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Question 1
Incorrect
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The following are pairs of neurotransmitters with their corresponding synthesising enzymes.
Which pair is correct?Your Answer: Catechol-O-methyl transferase and dopamine
Correct Answer: Glutamic acid decarboxylase and gamma-aminobutyric acid (GABA)
Explanation:Glutamic acid decarboxylase is responsible for the catalyses of glutamate to gamma-aminobutyric acid (GABA)
Catechol-o-methyl transferase catalyses the degradation and inactivation of dopamine into 3-methoxytyramine, epinephrine into metanephrine, and norepinephrine into normetanephrine and vanylmethylmandelic acid (VMA).
Monoamine oxidase catalyses the oxidation of norepinephrine to vanylmethylmandelic acid (VMA) and serotonin to 5-hydeoxyindole acetic acid (5-HIAA).
Cholinesterase functions to catalyse the split of acetylcholine into choline and acetic acid.
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This question is part of the following fields:
- Pathophysiology
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Question 2
Incorrect
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One of the non-pharmacologic management of COPD is smoking cessation. Given a case of a 60-year old patient with history of smoking for 30 years and a FEV1 of 70%, what would be the most probable five-year course of his FEV1 if he ceases to smoke?
Your Answer:
Correct Answer: The FEV1 will decrease at the same rate as a non-smoker
Explanation:For this patient, his forced expiratory volume in 1 second (FEV1) will decrease at the same rate as a non-smoker.
There is a notable, but slow, decline in FEV1 when an individual reaches the age of 26. An average reduction of 30 mls every year in non-smokers, while a more significant reduction of 50-70 mls is observed in approximately 20% of smokers.
Considering the age of the patient, individuals who begin smoking cessation by the age of 60 are far less likely to achieve normal FEV1 levels, even in the next five years. It is expected that their FEV1 will be approximately 14% less than their peers of the same age.
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This question is part of the following fields:
- Physiology
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Question 3
Incorrect
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During a fight, a 20-year-old male is stabbed in the thigh with a bottle. He is admitted for treatment.
Which feature, if present, suggests an injury to the femoral nerve?Your Answer:
Correct Answer: Loss of knee reflex
Explanation:Femoral nerve lesion (L2,L3 and L4) is characterised by weakness of the quadriceps femoris muscle. This results in weakness of extension of the knee, loss of sensation over the front of the thigh, and loss of the knee jerk reflex.
The skin over the lateral aspect of the thigh and knee, and the lower lateral quadrant of the buttock is supplied by the lateral cutaneous nerve of the thigh (L1,2).
The adductors of the hip are supplied by the obturator nerve (L2-4). This nerve also supplies sensation to the inner thigh.
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This question is part of the following fields:
- Anatomy
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Question 4
Incorrect
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A delayed hypersensitivity reaction is type ____?
Your Answer:
Correct Answer: IV
Explanation:Type I – immediate hypersensitivity reaction
Examples are: Atopy, urticaria, Anaphylaxis, Asthma( IgE mediated).
Type II – Antibody mediated cytotoxic reaction
Examples are: Autoimmune haemolytic anaemia, Thrombocytopenia( IgM or IgG mediated).
Type III – Immune complex mediated reaction
Examples are: Serum sickness,SLE – IgG., Farmers lungs, rheumatoid arthritis
Type IV – Delayed hypersensitivity reaction
Examples are: Contact dermatitis, drug allergies.
Type V – Autoimmune
Graves’
Myasthenia – IgM or IgG. -
This question is part of the following fields:
- Pathophysiology
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Question 5
Incorrect
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A 27-year-old woman presents to emergency department. She is experiencing generalised seizures.
She is given emergency management of her symptoms before being referred to the neurologist who diagnoses her with new onset of tonic-clonic epilepsy.
What is the most appropriate first line of treatment?Your Answer:
Correct Answer: Lamotrigine should be offered as first line of treatment
Explanation:Tonic-clonic (Grand mal) epilepsy is characterised by a general loss of consciousness with violent involuntary muscle contractions.
