Presentation on theme: "Malfunctions of the Immune System, Pathogens & Immunity."— Presentation transcript:
Malfunctions of the Immune System, Pathogens & Immunity
Immune System Malfunction The immune system can cause two very serious problems if it is not working properly: –Inappropriate attacks against non-threatening agents (Allergies). –Immune-deficiency diseases (AIDS). Allergies An allergy occurs when your immune system mistakes harmless cells for harmful invaders. Something harmless, like peanuts, mobilizes an antibody strike. Increased tissue swelling and mucous secretion, and sometimes constricted air passages are all a part of this response.
Allergic Response When you come into contact with the “vicious” peanut, your cells perceive they are in danger and release a chemical signal called bradykinin which triggers the release of another chemical signal called histamine. Histamine is produced by the basophils (a type of white blood cell) and it changes the cells of the capillaries – increases their size and permeability. Proteins and white blood cells can leave the capillary in search of the “invader” and alter the osmotic pressure in the blood vessel – this causes the swelling. Drugs such called antihistamines are used to try and block their release and action.
Autoimmune Disease The immune system can go awry and recognize the body’s own cells as invaders or foreign entities. This could result in an attack being launched by you against yourself. Renegade T cells and B cells are the problem – they do the recognizing and attacking. They can be held in check by suppressor T cells that recognize these renegades and intercept them before they can do any damage, but, if the suppressor T cells do not stop them they break the body down. This can be seen in such diseases as rheumatoid arthritis, type 1 diabetes and lupus. The suppressor T cells can be weakened by drugs or serious infections and this may open you up to autoimmune diseases. Drugs exist that help lessen the intensity of the renegade T and B cell attacks.
Pathogens & Disease A pathogen is any organism or entity that causes disease within the body. Pathogens may include bacteria, viruses, prions and a wide variety of parasites – both protists and animals. Many diseases are believed to have originated in domestic animals and, through random mutation, become communicable to humans. When a disease is considered for its pathogenic capabilities, both the virulence and transmissibility of the disease are examined.
How To Get Sick Pathogens are transmitted through a variety of methods. Droplet Infection – A sneeze or cough can put out thousands of water droplets that each contain many microbes. These droplets can be inhaled or introduced directly to the body through food water or skin contact. Waterborne – Some infections must enter the body through water or they dry out and die quite quickly. The most common cause of waterborne infections is unsanitary disposal of waste near a water collecting area that is used for drinking. Direct Contact – These infections are slower spreading and can be avoided if the proper precaution is taken. Methods of introduction include animal bites, unsanitary food preparation, sexual contact and drug use with unclean syringes. Vectors – A vector is a disease-carrying animal (usually an insect) that picks up the microbes by hanging out near waste that may be contaminated. They then transfer these microbes when they come into contact with you. Lice, ticks, fleas and mosquitoes are all excellent vectors.
Induced Immunity Induced immunity is an immune response brought about by intervention from one’s own body or form an outside source. There are two forms of induced immunity – active immunity and passive immunity – both are common. Active Immunity is gained when your own inner workings produce antibodies against an invading pathogen. Active immunity lasts a lifetime. Passive Immunity is protection (antibodies or an inducer of antibody formation) that is introduced into the body from an outside source such as a vaccination. Passive immunity is often only temporary in its effectiveness.
Vaccination A vaccine is an antigen-containing substance that can be swallowed or injected to provide continued immunity to a specific disease/pathogen. The vaccine usually contains a weakened or dead form of the pathogen it is meant to target. The body can now produce antibodies against this weak/dead pathogen so when the full- strength invader enters the body, it has a defense ready to combat it. Many vaccines have to receive boosters occasionally to keep up their strength. Labs are now developing genetically modified forms of vaccines that can target specific pathogens and bring about the immune response in an attempt to keep up with their somewhat rapid evolution.
Chemical Controls Certain chemicals can target specific pathogens and kill them by not allowing them to carry out the reactions necessary to survive. Antibiotics are chemicals that are obtained from living things that are toxic to other living things – often used against predators, prey or the competition. Penicillin was “discovered” by Alexander Fleming when mould had contaminated an experiment involving bacteria. He was awarded the Nobel Prize in Medicine. Penicillin interferes with bacterial cell walls – they become thin and eventually burst under the pressure of the cell’s own cytoplasm.
Antibiotic Resistance Bacteria can reproduce asexually at a frightening rate – 20 minutes if conditions are optimal. Mutation may occur each time they multiply – usually it is 1 mutant per 200 bacteria. A spoonful of dirt may contain over a billion bacteria – this would yield about 5 million mutants. Some of these mutations give the bacteria the ability to resist certain antibiotics. Canadian hospitals have had bouts with Clostridium difficile – a bacteria that infects the colon and releases a toxin inside the body. It has developed a resistance to many antibiotics.
Sharing A Problem Bacteria can carry out a process called conjugation with another bacterial cell. During conjugation, the bacteria form a tube (called a sex pilus) between themselves and exchange copies of their genetic information called plasmids. These plasmids are the extra pieces of DNA that often house the genes for resistance. The result may be: –Bacteria becoming more resistant as the plasmid is shared throughout the colony. –Bacteria trading plasmids and, in doing so, trading resistance genes that will see them become “super bugs”.