biology module 8

organs affected by cancer

While cancer can begin almost anywhere in the human body, some cancers are diagnosed with much greater frequency than others. According to the American Cancer Society, the cancers listed below are the most commonly occurring cancers in the United States. See if you can identify the type of cancer represented by each image. First, write down or think about your answer. Then click the image to check your answer. Bladder cancerBreast cancerCervical cancerColorectal cancerLung cancerOvarian cancerPancreatic cancerProstate cancerLeukemiaThyroid cancer Question Suppose a tumor formed in a man's prostate gland and then the cancer spread to his bladder. What type of cancer would he have? Prostate cancer; a person's cancer is named according to the organ where a tumor first appeared.

Tabacco use

You just learned about alcohol abuse and how it adversely affects your body, but there is another drug sometimes used by teenagers that has deadly consequences as well. Tobacco use is the leading preventable cause of disease, disability, and death in the United States. Like alcohol abuse, the use of tobacco affects the body's organs in harmful ways. In some ways, tobacco is even more dangerous, though. Nicotine, a key ingredient in tobacco, is highly and quickly addictive. And once people are addicted, they usually find it very difficult to stop using tobacco. Tobacco use is such a serious and widespread issue that the United States government has become involved in discouraging young people from smoking. Take a look at this Public Service Announcement that illustrates some reasons not to start smoking. Bully/Cigarette: "Hey buddy! Let's take a little walk. When I say go outside, we go outside. When I say fork it over, you fork it over. Hey, when I say pause the movie, we pause the movie. Come on big boy. Pucker up." Narrator: Cigarettes are bullies. Don't let tobacco control you. Transcript Why does the video compare smoking cigarettes to being bullied? Bullies have control over you, just like cigarettes. You may want to stop smoking but can't because you're addicted. Cigarettes may be the most common way to consume tobacco, but tobacco and nicotine products come in many forms. People either smoke or chew tobacco, or they inhale a vapor produced from tobacco. Smoked Tobacco Products Smokeless Tobacco Products Electronic Cigarettes All types of cigarettes, cigars, and hookah (water) pipes contain tobacco. When smoked, these items produce chemicals that can cause harm to the body. What are some health problems caused by smoking? Some problems include lung cancer, emphysema, heart problems, and diabetes. Other forms of tobacco (snuff or dip) are either inhaled or placed between the cheek and gums. Even though it is not smoked, this form of tobacco contains high levels of nicotine and can lead to health problems. What are some health problems specifically linked to chewing tobacco? Problems include mouth sores and cancer of the mouth and throat. Electronic cigarettes are also called e-cigarettes or vapor cigarettes. These are smokeless battery-operated devices that deliver flavored nicotine to the lungs without burning tobacco. Considering that e-cigarettes are fairly new, what do you think are some health issues caused by them? New research shows that the vapors or solvents mixed with the nicotine can be harmful to the lungs. They can cause inflammation in the lungs leading to asthma and bacterial infections. These vapor cigarettes also may be linked to cancer and heart disease.

immune system

Bone MarrowMarrow exists inside the hollow space of all bones. At birth, all bone marrow is red, but as a baby develops into a toddler, some red bone marrow converts to yellow. The yellow color is due to the presence of fat. Red bone marrow makes platelets, all red blood cells, and most white blood cells. Platelets help blood to clot when the body has a cut blood vessel. Red blood cells circulate oxygen and pick up carbon dioxide. When someone suffers from severe starvation, the fat from the yellow marrow can serve as food energy. White Blood CellsWhite blood cells, also called leukocytes, fight against antigens. Some leukocytes, called lymphocytes, develop in the yellow bone marrow. In the case of severe blood loss, yellow bone marrow can convert back into red bone marrow to increase red blood cell production. T cells are a type of lymphocyte (called T because they mature in the thymus). Cells that are infected by an antigen give off a chemical message called a cytokine. Cytokine activates killer T cells, which attach to the infected cell and destroy it. AntibodiesSome lymphocytes secrete antibodies in the presence of an antigen. Antibodies are blood proteins that neutralize antigens. Notice how the antibodies are shaped specifically to the antigens they neutralize. ThymusThe thymus is located between the lungs. It is largest during childhood because in childhood the thymus is at its most active. Some lymphocytes leave the yellow bone marrow and enter the thymus. Under the influence of the hormone (chemical messenger) thymosin, those lymphocytes develop into disease-fighting cells. Because they complete their development in the thymus, they are called T lymphocytes, or T cells for short. As a person finishes puberty, the thymus slows down its activity and begins to shrink. Additionally, thymus cells are replaced with fat cells because the thymus no longer has to secrete thymosin. So by the end of puberty, a person has all the T cells she or he will have for a lifetime! SpleenThe spleen is the largest lymphatic organ. Lymph, a pale yellow fluid, comes from blood vessels, but does not contain red or white blood cells or large molecules like glucose. The spleen filters both lymph and blood for pathogens. For this reason, the spleen stores leukocytes and platelets. Also, the spleen recycles worn out red blood cells. The spleen fights against bacterial infections such as pneumonia (a lung infection) and meningitis (a membrane infection of the brain and spinal cord). Lymphatic SystemThe lymphatic system, shown in the image as a network of green vessels, is located throughout the body near blood vessels. As the liquid part of the blood (plasma) oozes from the capillaries, some flows through the body cells and is recaptured in the lymphatic system. This network of vessels returns the lymph to the blood circulatory system so fluids don't collect and cause swelling. Before the lymph returns to the circulatory system, nodes (shown as green bumps along the vessels) filter the lymph for antigens and cancer cells. Lymphatic TissueLymphatic tissues, such as tonsils and lymph nodes, are found throughout the lymphatic system to assist the spleen in filtering pathogens, worn out cells, waste products, and cancer cells. Once filtered, the lymph moves to an enlarged part of the lymphatic system called the cisternal chyli. From there, lymph enters the thoracic duct to be added into the bloodstream.

common infectious diseases

Chickenpox is a highly contagious infection caused by the varicella-zoster virus. The symptoms include an itchy, blisterlike rash, tiredness, and fever. Chickenpox is spread by saliva droplets in sneezes and coughs and by direct contact with the blisters. Most children who have chicken pox recover completely and develop an active immunity to the disease so they never get the infection again. Why do people who have had chickenpox as a child usually avoid getting the infection again? People who've had chickenpox as a child now have immunity against the infection. It is an active immunity, which means that being exposed to the disease triggers the immune system to produce antibodies that fight the virus if it comes into contact with the person's immune system in the future. Hepatitis is a contagious viral infection that leads to the inflammation and swelling of the liver. It also leads to jaundice, which is the the yellowing of eyes and skin. There are three types of hepatitis viruses: A, B, and C. These three viruses differ in the way they are spread, the symptoms of the diseases they cause, and how they are treated. Chlamydia is a contagious bacterial infection, shown in this image by arrows. Chlamydia is spread by having unprotected sexual contact with an infected person. Symptoms in women may include an abnormal vaginal discharge and a burning sensation during urination. Symptoms in men may include an abnormal discharge from their penis, a burning sensation during urination, and pain and swelling in one or both testicles. Because chlamydia is a bacterial disease, it can be cured with the right treatment. If left untreated for some time, chlamydia may cause a woman to have difficulties becoming pregnant. Pneumonia is an infection in which a thick fluid, called phlegm, collects in alveoli (the air sacs of the lungs). Viruses, bacteria, fungi, or chemicals can cause pneumonia; therefore, it may or may not be contagious. Symptoms of pneumonia include difficulty breathing, coughing that may include phlegm or blood, fever, chills, chest pain, headache, excessive sweating, and loss of appetite. Treatment for pneumonia depends on its cause. Anyone who displays the symptoms of pneumonia should go to a medical facility and get tested to see which pathogen has caused the infection. Athlete's foot is a contagious fungal infection that starts between the toes of some people who have sweaty feet and wear closed shoes. The symptoms may include a scaly rash, itching, stinging, and burning. If left untreated, athlete's foot can spread to the toenails, causing them to become yellow, thick, and brittle, as shown in the image. The infection spreads through contact with a contaminated floor, towel, or clothing. Infected people can get an over-the-counter (OTC) treatment from a local pharmacy to rid themselves of the infection. They can prevent the infection with good hygiene, by using foot powder to absorb sweat, and by wearing shower shoes in public showers. Candidiasis is a contagious fungal infection that is caused by the Candida yeast. Normally, Candida yeast live on the surface of the skin without causing any problems. Infection occurs with an overpopulation of the yeast, which can be triggered by antibiotics, diabetes, smoking, wearing dentures, excessive stress, unprotected sex with an infected person, or a weakened immune system. When candidiasis affects the mouth, as shown above, it is called thrush. When candidiasis affects the genital area, it is called a yeast infection. The symptoms of thrush may include a sore, painful mouth; a burning mouth or tongue; thick, whitish patches; and difficulty swallowing. The symptoms of a yeast infection may include itching; irritation; a burning sensation, especially during urination; pain and soreness around the affected area; and thick, white, odorless, clumpy discharge. Treatment for thrush must be handled by a medical facility, but treatment for yeast infections can be purchased over-the-counter (OTC) at a local pharmacy. A Giardia infection is caused by a protozoan, represented here in the image. A person can get giardiasis through contact with watery, contaminated areas such as wells, streams, lakes, and hot tubs. The symptoms may include watery, unusually bad-smelling diarrhea; tiredness; abdominal cramps and bloating; sulfur burps; nausea; and vomiting. Once a medical professional has confirmed giardiasis, he or she can give an infected person treatment to cure the infection. Looking at the Giardia pathogen and reading about the places it is found, what do you suppose is its main form of travel? Based upon its shape and the fact that it is found in watery places, it is likely that the Giardia pathogen swims. Malaria is a noncontagious infection caused by a protozoan called Plasmodium. A person gets malaria when bitten by an Anopheles mosquito infected with Plasmodium. You can see in this image what happens next. In the last step, the bursting of red blood cells causes chills and releases the pathogens' chemical waste products, which leads to fever. To prevent malaria, it is necessary to prevent getting bitten by Anopheles mosquitoes. The symptoms of malaria may include periodic cycles of fever and chills, sweating, nausea, vomiting, diarrhea, and anemia (a low number of red blood cells). A person can determine if he or she has malaria with a blood test. Once the presence of the infection is confirmed, he or she can start treatments to kill the pathogens in the blood and in the liver. If a person has an infectious disease, why shouldn't he or she just be prescribed an antibiotic? Antibiotics are used to treat bacterial infections, but not all infectious diseases are caused by bacteria. Viruses, fungi, and protozoans can also cause infectious diseases.

cardiovascular disease

Have you ever been stuck in a traffic jam? It can be a very frustrating experience. Slow-moving traffic keeps people from getting where they are going and it doesn't discriminate against anyone—people headed to work, trucks hauling cargo, and even emergency vehicles like fire trucks and ambulances all slow down to a crawl.Slow-moving traffic can be annoying; slow-moving blood can be much more serious. Cardiovascular disease is a class of diseases that occur when something goes wrong with the heart or blood vessels. (This is literally what the term cardiovascular means: "cardio" means heart and "vascular" means vessels.) Also called heart disease, cardiovascular disease results in the blood vessels either becoming more narrow or blocked. This leads to a "traffic jam" in which blood carrying crucial oxygen and nutrients can't get to the tissues that need it.

alcohol and tabacco

You probably know someone who drinks alcoholic beverages or smokes cigarettes. You may even be that person. Alcohol and tobacco can have some unfortunate--even deadly--consequences when abused. Tobacco abuse is defined as any habitual use of the tobacco plant leaf and its products. Alcohol abuse occurs when a person's drinking leads to problems in his or her life, but the person keeps drinking anyway. These two substances are often used together. Studies have found that people who smoke are much more likely to drink, and people who drink are much more likely to smoke. What are some problems that may result from alcohol abuse? People who smoke and/or drink may have problems in their personal relationships, trouble with the law, and issues at school, work, or home. Watch this video to learn why alcohol and tobacco are considered drugs. A drug in a general sense is a substance that elicits intended and unintended side effects within the body after it is ingested or inhaled. That is a pretty broad definition but includes medicines that people take to relieve a headache or rid the body of an infection. For instance, antibiotics have the intended effect of killing bacteria, but it may cause side effects such as vomiting and diarrhea. Illegal drugs, such as cocaine and heroine, may give someone a "high," but these drugs can also cause brain damage and death. Alcohol is an intoxicating agent derived from yeast fermentation of grains and starch. Notice the word intoxicating in the definition. The word toxic is in there for a reason. You may have heard that drinking red wine is good for you. While some exceptions to this exist, alcohol by itself is not very healthy when compared to much safer foods and drinks that provide the same benefits. In fact, alcohol has been shown to harm the liver, heart, and may even be linked to certain cancers. This is especially true if you drink a lot of alcohol over an extended period of time. Tobacco is obtained from the leaf of the tobacco plant and contains the drug, nicotine. Nicotine, like heroine and cocaine, affects the brain pathways that control reward and pleasure. For many tobacco users, long-term brain changes induced by continued nicotine exposure often result in addiction. That's why the motto "Say NO to drugs!" is so important, especially in relation to tobacco. If you start using tobacco, it can be extremely difficult to stop. Transcript Question Why are alcohol and tobacco considered drugs? They are both substances that cause specific effects in the body after use, sometimes with unintended side effects.

