The Third Line of Defence (Lymphatic System) Flashcards
What are Lymphocytes?
The third line of defence involves specific internal defences. These are special types of white blood cells called lymphocytes.
Lymphocytes are small white blood cells that play a role in the body’s immune response. They work on bacterial and viral infections.
There are two main types of lymphocytes called B and T cells. (Which are both complex cells)
What do Lymphocytes do?
The lymphocytes target a response that is specific to the pathogen to destroy it. Unlike your second line of defence which is non-specific and just destroys anything that is foreign, the immune cells in your third line of defence can recognise and kill specific pathogens.
The advantage of the specificity in these lymphocytes:
that some of these cells will go on to develop a memory for the pathogen that it encountered. In other words, they will be able to remember the specific pathogen that invaded the body.
This means that in the case that you are infected with the same pathogen again, your immune system is able to help produce a quick response to get rid of the pathogen before it can cause disease.
What do T Cells do?
T cells are mostly involved in producing molecules that actually do the killing.
What do B Cells do?
B cells produce antibodies which are molecules that bind to the antigen on the surface of the pathogen. This allows the pathogen to be recognised by other immune cells to be taken up and destroyed.
What do T and B Cells both do?
T cells and B cells both recognise foreign antigen, which are proteins that are found on pathogens, and result in an immune response.
What happens in the Three Lines of Immune Defence?
When a pathogen gets past the body’s first line of immune defence (the physical barriers) and into the body, the immune cells from the second line of immune defence (such as the neutrophils and macrophages) will take up the pathogens and destroy them.
However, sometimes pathogens have mechanisms to avoid being taken up by phagocytes. The immune cells of the second line of immune defence will call in immune cells of the third line of immune defence—your lymphocytes.These cells of the third line of immune defence will recognise antigens and produce antibodies and molecules specially targeted to kill the pathogen.
Some of the remaining lymphocytes will also go on to develop memory for the specific pathogen. This means that the immune system will be able remember the pathogen if it ever tries to invade the body again and destroy it before it causes infection.
What is the Lymphatic System?
The lymphatic system is an extensive drainage network that helps keep bodily fluid levels in balance and contains many immune cells that move around through the lymphatic system to help defend the body against infections.
The lymphatic system is made up of a network of lymphatic vessels. These vessels carry lymph throughout the body.
What is Lymph?
Lymph is a clear, watery fluid containing immune cells (such as lymphocytes), protein molecules, salts, glucose (sugar) and other substances.
Lymph helps to destroy potentially dangerous bacteria and cancer cells, and to filter waste and toxins.
What are Lymph nodes?
Lymph nodes are small round masses of tissue that can be found in specific areas in the body, such as the neck, and armpits. The lymph nodes filter out bacteria and other foreign materials out of the lymph and expose them to the lymphocytes and macrophages.
What is an advantage about the Lymphatic System?
Your lymphatic system helps to fight against infection and in the transport of immune cells around the body.
The lymphatic system transports lymph fluid that contains immune cells such as lymphocytes.
As the lymph fluid enters the lymph nodes, bacteria, viruses and other pathogens or foreign particles are filtered out of the lymph and exposed to the immune cells which can then destroy them by producing antibodies and other molecules.
What does the Lymphatic System consist of?
The lymphatic system consists of…
Lymph vessels which consist of…
Lymph which consists of…
Lymphocytes!
