Chapter 12- Immune Response/ Pathogens Flashcards
What are the 4 types of pathogen?
- Bacteria
- Viruses
- Fungi
- Protoctista
What type of pathogens causes TURBERCULOSIS?
Bacteria
What type of pathogen causes Influenza?
Virus
What type of pathogen causes Black Sigatoka?
Fungi
What type of pathogen causes HIV —> AIDS?
Virus
What type of pathogen causes Malaria?
Protoctista
What type of pathogen causes Ring Rot?
Bacteria
What type of pathogen causes Tobacco mosaic virus?
Viruses
What area of the plant does tobacco mosaic virus affect?
Leaves
What type of pathogen causes cattle ringworm?
Fungi
What type of pathogen causes Late blight?
Protoctista
What are the 2 ways in which transmission of pathogens can happen in animals and plants?
Direct transmission and Indirect transmission
What are the 2 types of direct transmission in humans?
Direct Contact
Droplet spread
E.g infected person coughs and expels droplets with infection. Then they are breathed in.
What are 2 types of INDIRECT transmission?
INGESTION: of contaminated food or water
VECTORS: Insects, water, air, spores
What are vectors?
Vectors are normally organisms that transfer an infection from an infected individual to a non infected individual.
- normally vectors are not harmed by pathogen.
Some vectors release SPORES, what are spores?
- They are small reproductive structures that can be highly infectious.
- Spores can also travel through water and the air and can cause disease when inhales.
State 4 different affecting factors that increase transmission of pathogens.
1) Dense population
2) Lack of trained health care workers
3) Insufficient health education
4) Climate Change: when climate is warmer, more pathogens and vectors able to survive.
Name a way that plants pass on pathogens by DIRECT transmission
Direct contact
What are 2 ways in which pathogens are transmitted via INDIRECT TRANSMISSION
1) Contaminated Soil
2) VECTORS: insects, water, air and humans
Name 3 ways that transmission of pathogens is increased in plants
1) Growing susceptible crops
2) overcrowding
3) Crops grown in damp warm environments
State 3 physical defences (in terms of barriers) that prevent pathogens from entering the plant
- Waxy cuticle
- Thick cellulose cell walls
- Closing Stomata
What happens if the physical barriers are unable to stop pathogens from getting into the plant?
- There are also physical defences that PREVENT the infection from spreading in the plant.
What is CALLOSE?
CALLOSE is a polysaccharide that is produced by the plant when a pathogen invades the plant.
CALLOSE is deposited between the cell surface membrane and the cell wall which reinforces the cell wall.
This makes it harder for pathogens to enter the cell.
What is ABSCISSION?
This a process where plants can detach the leaf if it is infected
What are chemical defences? (Plants)
Plants use chemical defences which are specific chemicals that plants produce.
Chemicals REPEL, KILL or PREVENT GROWTH of pathogens.
E.g some plants release hydrolytic enzymes that break down the cell wall of invading pathogens
What are NON specific defences?
Ways in which the body defends against ALL pathogens
Humans have 3 main ways of preventing pathogens from entering the body, what’s re these?
1) SKIN- covering entire body
2) MUCOUS MEMBRANES- line the air way, gut and reproductive system.
- they contain mucus producing GOBLET CELLS. This mucus TRAPS pathogens and contains ENZYMES and WHITE BLOOD CELLS that KILL bacteria
3) EXPULSIVE REFLEXES- removes pathogens e.g coughs and sneezes
What happens if the skin gets wounded?
- Blood near the wound clots using PLATELETS in the blood
- This forms a scab which seals the wound, preventing pathogens from entering the wound
- Beneath the scab, cells divide by mitosis to heal the wound
If pathogens manage to enter through a wound on the body, what happens in response to this?
- The site of the wound becomes INFLAMED
- this occurs when blood vessels around the site DIALTE and their PERMEABILITY INCREASES.
- this causes fluid to enter the tissue which creates SWELLING and allows white blood cells to enter the tissue to kill the pathogens
What are lymphocytes?
Lymphocytes are a type of white blood cell that can identify cells that don’t belong in our bodies
- They can tell the difference between self cells and non- self cells.
DEFINE an antigen
An antigen is a protein in the cell surface membrane that triggers an immune response
What do lymphocytes use to identify non self cells?
ANTIGENS
How do lymphocytes recognise ANTIGENS?
- All lymphocytes have ANTIGEN RECEPTORS on their cell surface.
Describe receptors on lymphocytes and how they help to identify antigen.
