LC BIOLOGY- Human Defence System

Pathogen

an organism that causes disease

Immunity

the ability to resist infection

General Defence System

acts as a barrier to all pathogens attempting to gain entry to the human body

First Line of General Defence

• skin

• blood clotting

• lysozyme

• chemicals in sebum

• mucous membranes

• cilia

• stomach acid

• lactic acid in the vagina

Second Line of General Defence

white blood cells that act by phagocytosis, defensive proteins (interferons and complement) and inflammation

Specific Defence System

aka immune system

attacks particular pathogens

Monocytes

• develop into macrophages

• destroy pathogens and display antigens on their membranes

Phagocytes

white blood cells that surround and ingest pathogens

Organs of the Immune System

• spleen

• thymus

• lymph nodes

Antigen

a foreign molecule that stimulates the production of antibodies

Antibody

a protein produced by white blood cells (lymphocytes) in response to a specific antigen

Induced Immunity

the ability to resist disease caused by specific pathogens by the production of antibodies

Active Immunity

involves the production of a person’s own antibodies in response to foreign antigens that enter the body

Natural Active Immunity

occurs when a pathogen enters the body in the normal way

Artificial Active Immunity

occurs when a pathogen is medically introduced into the body

Vaccine

a non disease-causing dose of a pathogen, which triggers the production of antibodies

Passive Immunity

occurs when individuals are given antibodies that were formed by another organism

Natural Passive Immunity

occurs when a child gets antibodies from its mother

Artificial Passive Immunity

occurs when a person is given an injection containing antibodies made by another organism

Vaccination

the administration of a non disease-causing dose of a pathogen to stimulate the production of antibodies

Immunisation

occurs when we produce or are injected with antibodies against a pathogen

Plasma B Cells

produce antibodies

Memory B Cells

survive for years after the infection is eliminated and can make the specific antibody if the same infection later enters the body

Helper T Cells

stimulate B cells and helper T cells

Killer T Cells

destroy abnormal human body cells

Suppressor T Cells

inhibit the immune response

Memory T Cells

survive for years after the infection is eliminated and can stimulate the specific B cells and killer T cells if the same infection later enters the body