Immune System Flashcards
What are non specific defence mechanisms?
Present from birth
Innate
Protect against wide range of dangers
What are specific defence mechanism?
Against one specific invader
The body ‘learns’ and ‘remember’ specific antigens building immunological memory
‘Adaptive’
What are the non-specific defences?
Epithelial barriers
Phagocytosis
Natural antimicrobial substances
Inflammatory response
Immunological surveillance
What are the epithelial barriers?
Skin and mucous membranes
Nose hair
Cilia: moves mucus and inhaled foreign materials towards the throat to be coughed or swallowed
What are epithelial secretions?
Oral, vaginal, gastric
Often acidic, containing antibodies and enzymes
What is phagocytosis and how does it work?
Cell eating
Neutrophils and macrophages are examples of phagocytic cells
Phagocytes migrate to site of inflammation and infection
Phagocytes attack, digest and destroy foreign cells
They release a toxic chemical into interstitial fluid
Chemical release alert the immune system
Neutrophils are short lived as they destroy themselves with their toxic chemicals
Macrophages live longer and link the non-specific defences with specific immunity
What is the inflammatory response , its triggers and what happens?
Inactivates and removes the causative agent and damaged tissue
Triggers: temp changes, pH, foreign bodies
Increased blood flow, accumulation of tissue fluid, migration of leukocytes, increased core temp, pain and suppuration
What happens when there is increased blood flow with inflammation?
Arterioles dilate, capillaries expand. Provides more O2 and nutrients to the area. Responsible for increased temp, swelling and redness. Caused by release of histamine and seretonin
What happens when there is an accumulation of tissue fluid when there’s inflammation?
Fluid leaves blood vessels and moves into interstitial space. Caused by increased blood flow and histamine, serotonin and prostaglandins making capillaries walls more permeable
What happens when there is a migration of leukocytes during inflammation?
Fluid is leaking from vessels to tissue. Less fluid in the vessel, the flow of blood is slower, so blood vessels can leach onto other vessels.
What are natural killer cells and their function?
Non-selective lymphocytes
Kill infected cells
Detect and control early signs of cancer
Where are T and B cells produced?
Bone marrow and some lymphatic tissues
What are T cells and their functions?
Migrate to thymus gland and mature under the influence of thymosin (hormone). T cells become specialised
When fully mature, circulate the bloodstream and lymphoid organs
Recognise 1 type of antigen
What are B cells and their functions?
Matured in bone marrow
Produce antibodies (immunoglobulin) which are proteins that bind to and destroy antigens
Each B-cels targets one specific antigen
What are the 4 types of T cells?
Cytotoxic
Helper
Memory
Regulatory
What is cell mediated immunity?
Destruction of pathogens through macrophages. They engulf, digest, put membrane on the outside then attach to T-cells
What is antibody mediated (humoral) immunity?
B-cells recognise and bind antigen particles directly
B cells make antibodies
Some enter the bloodstream
Helper T cells enable B cells to enlarge and proliferate making memory B cells and plasma cells
Memory: provides long term immunity
Plasma: produces antibodies that bind and destroy antigens
What is an antibody?
Foreign substance which induces an immune response
A protein, binds to the antigen on a foreign invader to neutralise it
What are the different types of antibodies and their functions?
IgM - a sign of recent invasion, short lived
IgA - coats epithelial membranes. Found in breastmilk and saliva. Effective against digestive tract pathogens
IgD - made by B-cells, they bind her
IgG - largest, longest lived, common antibody. Attacks many pathogens
IgE - found on cell membranes. Basophils and mast cells. Activates inflammatory response
What is clonal selection?
When a pathogen enters, B cells will find the right antigen with the right shape to bind to it then phagocytosis happens
What is clonal expansion?
B cells go through mitosis so it can make more of the correct antigen
What happens when leukocytes migrate to an inflammation site?
Due to loss of fluid, blood thickens so flow is slower
This gives the neutrophils time to attach to the vessel wall to start phagocytosis
What are chemotaxis?
Movement of cells due to chemical gradient - move towards or away