The NICE guidelines for treatment indicates the use of sodium valproate and lamotrigine, but sodium valproate unsuitable in this case and she is a woman of reproductive age and it is known to have teratogenic effects. Lamotrigine is a more suitable choice, prescribed as 800mg daily.
NICE guidelines also advice an additional prescription of 5mg of folic acid daily for women on anticonvulsant therapy looking to get pregnant. It also warns of the need for extra contraceptive precaution as there is a possibly that the anticonvulsant agent can reduce levels of contraceptive agents.
Stimulation of the vagal nerve stimulation is only necessary in patients who are refractory to medical treatment and not candidates for surgical resection.
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This question is part of the following fields:
- Pathophysiology
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Question 6
Incorrect
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Which of the following statement is true regarding the mechanism of action of doxycycline?
Your Answer:
Correct Answer: Inhibit 30S subunit of ribosomes
Explanation:Doxycycline belongs to the family of tetracyclines and inhibits protein synthesis through reversible binding to bacterial 30s ribosomal subunits, which prevent binding of new incoming amino acids (aminoacyl-tRNA) and thus interfere with peptide growth.
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This question is part of the following fields:
- Pharmacology
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Question 7
Incorrect
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Infrared radiation is absorbed by asymmetric, polyatomic polar molecules like carbon dioxide (CO2).
When measuring CO2 in gas samples, mainstream capnography uses this physical principle.
Which of the following gases is most likely to interfere with carbon dioxide's absorption spectrum?Your Answer:
Correct Answer: Nitrous oxide
Explanation:Carbon dioxide absorbs the most infrared (IR) light between the wavelengths of 4.2-4.4m (4.26m is ideal).
Nitrous oxide absorbs infrared light at wavelengths of 4.4-4.6m (very similar to CO2) and less so at 3.9m.
At a frequency of 4.7m, carbon monoxide absorbs the most IR light.
At 3.3 m and throughout the ranges 8-12 m, the volatile agents have strong absorption bands.
Although oxygen does not absorb infrared light, it collides with CO2 molecules, interfering with absorption. The absorption band is widened as a result of this (so called collision or pressure broadening). A drop of 0.5 percent in measured CO2 can be caused by 95% oxygen.
Nitrous oxide causes a greater inaccuracy of 0.1 percent per ten percent of nitrous oxide.
Water vapour absorbs infrared light as well, resulting in absorption band overlap, collision broadening, and partial pressure dilution. Water traps and water permeable tubing are used to reduce inaccuracies.
Collision broadening is compensated for in modern gas multi-gas analysers.
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This question is part of the following fields:
- Pharmacology
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Question 8
Incorrect
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Concerning the anterior pituitary gland, one of following is true.
Your Answer:
Correct Answer: Produces glycoproteins
Explanation:The posterior pituitary and the hypothalamus are connected by the pituitary stalk. It contains in the pituitary sella and has the optic chiasm and hypothalamus as superior relations.
The anterior pituitary produces thyroid-stimulating hormone (TSH), luteinising hormone (LH) and follicle-stimulating hormone (FSH) . These hormones are Glycoproteins and share a common alpha subunit with unique beta subunits.
The secretion of pituitary hormones are pulsatile. Examples are LH, adrenocorticotropic hormone (ACTH) and growth hormone (GH).
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This question is part of the following fields:
- Pathophysiology
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Question 9
Incorrect
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Which of the following facts about T cells is true?
Your Answer:
Correct Answer: Secrete IL-2 when activated
Explanation:T cells function as a part of the body’s adaptive immune system. There are different types of T cells, including:
Cytotoxic T cells: Function as killer cells by releasing cytotoxic granules into the membrane of targeted cells.
T-Helper cells: When activated, they function to activate other immune cell types, assist in antibody production with B cells and releasing cytokines including IL-2.
Memory T cells: Function as to provide immune memory against already encountered antigens.
T cells possess specific glycoproteins and receptors on their surface.
T-Helper cells work with HLA class II antigens on the cell surfaces in order to recognise foreign antigens
T cells survive ranges from a few weeks, to a lifetime depending on the subtype in question.
Immunoglobulins are expressed on the surface of, and secreted by B-lymphocytes.
