Human Defence System 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 and Specific defence system.
What is the 1st line of the general defence system?
Skin, Clotting, Sebum, Lysozyme, Mucus.
What is the function of the skin in the general defence system?
Acts as a barrier & prevents pathogens from entering the body.
What is the function of clotting in the general defence system?
Platelets in the blood form a clot, preventing the open wound from allowing pathogens.
What is the function of sebum in the general defence system?
Skin produces sebum & the chemical in sebum kills pathogens.
What is lysozyme?
An enzyme in saliva and tears that helps destroy pathogens’ cell walls.
What is the function of mucus in the general defence system?
Lungs & nose are lined with mucus. Traps pathogens in its sticky viscous.
What are cilia?
Tiny hairs in the nose that trap pathogens & move them out of the body.
What is the role of acid in the general defence system?
Found in stomach & vagina, they kill bacteria due to low pH.
What is the second line of the general defence?
White blood cells, Defence proteins, Inflammation.
What are white blood cells?
Phagocytes and Macrophages.
What is a phagocyte?
Surrounds, engulfs & destroys bacteria.
What is a macrophage?
A large phagocyte that kills bacteria in the lymphatic system.
What are defence proteins?
Complement and 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 causing redness, heat & discomfort, attracting more white blood cells.
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.
What are lymphocytes?
Produced in the red bone marrow & engulf infected body cells containing antigens.
What are antigens?
Foreign molecules that stimulate the production of antibodies.
What is an antibody?
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, stimulating antibody production specific to that antigen.
How do antibodies work?
They prevent bacteria/viruses from entering and trigger the stimulation of defence proteins.
What is induced immunity?
The stimulation of monocytes and lymphocytes to get rid of specific antigens.
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 infection from the environment.
Example: Resistance to a common cold.
What is artificial active immunity?
Occurs when lymphocytes produce antibodies in response to a pathogen administered through vaccines.
What is passive immunity?
Transfer of antibodies from one organism to another.
What is natural passive immunity?
When a baby receives antibodies from its mother through the placenta or 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 active immunity.
What is immunisation?
The protection against pathogens by the injection of antibodies.
What is the difference between artificial and 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 and attack by producing antibodies.
What are plasma B cells?
Produces antibody molecules which bind to pathogens and mark them for destruction.
What are memory B cells?
They live in the body and respond if the same antigen enters again, enabling immunity.
What are the functions of memory B cells?
Produces more antibodies, quicker production of antibodies, and produces antibodies in response to very little antigen.
What are T lymphocytes (T cells)?
Move from the bone marrow & mature in the thymus gland, attacking cells by invading antigens.
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?
Attack cells containing a foreign antigen and secrete perforin to destroy infected cell membranes.
What are suppressor cells?
Stops the immune response after the pathogen has been destroyed.
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 two organs specific to the immune system?
Thymus and 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.
