Three lines of defence Flashcards
(12 cards)
Identify the skins role in the first line of defence
The skin stops pathogens entering the body unless it is cut or damaged. When damaged the blood clots - sealing the cut with a scab stops pathogens getting in.
Identify the nose and lungs role in the first line of defence
Mucus and tiny hairs in the nose stop pathogens from entering the lungs - removed by coughs, sneezes or even swallowed.
Identify the eyes role in the first line of defence
Tears produce a substance which kills bacteria, by breaking down its cell wall, on the surface of the eye.
Identify the stomachs role in the first line of defence
Our stomach produces acid - can kill some pathogens if they are swallowed - Some pathogens can survive
What is the first line of defence made of + what kind of immune response is it
Made of both physical and chemical barriers - non specific immune response
what kind of immune response is the second line of defence and key purposes.
Non specific immune response
Detect and attack pathogens
Trigger inflammation
What are the first 3 steps in the second line of defence?
The damaged infected tissue releases chemical signals.
Blood vessels dilate (vasodilation) in response and plasma carries white blood cells (neutrophils and macrophages) and platelets to the infected area.
Neutrophils secrete chemicals that degrade and kill pathogens.
What are the last 2 steps in the second line of defence?
Macrophages (a type of phagocytic cells)engulf and destroy the pathogen.
The inflammatory response continues until the pathogen is eliminated and the wound has healed.
What type of immune response is the third line of defence and what is the role of the immune response.
The third line of defence in the immune system is specific and can identify different microorganisms.
What are the first two steps in the third line of defence?
When apathogen enters the body, the person feels sick whilst the third line of defence is identifying the pathogen.
B lymphocytes (B cells) move through the bloodstream looking for pathogens.
What are the first two steps in the third line of defence?
Pathogens have unique antigens on their surface.
B cells produce antibodies that attach to these antigens and mark the pathogen for destruction.
After the infection, some B cells become memory cells and stay in the blood. If the same pathogen returns, memory cells respond faster and make more antibodies.
How do vaccines build immunity against pathogens?
Vaccines help develop immunity by imitating an infection. Vaccines work by introducing a weakened, dead, or mRNA version of a pathogen to stimulate the immune system. The body produces B cells and specific antibodies, along with memory cells that stay in the body. Vaccines help build immunity without causing disease symptoms.