Native antigens are recognised by B cells. T cells only recognise antigens that have been processed by the cells and presented on the surface of the cell.
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This question is part of the following fields:
- Pathophysiology
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Question 10
Incorrect
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A 64-year old male has shortness of breath on exertion and presented to the cardiology clinic. He has a transthoracic echo performed to help in assessing the function of his heart.
How can this echo aid in calculating cardiac output?Your Answer:
Correct Answer: (end diastolic LV volume - end systolic LV volume) x heart rate
Explanation:Cardiac output = stroke volume x heart rate
Left ventricular ejection fraction = (stroke volume / end diastolic LV volume ) x 100%
Stroke volume = end diastolic LV volume – end systolic LV volume
Pulse pressure = Systolic Pressure – Diastolic Pressure
Systemic vascular resistance = mean arterial pressure / cardiac output
Factors that increase pulse pressure include:
-a less compliant aorta (this tends to occur with advancing age)
-increased stroke volume -
This question is part of the following fields:
- Physiology And Biochemistry
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Question 11
Incorrect
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A 35-year-old male presents to GP presenting an area of erythema which was around a recent cut on his right forearm. He was prescribed a short course of antibiotics and after 5 days again presented with progressive fatigue, headaches, and fevers.
On clinical examination:
Oxygen saturation: 98% on room air,
Respiratory rate: 22 per minute,
Heart rate: 100 beats per minute,
Blood pressure: 105/76 mmHg,
Temperature: 38.2 degree Celsius.
On physical examination, a dramatic increase in the area of erythema was noted.
Blood culture was done in the patient and indicated the presence of bacterium containing beta-lactamase. Which of the following antibiotics was likely prescribed to the patient?Your Answer:
Correct Answer: Amoxicillin
Explanation:Ciprofloxacin belongs to the quinolone group of antibiotics, and doxycycline and minocycline are tetracyclines. So, they are not affected by beta-lactamase.
However, amoxicillin is a beta-lactam antibiotic and beta-lactamase cleaves the beta-lactam ring present in amoxicillin. This results in the breakdown of the antibiotic and thus the area of erythema dramatically increased.
Co-amoxiclav contains amoxicillin and clavulanic acid which protects amoxicillin from beta-lactamase. -
This question is part of the following fields:
- Pharmacology
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Question 12
Incorrect
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All of the following statements about pH electrode are incorrect except:
Your Answer:
Correct Answer: A semi-permeable membrane reduces protein contamination
Explanation:Pulse oximeters combine the principles of oximetry and plethysmography to noninvasively measure oxygen saturation in arterial blood. A sensor containing two or three light emitting diodes and a photodiode is placed across a perfused body part, commonly a finger, to be transilluminated. Oximetry depends on oxyhaemoglobin and deoxyhaemoglobin, and their ability to absorb the beams of light produced by the light emitting diodes: red light at 660 nm and infrared light at 960 nm.
The isosbestic point is the point wherein two different substances absorb light to the same extent. For oxyhaemoglobin and deoxyhaemoglobin, the points are at 590 nm and 805 nm. These are considered reference points where light absorption is independent of the degree of saturation.
Non-constant absorption of light is often due to the presence of an arterial pulsation, whilst constant absorption of light is seen in non-pulsatile tissues.
Most pulse oximeters are inaccurate at low SpO2, but is accurate at +/- 2% within the range of 70% to 100% SpO2. All pulse oximeters demonstrate a delay in between changes in SaO2 and SpO2, and display average readings every 10 to 20 seconds, hence they are unable to detect acute desaturation episodes.
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This question is part of the following fields:
- Anaesthesia Related Apparatus
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Question 13
Incorrect
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The following statement is true with regards to the Nernst equation:
Your Answer:
Correct Answer: It is used to calculate the potential difference across a membrane when the individual ions are in equilibrium
Explanation:The Nernst equation is used to calculate the membrane potential at which the ions are in equilibrium across the cell membrane.
The normal resting membrane potential is -70 mV (not + 70 mV).
