Cellular Defense in animals
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Name three of the body's first lines of defence
- mucus and cilia
- coughing, sneezing, and vomiting
- acid in the stomach
- ear wax
- blood clotting
The body's second lines of defence are brought about mainly by what type of cells?
White blood cells
What do these white blood cells do?
They recognise and respond to the presence of invading foreign particles
What is phagocytosis?
Phagocytosis is the process by which foreign bodies, such as bacteria, are engulfed and destroyed.
Cell which carry out phagocytosis are called...?
- A phagocyte detects chemicals released by a bacterium and moves along a concentration gradient towards it
- The phagocyte attaches to the bacterium and engulfs it in a vacuole
- Lysosomes move towards and fuse with the vacoule and release their powerful digestive enzymes into it
- The bacterium is digested and the breakdown products are absorbed by the phagocyte
Where are lysosomes found in a phagocyte?
In the phagocyte's cytoplasm
What is a person's primary response?
- When a person is infected with a virus their body produces antibodies, this is called the primary response.
- The primary response is often unable to prevent the person becoming ill
What is a person's secondary response?
- If the person recovers and is re-exposed to the same antigen this results in the secondary response
- This time the disease is usually prevented because:
- anitbody production is more rapid
- the concentraion of antibodies produces reaches a higher level
- the higher concentration of antibodies is maintained for a longer time
The secondary response is made possible by _____ cells?
What are lymphocytes?
Lymphocytes are white blood cells which produce antibodies
These lymphocytes are _____ to the antigen from the first exposure?
Each lymphocyte is capable of recognising and responding to one...?
What shape is an antibody?
What does each arm of a lymphocyte bear?
A receptor site
How does a person have naturally acquired immunity?
The person is exposed to the disease-causing antigen, suffers the disease, makes antibodies and continues to be able to for a long time (or even permanently) after recovery. The person is therefore immune to future attacks by that antigen
How does a person have artificially acquired immunity?
The person recieves a small amount of vaccine containing antigens which have been treated in a certain way so that they induce antibody formation but do not cause the disease
What is passive immunity?
Instead of the individuals making antibodies in response to the antigen, ready made antibodies are passed into his/her body.
Where does passive immunity occur naturally?
When antibodies cross the placenta from mother to foetus and from milk to suckling baby.
How is passive immunity brought about artificially?
By extracting antibodies that have been made by one organism (eg horse) and injecting them into another (eg human).
What is tissue rejection?
When the T lymphocytes of the recipient's immune system reagard the new tissue as a collection of foreign antigens and attempt to destroy them
Tissue rejection always occurs unless donor and recipient are genetically _______?
What kind of drugs are used to increase the chance of a successfull organ transplant?
What is the problem with immunosuppressor drugs?
They greatly inhibit the recipient's immune system and make the person more susceptible to disease
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