Summer MCQ Flashcards
The attached gingivae are often observed to have a stippled appearance. Which of the following is the most likely cause of the stippling?
Binding by collagen in lamina propria
Which one of these structures secretes a hormone which is responsible for bringing about some of the effects of the sympathetic nervous system?
Adrenal medulla
Which one of the following conditions is most likely to cause an INCREASE in glomerular filtration rate
Constriction of efferent arterioles
In an ECG recorded from a 20 year-old student, the average interval between successive R-waves (the R-R interval) recorded over a period of time was found to be 0.6 seconds.
What is his average heart rate (in beats per minute) over that period of time, ?
100
A 50-year old male complains that “food gets stuck inside my cheek when I’m eating”. He is in good general health and has a complete dentition. His problem began after he had an operation to remove a small tumour in his left parotid gland.
Paralysis of which one of the following muscles is most likely to account for his complaint?
Buccinator
Mr Jones, a 45 year-old builder, presents at your practice complaining of “raging toothache”. He says that “the pain keeps me awake at night and I want the tooth out”.
What is the next thing you should do?
Ask him about his toothache
Which of the following question styles should be AVOIDED when interviewing a patient as part of a clinical examination?
Leading questions
Which one of the following is least likely to be found in dentinal tubules near the pulp?
Blood vessels
Which of the following types of enzyme inhibition can be reversed by increasing substrate concentration?
Competitive inhibition
Which one of the following best describes the mechanism of attachment of the junctional epithelium to the tooth surface at the base of the gingival sulcus?
Hemidesmosomes
Some drugs used to treat medical conditions can have oral side-effects. Which one of these drugs is most likely to cause a fibrous hyperplasia (overgrowth) of the gingivae?
Nifedipine
Which one of these organs does NOT drain its venous blood into the hepatic portal vein?
Left kidney
Which one of the following best describes the function of the oesophagus?
Peristalsis
Which one of the following spaces is NOT directly continuous with a part of the pharynx?
The middle ear
The wall of the intestine consists of a number of layers. Which of the sequences listed below gives the correct order of the layers (number 1-5), arranged from the mucosa (luminal) side to the serosa (outer) aspect?
- Circular muscle 2. Epithelium 3. Lamina propria 4. Longitudinal muscle 5. Muscularis mucosae
- Epithelium
- Lamina propria
- Muscularis mucosae
- Circular muscle
- Longitudinal muscle
Which one of these actions contributes LEAST to preventing food from entering the trachea during the pharyngeal phase of swallowing?
Contraction of upper oesophageal sphincter
‘Intrinsic factor’ is required for the absorption of which one of the following vitamins?
Vitamin B12
What is the hydrogen ion concentration in a solution with a pH of 7.0?
0.1 micromoles/litre
In which part of the tooth does the caries lesion usually begin?
Just below the enamel surface
Acetic acid (CH3COOH) dissociates in solution to acetate (CH3COO-) and hydrogen ions (H+).
The pKa for the dissociation of acetic acid is 4.73.
If the concentration of acetic acid in solution is 5 mM,
what is the concentation of acetate (CH3COO-) at a pH of 6.00?
93.1 mM
What movement of ions across the nerve cell membrane is responsible for the ‘falling’ or ‘repolarisation’ phase of the action potential?
Outward diffusion of potassium ions
Caries is a “multifactorial” disease process. But which one of the following is not regarded as an essential factor for caries initiation and progression.
Saliva
Which one of these arteries is a primary branch of the external carotid artery?
Lingual artery
Which of the following is not a layer found within the epithelium of a masticatory mucosa?
Lamina propria
Botulinum toxin, produced by the bacterium Clostridium botulinum, and known commercially as ‘Botox’, causes muscle paralysis by interfering with neuromuscular transmission. ‘Botox’ blocks neuromuscular transmission by which one of the following mechanisms?
Prevents ACh release from motor neuron
Which one of the following processes is not an important function of endothelial cells?
Absorption of plasma proteins
Concerning growth, which of the following statements is not correct?
Acromegaly is due to over-secretion of parathyroid hormone
A neuron’s membrane potential is altered from an initial, resting value of -70mV to a new value of -80mV. Which one of the following terms best describes this change in membrane potential?
Hyperpolarisation
In a paraffin section of a peripheral nerve the most prominent connective tissue layer is the:
Perineurium
Valves are present in which one of these blood vessels?
Veins in the neck
In anaerobic glycolysis, the end product is lactate rather than pyruvate. What is the metabolic advantage of converting pyruvate to lactate, rather than accumulating pyruvate?
NAD+ is regenerated from NADH
The figure shows a recording of the arterial blood pressure in a healthy human being. Which one of the following statements is INCORRECT?
Mean blood pressure is 100mmHg
Which one of the following is not part of the heart’s conduction system?
Vagus nerve
Which ONE of the following components of the ECG corresponds to ventricular diastole?
T-Q interval
The picture shows an electrocardiogram recorded from a healty young adult. Which of the following events is represented by the waveform arrowed?
Ventricular repolarisation
Phase ‘0’ of the SA node action potential is mediated by which one of the following?
Inward movement of calcium ions
Which one of the following does NOT have a role in modulating heart rate?
Conduction along the Purkinje fibres
Which one of the following actions best describes the mechanism by which the drug prazosin lowers blood pressure?
Blocking alpha adrenoreceptors
Which one of the following factors best explains these differences in fluid exchange in pulmonary capillaries?
Pulmonary capillary pressure is less than 8mmHg
The resistance to flow along a blood vessel is proportional to the RECIPROCAL of which one of the following variables?
Vessel radius raised to power of four
Dietary starch is a mixture of which of the following pairs of molecules?
Amylose and amylopectin
Which one of the following pairs of relationships is defined by Starling’s Law of the Heart?
Stroke volume and end-diastolic volume
In the tilt-table demonstration video, you saw how various cardiovascular parameters altered when the subject was moved from a horizontal position (‘pre-tilt’) to a vertical posture (‘during tilt’). From the results you recorded during the practical class, decide which ONE of the following variables DECREASED during the tilt.
Pulse pressure
In a survey of 3,500 consecutive self-referred patients at a temporomandibular (TM) joint clinic, it was found that 85% of the patients were females. Which of the following is the most likely explanation for this observation?
Choose one answer.
Males are less likely to self-refer to a clinic
Which one of the following terms best describes a developing embryo when it consists of a hollow ball of cells?
Blastocyst
Red blood corpuscles (erythrocytes) are most likely to haemolyse when placed in which ONE of these solutions?
300 milliOsmoles per litre sucrose solution
Which stage of enamel organ in the developing tooth corresponds to when mineralised dentine first seen?
Bell stage (late)
By which one of the following mechanisms are monoglycerides absorbed from the gut lumen into enterocytes?
Simple diffusion
Four of these structures, at least in part, lie in the mediastinum. Which other one does not?
Lung
Which one of these factors is likely to be most influential in promoting growth and development in a neonate?
Thyroxine
In a class of 120 students, the mean height is 1.60 metres, with a standard deviation of 0.20 metres. Assuming that the data is normally distributed, how many students are 1.80 metres or taller?
20
Swelling (tumor) one of the cardinal signs of inflammation, is caused by leakage from capillaries of which of the following factors?
Plasma proteins
Which part of the brain displays increased activity during perception of painful stimulus?
Anterior cingulate cortex
Which one of these structures will be most visible in a patient’s open mouth, without having to displace the tongue?
Circumvallate papillae