- Lymphocytes have receptors that are complementary to the particular antigen.
- So lymphocytes receptors can bind to the antigen which activates the lymphocyte to trigger an immune response.
Do lymphocytes trigger a SPECIFIC or NON SPECIFIC IMMUNE response?
SPECIFIC IMMUNE RESONSE
- due to their receptors being complementary to a single antigen.
Are we born or not born with lymphocytes?
Born with them, body has around 10 million different lymphocytes in body
What are phagocytes?
A type of white blood cell, they recognise ALL non self cells
How do phagocytes identify pathogens?
- They use molecular patterns on the surface of pathogens.
- Phagocytes have receptors that are complementary to the patterns the pathogens have.
- They bind to the molecular patterns on the pathogen which causes an immune response.
Do phagocytes produce a SPECIFIC or NON SPECIFIC immune response?
NON SPECIFIC Immune response
Describe the process of phagocytosis (6 marks)
1) Pathogens release toxins that attract phagocytes and so attract them to the area of the pathogens. They move along a concentration gradient.
2) When they reach pathogens, they bind to pathogen, recognising it as a non self cell due to their molecular pattern on pathogens surface.
3) Phagocyte then CHANGES shape, moving around the pathogen and ENGULFING it. It leaves the pathogen in a sack like structure, vesicle. This vesicle containing the pathogen is called a PHAGOSOME.
4) Once Phagosome formed, some of the lysosomes in phagocyte move towards PHAGOSOME and FUSE with it forming a PHAGOLYSOSOME.
5) LYSOSOMES then release some LYSOZOMES, this catalyses a hydrolysis reaction of the break down of the pathogen.
What is the structure called when the pathogen has been engulfed in the phagocyte?
Vesicle like structure, PHAGOSOME.
What are CYTOKINES and what do they do?
- They are CHEMICALS ,released by phagocyte when they engulf a pathogen.
- CYTOKINES attract more phagocytes to the site of infection making sure they destroy as many pathogens as possible.
What are OPSONINS and what do they do?
- They make it easier for phagocytes to recognise pathogens.
- Opsonins BIND to antigens on a pathogen and prevent the pathogen from repelling phagocytes.
- Phagocytes have receptors which are complementary to ops is which means that they can bind to pathogens and phagocytes.
What are phagocytes with a lobed nucleus called?
Neutrophil
What are white blood cells called with a round nucleus called/
LYMPHOCYTES
Where are lymphocytes initially produced?
Bone marrow (special tissue in bones)
What type of lymphocytes stay in the bind marrow to mature?
B Lymphocytes (or B cells)
Which type of lymphocyte move out f the bone marrow and mature in the THYMUS?
T Lymphocytes (T cells)
What are naive B cells?
B cells that haven’t came into contact with a pathogen before.
What happens when a naive B cell comes into contact with a pathogen?
- Naive B cell has receptors that bind to antigens on pathogen.
- Naive B cell then internalises the pathogen and breaks it down.
- Instead of the B cell absorbing/ rejecting all of the broken down pathogen, B cell keeps a hold of antigens of pathogen, processes them and then presents them on surface of B cell.
What happens after the Naive B cell has presented the pathogens antigens on the B cell surface?
- T cells with complementary receptors to the antigens the B cell has presented on its surface.
- T cells then bind to those antigens
- When this happens, T cells release chemicals called INTERLEUKINS
- These INTERLEUKINS stimulate the B cells which encourages them to CLONE itself.
What types of cells can B cell clones differentiate into?
Plasma cell (producing antibodies)
OR
Memory B cells (sit and wait until pathogen and antigen have been dealt with)
What are the T cells called that bind to B cells that have presented antigens of a pathogen on their surface, which stimulate the B cells to clone them selves?
Helper T cells
How long do plasma cells last for?
Typically a few days
What do plasma cells do?
Secrete a protein called an antibody
(Antibodies contribute to the destruction of antigens)
What is the structure of antibodies?
4 chains which consist of amino acids held together by peptide bonds.
Can antibodies bind to all antigens of pathogens?
NO
- They have individual antigen binding sites (formed as a result of antibodies tertiary structure)
What is the antigen binding site on an antibody known as?
VARIABLE region
How are plasma cell formed?
Formed as a result of naive B cell cloning itself after binding itself to a specific antigen.
Once a plasma cell exists, what happens after? (To do with antibodies)
- Once plasma cell exists, doesn’t need to wait to come into contact with offending antigen again.
- It secretes the relevant antibody automatically.
