Flashcards in 12.1 - The immune system Deck (42):
What 2 types of defence mechanisms are there?
Give examples of non-specific responses
Give examples of specific responses
Humoral response using antibodies
Cell-mediated response using T lymphocytes
List physical barriers
Ciliated epithelial lining
What is the outside of skin made of?
What is keratin?
An insoluble protein
What is the role of the skin?
To prevent entry of pathogens
What is the conjunctiva?
Membrane covering the eye
What does the conjunctiva contain?
What does the conjunctiva do?
Enzymes digest bacterial cell walls, destroying the bacteria
How do ciliated cells protect the body?
They waft mucus containing trapped pathogens out of the airways to the throat, where it is swallowed
How does the stomach lining protect us from pathogens?
Secretes HCl which destroys swallowed pathogens
How does the lining of the vagina protect us?
Acidic pH, reducing the ability of the bacteria to survive (enzymes don't function at acidic pH values
What is the inflammatory response?
A reaction which releases histamine, serotonin, and prostaglandins
Causes pain, swelling, redness
What effect does the release of histamine, serotonin, and prostaglandins have?
Make walls of the capillaries more permeable
Increase blood flow to the area
Why does the inflammatory response make capillary walls more permeable?
Enables phagocytic cells to leave the blood more easily
Outline the stages of phagocytosis
1) Pathogens release chemicals
2) Damaged cells release cytokines which attract the phagocytes
3) Pathogen attaches to receptors on cell surface membrane of the phagocyte (directly/through opsonins)
4) Phagocytes surround the pathogen
5) Phagosome is formed
6) Lysosomes fuse with the phagosome
7) Hydrolytic enzymes digest and destroy the bacteria within the phagosome
8) Harmless products are released into the cytoplasm
What are phagocytes?
A specialised leucocyte that destroys bacteria by phagocytosis
Name phagocytic cells
What are cytokines?
Cell signalling molecules used for communication between cells
What are opsonins?
Antibodies which bind to pathogens, making it more susceptible to phagocytosis
What is a phagosome?
A vacuole inside a phagocyte containing a foreign particle
What are monocytes?
White blood cells that differentiate to form macrophages
What are macrophages?
Phagocytic cells that release chemicals to attack bacterial cells, inhibit viral replication, and attract more macrophages
What triggers the specific immune response?
Antigens on the outer surfaces of organisms.
Non-self cells are targeted and destroyed.
What are the cells of the specific immune response?
T and B lymphocytes
Where are T and B lymphocytes produced?
Where are T lymphocytes processed?
Where are B lymphocytes processed?
How are antigen presenting cells formed?
Dendritic cells engulf and digest pathogen and display its antigens on its cell surface membrane
What are dendritic cells?
Type of macrophage which becomes an antigen presenting cell
How are T cells formed?
T helper cell with complementary antigen to the dendritic cell is located.
The dendritic cell activates the T helper cell
T helper cells rapidly divide by mitosis, forming clones
What are types of T lymphocytes?
T helper cells
T regulatory cells
T killer cells
What do B cells have?
Receptors that are complementary to the pathogens antigens
What process do B cells use to divide?
What can B cells differentiate into?
B memory cells
What do plasma cells do?
Synthesise and secrete antibodies with a complementary binding site to the pathogens antigens
What are T regulatory cells?
T cells that regulate the immune system, maintain tolerance to self-antigens, and prevent autoimmune disease.
What do T helper cells do?
Use cytokines to stimulate specific B lymphocyte production
How do B lymphocytes respond to a foreign antigen?
B cell with complementary receptors is stimulated to divide, forming a clone of plasma cells and a clone of memory cells. Plasma cells secrete antibodies into the circulation.
What will happen if a pathogen with the same antigens is encountered again?
Quicker antigen presentation
Quicker clonal selection and clonal expansion
Specific antibodies produced faster