Causes of Disease (UNIT 1)

Question 1

MICROORGANISM

Answer 1

A single celled organism that is too small to be seen without a microscope.
Includes viruses and bacteria and fungi

Question 2

PATHOGENS

Answer 2

Disease causing micro-organism

Question 3

What must a micro-organism do to be considered a pathogen?

Answer 3

• gain entry to host
• colonise the tissue of the host
• resist defences of the host
• cause damage to hosts tissues.

Question 4

An infection occurs when…

Answer 4

a pathogen gets into the host and colonises its tissue

Question 5

Disease occurs when…

Answer 5

an infection leads to recognisable symptoms in the host.

Question 6

TRANSMISSION

Answer 6

When a pathogen is transferred from one individual to another

Question 7

What are the two common points of entry for a pathogen?

Answer 7

The gas exchange system- Many enter body through gas exchange surfaces. e.g. pathogens that cause influenza, tuberculosis and bronchitis

The digestive system- Food and water may carry pathogens into the stomach and intestines via mouth.
e.g. cholera, typhoid and dysentery pathogens

Question 8

What are some of the bodies defences against pathogens?

Answer 8

• A mucus layer that covers exchange surfaces and forms thick stick barrier that is difficult to penetrate.
• Production of enzymes that break down the pathogens
• Production of stomach acid, which kills micro-organisms
• skin

Question 9

What are the two main ways pathogens affect the body?

Answer 9

-By damaging hosts tissue- sometimes sheer number of pathogens causes damage e.g. by preventing tissue from functioning properly.
Viruses inhibit the synthesis of DNA, RNA and proteins by the host cells.
Many pathogens break down the membranes of the host cells.

-By producing toxins- Most bacterial pathogens produce toxins

Question 10

What determines how quick a pathogen can cause damage?

Answer 10

Related to how quickly pathogen divides.

Question 11

When does a correlation occur?

Answer 11

When a change in one of two variables is reflected by a change in the other variable.

Question 12

Define risk in term of health,

Answer 12

A measure of the probability that damage to health will occur as a result of a given hazard.

Question 13

What lifestyle factors contribute to cancer?

Answer 13

SMOKING

DIET

OBESITY

PHYSICAL ACTIVITY

SUNLIGHT

Question 14

Risk factors of coronary heart disease.

Answer 14

Smoking

High blood pressure- stress, diet, lack of exercise increase BP.

Blood cholesterol levels- fewer sat fats.

Obesity

Diet- high levels of salt raise blood pressure, while high levels of sat fat increase cholesterol. Dietary fibre reduce risk of CHD by lowering blood cholesterol.

Physical activity- Aerobic exercise can lower and blood cholesterol. Avoid obesity.