Chapter 10) Diseases and immunity

Pathogen

microorganism that causes disease

Disease

condition that impairs normal functioning of the body

Infectious disease

disease caused by pathogens that can be transmitted

Transmission

spread of pathogens from one host to another

Direct contact

transmission by physical contact

Indirect contact

transmission via contaminated surfaces or objects

Airborne transmission

spread through droplets in the air

Vector

organism that carries and transmits pathogens

Bacteria

single-celled microorganisms without a nucleus

Virus

tiny pathogen that reproduces inside host cells

Fungus

organism that can cause disease (e.g. athlete’s foot)

Protoctist

single-celled organism with nucleus, some cause disease

Cholera

bacterial disease causing severe diarrhoea and dehydration

Tuberculosis (TB)

bacterial disease affecting lungs

Malaria

disease caused by protoctist, transmitted by mosquitoes

HIV

virus that attacks the immune system

Immune system

body’s defence against pathogens

White blood cells

cells that defend against pathogens

Phagocyte

white blood cell that engulfs and digests pathogens

Lymphocyte

white blood cell that produces antibodies

Antibody

protein that binds to specific antigens on pathogens

Antigen

molecule on pathogen surface that triggers immune response

Antitoxin

antibody that neutralises toxins produced by pathogens

Immunity

ability to resist a specific disease

Active immunity

immunity produced by body after exposure to antigen

Passive immunity

immunity gained from another source (e.g. mother)

Vaccination

introduction of weakened/dead pathogen to stimulate immune response

Memory cells

cells that remember pathogens and respond faster on reinfection

Antibiotic

drug that kills bacteria or stops their growth

Antibiotic resistance

bacteria no longer affected by antibiotics

Painkiller

drug that relieves symptoms but does not kill pathogens

Hygiene

practices that reduce spread of disease

Sterilisation

removal of all microorganisms

Disinfection

reducing number of microorganisms

Isolation

separating infected individuals to prevent spread

Contamination

presence of harmful microorganisms