Human Defence System 2.0 Flashcards
What is immunity?
The resistance to an infection.
What is a pathogen?
A disease causing organism.
What are the two defence systems?
• General defence system
• Specific defence system
What is the 1st line of the general defence system?
• Skin
• Clotting
• Sebum
• Lysozyme
• Mucus
What is the role of skin in the general defence system?
Acts as a barrier & prevents pathogens from entering the body.
What is the role of clotting in the general defence system?
Platelets in the blood form a clot, preventing the open wound from allowing pathogens.
What is the role of sebum in the general defence system?
Skin produces sebum & the chemical in sebum kills pathogens.
What is the role of lysozyme in the general defence system?
An enzyme in saliva and tears that helps destroy pathogens cell walls.
What is the role of mucus in the general defence system?
Lungs & nose are lined with mucus. Traps pathogens in its sticky viscus.
What is the role of cilia in the general defence system?
Tiny hairs in nose that trap pathogens & moves them out of the body by moving the hairs in an upward direction.
What is the role of acid in the general defence system?
Found in stomach & vagina. They kill bacteria & enter due to low PH of these areas.
What are the physical properties of humans related to immunity?
First line of the general defence system. If pathogens get past these barriers, the body can still destroy them via the second line of the general defence system.
What is the second line of the general defence?
• White blood cells.
• Defence proteins.
• Inflammation.
What are white blood cells?
• Phagocytes
• Macrophage
What is the role of phagocytes?
Surround, engulf & destroy bacteria.
What is the role of macrophages?
Is a large phagocyte that kills bacteria in the lymphatic system.
What are defence proteins?
• Complement
• Interferons
What are complement proteins?
A set of proteins that destroy bacteria.
What are interferons?
A set of proteins that prevent viruses from reproducing & spreading.
What is inflammation?
Chemicals released by damaged cells. Causes redness, heat & discomfort. Attracts more white blood cells to the site of the pathogen.
What is the specific defence system?
Designed to attack particular pathogens.
What are monocytes?
• Type of white blood cell, produced in the red bone marrow.
• Released into the bloodstream & lymphatic system. Surround & engulf pathogens to destroy them.
What are lymphocytes?
• Produced in the red bone marrow & engulf infected body cells containing antigens on their surface.
What are antigens?
Foreign molecule that stimulates production of antibodies.
What are antibodies?
Proteins produced by white blood cells in response to the presence of antigens.
What is the relationship between antigens and antibodies?
• An antigen is displayed on the surface of a pathogen.
• This stimulates antibody production.
• This antibody is specific to this antigen meaning, the antibody will only work on this particular antigen.
How do antibodies work?
• Antigens present on the macrophages & prevent bacteria/viruses from entering. A new phagocyte then destroys the pathogen.
• Antibodies cause the pathogens in a cell to clump together & phagocytes then destroy the pathogen.
• Antibodies trigger the stimulation of the defence proteins, & complement proteins destroy the pathogen.
What is induced immunity?
The stimulation of monocytes and lymphocytes to get rid of specific antigens present in the body.
What is active immunity?
The production of antibodies by lymphocytes in response to a specific antigen.
What is natural active immunity?
Occurs when lymphocytes produce antibodies in response to the body becoming infected by a pathogen from the environment.
EG: resistance to a common cold. Longer lasting due to memory cells.
What is artificial active immunity?
Occurs when lymphocytes produce antibodies in response to the pathogen being administered through vaccines.
Antibodies are administered. Short-term immunity. EG: Breastfeeding.
What is passive immunity?
Transfer of antibodies from one organism to another.
What is natural passive immunity?
When a baby receives antibodies directly from its mother through the placenta before birth or via breast milk.
What is artificial passive immunity?
When a person receives an injection of antibodies made in another organism.
What is vaccination?
The administration of a non-disease-causing dose of the pathogen or part of a pathogen which stimulates and results in active immunity.
What is immunisation?
The protection against pathogens by the injection of antibodies.
What is the difference between artificial & natural immunity?
Artificial is the administration of antibodies & natural is the production of antibodies.
What are B-lymphocytes?
• Mature in the bone marrow before moving to the lymph nodes.
• Attack by producing antibodies.
What are plasma B cells?
Produces antibody molecules which bind to the pathogens & mark them for destruction by monocytes.
What are memory B cells?
They live in the body & respond if the same antigen enters again. - enable immunity.
What are the functions of memory B cells?
• Produces more antibodies.
• Quicker production of antibodies.
• Produces antibodies in response to very little antigen.
What are T lymphocytes (T cells)?
Move from the bone marrow & matures in the thymus gland. They attack cells by invading antigens on their cell membrane.
What are the 4 types of T-lymphocytes?
• Helper T cells
• Killer T cells
• Suppressor T cells
• Memory T cells
What are helper T cells?
Recognise antigens & stimulate the production of B cells & Killer T cells.
What are killer T cells?
Attacks cells containing a foreign antigen & secretes perforin which breaks down infected cell membranes allowing them to be flooded with water and causing them to burst. Pathogen-containing cells are destroyed.
What are suppressor T cells?
Stops the immune response after the pathogen has been destroyed and are active when the antigen is gone. No more antibodies produced.
What are memory T cells?
Triggers the production of B & T cells much quicker if a pathogen enters the body.
Where do B lymphocytes mature?
Bone marrow.
Where do T lymphocytes mature?
Thymus.
Why does active immunity result in longer lasting immunity?
As memory T cells are produced and better able to respond.
How do vaccines give immunity?
Stimulate antibody production.
What are the two types of induced immunity?
Active and passive.
What are the two organs specific to the immune system?
• Thymus
• Lymph nodes
Name a group of WBCs other than lymphocytes.
Monocytes.
What WBCs produce antibodies?
B-lymphocytes.
What part of a virus is recognised by antibodies?
Antigens.
What is the function of antibodies?
Recognise antigens.
What is the difference between active and passive immunity?
Active lasts longer than passive.