The equation is:
E = RT/FZ ln {[X]o
/[X]i}Where:
E is the equilibrium potential
R is the universal gas constant
T is the absolute temperature
F is the Faraday constant
Z is the valency of the ion
[X]o is the extracellular concentration of ion X
[X]i is the intracellular concentration of ion X. -
This question is part of the following fields:
- Physiology
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Question 14
Incorrect
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In the adrenal gland:
Your Answer:
Correct Answer: Catecholamine release is mediated by cholinergic nicotinic transmission
Explanation:The adrenal (suprarenal) gland is composed of two main parts: the adrenal cortex, which is the largest and outer part of the gland, and the adrenal medulla. The adrenal cortex consists of three zones: 1. Zona glomerulosa (outermost layer) is responsible for the production of mineralocorticoids, mainly aldosterone, which regulates blood pressure and electrolyte balance. 2. Zona fasciculata (middle layer) is responsible for the production of glucocorticoids, predominantly cortisol, which increases blood sugar levels via gluconeogenesis, suppresses the immune system, and aids in metabolism. It also produces 11-deoxycorticosterone and corticosterone in addition to cortisol. 3. Zona reticularis (innermost layer) is responsible for the production of gonadocorticoids, mainly dehydroepiandrosterone (DHEA), which serves as the starting material for many other important hormones produced by the adrenal gland, such as oestrogen, progesterone, testosterone, and cortisol. It is also responsible for administering these hormones to the reproductive regions of the body.
The adrenal medulla majorly secretes epinephrine (adrenaline), and norepinephrine in small quantity. Both hormones have similar functions and initiate the flight or fight response.
Catecholamine is mediated by cholinergic nicotinic transmission through changes in sympathetic nervous system (T5 – T11), being increased during stress and hypoglycaemia.
Blood supply to the adrenal gland is by these three arteries: superior suprarenal arteries, middle suprarenal artery and inferior suprarenal artery. Venous drainage is via the suprarenal vein to the left renal vein or directly to the inferior vena cava on the right side. There is no portal (venous) system between cortex and medulla.
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This question is part of the following fields:
- Anatomy
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Question 15
Incorrect
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Iron is one of the most important micronutrients in the body.
Out of the following, which one has the most abundant storage of iron in the body?Your Answer:
Correct Answer: Haemoglobin
Explanation:Iron is a necessary micronutrient for proper erythropoietic function, oxidative metabolism, and cellular immune responses. Although dietary iron absorption (1-2 mg/d) is tightly controlled, it is only just balanced by losses.
The adult body contains 35-45 mg/kg iron (about 4-5 g)
Iron can be found in a variety of forms, including haemoglobin, ferritin, haemosiderin, myoglobin, haem enzymes, and transferrin bound proteins.
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This question is part of the following fields:
- Pathophysiology
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Question 16
Incorrect
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The ED95 of muscle relaxants is the dose required to reduce twitch height by 95% in half of the target population. The dose of non-depolarizing muscle relaxants used for intubation is 2-3 times the ED95.
For procedures that need a short duration of muscle relaxation and abrupt recovery, the short-acting drug Mivacurium is given at less than 2 times the ED95. What is the explanation for Mivacurium being an exception to this rule?Your Answer:
Correct Answer: Dose related histamine release occurs which frequently leads to tachycardia and hypotension
Explanation:Mivacurium, when administered at doses greater than 0.2 mg/kg,increases the risk for hypotension, tachycardia, and erythema. This is due to the ability of mivacurium to release histamine with increasing dose. Contrary to this fact, anaphylaxis is rare for mivacurium because of the short duration of histamine release.
The effective dose 50 (ED50) of mivacurium is between 0.08-0.15 mg/kg. It is administered slowly to prevent and decrease the risk of developing adverse effects.
Mivacurium has a high potency thus a longer duration of action, however this is not the answer that we are looking for.
Although drug metabolism takes longer for mivacurium than succinylcholine, it has no effect on the dose required for intubation.
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This question is part of the following fields:
- Pharmacology
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Question 17
Incorrect
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Which of the following is an expected change in pulmonary function seen during a moderate asthma attack?
