3.2.4 Cell Recognition + The Immune System Flashcards
What are pathogens
Micro-organisms that cause disease
What are the 2 types of pathogens and how do they cause disease
Virus - invade cells, take over + burst them (kill body cells)
Bacteria - release toxins that make you ill
Why do many pathogens not harm us
As were resistant to them not having the needed conditions
5 examples of defences we have for pathogens that do harm us
Tears Ear wax Skin Mucus Sweat Cilia Anus Urine
What antibacterial enzymes do tears contain
Lysozymes
How do earwax and skin work as defences
Earwax - has antiseptic properties
Skin - barrier
How do mucus and sweat work as defences
Mucus - traps bacteria in airways
Sweat - has antiseptic properties
What does cilia do to mucus as a defence
Traps and sweeps mucus up
What does the harmless bacteria in the anus do to pathogens
Outcompetes them
How does urine work as a defence
It’s antiseptic and so flushed bacteria out of urethra
What are antigens
4 things they identify
Markers on the cell surface that allow the immune system to identify:
pathogens
cells from other organisms of same species
Abnormal body cells -> mutated
Toxins
4 things antigens can be made from
Proteins
Carbohydrates
Glycoproteins
DNA
What are non-self antigens detected by
White blood cells
What are the 2 types of immune response
Non-specific immune response
Specific immune response
What’s a non-specific immune response launched against
Anything (to any non-self antigen) bacteria that doesn’t belong to you
Advantage and disadvantage of non-specific immune repsinse
Fast response to possible infection
Only temporary, doesn’t give long lasting immunity
What are the 3 types of non-specific immune response
Fever
Inflammation
Phagocytosis
How do pathogens cause a fever
They cause the hypothalamus in the brain to change the body’s thermostat
What does a fever do do the pathogen more so than the body cells
What’s the temperature for this
Increased temperature damages pathogen more than body cells
37*c + can denature pathogen
What inflammation a build up of
4 symptoms of it
Build up of fluid
Redness
Swelling
Pain
Heat
What becomes more permeable when there’s inflammation
Therefore what can escape the blood and enter tissue fluid easier (3)
Capillaries
White blood cells
Antibodies
Compliment proteins
What do compliment proteins do
Trigger a series of events that leads to lysis of bacteria
What are the 2 phagocytes
Macrophages (most useful)
Neutrophils
What do phagocytes target
Anything that doesn’t belong to you (non-self antigens)
What’s phagocytosis
Ingestion + digestion of microbes by phagocytes (type of WBC)
Describe the process of phagocytosis (6)
- Damaged tissue by infection released mediators
- Chemotaxis occurs + phagocytes engulf pathogen
- Once engulfed, the pathogen is stored in a phagosome vesicle
- Lysosomes in phagocyte migrate to phagosome and fuse with membrane, secreting lysozyme enzymes
- The enzymes digest the pathogen
- Pathogens remains (debris) is absorbed and can be used again by cell
What are mediators
Chemicals that attract macrophages (released by damaged tissue)
What’s chemotaxis
Movement in direction of a chemical
How to phagocytes engulf a pathogen
By extending , wrapping membranes around + engulfing
What’s the vesicle called that a pathogen is enclosed and stored in
Phagosome
What do lysosomes secrete and what do they do
Lysozyme enzymes that digest the pathogen
What are the 2 types of WBCs used
Phagocytes
Lymphocytes
What responses are lymphocytes involved in
Specific immune response
What part of the body is protected from infections by lymphocytes
Foetus
Adv + disadvantage of specific immune response
Slower
But longer lasting
2 types of specific immune response
Humoral (antibody mediated response)
Cell mediated response
What particular type of lymphocyte does cell mediated immunity involve
T-cell
How many types of lymphocytes are there
10 million
What are T-cells called this
T - matured in thymus gland (centre of chest)
What are the many different types of T cell each capable of
Recognising a different antigen
What does each T-cell have in its surface
A different type of receptor - complimentary to 1 specific antigen (only 1 t-cell for each disease)
Why does cell mediate response take a long time
As there’s only 1 individual T-lymphocyte that matches 9tsk4s dats to come into contact)
What does every pathogen have that different
Different antigen
What happens to a t-cell if a t-cell receptor binds to an antigen
The T-cell multiplies rapidly via mitosis (activated)
Once bound to a non-self antigen, what are the T cells known as
T helper cells
What 4 things do t helper cells cause to happen once bound to a non-self antigen
- Memory cells form
- Further phagocytosis
- B lymphocytes to divide
- Activate cytotoxic T cells
What do memory cells enable
Quick responses to secondary infection
What does further phagocytosis activate more of
Macrophages
How are cytotoxic T cells activated
By release of chemicals (cytokines)
What are cytotoxic T cells also known as
Killer T cells
What do lots of cytotoxic T cells do (2)
All bind do antigens and either:
- Release chemicals (perforins) that cause holes in pathogens membrane so it’s permeable and will die
- Coat the cell in chemicals so it’s a target for phagocytosis (chemotaxis)
What are the chemicals called that cytotoxic T cells release causing holes in pathogens membrane
Perforins
What happens to the pathogen once perforins make it permeable
It will die as it can fill with water and explode
What type of antigens on body cells can T cells specifically recognise
Foreign antigens
Where is an antigen fragment associated with an MHC molecule transported to and what recognises this combination
Transported to the cell’s surface. Where the combination is recognised by a T cell, alerting it to the infection
Describe the cell mediated immune response (3)
- The T cells secrete cytokines (chemicals)
- The cytokines cause the division of killer T cells by mitosis
- The killer T cells divide into killer cells + memory cells
What’s the process of stimulating the production of active killer T cells called
Colonial expansion/selection
What types of cells do killer T cells terminate
Cancer cells
Cell infected by a virus/bacterium
What is cell mediated response protection from (6)
Viruses Bacteria Cancerous cells Transplanted tissue Fungi Parasitic worms
What do B cells attack
What do T cells attack
B cells -> attack invaders outside cells
T cells -> attack invaders inside cells
What are antibodies a type of
What’s this specific type called
Proteins (amino acids held by polypeptide bonds)
Specific type of protein called immunoglobulins
What shape are antibodies and what are they made up of
What’s the type of structure
Y shaped
Made up of 4 polypeptide chains
Quaternary structure
What are the 2 types of chains on an antibody
Light chain (short) Heavy chain (long)
What bit of an antibody is the variable region (differs), bit that binds to antigen
Top of light chain (short)
How many binding sites does an antibody have
What does it form when it binds to antigen
2 binding sites so can bind to 2 antigens
Forms an antibody antigen complex
What are antibodies produced by
White blood cells called b-lymphocytes (b cells)
When do b lymphocytes develop
Where to they remain inactive until infection will activate them (3)
Develop before/just after birth
Remain inactive in lymph nodes/ liver/ spleen
What does the B cell do once an antigen binds to its receptor
Antigen is absorbed into B cell and displayed on B cells membrane
What cells attach to the presented antigen on the B cell that causes mitosis
T-helper cells
What 2 things can B-cells become after mitosis
Plasma cell
Memory cell
What 2 components are plasma cells filled with and why
RER -> to make proteins
Mitochondria -> for energy
What’s the life span of plasma cells and what do they do
What type of response involves plasma cells
Life span of a few days and they secrete antibodies into the blood
This is a primary immune response
What’s the life span of memory cells and what do they do
What type of response involves memory cells
Can live for decades in blood/tissue fluid
They retain information on antibody production and can divide if the correct antigen is present
Type of secondary immune response
