. The respiratory system defends the body by sneezing and coughing. Many systems defend the body from harmful materials. If pathogens enter the digestive system, they can be destroyed by saliva, mucus, enzymes, and stomach acids.

4. The immune system has response structures. Main Idea Detail Notes Response structures are produced in several organs. White blood cells destroy foreign organisms. Antibodies are proteins that attack specific foreign materials. • The immune system has response structures.

5. Two systems carry blood cells to an injured and infected area of the body. Circulatory System Lymphatic System Carries lymph which is fluid left in the tissues by circulatory system. Lymph moves through skeletal movement. Lymph nodes filter out pathogens and store white blood cells and antibodies. Can swell when you get sick. • Specialized cells called white blood cells • Recognize foreign material • Increase during an immune response • Travel through circulatory system and lymphatic system.

6. The immune system responds to attack. Nonspecific Response Specific Response Triggered by antigens, a chemical marker on a cell’s surface that indicates body or foreign material. Foreign antigens trigger specific responses. Provides future protection from exposure to the same material. Phagocytes, T cells, and B cells function together in a specific response. • WBCs that first respond attack in a nonspecific response. • Attack foreign materials and produce chemicals to help other WBCs work better. • Irritated tissue releases histamine. • Histamine raises tissues temperature which improve ability of WBCs • When many areas of your body are affected, your body temperature is raised.

7. Specific Response • Phagocytes • Eat and break down foreign materials • Foreign materials show on surface of phagocyte • T cells • Detect phagocytes as foreign • Divide rapidly and attack foreign particles • B cells • After T cell division, B cells are activated and divide rapidly • Produce antibodies which attach to the foreign antigens, marking them for the killer T cells. • Some B cells stay in the body to “remember” that specific antigen so the immune system will respond to it quicker.

8. What will happen if I cut my finger? • Injured tissues will send out signals to immune system cells. • Immune cells release a substance called histamine which increase blood flow to the area. • The areawill become red, swollen, and warm. • Immune cells quickly migrate to the injured area. • Phagocytes engulf bacteria. • T cells attack the bacteria and phagocytes • B cells product antibodies • Other cells release bacteria-killing chemicals. • The cut heals.

9. Vaccination and Treatment Passive immunity is passed on by someone else (from mother to child) Resistance to a sickness Takes two forms Immunity In active immunity the body makes its own antibodies

10. Vaccination and Treatment Composed of a small amount of weakened pathogens. Stimulates and immune response Too weak to make you sick Vaccine Enables the body to develop an active immunity

11. Many diseases are treatable. • Some treatments reduce symptoms while the immune system fights the disease. • Some treatments attack the pathogens directly. • Antibiotics block the growth and reproduction of bacteria. • Medicines for viruses, fungi, and parasites. • Sometimes treatment can only prevent further damage to a pathogen that cannot be cured or defeated by the immune system.