Your Answer:
Correct Answer: Decreased forced expiratory volume in 1 sec (FEV1)
Explanation:Asthma is a lung condition that causes reversible narrowing and swelling of airway passages. It is classified by the frequency and severity of symptoms.
The following are symptoms of moderate asthma:
Symptoms include cough, wheezing, chest tightness, or difficulty breathing which occurs daily
Decreased activity levels due to flare-ups
Night-time symptoms 5 or more times a month
Lung function test FEV1 is 60-80% of predicted normal values
Peak flow has more than 30% variabilityWith moderate asthma attacks, the arterial pCO2 levels may decrease, but as severity increases, so does the pCO2, reaching normal levels, and then exceeding them in severe asthma attacks.
Airway obstruction increases the functional residual capacity.
Concentration of serum bicarbonate would not increase in moderate asthma, but it could possibly increase in life-threatening asthma via the same mechanism as what increases arterial PCO2.
FEV1 is a good measure of airway obstruction. and is reduced in acute asthma attacks.
In the case of a pneumothorax, a decrease in arterial PO2 is higher.
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This question is part of the following fields:
- Pathophysiology
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Question 18
Incorrect
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Which of the following causes a left shift of the haemoglobin dissociation curve?
Your Answer:
Correct Answer:
Explanation:With respect to oxygen transport in cells, almost all oxygen is transported within erythrocytes. There is limited solubility and only 1% is carried as solution. Thus, the amount of oxygen transported depends upon haemoglobin concentration and its degree of saturation.
Haemoglobin is a globular protein composed of 4 subunits. Haem is made up of a protoporphyrin ring surrounding an iron atom in its ferrous state. The iron can form two additional bonds – one is with oxygen and the other with a polypeptide chain.
There are two alpha and two beta subunits to this polypeptide chain in an adult and together these form globin. Globin cannot bind oxygen but can bind to CO2 and hydrogen ions.
The beta chains are able to bind to 2,3 diphosphoglycerate. The oxygenation of haemoglobin is a reversible reaction. The molecular shape of haemoglobin is such that binding of one oxygen molecule facilitates the binding of subsequent molecules.The oxygen dissociation curve (ODC) describes the relationship between the percentage of saturated haemoglobin and partial pressure of oxygen in the blood.
Of note, it is not affected by haemoglobin concentration.Chronic anaemia causes 2, 3 DPG levels to increase, hence shifting the curve to the right
Haldane effect – Causes the ODC to shift to the left. For a given oxygen tension there is increased saturation of Hb with oxygen i.e. Decreased oxygen delivery to tissues.
This can be caused by:
-HbF, methaemoglobin, carboxyhaemoglobin
-low [H+] (alkali)
-low pCO2
-ow 2,3-DPG
-ow temperatureBohr effect – causes the ODC to shifts to the right = for given oxygen tension there is reduced saturation of Hb with oxygen i.e. Enhanced oxygen delivery to tissues. This can be caused by:
– raised [H+] (acidic)
– raised pCO2
-raised 2,3-DPG
-raised temperature -
This question is part of the following fields:
- Physiology And Biochemistry
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Question 19
Incorrect
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Considering research studies, which of the following is considered as a limitation of the Delphi method?
Your Answer:
Correct Answer: Potential low response rates
Explanation:The Delphi technique was developed in the 1950s and is a widely used and accepted method for achieving convergence of opinion concerning real-world knowledge solicited from experts within certain topic areas. Choosing the appropriate subjects is the most important step in the entire process because it directly relates to the quality of the results generated, despite this, there is no exact criterion currently listed in the literature concerning the selection of Delphi participants.
Therefore, due to the potential scarcity of qualified participants and the relatively small number of subjects used in a Delphi study, the ability to achieve and maintain an ideal response rate can either ensure or jeopardize the validity of a Delphi study.
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This question is part of the following fields:
- Statistical Methods
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Question 20
Incorrect
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Which of the following statements is correct about a characteristic that is normally distributed in a population?
Your Answer:
Correct Answer: There will be approximately equal numbers who have more or less of the characteristic than the mean
Explanation:68% of the population will be found in one standard deviation (SD) above plus one SD below the mean. Two SDs above plus two SDs below the mean will include 95% of the population.
