Defense against Disease

Physical and Chemical Defenses Skin- Both a physical and chemical barrier. Sweat contains acids that kill many bacteria. Skin cells shed constantly and pathogens on those skin cells shed with them. Mucous Membranes- Openings such as mouth, eyes, and nose. Secrete liquid called mucus, which trap pathogens and washes them away. Also contains chemicals that attack pathogens.

Cilia- Tiny hair like projections. Line mucous membranes. Ex Cilia- Tiny hair like projections. Line mucous membranes. Ex. Breathing in dust. Saliva and tears- Contain chemicals and also wash away pathogens Digestive system- Chemicals such as acid, the motions of the digestive system, and excretion all help get rid of pathogens

Inflammation This is your bodies general response to injuries Phagocytes- White blood cells that leak out of cells when injury occurs Phagocytes engulf and destroy pathogens while the area is inflamed Phagocytes also give off substances that promote healing.

The Immune System White blood cells called Lymphocytes carry out most of the immune system’s functions Immunity is when the body is already equipped to destroy pathogens that enter the body

Lymphocytes Killer T cells- Destroy pathogen Helper T cells- Produce chemicals that stimulate other T cells and B cells to fight off infection Suppressor T cells- turn off other immune system cells when an infection has been brought under control

B cells produce antibodies. Antibodies are proteins that attach to the surface of pathogens or to the toxins produced by pathogens.

The Lymphatic System A network of vessels that collect fluid from your tissues and return it to the blood stream. This fluid is called lymph fluid. Have hundreds of small stations called lymph nodes Lymph nodes act as a sort of filter Phagocytes and lymphocytes are contained in the lymph node and attack pathogens

Passive and Active Immunity Passive: Immunity acquired by receiving antibodies from a source other then one’s own immune system. This is temporary and not life long. Ex. Babies receive antibodies from the mother’s milk Active: Results from having a disease or receiving a vaccine.

Common Infectious Diseases Bacterial Diseases Strep Throat: Found usually in the nose and throat. Symptoms: Swollen lymph nodes, sore throat, head ache, and fever. Diagnosed by swabbing the throat Lyme Disease: contracted when bitten by a tick. Symptoms: red rash at bite site, fevers, chills and body aches.

III. Bacterial Meningitis: Infection of the spinal cord and the fluid that surrounds the brain. Symptoms: high fever, headache, vomiting, and stiff neck. IV. Tuberculosis (TB): Transmitted when droplets of an infected persons cough or sneeze are inhaled. Symptoms: Fatigue, mild fever, and a constant cough. The disease may not show up for years after contraction.

Treating Bacterial Infections Antibiotics are used to treat bacterial infections Antibiotic resistance can happen when a person does not take all of their prescribed medicine.

Viral Infections Common cold: Symptoms include sneezing, sore throat, coughing, chest congestion, head aches and muscle aches. Most last three to seven days. Colds spread when a person touches a contaminated object or inhales droplets from a sneeze or a cough. Influenza: Infection of the upper respiratory system. Symptoms: High fever, sore throat, headache, and a cough. Spread same as cold.

Pneumonia: People who have heart disease or are elderly may experience their flu turn into pneumonia. Hepatitis: Type A: Transmitted through human wastes or contaminated water. Type B: More severe then type A. Transmitted through blood or sexual contact. Type C: Transmitted through blood or sexual contact. Type C is the number one reason for liver transplants in the U.S

Treatment of Viral Infections In most cases there are no particular medicine that can cure a viral infection. Best treatments are : rest, a well-balanced diet, and plenty of fluids. There are also many medicines that treat viral symptoms These medicines make a person feel better but do not rid the body of the virus.

When Should I See a Doctor? Extremely sore throat, earache, vomiting, diarrhea, or temperature of 101 F that lasts for more then two days Mucus from your nose or throat is thick and yellow Difficulty breathing, or severe pain anywhere A cut or scrape that does not heal as it should An illness that lasts longer then usual

Prevention Wash Hands Do not share items that transfer pathogens (towels, eating utensils, cups or hair brushes) Cook and store food properly Avoid close contact with infected individuals Stay home when not feeling well Learn to manage stress in healthful ways Sleep at least 8 hours a night Avoid unhealthful substances. Ex: Drugs