11. Animal Physiology : 11.1 Antibodies Flashcards
What is meant by immunity?
Immunity:
- recognition of self
- destroy foreign matter
- has memory cells that produce antibodies to recognise and eliminate threats
What do the surface of human cells contain? What about cells of bacteria and viruses?
- human: large carbohydrates, glycoproteins, polypeptides
- Bacteria: molecules
Define an antigen.
An antigen is any molecule that can trigger an immune response leading to the generation of antibodies.
Give some examples of non-self molecules.
Viruses Fungi Parasite Bacteria Pollen Transplant of organs Foreign substances
What is a rhesus factor?
Rh+ antigen found on the surface of red blood cells in people who are rhesus positive or Rh- when you lack it
What does red blood cells have? Explain the three blood groups.
- have antigen H on surface
- A: molecule of N-acetylgalactosamine + antigen H
- B: molecule galactose
- AB: both molecules
What is hemolysis?
- the breakage of the red blood cell’s membrane, leading to the release of the haemoglobin and other internal components into the surrounding fluid
- Agglutination causes hemolysis
- May lead to death
Why is there a trigger once an antigen enters body?
- body needs to assure the antigen doesnt spread
- produce memory cells
Explain the process of the immune system once an antigen enters the body.
- Antigen is ingested by macrophages and B cells for processing
- the macrophage interacts with T helper cell and activates it
- T cell interacts with B cell, B cell divides to form clones of plasma and memory cells
- Memory cells stays in body for long time to provide long term immunity to diseases
What makes plasma cells well suited for producing antibodies againts the antigen?
Possess a lot of rough endoplasmic reticulum and a golgi apparatus
Where are antibodies produced?
The memory B cells divide to form plasma cells. Produces once the immune system has reacted to the invasion of an antigen.
What are the two variable regions of an antibody?
The part of the antibody which is specific to the antigen
The long and short chains are held together by disulphide bonds
What is opsonization?
The coating of a pathogen with antibodies to promote and enhance phagocytosis
When do complement proteins become activated?
When interaction with antigen, the function is fulfilled with antigens.
How do antibodies help the destruction of pathogens?
- antigen is presented to complement protein
- the latter is split in two to give rise to the protein that binds to the membrane of pathogens
- it may increase its change of being engulfed by phagocytic cell
- may trigger the release of histamine
- these eliminates pathogens
What occurs in a primary response and a secondary response?
- 1st: memory cells are produced to ensure that body remembers the infection
- 2nd: faster reaction of same antigens, memory cells divide by mitosis to form clones of plasma cells and more memory cells, divide faster becoz it doesnt need an antigen
Why are vaccines used to trigger immunity?
- helps body get used to same antigen
- contains antigens that help produce memory cells that recognises the pathogen
- more cells are produced faster next time
Why are flu shots against influenza virus necessary?
- the virus mutate quickly so body might not recognize
- mutations change antigens so need new type of vaccines each year
What is an allergen and what occurs when there is an allergic reaction?
Allergen: substance that cause allergic reaction
- allergic reaction caused by histamines (strong response of immune system)
Describe how histamines are released in response to allergens.
- released by basophils and mast cells in the connective tissues
- white blood cells and some proteins invade the affected tissues and engage the allergens
- can bind to membrane-bound histamine receptors and cause allergic reactions
What are antihistamines?
Drugs that inhibit the action of histamine in the body by blocking the receptors of histamine
Explain the process of an immune response to an allergen.
- Allergen enters body
- B cell comes into contact with the allergen
- Plasma cells start producing the allergen-specific IgE, an antibody that circulates in the blood and binds to mast cells
- This triggers the release of histamines and other cellular inflammatory compounds
What are monoclonal antibodies used as?
Used as therapeutic agents in rheumatoid arthritis, B cell leukaemia and non-hodgkin’s lymphoma
What are monoclonal antibodies?
Monospecific antibodies that target the same antigen, produced from one cloned plasma cell
They can recognise and bind to one specific region of the antigen
What are polyclonal antibodies?
Antibodies secreted by plasma cells from different B cell lineages that have recognised different epitopes of one specific antigen
How are monoclonal antibodies produced?
Fusion of a tumour cell with an antibody-producing plasma cell creates a hybridoma cell
A hybridoma cell creates monoclonal antibodies.
How do pregnancy tests work?
- Dipstick in urine of woman
- If urine contains hCG, the anti hCG will bind to the hormone
- If the hormone then binds to the monoclonal antibody, a blue line will appear and woman is pregnant.
- If urine moves up to the dipstick, crosses another line ‘control line’
- Control line: contains an antibody to the dye
- If the second line is not indicated, the test is invalid
Explain how monoclonal antibodies are produced.
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