The median can be greater or less than the mean as it is simply the mid point of the data after the data is arranged. Half the data are above and half below the median .
The mode is a true score, unlike the mean or the median. It is the most common score or the score obtained from the largest number of subjects in any given data.
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This question is part of the following fields:
- Statistical Methods
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Question 21
Incorrect
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Regarding the following induction agents, which one is cleared at the fastest rate from the plasma?
Your Answer:
Correct Answer: Propofol
Explanation:Propofol is cleared at the fastest rate at the rate of 60ml/kg/min.
Clearance rate of other drugs are as follows:
– Thiopental: 3.5 ml/kg/min
– Methohexitone: 11 ml/kg/min
– Ketamine: 17 ml/kg/min
– Etomidate: 10-20 ml/kg/min -
This question is part of the following fields:
- Pharmacology
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Question 22
Incorrect
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Modified rapid sequence induction with 1mg/kg rocuronium was done is a 42-year-old male for emergency appendicectomy. The patient weight was 70 kg and a failed intubation indicated immediate reversal of neuromuscular blockade.
Which of the following is the correct dose of sugammadex for this patient?Your Answer:
Correct Answer: 1120 mg
Explanation:Sugammadex is used for immediate reversal of rocuronium-induced neuromuscular blockade.
It is used at a dose of 16 mg/kg.Since the patient in the question is 70 kg, the required dose of sugammadex can be calculated as:
16×70 = 1120 mg.Sugammadex selectively binds rocuronium or vecuronium, thereby reversing their neuromuscular blocking action. Due to its 1:1 binding of rocuronium or vecuronium, it can reverse any depth of neuromuscular block.
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This question is part of the following fields:
- Pharmacology
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Question 23
Incorrect
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At which of the following location is there no physiological oesophageal constriction?
Your Answer:
Correct Answer: Lower oesophageal sphincter
Explanation:The oesophagus is a muscular tube that connects the pharynx to the stomach. It begins at the lower border of the cricoid cartilage and C6 vertebra. It ends at T11.
The oesophagus has physiological constrictions at the following levels:
1. Cervical constriction: Pharyngo-oesophageal junction (15 cm from the incisor teeth) produced by the cricopharyngeal part of the inferior pharyngeal constrictor muscle
2. Thoracic constrictions:
i. where the oesophagus is first crossed by the arch of the aorta (22.5 cm from the incisor teeth)
ii. where the oesophagus is crossed by the left main bronchus (27.5 cm from the incisor teeth)
3. Diaphragmatic constriction: where the oesophagus passes through the oesophageal hiatus of the diaphragm (40 cm from the incisor teeth)Awareness of these constrictions is important for clinical purposes when it is required to pass instruments through the oesophagus into the stomach or when viewing radiographs of patients’ oesophagus.
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This question is part of the following fields:
- Anatomy
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Question 24
Incorrect
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In North America, there have been reports of paediatric patients dying after undergoing adenotonsillectomy for obstructive sleep apnoea.
Respiratory depression/obstruction is thought to be the cause of death. The codeine dose was 0.5-1 mg/kg, given every 4-6 hours.
In this group of patients, which of the following is the most likely cause of respiratory depression and obstruction?Your Answer:
Correct Answer: Exaggerated metabolism of codeine
Explanation:Codeine is easily absorbed from the gastrointestinal tract and converted to morphine and norcodeine in the liver via O- and N-demethylation. Morphine and norcodeine are excreted almost entirely by the kidney, primarily as conjugates with glucuronic acid.
By glucuronidation, phase II metabolism enzyme UDP-glucuronosyl transferase-2B7 converts morphine to morphine-3-glucuronide (M3G) and morphine-6-glucuronide (M6G) (UGT2B7).
Approximately 60% of morphine is converted to M3G, with the remaining 6-10% converted to M6G. M3G is inactive, but M6G is said to be 4 to 650 times more potent on the MOP receptor than morphine.
When codeine is consumed, cytochrome P450 2D6 in the liver converts it to morphine (CYP2D6).
