immunity and infection
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example of chemical barrier
lysozyme in mucus hydrochloric acid in the stomach
describe infection control practices hospitals have introduced
hand wash stations testing patients for presence of antibiotic resistant bacteria before admission increased washing of bedding/ disinfection
Explain how changes in the blood vessels result in the redness and swelling seen at the site of inflammation
histamine is released - causes vasodilation increases blood flow to affected area - also increases permeability of capillaries to increase allows blood plasma to leave the capillary
describe how HIV particles are able to enter t helper cells
glycoproteins on the surface of the virus (GP120) bind to CD4 receptors on the surface of T helper cells viral envelope fuses with the cell membrane of T helper cells viral RNA enters the cell
Explain why the destruction of T helper cells causes the symptoms of AIDS.
lack of T helper cells reduces cytokine production - reduces activation of B cells reduces antibody production increased risk of opportunistic infections
how to bacteriostatic antibiotics work
preventing multiplication of bacteria
which cell produces antibodies
plasma cell
Explain why the presence of microorganisms on the skin and in the gut helps to prevent pathogenic organisms multiplying in the body.
flora in the gut and skin are better adapted to conditions in body so they can outcompete pathogenic organisms bacteria in the gut secrete chemicals which help destroy pathogens
Explain why these antibiotics could affect the production of proteins in bacteria.
ribosome shape is altered mRNA prevented from binding to ribosome translation can not occur protein is not synthesised
Devise a laboratory procedure to compare the effectiveness of penicillin with one of the new antibiotics. (6)
prepare agar plates seeded with bacteria- that is resistant to other antibiotics prepare solutions of new antibiotic and penicillin place solution onto paper discs control time and temp of incubation and conc of antibiotic measure zone of inhibition repeat for effective antibiotics repeat with different strains of resistant bacteria
A person who has been vaccinated becomes infected with HPV-16. Explain the role of the T cells in the body of this person.
vaccinated person will have t memory cells - these recognise antigens specific to virus - t helper cells activate b cells/ t killer cells t killer cells destroy cells infected with virus
Explain why there are relatively few species of bacteria in the stomach
pH in stomach is too low for enzymes of most bacteria to function any enzymes in the stomach have adaptations that allow them to survive
what is meant by term bacteriostatic antibiotic
substance which can inhibit the growth of bacteria
structure of HIV
contains two strands of RNA have glycoproteins HIV is spherical