AQA AS Biology Unit 1 3.1.1 Pathogens and Lifestyle

Unit 1 Biology and Disease
3.1.1 PATHOGENS AND LIFESTYLE…read more

Pathogens
PATHOGENS
INFECTION AND TRANSMISSION
ENTRY AND PREVENTION
SPREAD OF DISEASE
HOW PATHOGENS CAUSE DISEASE…read more

Pathogens
Communicable diseases (infectious diseases) are
cause by microorganisms.
Microorganisms single celled organisms.
Microorganisms that cause disease are called
pathogens.
The most common pathogens are;
Viruses
Bacteria
Fungi…read more

Infection and Transmission
Infection occurs when a pathogen;
Enters the host
Colonises the tissues of the host
Resists the defences of the host
Causes damage to the host tissues
Transmission when a pathogen is transferred from
one individual to another.
Transmission may occur through;
Air
Water
Contaminated food
Direct contact (including sexual intercourse)
Animals (vectors)…read more

Entry and Prevention
A pathogen may gain entry to the host through;
The respiratory system (nose, mouth)
The digestive system (food and water may carry pathogens
into the stomach and intestines via the mouth)
The urino-genitary system
The body prevents the entry of pathogens with
A thick layer of skin
Mucus
· Found in the respiratory and reproductive systems
Stomach acid
Enzymes that specifically destroy pathogens…read more

Spread of Disease
Overcrowded conditions enable diseases to spread
rapidly.
Epidemics
Widespread outbreaks of disease.
Pandemics
Epidemics that spread internationally.
Measures to protect and prevent from disease in
developed countries
Clean drinking water
Sewage treatment
Food hygiene
Immunisation…read more