Immunity Flashcards
Pathogen
A disease causing organism (bacteria or virus).
Bacteria description
- Pathogenic?
- DNA/RNA?
- Structure?
- Reproduce?
The majority of bacteria are harmless/non-pathogenic. They are living, single cell organisms, only seen with a microscope. Bacteria have flagella and a cell membrane similar to that of other cells. It contains DNA and RNA and reproduces by division like other human cells.
Bacteria example
Pneumonia and Tuberculosis.
Virus description
- Pathogenic?
- DNA/RNA?
- Structure?
- Reproduce?
The majority of viruses are harmful/pathogenic. They are non-living and can only be seen with an electron microscope. Viruses contain DNA or RNA, never both. In order to reproduce, viruses invade a host cell, infecting it with its DNA/RNA, taking over and causing rapid reproduction.
Virus examples
HIV/AIDS, Chicken Pox and Colds.
Communicable disease
Diseases that are caused by foreign organism invading the body and multiplying there. Known as infectious diseases.
Zoonotic disease
Infections that pass from animals to humans.
Bacteriophage
A virus that infects bacteria
List the 6 types of transmission of pathogens
contact bodily fluid droplets ingestion airborne vectors
Contact
Involves the spread of the pathogen by actual physical contact. The contact may be direct, actually touching an infected person, or indirect, touching an object that has been touched by an infected individual.
Bodily fluid
Involves blood other bodily fluids from an infected person coming into contact with the mucous membranes or the blood stream of an uninfected person.
Droplets
Involves tiny droplets of moisture, harbouring pathogenic organisms that have been emitted through breathing, talking, coughing and sneezing etc, being inhaled or ingested when settled on food.
Vectors
Involves the transfer of pathogens by other animals. Some vectors transfer pathogen directly (a house fly spreading pathogen to food/water that is then ingested), others are spread by a specific vector (malaria and mosquitos).
Airborne
When the moisture in exhaled droplets evaporates, many bacteria are killed, but viruses and some bacteria remain viable and can cause infection when inhaled.
Whats the external non-specific defence
External non-specific defence are the first line of defence, prevent pathogens entering the body. it includes the; skin mucous membranes hairs cilia acids lysosomes acids cerumen flushing action and protective reflexes
The skin
An effective barrier covering the outside of the body stops the entry of micro-organisms, provided it is not broken by cuts and abrasions. An oily secretion (sebum) produced by oil glands contains substance that will kill some bacteria, sweat secreted onto the skin contains salts and fatty acids that prevent growth of micro-organisms. The top layer is dead (need to invade living cells).
Mucous membranes
Membranes line body cavities that are open to exterior. The mucus inhibits the entry of micro-organisms to the organs of the body. The whole digestive, urinary and reproductive tracts are protected this way.
Hairs
Found in the nose cavity and ears. The hairs trap particles entering the cavities.
Cilia
Tiny hair-like projections from cells that are capable of a beating motion. Nose cavity, trachea and other air passages have cilia. They beat mucus containing trapped particles and micro-organisms, towards the throat where it can be coughed up or swallowed.
Acids
Acid in the stomach kills many of the bacteria consumed with food or the bacteria contained in the mucus swallowed from the nose and windpipe. The vagina also has acid secretions to reduce the growth of micro-organisms and sweat on the skin is slightly acidic.
Lysosomes
An enzyme that kills bacteria. Eyes are protected by the flushing action of tears containing lysosymes. The enzyme is contained in saliva, sweat, nose secretions and tissue fluid.
Cerumen
Ear-Wax
Protects the outer ear against infection by some bacteria. It is slightly acidic and contains lysozyme.
Flushing action
The flushing action of bodily fluids, keeps some areas free from pathogens. Urine flowing through the urethra has a cleansing action that prevents bacterial growth and stops bacteria reaching the bladder and kidneys. Tears sweat and saliva also utilise the flushing action.
Reflex definition
A reflex is a rapid autonomic response to a stimulus. Protective reflexes help to protect the body from injury (blinking) or infection
Coughing
Air is forced from the lungs to try and remove irritant; the air drives the mucus and foreign matter up the trachea towards the throat and mouth. The stimulus is irritation and the lower respiratory tract (bronchi and bronchioles).
Sneezing
The forceful expulsion of air from the lungs carries mucus, foreign particles and irritating genes out through the nose and mouth. It is caused by the irritation of the walls of the nasal cavity, which can be the result of noxious fumes or dust particles, likely to be carrying micro-organisms.