Pathogens

All viruses consist of an outer protein coat and genetic material (DNA or RNA). The genetic material is the inner, curly, light-blue structure in most of the viruses shown in the image. Because viruses lack most of the structures of a typical cell, especially a nucleus, their cellularity is acellular. Because viruses cannot survive independent of a host, they are not considered to be "alive." Therefore, viruses aren't considered organisms; rather, they are considered agents that cause disease. As a result, viruses are not classified into a kingdom. They depend on a host organism to supply it with the necessary materials to sustain life. Vaccines, which are substances used to improve immunity, can be used to prevent a life-threatening viral infection. Doctors can also prescribe medicines called antivirals to treat specific viral infections. What is the difference between a vaccine and an antiviral? Think about the answer, and then click "Show Me" to see if you are correct. A vaccine prevents a viral infection from occurring. Antivirals treat a viral infection after it occurs. Bacteria (singular: bacterium) represent the oldest unicellular organisms. Because their genetic material is not found in a nucleus, they are prokaryotic. Bacteria are classified in Kingdom Monera. Bacteria can also be classified by their shape: cocci (spherical), bacilli (rod-shaped), and spiral (listed as Others in this image). Vaccines can prevent bacterial infections and antibiotics can help treat them. What is the difference between an antiviral and an antibiotic? Think about the answer, and then click "Show Me" to see if you are correct. Antivirals are used to treat infections caused by viruses (called viral infections). Antibiotics are used to treat infections caused by bacteria (called bacterial infections). Fungi (singular: fungus) can be unicellular or multicellular. They are eukaryotic organisms that are classified in Kingdom Fungi. The fuzzy white and light pinks spots in the image are made of fungal structures called hyphae, which spread over or throughout a host in order to absorb nutrients. Antifungal drugs can be used to treat fungal infections. Protozoans are unicellular, eukaryotic organisms. They belong to the Kingdom Protista. Plasmodium is a genus of parasitic protozoa. The four species of Plasmodium that cause malaria are shown in the image. Some protozoal infections can be prevented with a regular dose of mild antiprotozal drugs. Stronger antiprotozal drugs can be used to treat a protozoal infection once it has occurred.

what does alcohol abuse do to the body

As soon as you taste that first sip of alcohol, it is already affecting your body. It begins to slightly irritate the lining of your mouth and throat. Once it is swallowed, about 20% of it is rapidly absorbed into the bloodstream. Other than the 20% that was directly absorbed into the blood, the rest of the alcohol is processed through the gastrointestinal tract. When a person drinks more alcohol than the liver can efficiently metabolize, then the amount of alcohol in the bloodstream becomes more elevated. What body system includes the liver and the gastrointestinal tract? The digestive system includes both of these. Cell membranes are highly permeable to alcohol. As a result, once alcohol enters the bloodstream, it can move into almost every biological tissue in the body. Because alcohol so easily enters cells, prolonged alcohol abuse can wreak havoc on all kinds of bodily functions. Alcohol can prevent some cells from taking in required vitamins and minerals, and it prevents other cells from producing and releasing vital enzymes and hormones. Alcohol can also interfere with a nerve cell's ability to release neurotransmitters. What are neurotransmitters? Neurotransmitters are chemicals produced by nerve cells that communicate with other cells. Alcohol prevents nerve cells from communicating effectively with other cells, such as muscle cells, leading to the more obvious effects of intoxication. What are some signs of miscommunication between neurotransmitters? Signs include slurred speech, lack of coordination, stumbling, and impaired thinking. While some effects of alcohol abuse can be seen and felt right away, others develop over months or years. When alcohol is continuously consumed over a period of time, it begins to affect body organs and organ systems in many ways. For instance, alcohol consumption increases the risk of many cancers, including liver, breast, esophagus, pancreas, and mouth. Determine which body organ or system is designated in each image below. Then click on the image to reveal how it is damaged by alcohol. The liver can accumulate fat, called fatty liver. Fatty liver can lead to inflammation of the liver, called hepatitis. Continued abuse can lead to cirrhosis of the liver when liver cells become so damaged that liver failure occurs.Alcohol creates irritation and inflammation in the stomach lining, which can lead to ulcers, bleeding, and some forms of cancer.Excessive alcohol use can cause pancreatitis, inflammation of the pancreas. This disease impairs the organ's ability to produce insulin, which often leads to diabetes.Heavy drinking can be very hard on the heart, causing cardiomyopathy--the stretching and drooping of the heart muscle. It can also cause arrhythmia or irregular heartbeat. Alcohol also raises blood pressure and blood lipids, increasing the risk of raised cholesterol and high blood pressure.Since alcohol use flushes calcium from the bones, excessive drinking can accelerate the rate of bone deterioration and increase the risk of bone fracture and osteoporosis.Alcohol abuse can cause cell damage in the central nervous system, creating neuropathy. Neuropathy, or nerve damage, causes alternating feelings of weakness, burning, pain, and numbness in the hands and feet. liverorgan that metabolizes alcoholintoxicationresult of elevated blood alcohol levelsneurotransmitterchemical released by nerve cellscirrhosisdisease resulting from damage to liver cellspancreatitisdisease that affects release of insulinneuropathydisorder resulting in burning, trembling, and pain

symptoms of Atherosclerosis

Atherosclerosis develops when plaque builds up in the walls of arteries. This buildup makes it harder for blood to flow through the arteries. People often do not realize that they have atherosclerosis until they develop a cardiovascular disease. By that time, the arteries are affected to the point where they cannot supply an adequate amount of blood to the organs and tissues. Heart attack (medically called myocardial infarction), occurs when blood flow to the heart is blocked by an obstruction. If the heart muscle does not receive oxygen and nutrients from the blood, some of its cells begin to die. When this happens, a person may experience palpitations (the feeling that the heart is "skipping a beat"), pain in the chest (called angina), and shortness of breath. Heart attacks are serious, and must be treated immediately. Treatment for heart attacks includes medicines that dissolve blood clots, extra oxygen, and surgery to restore blood flow to the heart. Stroke (medically called ischemic stroke) occurs when blood flow to the brain is blocked by an obstruction. When the brain does not receive nutrient- and oxygen-rich blood, its cells begin to die. Symptoms of stroke include sudden numbness or weakness, dizziness, confusion, or trouble walking. Strokes are serious, and must be treated immediately. Furthermore, because brain cells aren't always able to repair themselves, a stroke victim may have permanent damage to his or her brain. Medicines that dissolve blood clots are usually given for stroke. In cases where the blood vessel breaks or leaks (hemorrhagic stroke), surgery is usually recommended. Heart failure (sometimes called congestive heart failure) means that the heart is not pumping blood through the body effectively. Initially, a heart in failure will become larger, add more muscle, and pump more quickly. However, eventually these temporary measures fail, and patients experience symptoms like shortness of breath, coughing, and swelling of tissues, especially in the legs, because the blood isn't moving through the body as quickly as it should. Treatments include medicines that prevent too much fluid from accumulating in the tissues and that increase the heart's pumping ability. Arrhythmia is a general term that means any type of irregular heartbeat. There are many kinds of arrhythmias. Atrial fibrillation occurs due to problems with the atria (top chambers) of the heart. In this common type of arrhythmia, the atria contract very quickly and "out of sync" with the rest of the heart because of an error in the heart's electrical system. The blood does not enter the ventricles (lower heart chambers) correctly, which can lead to stroke or heart failure. Arrhythmia is usually treated with surgery, medicine, or a pacemaker, which is a device implanted into the chest that sends out electrical signals to keep the heart's electrical system working properly.

smallpox

By the late 1700s, a disease called smallpox had been killing thousands of people a year for thousands of years. During the 20th century alone, smallpox is estimated to have killed over 300 million people. Smallpox is an infectious disease. Recall that pathogens cause infectious diseases. A small pox infection results in sores that cover the skin and eventually line the mucous membranes and digestive system. It kills a significant percentage of those who contract it. Smallpox is caused by a virus, is highly contagious, and has devastated civilizations for thousands of years. Watch the video below to see a brief history of smallpox. Smallpox is an ancient disease. There is evidence from Egyptian mummies that smallpox has afflicted humans since as early as 10,000 B.C. It was extremely contagious, and often fatal, sweeping through entire civilizations, like the Aztecs, killing monarchs and peasants alike. Smallpox is caused by a microscopic virus that infects skin cells. It causes blisters that line the skin. If one recovered from smallpox, they were often permanently disfigured. Others had blisters that traveled down the mucous membranes, lining the digestive system which eventually killed them. Transcript Cowpox sores on cow udder. In the late 1700s, an English doctor named Edward Jenner heard that milkmaids who contracted a relatively harmless disease called cowpox from the cows they milked did not get smallpox. Based on a Chinese technique called variolation, in which healthy patients were deliberately exposed to people with smallpox in an unsuccessful attempt to prevent them from getting sick, Dr. Jenner decided to inject fluid from cowpox blisters into a healthy patient. A few months later, he injected that same patient with the smallpox virus, and the patient did not get smallpox. He called this injection a vaccine, from the Latin word vaccinus, meaning "from cows." A vaccine is a substance that produces immunity to a disease. The technique of injecting the cowpox fluid was referred to as vaccination. We now know that Dr. Jenner's vaccine was effective because the viruses that cause cowpox and smallpox are closely related. Even after the discovery of the vaccine, smallpox continued to ravage communities. In fact, it was not until a worldwide vaccination effort in the mid-1900s that the disease was sufficiently controlled. The last known case of smallpox occurred in Somalia in 1977. After that, the virus that causes smallpox was declared absent from nature. After killing hundreds of millions of people over the course of human history, smallpox became the first infectious disease to be eradicated from humans via vaccination. Because it no longer appears to occur in nature, there is no longer thought to be a need for routine vaccinations. Question What would likely happen if we were exposed to the smallpox virus today? Because of the widespread use of the smallpox vaccination, not a single case of smallpox has been reported since the 1970s, and the virus is now believed to be completely absent from nature. Many possibilities for preventing infectious diseases emerged from that original vaccine. In the United States, routine vaccinations have basically eliminated several diseases that were historically fatal or paralyzing. Although not all of these vaccinations come from cows, the word vaccine is still used today to refer to any solution that contains a harmless version of a pathogen. Vaccines are usually given via injection, and they are used to stimulate a healthy subject's immune system. Recall that pathogens like bacteria and viruses have parts that act as antigens, or antibody generators. When exposed to antigens, the body mounts an immune response to prevent infection and disease. Vaccines contain the same antigens (or parts of antigens) that cause diseases. The antigens in vaccines are either killed or weakened to the point that they don't cause disease, but they still trigger the immune system to produce antibodies. These antibodies are dissolved or suspended in a liquid that is usually injected, although a few vaccines are delivered via inhalation or ingestion. Look through the slides below to learn what happens after a person receives a vaccination. Cell-Mediated Immune Response T-cells attacking an infected cell. One part of the immune response to a pathogen is the cell-mediated immune response, which activates T cells to identify and neutralize infected cells. The other part of the immune response is the humoral immune response, which activates B cells to secrete antibodies into your bloodstream and form memory cells. By making antibodies and memory cells that are specific to a pathogen's antigens, the immune system will be much faster and more efficient at responding to a pathogen if it is exposed to that pathogen again. The response to a second exposure to a pathogen is referred to as the secondary immune response; it is much faster and more efficient than the initial, or primary immune response. The graph above illustrates this process. Vaccinations take advantage of this system by exposing recipients to antigens without making them sick. During the several days after a vaccination, the immune system will make antibodies and memory cells that are specific to those antigens. This process has long-lasting effects. If the person who has received the vaccine is exposed to the real pathogen, his or her immune system can respond swiftly and strongly to prevent an infection. This state of resistance to a particular infectious disease is referred to as immunity.

