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The International Encyclopedia of Primatology - PDF

Added on - 15 Jun 2021

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Please provide answers to the following questions. Some of the answers needs to be referencedin text and create a reference list.Questions:1-Name two routes of entry for pathogenic organisms1.Faecal oral route usually from an infected person or contaminated food.2.Droplet contact from coughing and sneezing from an infected person.2-Describe what mechanisms the body uses to prevent organisms it encounters for the firsttime from causing disease. (just 6 lines) with referenceIntact skin acts as a physical barrier to prevent entry of microorganisms. Mucus, broom likeaction of cilia and flushing action of tears saliva and diarrhoea acts as mechanical barriers toentry of microorganisms. Also secretions like sebum and cerumen, low PH of urine, gastricjuice, urinary and vaginal tract and lysozymes all act as chemical barrier againstmicroorganisms. Phagocytic cell such as macrophages, neutrophils and dendritic cells engulfand digest microorganisms. Secretory cells such as eosinophils, basophils and mast cell alsoplay a role. (Falkow, 2007.).3-Provide a labelled diagram to illustrate a neutrophil killing a bacterium by phagocytosis(reference the picture)(Gordon 2016)4-Explain the process of phagocytosis of an invading organism by a macrophage and thesubsequent of antigen presentation. (6 lines)Macrophages recognise certain structures which are present in microorganisms but not inhuman cells(PAMPs) such as peptidoglycan and flagella. Then it engulfs the microbe byendocytosis and produce molecules such as reactive oxygen species, lysozyme and nitricoxide which helps in phagocytosis. Inflammation then result through production of pro-inflammatory cytokines such as TNF, IL-1 and chemokines. Adaptive immunity is thenactivated through antigen presentation by use of MHC molecules.5-Give a brief overview of the role of the major histocompatibilityMHC is a cluster of genes present in all mammals. It is found in chromosome 6 in humansand plays a role in discriminating between self and non-self antigens. Also in antigenprocessing and presentation.
6-Fill in the following table of donor-recipient compatibility in the ABO blood group system,using ticks and crosses to indicate compatibility and non-compatibility, respectively, for adonation of one or two units of whole blood.DONOR0ABABRECIPIENTOABAB7-Explain why some transfusions are safe one way round but if the same donor-recipientpair are reversed (i.e. donor becomes recipient and vice-versa) there is likely to be anagglutination reaction. (5 lines)Many have RH factor on the surface of red blood cells. Those who have this antigen arecalled Rh+ and those without are Rh-. Rh- people do not have rhesus antibodies naturally intheir blood plasma. When a Rh+ receives blood from a Rh- there is no agglutination butwhen a Rh- receives blood from a Rh+ agglutination occurs because rhesus antigen cantrigger production of rhesus antibodies in the person with Rh- blood.8-What happens if you transfuse a large volume of blood from a compatible donor(according to the previous table), but with a different blood type? (4 lines)There is no antigen-antibody reaction that will occur hence there is no transfusion reaction islikely to occur but transfusing large volume of fluid may lead to fluid overload which mayresult to pulmonary oedema and acute respiratory failure.9-Use this principle to predict whether blood donors who are positive for Rhesus factor (D-antigen) cab donate small quantities (10r 2 units) of whole blood to Rhesus negativerecipients or vice-versa. (8 /10 lines)Rh positive person can donate to the Rh negative blood person only if it is for the first time.Since Rh- blood person does not have Rh antibodies naturally in their blood plasma there islikely to be no immediate danger. But on subsequent transfusion there will be severetransfusion reaction as the Rh- individual has been initial exposed to the Rh antigen and hasdeveloped antibodies against it hence agglutination will occur. A Rh- individual can donate toboth the Rh+ individual or Rh- individual without any adverse transfusion reaction occurring.This is because there is no antigen antibody reaction against the Rh antigen.10-Draw a chart to illustrate the titre (relative concentration) of specific antibodies in theblood of a patient who has been challenged with a microorganism once, and then againwith the same organism at a later date.
11-Explain the shape of this curve in terms of the role played by B and T memory cells. ( 15lines )The amount of antibodies produced during first infection is lower than during re-infection. This isbecause during first infection the antigen after being phagocytosed it is presented to T cellswhich undergo clonal expansion to produce B cells specific to the same antigen. Most of it formplasma cells which produce first antibodies which clears the infection. A fraction of it persist on along term basis as dormant memory cells and undergo mutation and selection. These B cells thathave undergone mutation have high affinity surface immunoglobulin and hence recognisesantigen better. On second infection or re-infection the number of B cells clones increaseproducing a polyclonal response hence a stronger antibody response. This increased antibodytitre and its affinity helps to clear infection faster than first infection. This is usually observed insecondary immune response. This explains why contracting such diseases as chicken pox for thefirst time signs and symptoms can be so severe and there after they gain immunity against thedisease or symptoms may be mild.12-Explain the concept of ‘Herd Immunity’ and use it to comment on the rise in recordeddeaths from measles following the campaign by Andrew Wakefield to persuade the publicthat MMR vaccine is linked to autism. (15 lines)Herd immunity is when a portion of the population is vaccinated enough to provideprotection to the rest of population not vaccinated against the disease.Andrew Wakefield and 12 of his colleagues in 1998 published a case series inLancetsuggesting that the measles, mumps and rubella vaccine may predispose autism in children.This received wide publicity and the MMR vaccination rates began to drop because parentswere worried about risk of autism after vaccination. Andrew’s claims however were provenunfounded. Following this, there was massive rise in measles epidemic outbreaks and mostcases, the deaths were linked to people were not vaccinated. This therefore, shows that theanti-MMR campaign by Andrew Wakefield interrupted the Herd Immunity which lead tomost children mot being immunised against the disease. Whenever there was measlesoutbreak therefore those not immunised were affected.13-Give a definition of the term pathogen (5 lines)
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