Immunity Flashcards
What are innate (non specific) defences?
You are born with these and contain surface barriers and internal defences.
What are adaptive (specific) defences?
These are developed after meeting a pathogen (best way to fight them and for future) and contain humoral and cellular immunity.
How is skin a mechanical barrier?
(first line of defence)
Produces sebum (oily, greasy substance) that acts as film on skin to stop things living on it, also has pH of 4.5- 6- prevents things growing on it.
What is the pH of the skin?
4.5-6
How are mucous membranes a mechanical barrier?
(first line of defence)
Any opening in the body is a weak point. Mucous helps trap dust and bacteria and brings it up to the throat to either cough or swallow it.
How is stomach acid a chemical barrier?
(first line of defence)
Has a pH of 1.2-3 so things get killed (very inhospitable).
How are lysozymes a chemical barrier?
(first line of defence)
This is found in tears and saliva (tears help dissolve any pathogens etc).
How are Stomach interferon antimicrobial proteins?
(second line of defence)
If a cell is infected, these alert neighbouring cell to get in the way of viral replication (produce antimicrobial proteins).
How are complements antimicrobial proteins?
(second line of defence)
These are like ‘cheer leaders’ and help to enhance the immune response (make it more effective).
How are transferrins antimicrobial proteins?
(second line of defence)
These inhibit bacterial growth as they are iron finding proteins. They bind to Fe to prevents bacteria binding and replicating.
What do natural killer cells do?
(second line of defence)
These release perforins which enter into the pathogen and make the membrane leaky so the cell ‘blows up’ or can attach the cell directly.
What do phagocytes do?
(second line of defence)
These engulf cells (pathogens) and can be fixed or wandering macrophages (secrete enzymes to break down).
How is inflammation a secondary line of defence?
This causes redness, pain, heat and swelling.
How is (mild) fever a secondary line of defence?
This is when the body’s thermostat is reset to a higher temp which is helpful as bacteria don’t like higher temp as it slows them down. Higher temp also enhances interferon, inhibits microbial growth and speeds up repair.- all for a mild fever.
What is the problem with a high fever?
This isn’t good for our bodies as this can denature enzymes.
What are adaptive defences characterised by?
-Specificity- invading agent recognised as different (unique properties)
-Memory (second response greater than the first).
What does cells being ‘non-self’ mean?- (antigens)
This means they don’t belong in our body and need to be gotten rid of.
Where do lymphocytes originate?
Bone marrow.
What happens once lymphocytes are mature?
They acquire specific antigen receptors so they can recognise a specific invading agent.
What is meant by immunocompetence?
This is the ability to detect, identify and respond.
What is meant by self- tolerance?
This is the ability to identify self cells from non- self cells.
How are B and T cells different?
It depends on where they mature.
Where do B cells mature?
In the bone.
Where do T cells mature?
In the thymus.
Why is it called the humoral response?
This is everything to do with the humors (fluids) in the body.
How are antibodies produced from B cells?
Once an antigen is identified by a B cell, this activates it. They then form a clone and become plasma cells.
Plasma cells then secrete antibodies.
What are memory B cells?
These are B cells that don’t clone and are used to retain knowledge so that the response can be used in future and even better.
What is the class of antibodies- IgG?
This is the main antibody that can cross the placenta (supports newborn babies).
What is the class of antibodies- IgE?
These are associated with allergies and parasitic infections.
What process are T cells involved in?
Cell mediated immune responses.
What are cell mediated immune responses?
These are directed against intracellular pathogens like viruses, cancer cells and tissue transplants.
What are the two types of T cells?
Killer T cells and helper T cells.
What do killer T cells do?
These directly attack the invading pathogen.
What do helper T cells do?
These help antibody and cell mediated responses.
What do T cells have to have to become activated?
They have to be presented with a fragment of a killed pathogen to recognise.
What is an APC cell?
These are antigen presenting cells (often dendritic cells) (show how to get rid of the pathogen).
What are CD4 cells?
These become helper T cells.
What are CD8 cells?
These become cytotoxic/ killer T cells.
What is the function of memory cells?
Produced by both B and T, have memory of antigen, allows for further response to be much quicker and greater (end result is the symptoms aren’t seen by us).
Why are primary responses slow and ineffective?
There aren’t any memory cells to help defeat the invading pathogen quicker so signs and symptoms are seen.
What is an autoimmune response?
This is where the body attacks its own tissues and doesnt recognise them as self.
When does an allergy occur?
When a person reacts to a substance that’s normally tolerated by people (eg pollen, dust mites)- caused by allergens.