how cancer affects the body

Cancer is not just one disease, but many diseases. There are more than 100 types of cancer that have been discovered at this time. Most cancers are named for the organ or type of cell where the abnormal cell growth begins. For example, cancer that begins in the melanocytes of the skin is called melanoma. If the abnormal cells spread through the bloodstream or lymphatic system to other organs, such as the lung or liver, the cancer is still called melanoma. Likewise, if a cancer starts in a lung, it is considered lung cancer even after it spreads to other parts of the body. Cancer that begins in the skin or in tissues that line or cover internal organs is called a carcinoma. Basal cell carcinoma is a type of skin cancer that spreads very slowly, if at all, and is therefore considered a less dangerous form of cancer if detected and treated early. What do you think a tumor in the lining of the uterus would be called? Uterine or endometrial carcinoma Cancer that begins in bone, cartilage, fat, muscle tissue, or other connective tissues is called a sarcoma. Osteosarcoma is a type of bone cancer. Fat is composed of lipids. What might a malignant tumor of the fat tissue be called? A liposarcoma, which can occur anywhere in the body that contains fat tissue. Leukemia is a type of cancer that starts in blood-forming tissue such as bone marrow. If you know that bone marrow produces blood cells, what would leukemia cause? Leukemia causes the bone marrow to produce large numbers of abnormal blood cells rather than the bloods cells the body needs to function properly. Cancers that begin in the immune system are either lymphomas or myelomas. Most people recognize Hodgkin's lymphoma as the most familiar cancer of the immune system. Myeloma affects the cells in the bone marrow that produce the fluid part of the blood. Some cancers begin in the brain and spinal cord. Brain tumors are generally called neuroblastomas. What types of symptoms might result from a neuroblastoma? Symptoms involving the nervous system, such as reduced mobility or blurred vision, as well as seizures, problems thinking clearly, or other problems associated with higher brain functions.

categories of noninfectious disease

Cardiovascular disease is a set of disorders of the heart and blood vessels. Blood vessels supply blood, oxygen, and nutrients to all the tissues of the body, including the brain, heart, arms, legs, and organs. When these parts of the body are damaged or blocked, cells tissues can die, including brain tissue, which can be fatal. All the risk factors you have learned about are relevant to cardiovascular disease. Cancer occurs when cells grow and divide more than normal, causing tissues to grow abnormally large and invade nearby spaces (as shown in the diagram). Enlarged tissues can then prevent normal body function. This abnormal growth is due to a genetic mutation, which can be inherited, acquired with age after many rounds of cell division, or caused by exposure to radiation (such as sunlight, which causes skin cancer) or harmful chemicals (such as those found in tobacco smoke). All the risk factors you have learned about in this lesson are relevant to cancer. Examples of respiratory disease include asthma and chronic obstructive pulmonary disease (COPD), which is a lung disease in which airflow is persistently blocked. COPD can be fatal, as a person is unable to inhale enough oxygen to keep his or her cells alive. COPD is not curable, but it is preventable, as it is primarily caused by tobacco smoke. Recall that diabetes is the body's inability to metabolize and regulate glucose in the blood. Most cases of type 2 diabetes are acquired due to excess body weight and physical inactivity. The disease is increasingly seen in children as well as adults. Diabetes increases the risk of cardiovascular disease, as well as diseases of all other tissues, most commonly the nerves, kidneys, and eyes.

cardiovascular disease affects people worldwide

Cardiovascular diseases are the most common type of diseases in the world. Scientists called epidemiologists study how often a disease occurs in a particular area or group of people. Epidemiologists working for some health organizations have found that over 17 million people die of some kind of cardiovascular disease every year. Watch the video below to learn more about the epidemiology of cardiovascular disease. Cardiovascular diseases are by far the most common diseases in the world. The World Health Organization (WHO) estimates that about 30% of people in the world die from some kind of cardiovascular disease every year. The epidemiologists that work for the World Health Organization don't see that number getting any smaller. In fact, they project that that number will increase in the future. The question is, "why"? There is more than one answer to that question. One answer is that many people have many risk factors for cardiovascular disease. For example, almost half of Americans have at least one of three risk factors: high cholesterol, smoking, or high blood pressure. Another answer has to do with access to health care. Epidemiologists have noted that if a population of people has less access to doctors and hospitals, they are more likely to have cardiovascular diseases. Still another answer lies in misconceptions, things that that people "think" are true about cardiovascular disease, but are actually not. With technology comes a lot of misinformation. For example, some people think that if they are in their twenties, it's too early to worry about developing heart disease, or that they don't have to get their cholesterol levels checked. These things are not true! It's important to avoid risk factors like high cholesterol, obesity, and smoking even when you are not middle aged. The world's problems with cardiovascular disease aren't going away anytime soon. Epidemiologists will continue to study the problem of cardiovascular disease to help determine who is getting it, and why. Transcript Question A common myth is that if a family member has a cardiovascular disease, there isn't anything you can do to prevent getting that disease. Why isn't this true? Although genetics (family history) does play a role in whether a person gets cardiovascular disease, having other risk factors such as high cholesterol, smoking, and obesity make the likelihood that a person will get a cardiovascular disease even higher. On the other hand, not smoking, eating healthfully, and exercising can help reduce a person's likelihood of getting cardiovascular disease even if they have a family history of the disease.

risk factors of noninfectious diseases

Certain risk factors are strongly associated with diseases. However, if a person has a risk factor for a certain disease, he or she will not necessarily get that disease. For example, a person's dietary habits and percentage of body fat are strong determinants of whether he or she will get diabetes, but not every person who is overweight will become diabetic. Diabetes is a metabolic disorder in which a person's body does not properly process glucose. Normally, the body uses glucose as chemical building blocks for making many of the other molecules a cell needs. Cells need energy from glucose to perform their normal functions. If a person cannot digest glucose properly, their energy levels and the balance of chemicals in their body and brain may fluctuate wildly, causing dizziness, lightheadedness, and disorientation. Because all tissues need glucose, an inability to digest glucose can also lead to tissue damage, poor circulation, limb amputation, and even death. Genetics contributes to some instances of diabetes. However, a great number of cases of this debilitating, lifelong disease result from lifestyle choices, and are thus preventable. However, given two people who have a very similar diet and the same percentage of body fat, one may get diabetes and the other may not. A number of factors work together to influence a person's health, such as whether he or she smokes, the level of stress in his or her life, his or her combination of 20,000 protein-coding genes, and the combination of thousands of other stretches of DNA that do not encode proteins, but perform complex regulatory functions in cells. Watch this video to learn about the role that risk factors play in predicting whether a person will develop a disease. For the vast majority of non-infectious diseases, predicting whether someone will develop one is difficult; however, by looking at many risk factors and many diseases across many people, we can identify factors and diseases that are strongly associated. Based on these statistical data, we have identified several risk factors that clearly, negatively affect human health in many ways. Identifying associations between risk factors and diseases also allows scientists to develop hypotheses about whether a factor causes a disease, and design experiments to test those hypotheses. By testing whether a risk factor causes a disease in an animal whose body works in a similar fashion to ours (such as a rat, a common model organism in studies on human disease), we can try to prevent these diseases in humans. For the most part, it is up to each individual to decide what to do with this information, such as deciding what to eat, whether to smoke, and whether to maintain a healthy weight. Transcript Question Because risk factors do not predict diseases with 100 percent certainty, should you even pay attention to them?

Cancer

Chances are very good that you know someone who has had cancer. Over one million people get cancer each year, representing every racial, ethnic, and age group. Today, millions of people are living with cancer or have been cured of the disease, yet cancer remains one of the leading causes of death in the United States. In 1910, scientists had only recently discovered that every cell in the body is derived from another cell and that cancer cells divide in approximately the same fashion as normal cells. Around this time, Peyton Rous, a researcher at the Rockefeller Institute, carried out some experiments that seemed far-fetched at the time. He removed some fluid around a tumor that seemed to have appeared spontaneously in a chicken. Rous then injected this fluid into healthy chickens. Surprisingly enough, the healthy chickens developed similar tumors. In 1966, Peyton Rous received a Nobel Prize for his discovery that a virus could actually induce cancer. His revealed his motivation for continued cancer research in his acceptance speech. "Tumors destroy man in a unique and appalling way, as flesh of his own flesh which has somehow been rendered proliferative, rampant, predatory, and ungovernable . . . What can be the why for these happenings?" -Peyton Rous What does Rous mean when he says that someone's own flesh becomes "predatory" and "ungovernable"? Why does he describe cancer this way? By definition, cancer is a disease in which cells in a part of the body begin to grow out of control, causing damage to vital organs. In this sense, a person's own cells turn against him or her in a "predatory" way that is beyond his or her control, or "ungovernable." You may remember learning about the process of mitosis in an earlier lesson. Mitosis is the process by which normal cells grow and divide before dying. Through mitosis, normal cells are replaced by similar cells. Instead of dying, cancer cells continue to grow and divide, outliving normal cells and forming more new abnormal cells. If left untreated, cancer cells may eventually spread throughout the body, damaging essential systems to the point where they no longer function to keep the body alive. Question Although there are many types of cancers, what is the one common mechanism by which all cancer arises? All cancers result from out-of-control cell growth and division.

colorectal cancer

Colorectal cancer refers to cancers that develop in the colon or the rectum, both of which reside in the lower region of the digestive system where food is processed for nutrient adsorption. The colon, also known as the large intestine, absorbs water from food while the rectum holds feces until it is excreted through the anus. As you can see in the image on the left, the colon and the rectum both appear at the very end of the GI (gastrointestinal) tract. Colorectal cancer afflicts both men and women about equally, and the disease is the second-leading cause of cancer-related deaths. Most cancers of the colon are adenocarcinomas, or tumors that form in the glandular cells that line both the colon and the rectum and produce mucus and other fluids. Colorectal cancer tends to develop slowly over a period of years. It usually begins as an abnormal growth of tissue in the bowel, called a polyp. A procedure called a colonoscopy, in which a lighted camera is inserted up the GI tract, can help doctors detect polyps. Any polyps found during this procedure can be surgically removed so they don't develop into cancers. Many physicians and researchers believe that getting plenty of exercise; eating a healthy, high-fiber diet; and avoiding possible carcinogens can prevent colorectal cancer. For instance, some research in nonhuman animals links meats cooked at high temperatures, such as over open flames, to cancers, including colorectal cancer. The chemicals found in charred meat are thought to be carcinogenic in the same way as cigarette smoke and exhaust fumes are. This does not mean that eating a grilled burger every now and then is going to give you cancer. However, the more aware you are of possible prevention methods, the more you can reduce your overall risks. Question For the past couple of decades, the death rate from colorectal cancer has been dropping. What are some likely reasons for increased survival rates?

