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
Which one of the following statements about the jaw-jerk reflex pathway is correct?
The efferent axons are A-alpha fibres
Which of these values gives the most appropriate range for the latency of the ankle-jerk reflex?
25-35 milliseconds
A fit young man undertakes 5 minutes of moderately-intense (60% maximum) rhythmic exercise on an ergometer.
Which of the following variables is most likely to decrease?
Electrocardiogram R-R interval
The capsule of the TMJ is pierced by the tendone of which of these muscles?
Lateral pterygoid
The action of parathyroid hormone is most likely to bring about a decrease in which of the following events?
Phosphate absorption in the kidney
During a practical class, the following measurements of salivary volume were made by a student. Without any salivary stimulus, the student produced 1.5mL of saliva in 5 minutes. Then, she produced 4.8mL saliva in 2 minutes when chewing flavoured, sugar-free gum. How many times greater is the gum-stimulated salivary flow compared with the unstimulated (resting) flow rate?
8 times
What do the ‘spikes’ in a voluntary electromyogram (EMG) represent?
Muscle fibre action potential
Which one of the ‘jerk’ reflexes will have the shortest latency?
Jaw-jerk
A muscle spindle is best classified as belonging to which one of these types of receptor?
Proprioceptor
A muscle spindle provides information about which one of the following aspects of muscle functions or properties?
Muscle stretch
Which one of the following signs or symptoms is most indicative of an upper motor neuron lesion, as opposed to a lower motor neuron lesion
Exaggerated reflexes
The motor impairments present in Parkinson’s disease are due to lack of which one of these neurotransmitters in the substantia nigra?
Dopamine
Which one of the following features would be the most indicative of cerebellar impairment?
Intention tremor
According to a recent report by Macfarlane et al (J.Dent.Res 2004; 83(9): 712-7) on the prognosis of facial pain, which one of the following factors, identified at initial examination, was most predictive that the patient’s pain would still be present 4 years later?
Taking medications
Which one of these transmitter-receptor combinations is most likely to be involved in the ‘wind-up’ of neuropathic pain?
Glutamine and NDMA receptor
Which one of these structures is general too small to be seen clearly with the light microscope?
Hepatitis C virus
The movement of glucose molecules across a cell membrane from a region of high glucose concentration to a region of low concentration occurs by which one of the processes listed?
Facilitated diffusion
A 0.9% NaCl solution is referred to as ‘isotonic saline’. It is made by dissolving 0.9 grams NaCl in 100mL of water.
Which one of the following combinations will also produce an isotonic saline solution?
18 grams NaCl in 2 litres of water
Structures of the skin, outer to inner:
- Stratum corneum;
- Stratum granulosum;
- Stratum spinosum;
- Stratum basale;
- Dermis.
Which one of the following is NOT required during the procedure of gene cloning?
taq DNA polymerase
In order to get patients to improve their health-related behaviours, we must change their negative habits. Which one of the following statements about habits is true?
Habits are reinforcing
As part of the excitation-contraction coupling sequence, calcium ions bind to which of these muscle proteins?
Troponin
A sustained voluntary muscle contraction is called?
A tetanus
What volume of 1.0M HCl added to 100mL of water would give a final pH of 5.0?
0.001mL
Which of the following is true with respect to sickle-cell anaemia?
Arises due to non-conservative mutation
The picture shows a transverse section through the spinal cord, stained with the Weigert method. Identify the region arrowed.
Ventral form grey matter
Hydroxyapatite is the principal mineral present in dental hard tissues and bone.
Hydroxyapatite consists of crystals of which of these chemicals?
Calcium phosphate
Which one of the following is not part of the heart’s conduction system?
Vagus nerve
A 1mm ‘white-spot’ lesion is detected on the surface of a first permanent molar in a 10 year-old child.
Which of the following is the most appropriate approach to managing this lesion?
Apply topical fluoride paste (e.g. Duraphat)
Which one of the following is not a recognised factor in the local control of blood pressure?
Plasma albumin
Which one of the following is considered to be the key role of fluoride in preventing enamel caries?
Enhances salivary remineralisation
The photograph shows white areas on the labial surfaces of a patient’s anterior teeth.
Which one of the following options describes what the white areas are most likely to be?
Plaque
Which one of these statements about calculus is false?
It is easily removed by toothbrushing
Which of the following is classified as part of the adaptive immune system?
Lymphocytes
The following measurements were made on a healthy 19 year-old student while she is breathing air. Tidal volume = 450mL, breathing rate = 12/minute, anatomical dead space = 150mL.
What is her alveolar ventilation in mL/min?
3,600
Which one of these parts of the respiratory tract does NOT contribute to the anatomical dead space?
Alveolar sacs
Which one of the following cell types functions as ‘antigen-presenting’ cell?
Langerhans cells in skin
Local conditions can affect the affinity of haemoglobin for oxygen. Which of the following combinations of changes in blood temperature, acidity (pH), and 2,3-diphosphoglycerate concentration ([DPG]) will cause the greatest reduction in the affinity of haemoglobin for oxygen?
Increased temperature, decreased pH, increased [DPG]
Think exercise!
Carbon dioxide is carried in the blood in various forms. What proportion of carbon dioxide in mixed venous blood is carried as bicarbonate ions in plasma?
