15:Infectious and Chronic Diseases [Defenses Against Disease]

Which is a small amount of dead of modified toxin to produce immunity?

A vaccine

Which is a small amount of dead or modified toxin to produce immunity?

A vaccine

Which pathogens do antibiotics kill?

Bacteria

Recommended Immunizations

Birth - 4 months -Diphtheria, Tetanus, Pertussis -Haemophilus influenza type b -Pneumococcal conjugate -Hepatitis B -Polio 6 months - 18 months -Diphtheria, Tetanus, Pertussis -Haemophilus influenza type b -Pneumococcal conjugate -Hepatitis B -Polio -Varicella -Influenza -Measles, Mumps, Rubella 4 years - 12 years -Diphtheria, Tetanus, Pertussis -Polio -Measles, Mumps, Rubella -Tetanus, Diphtheria A vaccine causes your immune system to produce antibodies against the pathogen, as if you had actually been infected. You develop immunity without having to experience the disease. After a few years, you may receive a booster dose of some vaccines to "remind" your immune system to maintain your immunity. Many people need additional immunizations because of the work they do, the places to which they travel, or their exposure to an unusual pathogen. Other people may need to be immunized because of risk factors such as age or poor health. Influenza vaccines, for example, are given to elderly people to protect them from the flu.

What happens during inflammation?

Blood, fluids, and phagocytes leak out of blood vessels. As the phagocytes destroy pathogens, the infected area becomes red, swollen, and sore.

The lymphatic system collects fluid from body tissues and returns it to the ___.

Bloodstream

The immune system's B cells produce ___ that attach to the surface of pathogens of to the toxins produced by pathogens

Antibodies

Which describes a phagocyte?

White blood cells that engulf and destroy pathogens

Which describes a phagocyte?

White blood cells that engulf blood vessels

Which describes how the body's immune system works?

White blood cells, called lymphocytes, destroy pathogens and protect against future infections

Which describes how the body's immune system works?

White blood cells, calledlymphocytes, destroy pathogens and protect aainst future infections

Phagocytes

Within seconds after your body is injured, the damaged cells release chemicals that cause blood vessels in the injured area to enlarge. Blood, other fluids, and white blood cells called phagocytes (FAG uh syts) leak out of the enlarged vessels. The phagocytes engulf and destroy pathogens. Meanwhile, the infected area becomes red, swollen, and sore—in other words, inflamed.

*The Immune System*

Your body's third and most sophisticated line of defense against pathogens is your immune system. The immune system (ih MYOON) fights disease by producing a separate set of weapons for each kind of pathogen it encounters.

Saliva and Tears

Your saliva and tears can trap pathogens and wash them away. Like mucus, saliva and tears also contain chemicals that attack pathogens.

Skin

Your skin serves as both a physical and a chemical barrier against pathogens. The surface cells are hard and have no gaps between them. Sweat acts as a chemical barrier because it contains acids that kill many bacteria. Finally, old skin cells are shed constantly, and the pathogens on these cells are shed, too. Microorganisms usually cannot get through your skin unless you have a cut, scrape, burn, or other injury.

*DEFENSES AGAINST DISEASE*

*QUIZ*

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The Immune Response

1. T Cell Recognizes a Virus A T cell recognizes the virus. The T cell divides over and over, producing new T cells that also recognize the virus. 2. Killer T Cells Attack Killer T cells attack the damaged cells that contain viruses. They destroy the infected cells and the viruses. 3. B Cells Make Antibodies Helper T cells signal B cells to make antibodies against the virus. 4. Antibodies Destroy Viruses The antibodies then bind to the viruses they encounter. The viruses clump together and are destroyed by phagocytes.

Which best describes the location and role of the lymphatic system?

A network of vessels that collects fluid from body tissues and returns it to the bloodstream

Digestive System

Chemicals in your digestive system, including acids in your stomach, kill many pathogens. In addition, the normal motions of the digestive system not only move food through your system but also move pathogens out. Finally, bacteria that normally live in your digestive system produce substances that can harm or kill invading bacteria.

What are the tiny hair-like structures lining your body's mucous membranes which trap and remove pathogens?

Cilia

*Inflammation*

If pathogens are able to get past the physical and chemical defenses and begin to injure cells, your body is ready with its second line of defense—inflammation (in fluh MAY shun). Inflammation is your body's general response to all kinds of injury, from cuts and scrapes to internal damage. Inflammation fights infection and promotes the healing process.

*Physical and Chemical Defenses*

If pathogens are everywhere, why aren't you sick all the time? When you do get sick, what keeps the pathogens from multiplying until they take over your body? The answer to these questions is that your body has a number of defenses against infection. Your body's first line of defense against infectious disease includes both physical and chemical defenses that prevent pathogens from entering your body.

Active Immunity

Immunity that your own immune system creates is called active immunity. Active immunity results from either having a disease or from receiving a vaccine. When you were a baby, you may have received injections to protect you from some common childhood infectious diseases, such as measles, mumps, and rubella. These injections, which caused you to become immune to the disease, are called immunizations (im yuh nih ZAY shunz), or vaccinations. The substance that is injected is called a vaccine (vak SEEN). Vaccines contain small amounts of dead or modified pathogens or their toxins.

How are active and passive immunity different?

