biology - 5d - defence against parasitic attack Flashcards
What does immune response in mammals have?
Both non- specific and specific aspects.
What are examples of non-specific defences?
Physical barriers, chemical secretions, inflammatory response, phagocytes, and natural killer cells destroying cells infected with viruses.
Examples of non-specific defences.
Epithelial tissue blocks the entry of parasites; hydrolytic enzymes in mucus, saliva and tears destroy bacterial cell walls; low pH environments of the secretions of stomach, vagina and sweat glands denatures cellular proteins of pathogens.
What does injured cells releasing signalling molecules result in?
Enhanced blood flow to the site, bringing antimicrobial proteins and phagocytes.
How do you kill parasites?
Using powerful enzymes contained in lysosomes, by engulfing them and storing them inside a vacuole in the process of phagocytosis.
What can natural killer cells do?
Identify and attach to cells infected with viruses, releasing chemicals that lead to cell death by inducing apoptosis.
What are examples of specific cellular defences?
A range of white blood cells constantly circulate, monitoring the tissues.
If tissues become damaged or invaded, what do cells release?
Cytokines that increase blood flow resulting in non-specific and specific white blood cells accumulating at the site of infection or tissue damage
What do the many difference lymphocytes in mammals each possess?
A receptor on its surface, which can potentially recognise a parasite antigen.
What does binding of an antigen to a lymphocyte’s receptor do?
It selects that lymphocyte to then divide and produce a clonal population of this lymphocyte.
What do some selected lymphocytes do?
Produce antibodies, others can induce apoptosis in parasite-infected cells.
What do antibodies possess?
Regions where the amino acid sequence varies greatly between different antibodies. This variable region gives the antibody its specificity for binding antigen
When the antigen binds to this binding site, what can the antigen-antibody complex formed result in?
Inactivation of the parasite, rendering it susceptible to a phagocyte, or can stimulate a response that results in cell lysis. Memory lymphocyte cells are also formed
What does initial antigen exposure produce?
Memory lymphocyte cells specific for that antigen that can produce a secondary response when the same antigen enters the body in the future. When this occurs antibody production is enhanced in terms of speed of production, concentration in blood and duration.