60%
Which one of these components of the complement system plays a major role in opsonization?
C3b
When you fly in a commercial aeroplane, the cabin is pressured to an atmospheric pressure equivalent to an altitude of 2,500 metres (about 8,000 feet) above sea level. At this pressure, the arterial PO2 averages 60mmHg. What is the percentage oxygen saturation of haemoglobin in arterial blood at this PO2?
80%
A patient with severe respiratory disease is referred to Accident and Emergency. On admission, his arterial oxygen saturation measured by a pulse oximeter was 75%. What is the corresponding arterial PO2 in this patient?
40mmHg
The intrapleural pressure is the pressure in the pleural cavity between the lung and the chest wall. What is the intrapleural pressure, relative to atmospheric pressure, just before the onset of inspiration in a healthy human being?
- 4 mmHg
Which one of the following muscles best fits this description: it is attached to the ramus of the mandible and to the zygomatic arch. It acts to close the mouth.
Mylohyoid
Which one of the following is not a feature of the mandible?
Greater horn
Which one these circulating leukocytes has functions most similar to tissue mast cells?
Basophils
Which one of these bones forms the most superior part of the nasal septum?
Ethomoid
Which one of these bones forms the inferno-lateral part of the orbital rim?
Zygoma
Consider an oxygen molecule in one of the alveoli in your lungs. What is the minimum number of cell (plasma) membranes it has to pass through in order to bind to a molecule of haemoglobin in an erythrocyte in one of your pulmonary capillaries?
5
The respiratory centres are located in which part of the central nervous system?
Pons and medulla
Foramen magnum lies in which of these bones?
Occipital
Which one of these muscles attaches to the coronoid process of the mandible?
Temporalis
Which one of the following is the most appropriate value for the minimum thickness of the barrier separating air in the alveoli and blood in pulmonary capillaries?
0.2 micrometres
Which one of these changes is most likely to take place in the blood when it flows through systematic capillaries from arteries to veins?
Increase in plasma bicarbonate ion concentration
Which one of the following spaces does not communicate directly with a part of the pharynx?
Trachea
Which one of the following is most likely to stimulate salivary flow by means of a conditioned reflex?
Seeing plate of food
Which one of the following is a non-caloric, high-intensity sweetener?
Saccharin
Which of the following compounds is most likely to be found in the cytoplasm of cells, where is functions as a ‘second messenger;?
Cyclic AMP
The poison curare, and the related drug tubocurarin, block neuromuscular by which of the following mechanisms?
Blocks ACh receptor on muscle cell membrane
Which of these cations is present in greatest concentration in intracellular fluid?
Potassium
Which one of these tissues contains the LEAST amount of mineral?
Predentine
Apart from the nucleus, which other organelle contains DNA?
Mitochondrion
Which one of the following is a recognised effect of cortisol?
Anti-inflammatory action
The inspired and expired gas was continuously sampled in a fit young male student. The gas was analysed for carbon dioxide (CO2) content, which was displayed on a chart recorder. A sample of the recording is shown.
If the barometric pressure was 750mmHg, give the end-tidal CO2 in mmHg. (Assume that the humidity of the expired gas is zero).
41mmHg
Following haemorrhage, there is a change in Starling’s forces such that there is net reabsorption of interstitial fluid into the systematic capillaries.
Which one of the following changes is most likely to be responsible for this shift of fluid?
Decreased capillary hydrostatic pressure
Which one of these hormones is produced in the hypothalamus?
Thyrotropin releasing hormone
Which one of the following signs in most indicative of a deficiency of iodine in the diet?
Goitre
A patient has an abscess at the apex of his lower right central incisor. Which one of the following groups of lymph nodes is most likely to be swollen as a result of infection?
Submental
A 32-year old female complains that she “can’t open her mouth properly”. Examination identifies the cause as involving one particular muscle - but which one?
Anterior digastric
Myxoedema is caused by a deficiency of which one of the following hormones?
Thyroid hormone
Which cranial nerve provides the parasympathetic nerve supply to the parotid gland?
Glossopharyngeal nerve
The duct of the parotid salivary gland pierces which muscle before entering the mouth?
Buccinator
Blood platelets are derived from which one of the following cell types?
Megakaryocytes
Which one of these hormones is released from the posterior pituitary?
Oxytocin
Which one of the following is most likely to be secreted into the tubular fluid from cells of the proximal convoluted tubules?
Hydrogen ions
The submandibular gland is related to the posterior free margin of which of the following muscles?
Mylohyoid
In which one of the following parts of the nephron is the tubular fluid most likely to be hypo-osmolar with respect to plasma?
Start of the distal convoluted tubule
The vertebral artery arises from which other artery?
Subclavian
Synthesis of many blood clotting factors is dependent on which vitamin?
Vitamin K
Which muscle attaches to the temporomandibular joint disc and the anterior aspect of the neck of the mandibular condyle?
Lateral pterygoid
The duct of the submandibular gland opens into the mouth at which of the following sites?
At the sublingual papilla (caruncle)
The vallecula is the space between which of these pairs of structures?
Posterior tongue and epiglottic
In deciding on behavioural change what is the first thing that needs to be done?
Establish baseline
