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15 Cards in this Set

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  • Back

What is a disease & when does an infection occur?

*Disease is a description of certain symptoms. It is a malfunction of the body/mind which has a bad effect on health physically, mentally & socially.



*An infection occurs if a pathogen colonises the tissues of the host.

What are the three types of pathogens & what is transmission?

*Bacteria, Viruses & Fungus.



*Transmission is when a pathogen spreads from one person to another.

When is a microorganism a pathogen?

A microorganism is only a pathogen if it:-



*Enters the host.


*Colonises the tissues of the host.


*Moves into tissues & multiplies.


*Causes damage to the host tissues.


*Spreads - Invasiveness.

How do microorganisms get into the body?

*By penetrating 1 of the organisms interfaces with the environment.



*By entering from broken skin - cut, abrasion.



*Parts of body allowing exchange of material between internal & external environments.



*At these points the body linings are thin, moist, have a large surface area & are well supplied with blood vessels.

Explain what bacteria are?



Give an example from the syllabus.

*Simple, prokaryotic cells.


*No nucleus or membrane bound organelles.


*Not all are pathogenic.


*Can tolerate a wide range of conditions & multiply rapidly.


*They often release toxins.


*E.g. Cholera - Affects digestive system, releases toxins & causes severe diarrhoea.


*E.g. Tuberculosis - Affects the lungs.

Explain what viruses are?



Give an example from the syllabus.

*Not strictly cells.


*They are particles comprising of a protein coat containing genetic material & enzymes.


*All viruses are pathogenic.


*They must live as a parasite by invading host cells to reproduce - obligate parasites.


*E.g. Influenza - Afects lungs & trachea, host's immune system releases chemicals, which causes fever, muscle aches & fatigue.

Explain what fungi are?

*Complex, eukaryotic cells.


*Have a nucleus & other membrane bound organelles.


*Not all are pathogenic.


*Reproduce relatively slowly & rarely infect internal tissues.


*They tend to infect external epithelium.

What are the points of entry a pathogen uses to get into the body?



How do pathogens colonise an area, move into tissues & multiply?

*They enter through the gas - exchange system, digestive system, urinogenital system or the skin.


*To colonise they attach themselves to the cell membrane, often epithelial cells.


*To move into tissues they secrete proteolytic enzymes to break down the basement membrane of epithelial cells & enter tissues/fluids underneath.


*Their generation time decreases due to stimulation of the new environment & they multiply rapidly.

How do pathogens damage host tissues & spread?

*When pathogens enter host cells, these cells are often destroyed.


*Some pathogens release toxins called exotoxins & endotoxins.



*Exotoxins - Soluble proteins, travel in blood, effect other parts of the body. Examples :-


- Botulinum toxin - muscle paralysis


- Tetanus neurotoxin - muscle paralysis


- Gangrene toxin - Break down cell membranes


- Enterotoxins - Affect intestinal epithelium.



*Endotoxins - Part of the pathogen cell membrane, liberated when pathogen is destroyed, responsible for skin rashes, fever & increased permeability of blood vessels resulting in:-


- Severe drop in blood pressure


- Circulatory failure


- Death.



*To spread around the body, pathogens may move through lymph vessels & the blood stream, they may lodge themselves in particular tissues & multiply rapidly.

How does the body prevent the entry of pathogens?

*A mucous layer that forms a thick sticky barrier so its difficult to penetrate.


*Production of enzymes that break down pathogens & of stomach acid which kills microorganisms.


*Cilia which traps dust and pathogens.


*Tears produce enzymes which kill pathogens.


*The immune system which consists of white blood cells which fight infections.

What risk factors are associated with lifestyle that influence many diseases?

*Excercise


*Stress


*Diet:- Salt, fat, malnutrition.


*Smoking


*Alcohol consumption


*Exposure to:- Car fumes, pollution, coal dust, radiation, asbestos.

Explain asthma, fibrosis of the lungs, emphysema & atheroma diseases.

*Asthma - Caused by numerous allergens e.g. dust, smoking etc. & it effects the lungs.


*Fibrosis of the lungs - Can be caused by coal dust & effects the lung function.


*Emphysema - Can be caused by smoking & effects the lungs.


*Atheroma - Can be caused by excessive fats {LDLs} in diet which effects arteries & blood flow.

Explain aneurysm & thrombosis diseases.

*Aneurysm - Is the swelling of a blood vessel which can rupture causing internal bleeding & death, it can be made worse by smoking & high cholesterol.


*Thrombosis - Formed by a clot in a blood vessel which blocks the flow in or leading to an organ/tissue. Can be made worse by smoking & high cholesterol.

Explain coronary heart disease {CHD} & lactose intolerance.

*CHD is formed due to plaques on the walls of the coronary arteries that supply the heart. It can limit the blood flow to the heart. If dislodged, it can result in myocardial infarction which is when the blood supply to the heart is interrupted. Can be made worse by smoking & high cholesterol.


*Lactose intolerance can be brought about by reduced exposure to milk in diet. Production of lactase decreases with time & exposure to other diseases increases the likelihood of lactose intolerance e.g. coeliac disease.

Give examples of diseases which are influenced by genetic factors from the syllabus.

*Some diseases occur due to errors in DNA & the onset of these may be exacerbated by lifestyle.


*Cystic fibrosis is a genetic condition in which the lungs & digestive system become clogged with thick, sticky mucus.


*Genetic emphysema is an inherited condition, made worse by smoking & gets worse with time.


*Lactose intolerance is inherited.