Distribution of vaccines

Countries that are less industrialized generally have lower vaccination rates due to a lack of money, education, or the ability to distribute or administer vaccines. In the last 30 years, the virus that causes the paralyzing and often fatal disease of polio has been eliminated from the western hemisphere. A worldwide vaccination effort has lead to the elimination of the disease from many other countries, but polio is still widespread in three countries: Afghanistan, Nigeria, and Pakistan. The Polio Global Eradication Initiative is currently focused on these countries, delivering vaccines to children and educating parents about its safety and importance, with the hope of eliminating poliovirus entirely. Even in industrialized countries such as the United States, there are some people who choose not to be vaccinated even if vaccinations are readily available. Vaccination has become a highly polarizing issue, due to misinformation regarding their side effects, how they work, and a reliance on herd immunity. Herd immunity is a phenomenon that comes from the notion that if many people in a population are immune to a particular infectious disease, then it is less likely for an outbreak of that disease to occur. Some people decide not to get vaccinations, or not to vaccinate their children, because they assume that the rest of the population will be vaccinated and protect them from a disease outbreak. Pertussis, or whooping cough, is a bacterial disease that was a major cause of childhood death in the 20th century. The bacterial infection causes severe coughing fits that can induce vomiting, exhaustion, and the inability to breathe. It can also make the body susceptible to pneumonia and other complications. When a vaccine for pertussis became available in the 1940s, the disease became much less common. However, since the 1980s, pertussis has been gradually increasing. The reasons for this are unclear, but a lack of widespread vaccination is suspected as a factor, as is the overuse of antibiotics that may make drug-resistant pertussis bacteria more common. In 2014, there was an outbreak of pertussis in California, with over 8,000 cases reported. Many of those cases were associated with either a lack of pertussis vaccination or with the use of a vaccination that does not contain pertussis cells. The vaccine that does not contain pertussis cells does not provide protection for as long as the whole-cell vaccine does. The outbreak in California has served as a warning sign that we are still susceptible to diseases for which we have vaccinations.

infectious vs contagious

Ebola is a viral disease, which means it is caused by a virus. A virus is an example of a pathogen. Recall that a pathogen is a disease-causing organism or agent. In addition to viruses, bacteria, fungi, and protozoans can also be pathogens. An infectious disease is an illness caused by a pathogen, so pathogens are also called infectious agents. Pathogens live in or on another organism, called a host, and they make that organism sick. For example, a person could be the host for a flu pathogen. So, are all diseases caused by pathogens? Also, are all diseases easily spread from one person to another? Read the material in each tab below to find out. Infectious Diseases Contagious Diseases Malaria is an infectious disease, so it is caused by a pathogen. If the mosquito shown in the image has the pathogen that causes malaria, then the human that it bites could also get malaria. However, not all diseases are caused by pathogens. Diseases that are not caused by pathogens are called noninfectious diseases. Factors such as genetics, the environment, and lifestyle can cause non-infectious diseases. Cancer, or the uncontrolled growth of cells, is not usually caused by a pathogen. Why is malaria classified as an infectious disease while cancer is usually classified as a noninfectious disease? Think about the answer, and then click "Show Me" to see if you are correct. Malaria is classified as an infectious disease because it is caused by a pathogen. Cancer is classified as a noninfectious disease because it is not usually caused by a pathogen. A contagious disease is an illness caused by a pathogen that is easily spread from one person to another. The image shows two pathogens, symbolized by red and green spiky spheres, that two people can spread to each other through body fluids such as saliva, sweat, blood, and body tissue. Not all diseases caused by a pathogen are contagious. Malaria, for example, is caused by a pathogen but it is not passed from person to person. In the medical field, the term communicable is used as a synonym for the term contagious. Why is Ebola classified as a contagious disease while malaria is not? Think about the answer, and then click "Show me" to see if you are correct. Ebola is classified as a contagious disease because it is easily spread from one person to another. Malaria is not a contagious disease because it can be transmitted from a mosquito to a person but not from one person to another.

alcohol abuse

Ethyl alcohol, or ethanol, is an intoxicating ingredient found in beer, wine, and liquor. Alcohol is produced by the process of fermentation in yeast cells, a type of fungus. Sugars in grains, fruits, or starches are converted into cellular energy for the yeasts. Ethanol is a by-product of this process. When alcohol is ingested by humans, it acts as a nervous system depressant that is rapidly absorbed from the stomach and small intestine into the bloodstream. A standard drink equals 0.6 ounces of pure ethanol, which is the amount found in about twelve ounces of beer, five ounces of wine, or 1.5 ounces of liquor (gin, vodka, rum, or whiskey). Having excessive drinks leads to intoxication, which usually impairs brain function and motor skills. How does a drunk person appear to others? What behaviors indicate intoxication? An intoxicated person often has slurred speech, less control over movement (stumbling or falling), memory loss, and sometimes aggression. There are two types of problem drinking--alcohol abuse and alcoholism; however, the second type sometimes follows from the first. Study the content of these tabs to learn the difference between these two drinking problems. Alcohol Abuse Alcoholism Alcohol abuse occurs when drinking leads to problems, but the person is not physically dependent on alcohol. The alcohol abuser may miss school or work or have trouble at home getting along with loved ones. Arguments about the person's drinking habits become common. Additionally, the drinker participates in potentially dangerous situations, such as drinking and driving, which leads to legal and financial troubles. Alcoholism impacts individual and families when drinking causes serious problems throughout the drinker's life, and yet the alcoholic keeps drinking. Usually alcoholics have a physical dependency on alcohol. If they suddenly stop drinking, they may develop withdrawal symptoms such as uncontrollable shaking, hallucinations, and nausea. Alcoholics tend to develop a high tolerance for alcohol, which means they need more and more alcohol to feel drunk.

Cancer Diagnosis

Fifty years ago, a diagnosis of cancer was very close to a death sentence. Due to scientific advancements in recent years, though, many effective treatments are now available to cancer patients. Still, the key to successful treatment of any type of cancer is early detection of the disease. As with most diseases, sometimes cancer treatment is successful and sometimes it is not. Scientists and doctors still have much to learn about the factors that lead to a positive outcome. In many cases, oncologists suggest a combination of treatment types, which are summarized in the table below. You're probably aware of most of these options. See if you can guess the treatment type based on its description. Then click the description again to check your answer. DescriptionTreatmentCells or tumors are removed in order to diagnose, treat, or, in some cases, help prevent cancer.SurgeryThe patient receives drugs, either by mouth or intravenously, that are designed to kill cancer cells.ChemotherapyCancer cells are destroyed by waves of high-energy particles.Radiation TherapyCells that produce normal blood cells are transplanted from a healthy donor into a cancer patient.Stem cell (bone marrow) transplant

prostate cancer

Find the tumor in the prostate gland shown in the call-out image. Notice that the urethra, which empties the bladder, is partly surrounded by the prostate gland. Given this location, what symptoms might indicate a tumor in the prostate gland? Think about it, and then click the Answer button to check your answer. Symptoms of an enlarged and possibly cancerous prostate include difficulties with urination. However, other conditions may cause the prostate gland to swell—not just cancer. Fortunately, there are several reliable tests that can detect prostate cancer, and with early treatment, many, if not most, cases of the disease are curable. The PSA test is a blood test that detects a substance made by the prostate (a prostate-specific antigen) that may be present in high levels if cancer is present. The PSA test is typically performed along with a digital rectal exam, during which the prostate is physically examined by a physician to check for any obvious abnormalities. If the physician finds any abnormalities, he or she will order a bHormone TherapyHormones (chemical messengers) that may contribute tothe growth of tumors are removed or blocked so cancer cells stop growing.iopsy, or surgical removal of a small sample of cells, to see if cancerous cells are present in the prostate. If prostate cancer is diagnosed, the patient will be offered some combination of treatments designed specifically for the type and stage of prostate cancer. The following table outlines some of the more common treatments. SurgeryA malignant tumor (or the entire prostate gland) is removed. Radiation therapyHigh-energy X-rays are used to destroy cancer cells in the prostate. ChemotherapyDrugs are used to stop the growth of cancer cells. ImmunotherapySubstances made by the body are used to boost, direct, and restore the body's natural defenses against cancer. (This approach is also called biologic therapy.) Why do you think cancer researchers might seek millions of dollars from organizations such as the American Cancer Society and the National Cancer Institute each year? Cancer research is expensive! Some research is funded by the government, but donations from other organizations and individuals are needed to help fund many research projects.

teen alcohol use

Five thousand people under the age of 21 die each year from alcohol-related car crashes, homicides, suicides, alcohol poisoning, and other injuries due to falls, burns, and drownings. How are alcohol poisoning and binge drinking related? Binge drinking quickly elevates blood alcohol levels. In some cases, there is too much alcohol for the body to process, and, as a result, body organs shut down, resulting in coma and death. About 200,000 people under age 21 visit an emergency room for alcohol-related injuries each year. Why are injuries more likely to happen after a person has consumed alcohol? Alcohol can interfere with a person's normal sense of caution and cause the person to act recklessly. Reckless behavior can easily lead to injuries. Drinking can cause people to make poor decisions, which can then result in risky behavior. Youth who drink are more likely to carry out or be victims of a physical or sexual assault. Why do you think being under the influence of alcohol may increase your chances of becoming a victim? You may put yourself in a situation that you would normally avoid, such as walking home alone at night or being alone with someone you barely know. Scientists are currently conducting research studies that examine just how alcohol affects the brain of a young person. So far, researchers have shown that animals fed alcohol during the time of brain development continued to show mental impairment as they aged. The results of this and similar studies suggest that alcohol may have a significant impact on long-term thinking and memory skills. Why are the effects of alcohol on your brain so different than that of an adult? Remember that your brain is still growing and developing in ways that will impact your future. Elevated levels of liver enzyme that indicate liver damage have been found in some adolescents who drink alcohol. Young drinkers who were overweight showed elevated enzyme levels with only moderate levels of drinking. What is the function of the liver? The liver processes toxins, including alcohol. It also produces bile, a substance that helps break down fats you eat. Puberty is associated with hormonal changes, including increases in the sex hormones. What are the two major sex hormones in males and females? They are testosterone and estrogen. These hormones increase production of other hormones necessary for normal organ development. Drinking during this period of rapid growth and development may upset the hormone balance needed for normal development of organs, bones, and muscles.

hiv stages

HIV in the bloodstream The acute-infection stage, also called the primary-infection stage, is the initial stage of the infection. It is often accompanied by a short, flu-like illness. During this stage, large amounts of the virus are produced in the body, destroying CD4 cells (a type of T-cell) in the process. The immune system responds to this invasion by producing antibodies that kill antigens and killer T cells that kill antigen-infected cells. The clinical latency stage is also called the asymptomatic stage because during this stage, the virus is reproducing in the body, but without causing any symptoms. This symptom-free stage can last 10 years or more. AIDS is the final stage of an HIV infection. At this stage, the immune system is severely damaged due to the high amount of HIV and the low CD4 cell count. By this stage, HIV has destroyed so many of the CD4 cells that the body cannot fight infections anymore, which puts the person at risk for opportunistic infections. Opportunistic infections are caused by pathogens that a healthy immune system is usually able to fight. In a person with HIV, infections are able to take advantage of the body's weakened immune system, causing diseases that can affect nearly every organ system in the body. An infection is considered to have progressed from HIV to AIDS when the number of CD4 cells falls below 200 cells per cubic millimeter of blood (200 cells/mm3). In healthy adults, CD4 counts are between 500 and 1500 cells/mm3. An additional indicator that the infection has progressed from HIV to AIDS is that the person develops one or more HIV-related opportunistic diseases. Recall that AIDS stands for Acquired Immunodeficiency Syndrome. Think about what this means, and then click the Show Me button to see if you are correct. A is for Acquired: AIDS is acquired, not inherited.I is for Immuno: AIDS damages the body's immune system.D is for Deficiency: AIDS occurs when the immune system is deficient and unable to do its job.S is for Syndrome: AIDS is not a single disease, it is a syndrome, which is a collection of symptoms and signs of disease. Not everyone who has HIV progresses to AIDS. Antiretroviral therapy (ART) can help keep the level of HIV virus in the body low. ART prevents the virus from multiplying and destroying the immune system. In fact, a person who consistently takes ART will most likely never progress to AIDS. Question What's the difference between being HIV positive and having AIDS?

autoimmune disease

Have you ever played capture the flag, flag football, or tag? If so, you probably know that the game can get confusing at times. Sometimes, members of different teams wear colored shirts to distinguish them from one another. Normally, this helps keep the game organized. But say that you are trying to capture someone with a red shirt who is on the opposing team, and one of your own teammates, who is wearing a red-orange shirt, runs by. Without thinking, you might mistake him for being an "enemy" because his shirt color is similar to that of the members of the opposing team, and grab or tag him. That situation is somewhat similar to the way an autoimmune disease works in the body. An autoimmune disease occurs when the body attacks "targets" that are made of its own cells or molecules. Autoimmune attacks that cause disease can occur on one specific target, or on many different cells or tissue types in almost any system of the body. Scientists aren't sure exactly how many autoimmune diseases exist, but most researchers agree that there are a few criteria that most autoimmune diseases have in common. Many autoimmune diseases are linked to a problem with one or more genes, which are the "units of heredity" passed from parent to child. As a result, members of the same family are likely to share an autoimmune disease. Many autoimmune diseases are "kicked off" by an outside agent like a toxic chemical, a drug, a pathogen (bacteria or virus), or even certain foods. Most autoimmune diseases share some symptoms. Common symptoms for many autoimmune diseases include weight loss, difficulty concentrating, joint or muscle pain, fever, and fatigue (tiredness). Scientists have noticed that most people who have an autoimmune disease get at least one additional autoimmune disease. About 25 percent of people who have one autoimmune disease actually have three or more. Women are more likely to be affected by autoimmune diseases than men. In fact, about 75 percent of people who suffer from an autoimmune disease are female.

