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Question 1
Correct
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A 45 year old man who complains of chronic post prandial, burning epigastric pain undergoes a gastrointestinal endoscopy. There is no apparent mass or haemorrhage and a biopsy is taken from the lower oesophageal mucosa just above the gastro-oesophageal junction. The results reveal the presence of columnar cells interspersed with goblet cells. Which change best explains the above mentioned histology?
Your Answer: Metaplasia
Explanation:Metaplasia is the transformation of one type of epithelium into another as a means to better cope with external stress on that epithelium. In this case metaplasia occurs due to the inflammation resulting from gastro-oesophageal reflux disease. Dysplasia is disordered cellular growth. Hyperplasia is an increase in cell number but not cell type i.e. transformation. Carcinoma is characterized by cellular atypia. Ischaemia would result in necrosis with ulceration. Carcinoma insitu involves dysplastic atypical cells with the basement membrane intact and atrophy would mean a decrease in number of cells.
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This question is part of the following fields:
- Cell Injury & Wound Healing
- Pathology
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Question 2
Correct
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Which of the following cells release histamines when they are activated by binding of specific antigens to cell fixed IgE molecules?
Your Answer: Basophils
Explanation:Mast cells and basophils both contain granules of vasoactive histamine in their cytosol. Both of them express IgE receptors on their cell surface and upon binding with a specific antigen they release their cytokines including histamine.
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This question is part of the following fields:
- Immunology
- Physiology
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Question 3
Correct
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A 40 year old woman, who is under anaesthesia for an elective procedure, received an antibiotic injection. She immediately developed a rash and her airway constricted raising the airway pressure. Which mechanism is responsible for this reaction?
Your Answer: Type I hypersensitivity
Explanation:Type I hypersensitivity reaction is an immediate reaction that occurs due to binding of the antigen with antibodies attached to mast cells in a previously sensitized person. It has an immediate phase, which is characterised by vasodilation, leakage of plasma, smooth muscle spasm, or glandular secretions. This manifests in about 5-30 min and usually resolves within 60 mins. The delayed phase follows after 24 hours and can persist up to several days. It is due to infiltration of eosinophils, neutrophils, basophils and CD4+ cells and leads to tissue destruction. The nature of the reaction varies according to the site. It can take the form of skin allergy, hives, allergic rhinitis, conjunctivitis, bronchial asthma or food allergy.
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This question is part of the following fields:
- Immunology
- Pathology
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Question 4
Correct
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Cells mediating innate immunity include:
Your Answer: Natural killer cells
Explanation:Natural killer cells have features of both innate and adaptive immunity. They play an important part in defence against tumours and viruses. They are non specific and do not generate immunological memory
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This question is part of the following fields:
- Immunology
- Physiology
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Question 5
Correct
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Which cells produce the immunoglobulin proteins involved in mediating humoral immunity?
Your Answer: Differentiated forms of B lymphocytes known as plasma cells
Explanation:After the B cells have been activated by a certain antigens, they transform into plasma cells. These plasma cells are responsible for the generation of antibodies (or immunoglobulins Ig) which are also known as regulators of humoral immunity. There are fives classes of Ig: IgA, IgG, IgM, IgE and IgD
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This question is part of the following fields:
- Immunology
- Physiology
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Question 6
Correct
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In which of the following would you NOT typically see a neutropaenia:
Your Answer: Asplenism
Explanation:Causes of neutropaenia: Drug-induced (e.g. chemotherapy, chloramphenicol, co-trimoxazole, phenytoin, carbamazepine, carbimazole, furosemide, chloroquine, clozapine, some DMARDs) Benign (racial or familial) Cyclical Immune (e.g. SLE, Felty’s syndrome, hypersensitivity and anaphylaxis) Leukaemia Infections (e.g. HIV, hepatitis, fulminant bacterial infection) General Pancytopaenia Hypersplenism, aplastic anaemia, malignant infiltration of bone marrow, megaloblastic anaemia, chemotherapy, myelodysplasia
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This question is part of the following fields:
- Immunology
- Pathology
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Question 7
Correct
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The immunoglobulin found in the highest concentration in humans is
Your Answer: IgG
Explanation:Representing approximately 75% of serum antibodies in humans, IgG is the most common type of antibody found in the circulation. IgG molecules are created and released by plasma B cells.
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This question is part of the following fields:
- Immunology
- Physiology
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Question 8
Correct
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A 35 year old man presents to his family doctor with swelling of his face. On examination, the swelling was noted to be to the below and to the left of his nose. When the area is palpated, it feels like the underlying bone is cracking. What is the most likely diagnosis?
Your Answer: Ameloblastoma
Explanation:Ameloblastoma is a rare, benign or cancerous tumour of odontogenic epithelium (ameloblasts, or outside portion, of the teeth during development) much more commonly appearing in the lower jaw than the upper jaw.Ameloblastomas can be found both in the maxilla and mandible. Although, 80% are situated in the mandible with the posterior ramus area being the most frequent site. The neoplasms are often associated with the presence of unerupted teeth, displacement of adjacent teeth and resorption of roots.Symptoms include a slow-growing, painless swelling leading to facial deformity. As the swelling gets progressively larger it can impinge on other structures resulting in loose teeth and malocclusion. Bone can also be perforated leading to soft tissue involvement.The lesion has a tendency to expand the bony cortices because of the slow growth rate of the lesion allows time for the periosteum to develop a thin shell of bone ahead of the expanding lesion. This shell of bone cracks when palpated. This phenomenon is referred to as Egg Shell Cracking or crepitus, an important diagnostic feature.Maxillary ameloblastomas can be dangerous and even lethal. Due to thin bone and weak barriers, the neoplasm can extend into the sinonasal passages, pterygomaxillary fossa and eventually into the cranium and brain. Rare orbital invasion of the neoplasm has also been reported.
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This question is part of the following fields:
- Head & Neck
- Pathology
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Question 9
Correct
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Neutrophils are key components of the innate immune system. They contain numerous primary and secondary granules involved in killing and digesting microorganisms. With regard to defensins, they are:
Your Answer: Naturally occurring cysteine-rich antibacterial and antifungal polypeptides
Explanation:Cationic antimicrobial peptides, including defensins, cathelicidins, and thrombocidins, provide important initial defences against invading microbes. These peptides bind the bacterial membrane and form pores, killing the bacterium by hypo-osmotic lysis.
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This question is part of the following fields:
- Immunology
- Physiology
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Question 10
Correct
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What is the pH of freshly formed saliva at ultimate stimulation?
Your Answer: 8
Explanation:Saliva has four major components: mucus (lubricant), α-amylase (enzyme that initiates digestion of starch), lingual lipase (enzyme that begins fat digestion), and a slightly alkaline electrolyte solution for moistening food. As the secretion rate of saliva increases, its osmolality increases. Moreover, the pH changes from slightly acidic (at rest) to basic (pH 8) at ultimate stimulation. This occurs due to increase of HCO3-. Amylase and mucus also increase in concentration after stimulation.
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This question is part of the following fields:
- Fluids & Electrolytes
- Physiology
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SESSION STATS - PERFORMANCE PER SPECIALTY
