Flashcards in Immunity & Disease Deck (44)
What kind of things does our immunity protect against?
Our immune system distinguishes self from non-self. what are the two main pathways used to do this?
What is innate immunity?
-defence mechanisms present even before infection or activated
- works in non-specific way
What are examples of defences in innate immunity?
- skin and mucous membranes
- phagocytic cells (neutrophils, macrophages)
What are examples of defences in adaptive immunity?
- cell-mediated immunity ( activation of phagocytes, antigen specific cytotoxic T-lymphocytes)
- humoral immunity
How soon is innate immunity?
0-12 hours after infection
how soon is adaptive immunity?
12 hours to 7 days
Give 2 examples of non-specific defences.
- mucus and cilia
How does skin act in immunity?
- outer layer of keratin acts as mechanical barrier
- Dead skin cells constantly slough off - hard for invading bacteria to colonize
- sweat and oils contain anti-microbial chemicals
How does the mucous membrane act in immunity?
- normal flow of mucus washes bacteria and virus off mucus membrane
- cilia move bacteria (in respiratory tract)
- acid in the stomach and vagina
- enzymes in saliva and eye
How do chemical barriers such as proteins work in immunity?
- complement - works with other defence mechanisms of the body
- interferons - inhibit the replication of many viruses
Granulocytes such as neutrophils, eosinophils and basophils help with immunity how?
- remove dead cells and micro-organisms
- attracted by an inflammatory response of damaged cells
Monocytes such as macrophages help with immunity, how?
- in tissue which serves as filters for trapping microbes
- stimulate specific immune response (antigen - presenting)
- release protein signals (interleukin 1 and 6 )
what is the difference between the times and macrophages compared to granulocytes?
- macrophages live longer
- normally arrive later than granulocytes
What are the non-specific responses to infection?
pain, swelling and redness
acute-phase proteins released from liver
Why do we get fever with infection?
- because most bacteria grow optimally at temp below body temp
why do we get pain, swelling and redness with infection?
increasing capillary permeability
promoting blood flow
bring more phagocytic cells
Why is their an acute-phase of proteins released from the liver?
- to bind to bacteria and activate complement proteins
specific immunity relies on antigens, what are these?
specific substances found in foreign microbes
Where are lymphocytes produced?
in bone marrow
Where do B-cells mature?
in bone marrow and then concentrate in lymph nodes and spleen
Where do T-cells mature?
B and T- cells mature and then circulate in the blood and lymph, why is this important?
circulation ensures they come into contact with pathogens and each other
What are the functions of B-cells ?
- secrete antibodies (humoral immunity)
- recognise pathogens outside cells
What are the functions of T-cells ?
- recognise antigen presented by major histocompatibility comples (class 1 and 2 )
- directly attack invaders (cytotoxic, CD8, MHC I )
-recognise pathogens that have entered cells
- also help B-cells (helper cells, CD4, MHC II)
What do cytotoxic T-cells do?
- seek out and destroy any antigens in the system and destroy microbes 'tagged' by antibodies
- some can recognise and destroy cancel cells
What do helper T-cells do?
- stimulate B-cells
- Activate cytotoxic cells and macrophages to attack infected cells
How do T-cells recognise an invader?
by protein marker on cell surface
- will bring to helper T-cell for ID
- if helper T-cells recognises as 'not-self' it will launch immune response
What happens to helper T-cells in HIV?
destroys helper T cells