Vomiting
Physiological stimuli, excessive stretching of the stomach and bacterial toxins can all induce vomiting. It is not contraction of the stomach but contraction of the muscles of the abdomen and the diaphragm that expel the stomach contents.
Diarrhoea
The increases of contractions of the muscles of the wall of the intestines so that the irritant can be removed as quickly as possible. Irritation of the small and large intestines by bacteria, viruses or protozoans can cause diarrhoea
Inflammation definition
A response to any damage to the tissues. Words ending in itis indicate the inflammation to specific organs or tissues.
Purpose of inflammation
- Reduce the spread of pathogens, to destroy them and to prevent the entry of any additional pathogens.
- Remove damaged tissue cell debris.
- Begin the repair of damaged tissues.
Four signs of inflammation and why?
- Redness. Caused by the release of the histamine, dilating blood vessels.
- Swelling. Caused by the release of histamine, which results in more fluid being released into tissue.
- Heat. Produced by the white blood cells removing pathogens.
- Pain. Caused by the cytokines making the nerve endings sensitive.
1-3 of the inflammation process
- The skin is broken/tissue damaged, allowing pathogens to enter.
- Mast cells become stimulated and release cytokines including pyrogens.
- The release of cytokines causes the release of a histamine and heparin.
4-5 of the inflammation process
- The histamine causes the blood vessels to dilate and become leaky so fluid leaks into tissue. This causes redness and swelling and attracts white blood cells to the site to remove pathogens.
- Heparin keeps the site of the infection fluid and constricts blood vessels around the site to prevent the spread of pathogen.
6-7 of inflammation process
- Heat is produced as the white blood cells remove pathogens.
- Cytokines also cause the nerve endings to be sensitive, causing pain. The pain is meant to slow the body down, so it can concentrate on the problem.
Heparin
Anticoagulant (blood thinner) found in blood and tissue cells.
Histamine
A substance (nitrogenous compound) released by mast cells in response to injury to cells; it results in increased blood flow.
Pus
The thick fluid that results from inflammation; it contains dead phagocytes.
What is a fever?
Presence of an abnormally high body temperature
Steps 1-2 of fever process
- Pyrogens go to the hypothalamus.
- If levels of pyrogens high enough fever will be instigated. This results in;
- The body to increase in temperature (turn up thermostat).
- The body will think it’s cold, and try to warm up by shivering, as the temperature has been suddenly raised.
- The higher temperature slows the growth of some bacteria and viruses as they’re heat sensitive. It also allows chemical reactions to take place at a faster rate, which can increase the rate at which body cells repair themselves during a disease.
Steps 3-4 of fever process
- Once pyrogens stop being made, the hypothalamus decrease the body’s temperature (thermostat down) to bring it back to normal.
- Body will them think it’s hot, start to sweat in an effort to cool down.
Phagocytes
Organisms that penetrate external defences are attacked by phagocytes, the phagocytes are cells that can engulf and digest micro-organisms and cell debris.
Macrophages
Large phagocytic cells that develop from a white blood cell. They are able to consume foreign substances and micro-organisms through a process known as phagocytosis or release substances that destroy them.
Natural killer cells
Release chemicals causing infection. Causes the death to cells infected and some surrounding cell.
The internal non-specific defence layout
pathogen invasion -> cytokines released by damaged/infected cell -> Natural killer cells OR Macrophages.
Humoral response
B-Cells are sensitised and enlarged, then dividing and cloning. They clone into plasma cells forming antibodies which are released into the blood attacking antigens and memory cells which are stored in the lymph nodes, prepared to make antibodies again if the antigen re-invades.
Cell mediated response
T-cells are sensitised and enlarged, then dividing and cloning into 4 different types of cells. helper t-cells, memory cells.
cytotoxic cell and suppressor t-cells.
Helper t-cells
visit the site of infection increasing activity of macrophages and attracting white blood cells to site, as well as assisting B-cells in division and cloning.
Memory t-cells
recognise infection, activated if the pathogen is encountered again.
Cytotoxic t-cells
release a chemical to kill the infected cell (specific)
Suppressor t-cells
keeps cells in check until infection is dealt with, where it stimulates the death to cells no longer needed.
What are antibodies
A specialised protein that is produced in response to a non-self-antigen.
How do antibodies destroy pathogens
- Bind to the surface of pathogens/antigens. The cell membrane cannot recognise, stopping the pathogen from entering the cells.
