Unit 2 - Topic 5 - Parasitism - Section D - Defence against Parasitic Attack Flashcards
Immune response in mammals has what two aspects
Non-specific and specific aspects
What are examples of non-specific defence
Physical barriers, chemical secretions, inflammatory response, phagocytes, and natural killer cells destroying cells infected with viruses
Examples of physical barriers and chemical secretions
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
Explain the inflammatory response
Injured cells release signalling molecules. This results in enhanced blood flow to the site, bringing antimicrobial proteins and phagocytes.
Describe phagocytosis
Killing of parasites using powerful enzymes contained in lysosomes, by engulfing them and storing them inside a vacuole in the process of phagocytosis.
Explain natural killer cells
Natural killer cells can identify and attach to cells infected with viruses, releasing chemicals that lead to cell death by inducing apoptosis
What type of cell constantly circulate and monitor tissues
White blood cells
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
Mammals contain many different what which can potentially recognise a parasite antigen
Mammals contain many different lymphocytes, each possessing a receptor on its surface, which can potentially recognise a parasite antigen
What happens when a antigen binds to a lymphocyte’s receptor
Binding of an antigen to a lymphocyte’s receptor selects that lymphocyte to then divide and produce a clonal population of this lymphocyte
What do some selected lymphocytes produce
Antibodies, others can induce apoptosis in parasite-infected cells
Antibodies posses what and what does this region give antibodies
Regions where the amino acid sequence varies greatly between different antibodies. This variable region gives the antibody its specificity for binding antigen
What happens when an antigen binds to this biding site
The antigen-antibody 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 lymphocytes are also formed
Memory lymphocytes
How are memory lymphocytes formed
Initial antigen exposure produces 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.