Define an antibody
An antibody is a protein produced by a naive B cell in response to the presence of a specific antigen.
What is it called when plasma cells secrete one type of specific antibodies?
Monoclonal antibodies
Define monoclonal antibodies
Antibodies with the same tertiary structure, produced from cloned b cells.
What is it called when an antibody binds to antigen complementary antigen?
When they bind, it is called an ANTIGEN- ANTIBODY COMPLEX.
How many antigen binding sites do antibodies have?
2 antigen binding sites which means antibodies can bind to two antigens at once.
What is AGGLUTINATION and why is it a benefit for antibodies and phagocytosis?
- When antibodies bind to 2 antigens at once and other antibodies this causes the antigens to clump together.
- This makes it harder for pathogens to move through the body.
- This makes it EASIER for phagocytes to locate them and destroy a large amount of pathogens in one go.
What are antibodies called that carry out agglutination?
AGGLUTININS
Describe antibodies that act as Opsonins
- Phagocytes have receptors that are complementary to some antibodies in blood.
- Therefore, antibodies can bind to pathogen and phagocytes, allowing phagocyte to destroy it.
- This also helps phagocytes to identify the pathogens.
Describe antibodies acting as anti toxins
- Most pathogens invading our bodies produce toxins which can damage cells
- Some antibodies can bind to these toxins and prevent them from functioning, keeping cells healthy.
How long can B memory cells survive in our bodies?
Can survive for years in body
Why do B memory cells last in the body for a while?
They remain once ALL non self cells and specific antigens have been debult with
They wait to attack in case the non self cell with familiar antigen invades again.
What happens if a familiar antigen invades again with memory B cells present?
- Memory B cells act in the same way as naive B cells would.
- So memory B cell receptors bind to antigen, internalise them, processes antigens and presents them o its surface.
- T helper cell stimulates B memory cell to clone itself
- Clones then either differentiate into plasma cells or remain as memory B cells.
State the differences between Naive B cells and Memory B cell
Naive B cells doesn’t know antigen, responds much slower than memory cells that remember antigens so can respond quicker.
Due to memory B cells drastically outweighing naive B cells, cloning happens in greater amounts including plasma cells being produced therefore overall antibody producing is greater in second response.
What is the entire process of primary and secondary response to antigens known as?
The Humoral Response
Where does the Humoral response take place?
Bodily fluids- blood
Why type of cells do T cells receptors bind to?
Antigen- presenting cells
What are some examples of antigen presenting cells?
1) Phagocytes can become antigen presenting cells.
Once the phagocyte has finished hydrolysis of pathogen it has engulfed, some phagocytes process the pathogens antigens and present them on their surface.
2) Own body cells can also become antigen presenting cells
When virus enters body cell, virus beings to replicate in cel.
During replication, antigens form which body cell can process and present on their cell surface.
Why do T cells only bind to antigen presenting cells?
-When antigens processes, they are changed slightly
- T cell receptors are only complementary to these changes not when they haven’t been changes.
When T cells are in the THYMUS, they can develop into 3 different types of T cell. State all three types.
Helper T cells
Killer T cells
Regulatory T cells
What are Naive Helper T cells?
They are T cells that haven’t encountered an antigen before.
What happens when naive helper T cells encounter an antigen on an antigen presenting cells?
Receptor of T helper cell binds to antigen on phagocyte
When they bind together, this stimulates T cell to form clones
What are the roles of cloned helper T cells?
- BIND TO ANTIGEN PRESENTED ON B CELL, which stimulates B cell to clone and then differentiate.
- RELEASE CHEMICALS that attract phagocytes to pathogens.
- STIMULATE KILLER T CELLS, helps them target INFECTED BODY CELLS (by virus) ad kill them.
- DEVELOP INTO MEMORY CELL
When cloned T helper cells take on different roles, what is their activity called?
MEDIATED RESPONSE
What are the receptors on Killer T cells complementary to?
Virus infected cells with antigens presented on their surface
What do Killer T cells release when they bind to antigens?
PERFORIN
What does the chemical PERFORIN do when it is released by killer T cells?
Causes holes to form in virus infected body cells cell membrane.
This means it is easier for substances e.g iron to flow in and out of cell in an uncontrolled way.
This disrupts cell and leads to infected cells death.
What do regulatory T cells do?
Suppress an immune response
- They identify when all of the foreign antigens in body have been completely eliminated.
- Once done, shuts down immune response keeping own cells safe.
What would happen if our immune system wasn’t monitored and regulated?
Immune system would attack our own cells and make us ill.
