diseases and immunity

Pathogen

A pathogen is a disease causing organism

Describe a transmissible disease

Pathogens are passed on from one host to another and therefore the diseases they cause are known as transmissible diseases

How is pathogens transmitted?

>direct contact :pathogens is passed directly from one host to another by Body fuids such as blood or semen

>indirect contact :the pathogens leaves the host and is carried in some way to another uninfected individual

Describe the body defenses

>mechanical barrier : structures that make it difficult for pathogens to get past them and into the body

>chemical barrier : substances produced by the body cells that trap pathogens before they can get further into the body and cause diseases

>cells : different types of white blood cells work to prevent pathogens reaching areas of the body they can replicate in

Describe active immunity

Making antibodies and developing memory cells for future responses to infection is known as active immunity

How is active immunity gained

>infected by pathogens

>vaccination

Antigen

An antigen is a molecule found in the surface of a cell

Antibody

An antibody is a protein made by lymphocytes that is complementary to an antigen and when attached,clumps them together and signals the cells they are on for destruction

Antitoxin

An antitoxin is a protein that neutralizes the toxins produced by bacteria

Aggultination

Clump pathogenic cells together so they can't move as easily

Phagocytosis

The process by which white blood cells (phagocytes) engulfs and destroys path

Passive immunity

Passive immunity is a fast acting, short term defense against a pathogen by antibodies acquired from another individual

How is passive immunity gained

>mother to infant via breast milk

Explain the importance of breast feeding for the development of passive immunity in infants?

It helps the very young to fight off infections until they are older and stronger and their immune system is more responsive

Explain the role of vaccination in controlling the spread of diseases

Provides protection from the entire population

Herd immunity

Herd immunity prevents epidemics and pandemics from occurring in populations