Introduction to the immune System Flashcards
What is the immune system?
a collection of passive and active processes that protect us from the outside world and ourselves
What is the role of the intrinsic system?
(barriers) prevent problems from happening
What is the role of the innate system?
recognise non-self non-specifically
What is the role of the adaptive system?
recognition of non-self specifically
Where are immune cells made?
bone marrow and thymus
What factors does the immune response depend on?
- having the right cell type in the right numbers to do the job neutropenia/ lymphopaenia
- can the cell travel to the infection site
- do the cells produce the appropriate molecules to kill/ restrict the pathogen
What are the two mechanisms that the immune system uses to kill threats?
CONTACT DEPENDENT:
- immune cells encounter pathogens, engulf and destroy them
- immune cells communicate with each other to co-ordinate a response
SOLAUBLE FACTORS:
- the immune system produce soluble factors that kill pathogens directly
- the immune system produces molecules that regulate the immune response
Give examples of biochemical barriers.
-lysosomes in tears
-nasal secretions
-saliva
sebaceous gland secretions
-commensal organsims in gut and vagina
-spermine in semen
Give example of chemical and physical barriers
- mucus
- cilia lining trachea
- acid in stomach
- skin
Why is disease not necessarily the most common outcome from infection?
because infections becoming disease depends on many factors
What are the steps of progression of a typical infection?
- establishment of infection
- induction of adaptive response
- adaptive immune response
- immunological memory
Describe the innate response.
- non-specific
- induced rapidly
- same speed of first and second encounter
- release cytokines
- phagocytose bacteria
- induce adaptive immunity
Describe the adaptive response
- specific
- slow on first encounter
- faster on subsequent encounters
- vital for vaccine function
What protects intracellularly?
T cells
What is an antibody made up of?
- light chain
- heavy chain
- disulphide bonds
What can antibodies target?
- bacterial toxins
- bacteria in extracellular space
- bacteria in plasma
How do antibodies work against bacteria in plasma?
if enough antibodies bind they can activate complement (a soluble protein in blood) and cause direct death of bacterial cell
What is the role of vaccines?
to trick the body into making protective responses against pathogens without being infected
Where and why is adaptive immunity tightly controlled?
- in sites like lymph nodes
- to avoid autoimmunity
Where do T cells target?
inside cells
Where do B cells and antibodies target?
outside cells
What protects extracellularly?
antibodies
What do lymph nodes do?
Tightly control the induction of the adaptive immune system
Why must the adaptive immune system be tightly controlled?
To prevent autoimmunity
Which T-cell responds to antigens expressed through MHCI?
CD8 T-cells
Which T-cell responds to antigens expressed through MHCII?
CD4 T-cells
What type of bacteria have antigens expressed through MHCI?
Cytosolic bacteria
What type of bacteria have antigens expressed through MHCII?
Vacuole resident bacteria
What is the prophylactic function of the immune system?
Prevent infection/disease from occuring
What is the therapeutic function of the immune system?
Sort the infection/disease out when it gets out of hand/
How do antibodies work against bacteria in extracellular space?
Loads of antibodies will bind to the same bacterial molecule causing opsonisation which marks the bacteria cell for phagocytes to engulf them
How do antibodies work against bacterial toxins?
Antibodies bind to the bacteria toxins neutralising them and preventing them from binding to cells with receptors of the toxins
