Defence Against Parasitic Attack Flashcards
What does the immune response in mammals have?
Both non-specific and specific aspects
What is the definition of non-specific defences?
Immune system defence mechanisms in organisms that attempt to prevent any parasites forming infecting the potential host
What do examples of non-specific defences include?
-Physical barriers and chemical secretions
-Inflammatory response
-Phagocytes
-Natural killer cells destroying cells infected with viruses
What does the non specific defence physical barriers and chemical secretions do?
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 gland denatures cellular proteins of pathogens.
What does the non specific inflammatory response do?
Injured cells release signalling molecules. This results in enhanced blood flow to the site bringing antimicrobial proteins and phagocytes
What does the non specific phagocytes do?
Killing of parasites using powerful enzymes contained in lysosomes, by engulfing them and storing them inside a vacuole in the process of phagocytosis
What does the non specific natural killer cells destroying cells infected with virus do?
These cells can identify and attach to cells infected with viruses releasing chemicals that lead to cell death by inducing apoptosis
What do a range of white blood cells constantly do?
The constantly circulate monitoring the tissues.
What happens if tissues become damaged or invaded?
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 different lymphocytes that mammals each possess?
Each posses a receptor on its surface, which can potentially recognise a parasite antigen
What does the binding of an antigen to a lymphocyte’s receptors do?
The antigen selects that lymphocyte to then divide and produce a clonal population of this lymphocyte. Some selected lymphocytes will 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 to antigens
What happens when an antigen binds to to the antigen binding site on the variable region of an antibody?
The antibody-antigen complex formed can result in inactivation of the parasite, rendering it susceptible to a phagocyte, or can stimulate a response that results in cell lysis
What happens during initial antigen exposure?
Memory lymphocyte cells can be produced which are specific for an antigen. So that if the same antigen enters the body in the future, a secondary response can be produced by the memory lymphocyte cells. When this occurs antibody production is enhanced in terms of speed of production concentration in blood and duration.