- Making a soluble pathogen insoluble, this makes it easier for macrophage to digest it.
- Agglutination, making pathogens stick together so they cannot enter a cell.
- Covering pathogen with chemical easily digested by a macrophage.
- Combining with enzymes of pathogen and stopping the cell function.
Are antibodies specific?
Yes. The body makes antibodies with a specific function to deal with the markers on the outside of antigens of the pathogen.
Primary response to infection
At the beginning of infection only 1 B-cell is present, taking time to find this b-cell and then for it to multiply, causing the response. This is why it is slow and not intense. Once the infection is dealt with, antibodies are broken down, memory cells remain.
Secondary response to infection
Memory cells can quickly pick up the infection, producing a lot more plasma, which develop quickly into lots of antibodies. This is why the infection is usually dealt with before symptoms arise. The secondary response is quick and intense.
Immunisations
Programme the immune system so that the body can respond rapidly to infecting micro-organisms. This can occur naturally or artificially
Vaccination definition
The artificial introduction of antigens of pathogenic organisms so that the ability of the appropriate antibodies is acquired without the person having to suffer the disease.
Vaccine
A preparation made of weakened or dead pathogenic cells injected into the body in order to stimulate the production of antibodies. There is traditional and modern vaccines
Herd immunisations
The resistance of a group to an attack by a disease to which a large proportion of the members of the group are immune.
How do vaccinations work?
The idea of vaccinations, is to put antigen into the body, however the antigen, has been altered to not cause disease. The body then has the time to identify antigens and make memory cells. This way if the pathogen enters, the infection can be dealt with quickly so the individual does not get sick (will be the secondary response).
Traditional vaccines
Dead micro-organisms, sub-unit (part of the pathogen), toxins from the pathogen or attenuated pathogen (altered pathogen, making it less virulent/likely to cause disease). This is done for less serious infections.
Modern vaccines
Take out DNA to produce antigen and insert into harmless bacteria (the bacteria produce antigen on the surface, but cannot reproduce) or alter the DNA in the pathogen (so it is harmless but still has antigens).
Ethical risks/benefits of vaccination
- Risk of causing disease/allergic reaction.
- Embryo/animal testing.
- Vaccines prepared inside animals – cross-contamination.
- Testing on the poor/uneducated. Virtually no consent.
- Human Tissue Testing.
- Don’t want to be responsible for giving other people disease.
Social risks/benefits of vaccination
- Religious grounds.
- Cannot attend schools without certain vaccinations.
- Friends previous experiences.
- Government pressure.
- Herd vaccinations protect the vulnerable.
- Tries to eliminate disease in society.
Economical risks/benefits to vaccination
- Not free in undeveloped countries.
- Countries may not have enough resources.
- People cannot get to where vaccines are given out.
- Not all vaccines are free.
- Less disease, which reduces cost for medical treatment.
- Vaccination is cheaper than the treatment of disease.
Immunity definition
The ability of an organism to resist a particular infection or toxin.
Natural types of immunity
Natural Passive. Antibodies enter the bloodstream across the placenta or in the breast milk.
Natural Active. Ability to manufacture antibodies results from attacks of a disease, in order to recover. This produces memory cells.
Artificial immunity
Artificial Passive. Antibodies are injected into the bloodstream. Used in serious conditions, this may not develop immunity.
Artificial Active. The ability to manufacture antibodies results from being given an antigen by vaccination, developing memory cells.
Definition of antibiotics
A chemical able to inhibit the growth of, or kill, micro-organisms - particularly bacteria. Some are broad spectrum and treat a wide range of bacteria, others are narrow-spectrum and are only effective against specific types of bacteria.
Bactericidal antibiotics
Kill bacteria by changing the structure if cell wall or membrane, or by disrupting action of essential enzymes.
Bacteriostatic antibiotics
Stop bacteria from reproducing, usually by disrupting protein synthesis.
Multiple drug resistance
The creation of ‘super bugs’ due to the overuse of antibiotics in medicine. Some strains of bacteria are now resistant to most or all types of antibiotics due to the widespread use of antibiotics, which in some cases were used to prevent infections, rather than treat infections.
Antivirals
Drugs used specifically for treating viral infections. They inhibit the development of the virus
Pyrogens
chemicals that induce fever
Thymosin
Group of hormones secreted by the thymus that stimulates the maturation of lymphocytes into T cells of the immune system
