7. The Immune System Flashcards
What is the difference between specific and non specific defence mechanism?
Defence mechanisms can be non-specific and protect us against a range of pathogens, or they can be specific and tailor made to fight a particular pathogen.
What is the first line of defence?
SHAFT is a non specific defence mechanism that prevents pathogens from entering the body.
Skin provides a mechanical barrier.
Hairs in the nose filter pathogens out of the air and are trapped by mucus.
Acids in the stomach kill bacteria, and vomiting or diarrhoea expels pathogens.
Fluids like saliva and tears have antiseptic properties and wash away pathogens.
The mucous membrane lines the eyes ear nose mouth and genitals. It provides a chemical barrier such as mucus and wax to prevent entry of pathogens.
What is the second line of defence?
If pathogens enter the body a non specific response is initiated in response to the infection. ISA
- Inflammation, the affected area becomes red, swollen and hot due to increased blood flow to the area.
- Special types of white blood cells named Neutrophils or macrophages engulf and digest the bacteria through phagocytosis. Dead neutrophils form pus around wounds.
- A fever may develop which is when the body temperatures rises and the pathogens do not function as effectively so the immune system can fight them more readily.
What is the third line of defence?
If pathogens are still active a specific response is initiated in the lymphatic system.
The lymphatic system is a network of tissues and organs that primarily consist of lymph vessels, lymph nodes and lymph.
Includes the adenoid tonsils spleen and thymus.
How does the lymphatic system work?
As lymph nodes filter the lymph, pathogens and other foreign particles are trapped in the fibres of the nodes.
Lymph nodes contain WBC called lymphocytes.
How does the production of antibodies occur?
The body recognises foreign proteins on the outside of the invading microbes, called antigens.
WBC called b lymphocytes produce antibodies in response to these antigens. The antibodies combine with the antigens and help destroy the pathogen. Antibodies can also be produced by B cells in response to the toxins released by some bacteria.
What are memory cells?
When B cells retain the ability to rapidly produce antibodies if we a invaded by the same pathogen again.
What is the difference between active and passive immunity?
Active, where the body produces antibodies
Passive where the body is given antibodies.