risk factors of cardiovascular disease

If narrowed arteries caused by atherosclerosis are like a construction project that causes traffic to slow down, then conditions like stroke and heart attack are similar to accidents caused by traffic jams. But as anyone who has ever tried to drive through a heavy storm or on icy roads knows, there are factors that make accidents and traffic jams more likely. These are called risk factors. In medicine, risk factors are defined as something that makes a person more likely to get a disease or condition. Hypertension, or "high blood pressure" (the root hyper- means high), is a major risk factor for cardiovascular disease. If blood is pushed through blood vessels at too high of a pressure over a long period of time (weeks or months, as opposed to, for example, when you're exercising), it can cause damage to blood vessels. Improving the diet and increasing the amount of exercise can often control hypertension; in more severe cases, medicine is needed. Recall that cholesterol is a lipid that can cause plaques and eventually lead to thrombosis. Not all cholesterol is bad, however. Some is needed for healthy cell membranes and for making certain hormones. A type of cholesterol called HDL actually protects the heart against cardiovascular disease. Another type, called LDL, has functions in the body, but if LDL levels become too high, heart disease can result. Treatment of high cholesterol includes increasing the number of fruits and vegetables and decreasing the amount of fats from animal products in the diet, increasting the amount of exercise, and taking medication. Being overweight or obese (significantly overweight) are major risk factors for developing cardiovascular disease. Eating a healthy diet (high in fruits and vegetables and low in sugar and fats that come from animal products) as well as getting daily exercise are good ways to manage weight and to cut your risk of cardiovascular disease. Smoking is another major risk factor for heart disease. Smoking accounts for at least 20 percent of cases of heart disease in the United States alone. The more an individual smokes, and the greater number of years he or she smokes, the greater the chance he or she has of getting heart disease. Risk factors that can't be controlled include:- genetics: Your family history can tell you a little bit about your likelihood of getting cardiovascular disease. If other members of your family have heart disease, you have a greater chance of getting it, too.- age and gender: Our risk of getting cardiovascular disease increases consistently as we get older. Women are particularly at risk, especially over the age of 55.

type 1 diabetes

In autoimmune diseases, the action of the body's immune system turns against cells that are on its own "team." In a disease called type 1 diabetes (sometimes called type one or type I diabetes), the immune system attacks specific cells that are part of the pancreas. Click through the slideshow to learn about this autoimmune disease. The pancreas has both digestiveand endocrine functions. Recall that the pancreas is an organ with two primary roles. First, in the digestive system, the pancreas secretes enzymes into the small intestine to help neutralize stomach acid and break down proteins and carbohydrates. Second, the pancreas acts as part of the endocrine system to produce two hormones: insulin and glucagon. Together, these hormones keep a consistent level of glucose (sugar) in the blood. Insulin lowers blood glucose by allowing it to enter cells, and glucagon raises blood glucose by, for example, releasing glucose from the liver. The pancreas contains groups of cells called "islets." (They are called islets because they look like little islands.) In a healthy pancreas, specific cells called beta cells make insulin. In type 1 diabetes, the immune system's T cells attack these beta cells and destroy them. Fewer or no beta cells means less or no insulin. In a healthy body, insulin binds to a receptor, which signals cells to take in glucose that is being carried in the blood. In type 1 diabetes, there is little to no insulin in the body. Therefore, not very much insulin binds to receptors, and little to no glucose gets into cells. The glucose instead stays in the blood. High blood glucose is a main symptom of type 1 diabetes. A constant high level of glucose in the blood causes widespread damage in the body. Nerve damage, kidney damage, and circulatory system (heart and blood vessel) problems are just some of the issues that type 1 diabetes can cause. Type 1 diabetes patients must take insulin daily for the rest of their lives in order to stay healthy. They must also test their blood glucose frequently to see how much insulin they need to take.

immune response

Innate immunity is a natural, nonspecific immune response and the body's first line of defense against antigens. Unbroken skin stops antigens from entering the body. Mucus, which is a thick liquid that covers the inside of the nose and throat, traps antigens and breaks them down. Tears protect the eyes. Coughing and sneezing help clear the throat and nose of foreign matter that may be harmful. Finally, stomach acid destroys antigens in food. What makes innate immunity a "nonspecific" immune response? Think about the answer, and then click Show Me to see if you are correct. Innate immunity is a nonspecific response because the immune system responds to antigens in a generic way. Innate immunity is not specific to any particular antigen. Inflammation is also a natural, nonspecific immune response, but it is part of the body's second line of defense. Once antigens, such as a splinter, enter the body, the damaged cells release inflammatory chemicals called cytokines, which are chemical messages that trigger an inflammatory response. 1) Mast cells transform into neutrophils. 2) The neutrophils exit the bloodstream. Blood and plasma flow to the damaged cells, causing the area to become red and swollen. The extra fluid traps the antigens. 3) The neutrophils locate the antigens by chemotaxis. 4) Neutrophils eat the antigens, damaged cells, and bacteria by phagocytosis. Dead bacteria, neutrophils, and dead cells collect as pus, which is a thick, white fluid. Passive immunity is a specific immune response. It is temporary because the antibodies involved are not made by a person him or herself. Unborn and breastfed babies receive natural passive immunity from their mothers. A person can also receive an acquired passive immunity via a shot of another organism's antibodies. This process helps treat certain cancers, multiple sclerosis, rheumatoid arthritis, Crohn's disease, and some cardiovascular diseases. Active immunity is a specific immune response. It is long-lasting because a person develops antibodies against an antigen him or herself. There are two types of active immunity: humoral and cell-mediated. In a humoral response, the immune system will increase a B cell population specific to the antigen. B cells will transform into plasma cells and secrete antibodies (shown as green "Y" shaped figures) to destroy the antigen. Memory cells will increase the immune response if the antigen appears again. In a cell-mediated response, the immune system will increase a killer T cell population that is specific to the antigen. The killer T cell will bind with a cell infected with the antigen and inject it with a cytotoxin (cell poison). Acquired active immunity occurs when a person receives a vaccine, which is a shot of a weakened antigen that triggers a humoral response. An allergic reaction is a specific immune response. Allergies are an overreaction to a harmless substance called an allergen. Anything can be an allergen: food, pollen, mold, animal fur, insect bites, latex, and so on. When an allergen triggers an immune response, the body makes antibodies. People suffering from allergies can experience itchy eyes, a skin rash, sneezing, or a more life-threatening condition called anaphylaxis, which can include low blood pressure, trouble breathing, swollen tongue or throat, flushed skin, dizziness or fainting, nausea, vomiting, or diarrhea. Which of the different types of immune responses are nonspecific immune responses? The nonspecific immune responses are innate immunity and inflammation.

1918 Influenza Pandemic

Jon enjoyed biology more than history. So when his world history teacher assigned class members to interview an older person about a historical moment in their lives, Jon decided to interview his great-grandmother about the 1918 influenza pandemic. His great-grandmother Josephine, or "Great Gran Jo" as he called her, was just a child at the time, but she helped her father, who was a doctor in Oakland, California, care for patients. Jon already knew that influenza, or the "flu" for short, is a contagious viral disease characterized by fever, chills, and sore muscles. But he wasn't sure why this outbreak was called a pandemic instead of an epidemic. After a bit of research, he learned that the terms pandemic and epidemic are both used to describe widespread outbreaks of a disease. In each case, an infectious disease spreads rapidly to many people. An epidemic occurs when the disease outbreak is concentrated in a particular region. A pandemic is a global disease outbreak. In other words, a pandemic is an epidemic of worldwide proportions. View this video to see what Jon learned in his interview with his Great Gran Jo about the 1918 influenza pandemic. Back then, people generally didn't know what the influenza was—people didn't realize it was a virus. It hit the Oakland neighborhood in 1918. People were very preoccupied with World War I at that time. At first, doctors tried to treat the flu with antibiotics, but it didn't work. Doctors realized it wasn't a bacteria, since they examined bodies of people who had died from the flu and didn't find any trace of a deadly bacteria. Vaccines didn't exist yet, either - they didn't become popular until the 1940's. It was very fashionable, in those days, to spit into a spittoon, which is a bowl or bottle often seen sitting on the floor. The disease spread quickly from people sneezing, coughing, and spitting. Doctors and public health officials started a campaign for people to cover their mouths when they coughed or sneezed and banned people from spitting. People wore medical masks, quarantined those who were sick, and banned spitting on the sidewalk. Because of the war, politicians didn't want people to know how many soldiers were being affected by this illness. Spain was a neutral country during World War One; so while all the countries fighting in the big war underreported how many flu cases they had, they freely reported how many were sick in Spain. This pandemic became known as the Spanish Flu, as if Spain was the hardest hit. This pandemic killed close to 675,000 Americans and nearly a fifth of the world's population, especially teens and young adults. That was more than were killed in war. Because of the severity of this pandemic, though, a lot of research about viruses occurred. Today, viral diseases still exist, but the severity has lessened thanks in large part to modern medicines like vaccines. Transcript Question Why don't we see deadly flu pandemics like the one in 1918 anymore?

atherosclerosis

Just as a traffic jam clogs the highways that help cars get from one place to another, cardiovascular disease clogs the body's blood vessels, preventing blood from smoothly getting around in the body. There are many specific conditions that fall under the category of cardiovascular disease, but most of them are related to a process called atherosclerosis. Atherosclerosis is the buildup of lipids called fat and cholesterol in the walls of blood vessels. This buildup, called plaque, causes arteries, which are the vessels that carry blood away from the heart, to become hardened and narrower. Normal artery walls are clear, and there are no plaques of cholesterol or other kinds of lipids. Plaques usually first form when we are in our late 20s and early 30s. Caused by injury to the blood vessels due to common factors like infections, plaques are made mostly of cell debris and fat. Plaques begin to extend to "fatty streaks." These streaks are the first visible sign of atherosclerosis. Atherosclerosis progresses as we age, and is accelerated due to smoking, consistent high blood pressure, and poor diet. The plaques form longer "fatty streaks," and tend to include connective tissue and the mineral calcium, which causes the arteries to harden. In severe cases of atherosclerosis, pieces of the plaque can break off, causing a thrombus (obstruction or "clot") of the blood vessel. This thrombus can have immediate and severe consequences, depending on what tissues become deprived of oxygen and nutrients due to the clot.

risk levels

LowMediumHighVirulenceThe virus has been around 5 years or longer.The virus has been around less than 5 years.It is a newly mutated viral strain.TransmissibilityMost people have received a flu shot (vaccine).Some people have received a flu shot (vaccine).Very few people have received a flu shot (vaccine).Societal and Environmental FactorsSociety has excellent transportation and communication systems. It is not winter or a rainy season.Society has good transportation and communication systems in big cities. It may be winter or a rainy season.Society has bad transportation and communication systems. It is winter or a rainy season.Medical and Nonmedical InterventionsThere is a sufficient supply of flu vaccine and antiviral drugs. Quarantines, closures, and travel restrictions are strictly enforced.There is a limited supply of flu vaccine and antiviral drugs. Quarantines, closures, and travel restrictions are mostly enforced.There is a very limited supply of flu vaccines and antiviral drugs. Quarantines, closures, and travel restrictions are not enforced.

tonsils

Nearly every year since middle school, Hamilton came down with a bacterial infection called strep throat at least twice a year. The infection always started with a sudden sore throat, followed by a response from his immune system—a high fever. The immune system is an organism's set of biological structures and processes that protect it from disease. An immune response is when parts of the immune system react to the presence of something it doesn't recognize as a part of the body. Anything Hamilton managed to swallow hurt badly. Until he recovered, he could only eat soft foods that were either cold or at room temperature. Most of the soft foods bored him, except for coconut ice cream. But this year, things are going to be different for Hamilton. He is going to have a tonsillectomy, or surgery to remove his tonsils. The doctor told Hamilton that after the surgery his body would still fight off antigens (any agent that provokes an immune response), especially the pathogens (disease-causing agents) that lead to strep throat. He also showed Hamilton a video about the surgery. Your tonsils, located in the back of your throat, are part of the immune system. The immune system is the body's second line of defense, after the skin, for fighting off infections caused mostly by viruses and bacteria, collectively known as pathogens. When an infection occurs, such as strep throat, the tonsils trap the pathogens. Sometimes, tonsils are overwhelmed by pathogens and become swollen and painful, making swallowing and breathing difficult. This condition is known as tonsillitis. Usually, doctors recommend using medicine to treat the infection and the tonsils shrink and recover. If the tonsils remain enlarged or tonsillitis reoccurs, then doctors may suggest removing the tonsils. Since you only need your tonsils to fight pathogens up to age three, having them removed is OK because your immune system has other ways of fighting infections. As a matter of fact, a tonsillectomy is one of the most common surgeries among teenagers and young adults. You have to skip dinner and breakfast before a tonsillectomy. While you sleep during the surgery, the doctor will use a device to keep your mouth open. Then, using either a scalpel or a laser, the doctor will cut out your tonsils. Afterwards, you should avoid spicy and crunchy food for the first two weeks, but drink a lot of liquids, especially water. While you're recovering at home, it's OK to have visitors, but ask anyone with a cold to wait until after your two-week recovery time. That way, your immune system has time to adjust. Transcript Question What do tonsils do? Tonsils trap pathogens, such as bacteria and viruses, that are found in the throat.

