Infectious diseases Flashcards
How are infectious diseases caused?
Infectious diseases are caused by the transmission of pathogens, which are microorganisms such as bacteria and viruses.
How are pathogens transmitted?
Pathogens can be transmitted by direct contact - horizontal and vertical transmission - and by indirect contact - vehicle-borne transmission and vector-borne transmission.
Where is cholera bacteria found?
Cholera bacteria are found in water contaminated with sewage.
What are bacteria?
Bacteria are living cells and, in favourable conditions, can multiply rapidly. Once inside the body they release poisons or toxins that make us feel ill.
What are viruses?
They are among the smallest organisms known and consist of a fragment of genetic material inside a protective protein coat.
How do viruses reproduce?
Viruses can only reproduce inside host cells, and they damage the cell when they do this. A virus can get inside a cell and, once there, take over and make hundreds of thousands of copies of itself. Eventually the virus copies fill the whole host cell and burst it open. The viruses are then passed out of the body in the bloodstream, the airways, or by other routes.
What is salmonella?
Salmonella is a type of food poisoning that comes from chickens.
What is HIV?
HIV is a virus hat causes AIDS. It destroys some of the white blood cells that help defend the body against pathogens.
What is athlete’s foot?
Athlete’s foot is a fungal infection that thrives in the warm, moist environment of sweaty feet.
What is diarrhoea?
Diarrhoea prevents digested food and water being absorbed, which can cause severe dehydration that can lead to death if not treated.
What are the two main ways that microorganisms can be transmitted?
- Direct contact
- Indirect contact
What are the two types of direct contact transmission?
Vertical transmission happens when microorganisms pass from a mother to her unborn baby through the placenta. German measles and HIV can be passed on this way.
Horizontal transmission happens when microorganisms pass from one person to another by touching, kissing or sexual intercourse.
What is one type of indirect contact transmission?
Vehicle-borne transmission involves an object carrying the disease-causing microorganism.
How does the skin protect us from pathogens?
The skin covers the whole body, protacting against physical damage, microbe infection and dehydration. Its dry, dead outer cells are difficult for microbes to penetrate, and the sebaceous glands produce oils that help kill microbes.
How does nasal hairs, mucus and cilia protect us?
The respiratory system (or gaseous exchange tract) is protected in several ways. Nasal hairs keep out dust and larger microorganisms. Sticky mucus traps dust and microbes, which are then carried away by cilia (tiny hairs on the cells that line the gaseous exchange tract).
How do tears protect us?
Tears, saliva and mucus contain an enzyme called lysozyme. This destroys microorganisms.