In active immunity, the body creates antibodies in response to either a vaccine or the disease. In passive immunity, the body receives antibodies from an external source.

Which describes your body's general response to all kinds of injury, from cuts and scrapes to internal damage?

Inflammation

How does the formation of pus protect the body?

It causes healing to begin an injury site

The Lymphatic System

Much of your immune system is contained within your lymphatic system. The lymphatic system (lim FAT ik) is a network of vessels that collects fluid from your tissues and returns it to the bloodstream. The fluid flowing through the lymphatic system is called lymph (limf). The lymphatic vessels have hundreds of small stations, called lymph nodes. Each lymph node acts as a sort of filter. Phagocytes and lymphocytes are present in the lymph nodes and attack pathogens as they pass through.

The body's natural defense against pathogens includes skin, tears, saliva ___.

Mucous membranes, and the digestive system

Membranes that secrete a liquid to remove pathogens are called ___ membranes

Mucus

How do mucous membranes help remove pathogens from the body?

Mucus traps pathogens and cilia move the mucus and pathogens to the nose or mouth, where they can be sneezed or coughed out.

Which condition is acquired temporarily when a person receives antibodies from an outside source?

Passive immunity

Passive Immunity

People can develop immunity if they are given antibodies against a pathogen. Immunity acquired by receiving antibodies from a source other than one's own immune system is called passive immunity. This type of immunity is temporary, not lifelong. It occurs naturally in babies, who receive antibodies from their mothers before birth. After birth, antibodies also pass to an infant in the mother's breast milk. These antibodies protect newborns before their own immune systems have fully developed. Passive immunity also can be artificially acquired. If you were bitten by a dog with rabies, a doctor would give you injections of rabies antibodies to prevent the disease. Eventually these antibodies would disappear from your body.

Healing

Phagocytes also give off substances that cause healing to begin. The fluids, phagocytes, and dead cells that accumulate at the injury site often result in the formation of a thick, white liquid called pus. Eventually, the inflammation process heals the damage, and the inflammation subsides.

What healing action is taking place when a wound becomes inflamed?

Phagocytes are destroying pathogens

Which is not a reason to seek additional vaccinations or immunizations against a pathogen?

Risk of exposure is low

Which acts as both a physical barrier against pathogens?

Skin

Cilia

Some of your body's mucous membranes are lined with tiny hair-like structures called cilia. Your air passages, for example, are lined with cilia. Together, cilia and mucus help trap and remove pathogens. When you inhale, dust and pathogens get trapped in the mucus of your air passages. The cilia beat rhythmically, moving the mucus up your windpipe toward your mouth and nose. When you cough, sneeze, or blow your nose, the pathogens are removed along with the mucus.

Which material, found in the digestive system, aids digestion and also kills pathogens?

Stomach acids

Which material, found in the dugestive system, aids digestion and also kills pathogens?

Stomach acids

B Cells

The B lymphocytes, or B cells, produce antibodies. Antibodies (AN tih bahd eez) are proteins that attach to the surface of pathogens or to the toxins produced by pathogens. This binding action keeps the pathogen or toxin from harming the body. Each type of B cell produces antibodies that attack a specific pathogen or toxin. Once an infection is overcome, your B cells stop producing antibodies, but they do not "forget" how to produce them. Those B cells continue to circulate in your body for years. They are ready to produce antibodies quickly if the same pathogen reenters your body. This memory capacity of B cells explains why you develop immunity to some diseases you've already had. T cells and B cells work together when fighting pathogens.

Mucous Membranes

The openings into your body, such as your mouth, eyes, and nose, are covered by protective linings called mucous membranes (MYOO kus). Mucous membranes secrete a liquid called mucus. The mucus traps many pathogens and washes them away. Mucus also contains chemicals that attack pathogens.

*Passive and Active Immunity*

There are two types of immunity—passive and active. Both types are important in protecting your body against infections.

T Cells

There are two types of lymphocytes—T lymphocytes, or T cells, and B lymphocytes, or B cells. T cells perform several functions. -Killer T cells Destroy any body cell that has been infected by a pathogen. -Helper T cells Produce chemicals that stimulate other T cells and B cells to fight off infection. -Suppressor T cells Produce chemicals that "turn off" other immune system cells when an infection has been brought under control. T cells also help your immune system "remember" pathogens. This memory capacity, along with the memory capacity of B cells, is what causes you to develop immunity to a previously encountered pathogen.

What healing capacity can tears provide?

They can wash away some pathogens

Which describe T cells

They produce chemicals to fight infection and later produce chemicals to "turn off" the immune system

The Immune Response

When a pathogen enters your body for the first time, it often causes disease. If your immune system is working, why does this happen? The explanation is that your immune system must build up its arsenal of weapons against the pathogen. This process takes time, during which the pathogen multiplies in your body and causes disease. Once the immune system's arsenal is built up, however, the immune system kills the pathogen, and your body gradually recovers. White blood cells called lymphocytes (LIM fuh syts) carry out most of the immune system's functions. What happens if a pathogen that has previously attacked your body enters your body again? This time, your immune system will quickly recognize the pathogen and launch an immediate attack. When this happens, you are said to be immune to the disease. Immunity (ih MYOON ih tee) is your body's ability to destroy pathogens that it has previously encountered before the pathogens are able to cause disease.