cancer prevention

Nearly half of all men and a little over one third of all women will develop cancer at some point in their lives. Your age, sex, and family medical history are risk factors that you cannot control, but changes in your lifestyle could help you reduce your risk of developing some types of cancer. Of course, having one or more more risk factors does not necessarily mean a person will develop any type of cancer. Some people with several risk factors never get the disease, while other people who have no apparent risk factors do develop cancer. The use of screening tests to detect the early presence of cancer cells provides better treatment opportunities, with more effective treatment outcomes and fewer side effects. Early detection does not actually prevent the disease from occurring, but it can decrease morbidity (death) rates.

flu facts

One of the cheapest ways to prevent getting the flu is to wash your hands frequently, avoid rubbing your eyes, and avoid biting your nails. If someone you live with has the flu, disinfecting objects such as toilet handles, doorknobs, and eating utensils can help prevent the spread of the infection. For extra protection, people can get a flu vaccine. There are three types of flu viruses that infect humans: A, B, and C. Only flu virus types A and B cause epidemics because type C causes mild to no symptoms. Therefore, flu vaccines consist of a combination of weakened A and B viruses. These weakened viruses trigger an antibody response. What is meant by "trigger an antibody response"? Think about the answer to this question, and then click the Answer button to see if you are correct. Triggering an antibody response means that the virus antigens cause the immune system to produce antibodies. The antibodies work to remove the antigens from the body. The way a pathogen spreads from one person to another is called transmission. The flu virus is transmitted by the saliva droplets of coughs and sneezes and by saliva on objects. The virus enters through the mucus membranes of the nose, eyes, and mouth. Normally, the virus is transmitted during "flu season." Flu season tends to be during the winter months or during rainy seasons when people stay indoors more often. As a result, the skin receives less sunlight to make vitamin D. One role of vitamin D is to help the immune system fight off bacterial and viral antigens. The onset of a flu infection is characterized by sudden sneezing, runny nose, and sore throat. Secondary symptoms for a flu infection include high fever, chills and sweats, aching muscles (especially the arms, legs, and back), tiredness, weakness, headache, and nasal congestion with a dry cough. Antiviral medications, which come in pills, liquids, and nasal sprays, can make you feel better faster and can make the symptoms milder. Antivirals can work in a number of different ways to block the virus from using the host cell to reproduce. While your immune system fights the flu, you should get plenty of rest and drink lots of liquids. What is the difference between using a vaccine and using an antiviral? Think about the answer, and then click the Answer button to see if you are correct. A vaccine is a preventive measure; an antiviral is used as treatment once a person hahas a viral infection. What are some ways to lessen the effects of the flu? You can reduce your chances of getting the flu by frequently washing your hands, by disinfecting objects a sick person has used, and by getting a flu vaccine. If you get the flu, you can use an antiviral, get plenty of rest, and drink lots of fluids to reduce the effects of the infection.

breast cancer

Other than easily treated skin cancers, breast cancer is the most common type of cancer found in women. Men can develop some forms of breast cancer as well, though the incidence of breast cancer in men is much lower. Breast cancer begins as a tumor that develops in the cells of some part of the breast. Watch the video below to learn about the different types of breast cancer as well as several other, more common, diseases of the breast. The female breast is composed of fat cells and milk-producing, or mammary, glands and ducts. It is also full of blood vessels and lymphatic vessels containing lymph nodes. In most women with breast cancer, tumors develop in the cells that line the ducts. Notice the development of the abnormal cells in the upper right. Over time, these abnormal cells produce a lump, or tumor. The woman may feel a lump form in the breast. Most breast lumps are benign, meaning they are not cancerous. Many are caused by changes in the fibrous tissue and are considered cysts rather than tumors. They are known as fibrocystic changes. These lumps are called fibroids. There are many types of breast cancer, and early detection is necessary for successful treatment. If a woman feels a lump in her breast, a sample of cells called a biopsy is removed from the lump to determine if cells are cancerous. If cancer is present, cancer cells may break free from the original breast tumor and spread to the surrounding tissues, usually through lymphatic vessels. These vessels contain lymph nodes that surround the breast area. There are several risk factors and symptoms to be aware of. In fact, recent studies show about 5 percent to 10 percent of all breast cancer cases are hereditary as a result of gene mutations in the genes often called "breast cancer genes." Normally these genes make proteins that prevent cells from dividing abnormally, but if you inherit a mutated gene from either parent, this increases your chance of developing breast cancer. Contact your doctor to find out the procedure for self-examination. Finding that lump early can save your life. Transcript Question During surgery to treat breast cancer, why is it sometimes necessary to remove lymph nodes along with breast tumors? Cancer cells can enter the lymphatic system through lymph nodes and spread throughout the body, leading to metastasis.

vaccines and viruses

PolioThe poliovirus causes polio, which is a disease that paralyzes the lower body. It can be fatal, but a vaccination against the disease eliminated it from the United States in the 1970s. The polio vaccine is administered via injection. An older vaccine was administered orally (swallowed), but its use was discontinued in the United States due to rare cases of people contracting polio from the vaccine and after the new vaccine became available. VaricellaThe varicella virus causes chickenpox. Until the 1990s, chickenpox was a highly contagious, common childhood illness. Since then, it has become standard to vaccinate against the varicella virus, either with a single vaccination or in combination with vaccinations for measles, mumps, and rubella via a vaccine called the MMRV vaccine. These vaccines contain antigens dissolved in water, which is then injected. HPVThe Human Papillomavirus (HPV) is the most common sexually transmitted infection. This virus can cause fever blisters and genital warts, as well as several types of cancer. Thus, vaccination against HPV creates immunity to one source of many cancers. Introduced in 2006, experts highly recommend this vaccine because of its effectiveness and because of how common the virus is. The vaccine is administered via injection. The ingredients of a vaccine depend on the antigens to which the body responds. A vaccine will not be effective if it fails to induce the production of specific antibodies and memory cells. Some viruses are extremely difficult to create vaccines for, despite a lot of research. For example, influenza and HIV are able to mutate and produce new forms of antigens at unusually high rates. These viruses are particularly successful at infecting humans because they rapidly change the antigens they present to the body. The human body creates antibodies and memory cells each time it is infected, but these will fail to recognize antigens on new, mutated viruses. Although epidemiologists, who are scientists that study outbreaks of infectious diseases, can predict with some success what type of influenza virus will be most widespread in the next flu season, the ability of influenza to mutate makes vaccinating against the flu extremely difficult. In the case of HIV, scientists have yet to engineer a successful vaccine because of its rapid mutation rate. They are, however, pursuing an alternative approach: to create vaccinations that are general enough to induce immunity to all the different types of influenza and HIV. Question Why can you get the flu many times during your life? The flu virus mutates rapidly, so there are many different types of flu. Getting sick with one type will not make you immune to other types, so you can get the flu over and over.

autoimmune disease in women

Recall that most researchers agree that there are a few criteria that most autoimmune diseases have in common. One of these factors is gender. A few autoimmune diseases are more likely to develop in men than women, and the autoimmune diseases that develop in men tend to be more severe. But, as a whole, women are more likely to be affected by autoimmune diseases than are men. In fact, more than 75 percent of the people in the United States who suffer from autoimmune diseases are women. Autoimmune diseases are estimated to be among the top 10 leading causes of death among women in all age groups up to 65 years. According to some sources, autoimmune diseases represent the fourth largest cause of disability in women.Scientists do not know why gender plays a role in autoimmunity, but there are a few theories. View this video to learn possible reasons for the increased risk for autoimmunity in women. There are over 100 autoimmune diseases. In each case, the body's immune system attacks the very organs it was designed to protect. More women are affected by these diseases than men. The reasons for the high prevalence of autoimmune disease in women are unknown, but scientists have some theories they are researching. A woman's inflammatory response is greater than a man's. While this is often beneficial to healthy women, this stronger immunity may also increase the women's chance of developing an autoimmune disease when something goes wrong. Female hormones, such as estrogen and progesterone, may also be involved. Women's hormones change with their menstrual cycle. Many women complain that the symptoms of their disease increase and decrease with these hormonal changes. Scientists believe there may even be a direct link between pregnancy and the autoimmune response. It could be that the exchange of cells between a mother and her children during pregnancy causes and autoimmune response. There is also evidence that the fetal cells remain in a woman's body after a pregnancy, which may trigger the disease. Researchers continue to investigate autoimmune diseases in order to determine why women are more susceptible, and to find new ways to treat and even cure these diseases. Some scientists have proposed that some autoimmune diseases are related to defects in the X chromosome. Why would defects in the X chromosome increase a woman's chance of developing an autoimmune disease?

Leukocytes

Recall that pathogens are harmful organisms that can cause a disease. Antigens are often found on the surface of some pathogens. When a harmful antigen enters the body, the immune system responds by producing antibodies against it. Lymphocytes come in three categories: B cells, T cells, and natural killer (NK) cells. The B cells and T cells are responsible for the recognition and removal of specific antigens. NK cells are nonspecific because they only distinguish healthy cells from infected or cancerous cells. NeutrophilsNeutrophils are a type of granulocyte, so named because of the granules (shown as orange circles) in their cytoplasm. These granules store chemicals used in an immune response. Neutrophils have a two- to five-lobed nucleus (shown in dark orange). Neutrophils are activated by an injury and move toward the injury by chemotaxis, a chemical-stimulating movement. They ingest bacteria via a process known as phagocytosis, or "cell eating." Neutrophils are the most numerous leukocyte, but they don't live long. EosinophilsEosinophils, another granulocyte, have a two-lobed nucleus. Eosinophils release a cytotoxin, or "cell poison" to kill pathogens. They also play a role in an allergic response. Allergies can be triggered by food, pollen, or mold. BasophilsBasophils are the least-numerous granulocyte. Basophils are activated by antigens that are bound to antibodies. MonocytesMonocytes are the largest leukocytes. They are transformed into macrophages, or "big eaters," and released into the bloodstream to ingest antigens by phagocytosis like neutrophils do, but they live longer. Macrophages will break down an antigen and present it to the T cell to activate an immune response.

rhuematoid arthritis

So far you've seen that T cells attack the pancreas in type 1 diabetes and an immune response destroys villi of the small intestine in celiac disease. In rheumatoid arthritis, the body's immune system targets joints. Recall that joints are the places where parts of the skeleton meet to allow movement. Click each image to compare a healthy joint with a joint affected by rheumatoid arthritis. Rheumatoid arthritis occurs when the body attacks certain parts of its joints. Answer these questions to test your knowledge of rheumatoid arthritis.

Causes of noninfectious diseases

Specific genetic mutations clearly cause some noninfectious diseases without involving any other factors. For example, Down syndrome occurs when chromosome 21 is duplicated before embryonic development. All the cells in the body of a person with Down syndrome contain three copies of chromosome 21 instead of the normal two. This mutation causes Down syndrome 100 percent of the time. But for most diseases, there is not such a clear cause-effect relationship between the genes a person has and his or her risk for particular diseases. Rather, certain mutations increase the likelihood a person will have a disease. This relationship is known as a genetic predisposition. Other causes of a noninfectious disease include anything that can affect human health, from how much sleep a person gets to his or her mother's diet during pregnancy. All of these variables work together, with the normal cellular damage that accumulates with age, to shape how the human body works. There are several factors that are most strongly associated with abnormal human health. These factors are referred to as risk factors because they are variables that increase an individual's chance of becoming sick with a noninfectious disease. Based on decades of statistical data and scientific research, the World Health Organization has identified a few risk factors that most consistently and severely affect a person's chances of acquiring a noninfectious disease. These risk factors are divided into four behaviors and four changes in a person's body. Click each image below to learn more about these risk factors. Risk Factors: Behaviors Tobacco UsePhysical InactivityUnhealthy DietHarmful Alcohol Use Risk Factors: Body Changes Raised Blood PressureObesityRaised Blood GlucoseRaised Cholesterol The risk factors that increase an individual's chance of developing a noninfectious disease can be divided into four behaviors and four body changes. Test your knowledge of these risk factors. Decide whether each action would increase or decrease a person's risk of noninfectious disease, and drag it to the appropriate position.

symptoms of noninfectious disease

Symptoms < 5 of 8 > What is used to diagnose a disease? Each disease has a set of symptoms typically associated with it. Symptoms are noticeable effects of the disease, such as a yellowing of the skin or eyes (associated with liver diseases such as hepatitis) or difficulty breathing when lying down (associated with excess fluid in the body, such as in congestive heart failure). It is important to pay attention to your body so that you know when it is behaving unusually. Changes in body function may be symptoms of a disease. Sets of symptoms can be used to diagnose, or identify, a disease. Because our bodies all share the same basic functions and mechanisms, many diseases have a predictable set of symptoms. However, the details of how our bodies work can vary greatly, so the exact symptoms and their severity can vary widely from person to person. The same disease can also affect men and women in very different ways. For example, when men have heart attacks, their symptoms are similar to what you may have seen in movies: sudden, intense chest pain and pressure, gasping for breath, and collapsing. Women who are having a heart attack, on the other hand, often complain mostly of nausea and other digestive problems, unusual fatigue, and perhaps slight chest pressure. This variation between individuals can make diagnosing a disease difficult, especially if the person has multiple health problems. However, diagnosing a disease is one step in identifying the cause or causes of the disease, which can potentially lead to curing the disease or preventing it from occurring in others.

hiv life cycle

The Human Immunodeficiency Virus has an outer phospholipid envelope, which allows the virus to attach onto the host cell using a structure called the docking glycoprotein 120 (gp 120). Underneath the envelope is the capsid. The capsid is a protein coat that protects the genetic material, which consists of segments of viral RNA. The host cell for HIV is a type of leukocyte (white blood cell) called a T cell, which is important for immune responses. One type of T cell has a receptor on its surface. These surface cells are called CD4 cells or T-helper cells. These "helper" cells initiate the body's response to antigens. Their main role is to send signals to other types of immune cells, including those that destroy the infectious agent. HIV docks to the T cell by attaching to the CD4 receptor. Once HIV has docked to the T cell, its viral envelope fuses with the surface of the T cell. This fusion allows the viral RNA to enter the T cell. Most organisms have DNA as their genetic material. However, some viruses, such as HIV, have RNA as their genetic material. This difference is why HIV is classified as a retrovirus. HIV uses the viral RNA to make complementary DNA (cDNA) in a process called reverse transcription. This process is considered reversed because normally DNA is used to make messenger RNA (mRNA). Before entering the nucleus of the T cell, the viral DNA (shown in red) becomes double stranded. The double-stranded viral DNA joins the T cell DNA (shown in blue) in a process called integration. The result is a provirus, which is a mixture of viral and T cell DNA. A provirus is capable of replication. A latent infection is the period of time between the presence of the provirus and the active replication of viral components. An active infection is when 1) proviral DNA is transcribed; 2) viral components are made; 3) viruses are assembled; and 4) newly made HIV are released through a process called budding. HIV docks onto what part of the T cell?HIV docks onto the CD4 receptor.What happens when HIV fuses with the T cell?The viral RNA enters the T cell.What is reverse transcription?Reverse transcription is when DNA is made from RNA.What is the result of integration?Integration results in a provirus.What is assembled in the cytoplasm of a T cell?Viral components are assembled.What buds out of the T cell?Newly made HIV bud out of the T cell.

noninfectious disease

The World Health Organization (WHO) is an international agency of the United Nations that gathers worldwide data about human health. The WHO estimates that noninfectious diseases cause over 60 percent of deaths each year. Recall that infectious diseases are caused by viruses, bacteria, or other pathogens. When pathogens invade the body, they can reproduce and cause an infection, stimulating the body's immune system to fight back. Infectious particles can be passed from person to person and sometimes between nonhuman animals and humans through a process called transmissibility, or communicability. Today, vaccines can prevent many of the most dangerous infectious diseases. Pathogens cause infectious diseasesOther factors, such as choices we make, cause noninfectious diseases Noninfectious diseases, on the other hand, are not caused by pathogens. They are abnormal health conditions caused by other factors, such as aging, genetic mutations, and the choices we make, including what we eat and drink, what drugs we expose ourselves to, and how we use our bodies. Sometimes noninfectious diseases, such as in autoimmune diseases, primarily involve the immune system. An autoimmune disease occurs when the body's immune system attacks "targets" that are made of its own cells or molecules. With the exception of genetic diseases, in which disease-causing mutations are inherited, noninfectious diseases are not transmissible, or communicable, between people. Thus, noninfectious diseases are often referred to as nontransmissible or noncommunicable diseases (NCDs). Check your understanding of the difference between infectious and noninfectious diseases with this activity. Determine whether each factor would cause an infectious disease or a noninfectious disease, and drag it to the appropriate location.

Flu risk assessment

The deadliness of a disease is called virulence. About every 50 years, the flu virus undergoes a genetic mutation that makes it different from previous strains of the virus. These newly mutated flu viruses tend to be more virulent because human populations don't have any antibodies against them. Once a particular viral strain has appeared, its virulence decreases as more people are exposed to it and a vaccine against it can be made. Transmissibility is a term that describes how likely an infected person is to give the infection to another person. Because the flu spreads from saliva droplets and objects used by an infected person, a flu infection is highly transmissible. Societal factors, such as the condition of roads and communication systems, affect the availability of supplies and the ability to transport sick people to hospitals and clinics. Environmental factors, such as weather, also affect the spread of the flu infection. For example, during the rainy season or in the winter, more people stay indoors. This tendency lowers their immunity because their bodies produce less vitamin D, which helps fight infections. Medical interventions include vaccines to prevent getting the flu and antiviral drugs to speed up recovery time once a person has the flu. Nonmedical interventions are ways of limiting infected people from the general population. Examples of nonmedical interventions include quarantines (separating sick people from other people for a period of time), school and business closures, and travel restrictions. How does understanding viral strain and environmental conditions help assess the risk of a flu epidemic? A new strain of the flu virus is deadlier than an older one because fewer people have the antibodies to fight it. Also, if a viral infection appears during the winter or rainy season, more people will be infected because more people will stay indoors and miss the helpful effects of vitamin D in fighting the disease.

Influenza

The flu is an infectious disease caused by a virus. Recall that an infectious disease is a disease caused by a pathogen. Viruses, bacteria, protozoans, and fungi are all pathogens. Unlike other pathogens, viruses needed a host (an organism) in order to reproduce. The influenza virus has an outer envelope that is studded with structures (the H and N spikes) that allow it to attach to the host cell. Below the envelope is a protective protein coat called a capsid. The capsid protects the genetic material, which are segments of RNA. Because viruses need a host in order to reproduce, the first step in influenza replication is to attach to a host's cell membrane. The flu virus enters and travels to the host's nucleus in a vesicle called a sac. Only the viral RNA segments (shown in green) enter the nucleus. Here the viral RNA is replicated. Some mistakes (mutations) in the RNA may occur at this stage and produce a different form of flu virus. The viral RNA then travels to the host's cytoplasm, where viral proteins are made. Newly made flu viruses travel to the host's cell membrane and destroy the host cell as they exit. The influenza virus affects the respiratory system (the green area inside the person in the image). Viral shedding is the period of time when one person can spread the virus to another person. It begins the day before the infected person shows any symptoms. A virus antigen is a toxin given off by the virus that causes a response from the immune system. A high fever signals that the infected person is shedding a lot of flu virus. This shedding occurs because, as the immune system detects the flu antigen, part of its response is to create challenging conditions, such as a high temperature, for the virus. Because the protective coat of a virus is made of protein, the high temperature helps to break down the protein and prevent the virus from replicating. Back in 1918, the relative healthy immune systems of teenagers and young adults overreacted to the flu virus. Cytokines signal immunity cells, such as T cells and macrophages, to an infection site. In healthy young people, the reaction can get out of control and be deadly if it occurs in the lungs and blocks off air. This overreaction is called a cytokine storm. Which body system does influenza mainly disrupt? Influenza mainly disrupts the respiratory system.

Tabacco affect on the body

This image depicts the addictive nicotine molecule contained in cigarettes and other forms of tobacco. Nicotine is quickly absorbed into the bloodstream when a tobacco product is smoked, chewed, or inhaled. Once nicotine enters the bloodstream, it immediately stimulates the adrenal glands to release the hormone epinephrine. You may know this hormone as adrenaline. The rush of adrenaline stimulates the central nervous system, increasing blood pressure, breathing rate, and heart rate. Like other drugs like cocaine and marijuana, nicotine increases levels of the neurotransmitter, dopamine. This natural chemical affects the brain pathways that control reward and pleasure. Dopamine is normally produced by the brain when you experience something pleasurable like a great meal or exercise. The flow of dopamine is shown by the arrows in the image, and the area in the brain that it stimulates are in color. When a person uses tobacco products, the release of dopamine causes similar effects, but this effect wears off quickly. Why do you think this "feel good" effect of dopamine may lead to addiction? Smokers get the urge to light up again for more of that good feeling. In smokeless tobacco, nicotine is absorbed through the mouth tissues directly into the bloodstream, where it goes to the brain. Nicotine stays in the blood longer for users of smokeless tobacco than for smokers. However, smokers have a greater health risk because of the other chemicals produced by smoking. Carbon monoxide, acetaldehyde, and tar can all cause harm to the body. CancerSmoking can be blamed for about one-third of all cancer deaths, including 90% of lung cancer cases.Lung ProblemsBronchitis (swelling of air passages), emphysema (damage to lungs), and pneumonia are linked to smoking.Heart DiseaseSmoking increases the risk of strokes, heart attacks, and vascular disease (affect circulation through body).CataractsPeople who smoke experience clouding of the eye, causing blurred vision.Aging Skin and TeethAfter smoking for a long time, people's skin ages faster and their teeth turn yellow or brown.Harm to Unborn BabyPregnant women who smoke are risking their baby's health. Smoking is associated with learning and behavior problems in children born to smokers. For people who do not smoke, just being around smokers is a health risk. Each year, about 50,000 nonsmokers die from diseases caused by inhaling smoke from other people's cigarettes. What is this smoke called? It is called secondhand smoke. Inhaling secondhand smoke increases a person's risk of developing heart disease, lung cancer, and other lung problems. It can also cause other health problems such as asthma in children. Smokeless tobacco increases the chance of getting cavities, gum disease, and sores in the mouth that can make eating and drinking painful. Almost 30 chemicals in smokeless tobacco have been found to cause cancer. Where do you think most cancers develop in a person who abuses smokeless tobacco? Most cancers develop in the mouth, lip, tongue, and throat (pharynx). Recent studies show that smokeless tobacco may play a role in causing heart disease and stroke. Because nicotine increases blood pressure and heart rate, this may be an ongoing health issue.

immune system

To see what kind of cells and processes attack the body's own structures during an autoimmune disease, it's helpful to review a few facts about the immune system. Recall that the immune system is the body's means of protecting itself from pathogens, which are agents like bacteria and viruses that can make you sick. It's made up of a complex network of special cells and tissues that work together. White blood cells, also called leukocytes, are cells that destroy pathogens. There are five types of leukocytes: monocytes, basophils, eosinophils, neutrophils, and lymphocytes. Each of these cells has a different function. Some of them work to "eat" invading particles by engulfing them through a process called phagocytosis. Lymphocytes, however, have a different function. There are two types of lymphocytes: B cells and T cells. Together, the white blood cells work to rid the body of pathogens. An increased movement of plasma and white blood cells from the blood to the site of an infection causes inflammation, which is a condition of warmth, redness, and swelling that occurs around the site of a painful infection. Inflammation quickly brings "tools" to the site of the infection to keep the pathogen from spreading to other tissues. The immune system is also involved in an allergic response. In this response, the body's immune system "overreacts" to a substance, causing its cells to respond with inflammation, mucus production, and other actions to try and rid the body of the substance. Connect the vocabulary term on the left with its definition on the right. Once you are comfortable with the terms, we'll learn about some specific autoimmune diseases. Antigens are any substances that are foreign to the body and that trigger a response from the immune system. (For example, bacteria have molecules in their cell walls that are antigens.) When an antigen enters the body, it's the job of cells called B lymphocytes (or B cells) to produce antibodies (special substances that bind to the antigens). The antigens are then destroyed by other cells. Several types of T lymphocytes (or T cells) are required for an immune response. Among the most important are cytotoxic T cells, which destroy cells that have been infected with viruses, and helper T cells, which secrete substances that help to coordinate the actions of all the cells involved in an immune response.

hiv baby

Tracy had already proven herself to be an excellent big sister. So when her parents told her about their intention to adopt a baby girl, Tracy was excited. Then they told Tracy that the baby they intended to adopt was born HIV positive. This means that blood tests on the baby revealed that she had antibodies to the Human Immunodeficiency Virus, or HIV, which is the virus that causes Acquired Immunodeficiency Syndrome, or AIDS. Recall that a virus antigen is a toxin given off by the virus that causes the immune system to produce antibodies that work to remove the antigen from the body. So, having the antibodies to the virus means that the virus is present in the body. Tracy knew that not everyone who has HIV develops AIDS. People survive an HIV infection at a higher rate these days than when her parents were teenagers. She'd also heard of a treatment called antiretroviral therapy, or ART, which uses medicines to fight the infection. Yet, Tracy didn't know which ART was available for infants or the precautions to take for raising an HIV-positive sibling, so she searched until she came across a video with the information she needed. View this video to learn how to take care of an HIV-positive infant. Once tests show that a baby has been born infected with HIV, the best course of action is to start antiretroviral therapy, or ART for short, within the first 12 weeks of life. This increases the infant's life expectancy by 75 percent. Since HIV targets the immune system, children treated with ART early recover quicker since their immune system has not been badly affected by the infection yet. Unlike adults who can swallow pills, infants must be given their ART in the form of syrups and powders. Caregivers must give infants their ART, which may consist of three or more drugs, all together to keep the infant from developing resistance to any one drug. If the infant does not show any symptoms due to the HIV infection, he or she needs to eat about 10 percent more calories than a non-infected baby the same age. If an infant does show symptoms, then he or she needs 20-30 percent more calories than a non-infected baby the same age. This is because studies have shown that people, including infants, who are HIV positive burn more energy than their HIV-negative counterparts. All babies need to be held, hugged, and kissed. HIV-positive children can share food and toys, although objects placed in the child's mouth should be washed in soapy water. These casual interactions do not put caregivers at risk when taking care of HIV-positive infants. It is safe to change an HIV-positive infant's diaper as long as there is no blood in the diaper. In that case, caregivers should wear disposable gloves and place the soiled diaper into a plastic bag prior to placing in a trash can. The care given to an HIV positive infant can mean a much better start for that little one with a better long-term prognosis. Transcript Question In general, are caregivers at risk of getting an HIV infection when taking care of an HIV-positive infant? As long as they do not come in direct contact with the infant's blood, caregivers are not at risk of getting an HIV infection when caring for an HIV-positive infant.

celiac disease

Type 1 diabetes is an autoimmune disease that occurs when the body's T cells wrongly receive a signal to destroy beta cells in the pancreas. This destruction of beta cells results in less insulin in the body and high blood glucose. Celiac disease (also called "celiac sprue disease") occurs when an autoimmune response destroys the villi of the small intestine. Click each image to learn more about celiac disease. Why is celiac disease an autoimmune disease? In healthy individuals, the cells that line the small intestine are sealed tightly together by "tight junctions." In individuals with celiac disease, gluten sneaks between these cells and triggers an immune response that destroys the villi in the small intestine. DescriptionTermA protein found in wheat that triggers the immune response in persons with celiac diseaseglutenFingerlike projections that are destroyed by the immune system in persons with celiac diseasevilliThe process of taking in nutrients, which is compromised by celiac diseaseabsorption

youth drug use

Unfortunately, many teenagers have experienced the consequences of drinking too much. As a result, underage drinking is a leading public health concern in this country. In 2009, about 10.4 million young people between the ages of twelve and twenty admitted to drinking more than just a few sips of alcohol. Young people tend to drink less often than adults, but when they do drink, they drink more than adults. On average, young people who drink have about five drinks on a single occasion, which is considered binge drinking. Why do some young people drink? Risk-TakingYour brain is still developing well into your twenties, establishing connections and refining key functions. This lengthy development period may explain why some teens seek out new and dangerous situations and act impulsively. You may not realize that your actions, such as drinking, have serious consequences. Sensitivity and Tolerance to AlcoholMany young drinkers are able to consume much larger amounts of alcohol than adults before experiencing drowsiness and lack of coordination. This unusual tolerance may help explain why young people are more likely than most adults to be binge drinkers. Personality CharacteristicsPeople who begin drinking at a very early age often share personality characteristics such as tendencies toward disruptive, hyperactive, or aggressive behavior. Adolescents who are depressed, withdrawn, or anxious are also more likely to drink. Environmental AspectsThe influence of parents and peers can play a large role in alcohol use. For instance, adolescents with older friends who drink are more likely to drink. Parents who view drinking favorably may send a more permissive message to their children regarding drinking and its negative consequences. Hereditary FactorsAccording to most studies, children of alcoholics are more likely to become alcoholics themselves than are children who have no close relatives with the disease. Children of alcoholics are also more likely to begin drinking at an early age.

hiv risks

Unprotected SexUnprotected sex means having sex without using a condom. Unprotected sex is by far the most common mode of HIV transmission. Mother-to-child transmissionMother-to-child transmission of HIV is the spread of HIV from an HIV-infected woman to her child during pregnancy, childbirth, or breastfeeding. The rate of HIV-positive mothers infecting their unborn children has been decreasing due to changes in the way hospitals and clinics now treat pregnant women. Hospitals routinely test pregnant women for HIV and administer ART to pregnant women who are HIV positive. These actions may prevent a mother from transmitting the virus to her unborn child. Injection Drug UseInjection drug use is the use of a hollow needle and a syringe to introduce a drug into the body. People who are injection drug users (IDUs) can get HIV from sharing needles with a person who has HIV. Injection drug use is responsible for about 10% of annual HIV cases.

factors of cancer

What causes a normal cell to spin out of control? Usually, no single event is enough to turn a normal cell into a cancer cell. Instead, scientists believe that it takes multiple changes, or mutations, in DNA over time to cause cancer. The accumulation of damage to many different genes that control cell growth may result in some form of the disease. While children and young adults can develop cancer, the majority of cancer patients are older adults. Based on what scientists know about the causes of cancer, why would the incidence of cancer increase with age? Over time, a person's body can accumulate more and more DNA damage or mutations. Several factors can cause DNA to mutate or become damaged. Read the information in the tabs to understand the different causes of cancer. Genetics may cause some cancers. In certain cases, a person inherits mutated DNA from a parent. One of the best-known examples is a mutated gene for certain types of breast cancer. If a woman inherits the mutated BRCA gene from her mother, her chance of developing breast cancer at some point in her life is greatly increased. How can your knowledge of the causes of cancer help you to live a better life? You can take steps to lower your risk of cancer by avoiding carcinogens and participating in screening programs that are designed to detect genetic mutations or the presence of cancer-causing viruses. Certain viruses can cause cancer by inserting their own genetic material into a host cell, damaging the cell's DNA. Peyton Rous discovered this fact during his research with chickens. A cell that is infected in this way does not respond to normal regulators for cell growth and starts to divide uncontrollably. In humans, some forms of HPV (Human papillomavirus) cause genital warts and another form of HPV can lead to cervical cancer. The yearly pelvic exams that women receive are intended to detect the presence of HPV and correct any damage done to cervical cells before tumors begin to grow. Carcinogens are substances that have been known to cause cancer. The prefix carci- means "cancer-causing" and the suffix -gen means "something produced." Something is carcinogenic if it has the potential to damage the DNA in normal cells. Exposure to carcinogens increases a person's cancer risk but it does not always result in cancer. You're probably familiar with some known carcinogens because of the public health campaigns developed by governments and nonprofit organizations to spread the word. Substances that have been proven to cause cancer are UV radiation from sunlight, tobacco use (both smoking and chewing tobacco), asbestos, radiation from X-rays, and numerous chemicals that are found in pollutants. Where is asbestos found? Asbestos is a naturally occurring compound with exceptional heat-absorbing properties. It exists in dangerous levels and forms within materials used to insulate homes and businesses, though its use has been banned in most developed countries.

cancer growth

What goes wrong in the body to make a cancer grow? It all begins with damage to a section of DNA—the hereditary information inside all your cells. Most of the time, when DNA becomes damaged, it is repaired by normal cell processes. In cancer cells, however, the DNA is not repaired. The presence of damaged DNA that remains damaged is what distinguishes a cancer cell from a normal cell. Do you remember the name for the process that controls the growth and reproduction of normal cells? Cell division, or mitosis In many types of cancer, DNA becomes damaged by exposure to something in the environment. If a person smokes cigarettes, for instance, the carcinogens in the smoke can damage the DNA in your lung cells. If the damage is not repaired by your DNA repair system, the altered cells begin to grow out of control, forming a cancerous tumor, which is a collection of abnormal cells. What other substances are known carcinogens? X-rays, sunlight, and many different chemicals in specific concentrations If exposure to carcinogens has altered the genetic mechanisms for cell growth, cancer usually starts as a tumor—a group or cluster of abnormal cells. Not all tumors are cancerous, though. Benign (noncancerous) tumors do not spread to other parts of the body; they stay localized in one spot. Cancerous tumors are categorized as malignant. Where are some common places in the body where tumors may form? Skin, breast, brain, bone, lung, liver A malignant tumor is a tumor that can spread to other areas in the body. The cancerous cells in a malignant tumor break away from the main cluster and spread to other areas of the body, where they continue to divide uncontrollably. What substances carry malignant cancer cells to other body parts? The blood and lymph transport cancer cells. The process by which cancerous cells spread throughout the body is called metastasis. Cancer cells that metastasize attach themselves to other body parts or organs and continue to divide there. These abnormal cells usually take over the blood supply and wrap themselves around nerve endings, which is how cancer causes pain. Cancer cells do not perform the normal functions of cells in a specific organ. So if the liver is full of cancer cells, these cells are not producing the chemicals necessary for digestion. Malignant cancer cells can interfere with life processes and destroy organs. How can metastasis eventually result in death? When the cells within an organ are not carrying out their normal functions, the organ will not function properly, and death can result. The study of cancerous tumors is called oncology. After a person is diagnosed with cancer, his or her treatment is managed by an oncologist, who is a physician who specializes in the diagnosis and treatment of all forms of cancer. What type of oncologist, specifically, treats cancer in children? A pediatric oncologist treats cancer in children. Remember that pediatricians treat and prevent illnesses in children.

Ebola outbreak

people survive. After two days of exposure to the Ebola virus, a person can come down with a fever, sore throat, muscle pains, and headaches. These symptoms can initially be mistaken for the flu, which is another common disease that's caused by a virus. The next few days, the telltale symptoms of red eyes and bloody vomit appear since the ebola virus causes small blood clots to form. As the virus progresses, spontaneous bleeding occurs from any part of the body. And, in the final stages of the disease, a person can lose consciousness, have seizures, and die from kidney failure due to loss of blood. One gets the Ebola virus only through direct contact of an infected person's blood, other body fluids, including semen, body tissues and handling the body of people who died of an Ebola infection. Family members and medical staff are the most at risk. Any bed linen or objects that may have an infected person's blood, sweat, saliva, or other body fluids need to be properly disposed of or cleaned before reuse. Also, people in direct contact with patients infected with the Ebola virus should wear a mask, goggles, gloves, and a gown. Anyone who suspects he or she may be infected with the Ebola virus needs to report to a medical facility and be evaluated. Transcript Question If Beatrice doesn't work with patients who have an Ebola infection and she doesn't live with people infected with the Ebola virus, does she need to wear a medical mask to avoid getting this disease? Explain. No, Beatrice doesn't need to wear a medical mask because she can only become infected by the Ebola virus through direct contact of an infected person's body fluid.