Some people have DNA variations that increase the activity of this enzyme, causing codeine to be converted to morphine more quickly and completely than in others. After taking codeine, these ultra-rapid metabolisers are more likely to have higher than normal levels of morphine in their blood.
Respiratory depression/obstruction can be caused by high levels of morphine and M6G, especially in people who have a history of obstructive sleep apnoea. The estimated number of ultra-rapid metabolisers ranges from 1 to 7 per 100 people, but some ethnic groups may have as many as 28 per 100 people.
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This question is part of the following fields:
- Pathophysiology
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Question 25
Incorrect
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Of the stated laws, which is correct?
Your Answer:
Correct Answer: Boyle's law states that at constant temperature the volume of a given mass of gas varies inversely with absolute pressure.
Explanation:Boyle’s law is correctly stated as it states that the volume of a gas of known mass is inversely proportional with absolute pressure, at a constant temperature.
Beer’s law states that radiation absorption by a solution of known thickness and concentration is identical to that of a solution of double thickness and half concentration.
Bougner’s (or Lambert’s) law states that every layer with the same thickness will absorb the same amount of radiation as it passes through.
Graham’s law states that the diffusion rate of a gas is inversely related to the square root of its molecular weight.
Raoult’s law states that the reduction of a solvent’s vapour pressure is directly proportional to the solute’s molar concentration.
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This question is part of the following fields:
- Statistical Methods
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Question 26
Incorrect
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Which of these statements is false relating to the posterior cerebral artery?
Your Answer:
Correct Answer: It is connected to the circle of Willis via the superior cerebellar artery
Explanation:The posterior cerebral arteries are the terminal branches of the basilar artery and are connected to the circle of Willis via the posterior communicating artery. The posterior cerebral artery supplies the visual areas of the cerebral cortex and other structures in the visual pathway.
The posterior cerebral artery is separated from the superior cerebellar artery near its origin by the oculomotor nerve (3rd cranial nerve) and, lateral to the midbrain, by the trochlear nerve.
PCA strokes will primarily cause a visual field loss or homonymous hemianopia to the opposite side. This large occipital or PCA stroke causes people to be €œblind€� on one side of the visual field. This is the most common symptom of a large occipital lesion or PCA stroke.
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This question is part of the following fields:
- Anatomy
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Question 27
Incorrect
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Sugammadex binds to certain drugs that affect neuromuscular function during anaesthesia in a stereospecific, non-covalent, and irreversible manner.
It has the greatest impact on the activity of which of the following drugs?Your Answer:
Correct Answer: Vecuronium
Explanation:Sugammadex is a modified cyclodextrin that works as an aminosteroid neuromuscular blocking (nmb) reversal agent. By encapsulating each molecule in the plasma, it rapidly reverses rocuronium and, to a lesser extent, vecuronium-induced neuromuscular blockade. Consequently, a concentration gradient favours the movement of these nmb agents away from the neuromuscular junction. Pancuronium-induced neuromuscular blockade at low levels has also been reversed.
By inhibiting voltage-dependent calcium channels at the neuromuscular junction, antibiotics in the aminoglycoside group potentiate neuromuscular blocking agents. This can be reversed by giving calcium but not neostigmine or sugammadex.
Sugammadex will not reverse the effects of mivacurium, which belongs to the benzylisoquinolinium class of drugs.
A phase II or desensitisation block occurs when the motor end-plate becomes less sensitive to acetylcholine as a result of an overdose or repeated administration of suxamethonium. The use of neostigmine has been shown to be effective in reversing this weakness.
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This question is part of the following fields:
- Pharmacology
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Question 28
Incorrect
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Which one is true with respect to the first rib?
Your Answer:
Correct Answer: Scalenus anterior is inserted onto the scalene tubercle
Explanation:Specific knowledge of the anatomical relationship is required to address this examination question.
The first rib is small and thick and contains a single facet that articulates at the costovertebral joint. It consist of a head, neck and shaft but a discrete angle is deficit. Along the side the shaft is indented with a groove for the subclavian artery and the lower brachial plexus trunk. Front to the scalene tubercle is a space for the subclavian vein.
The first rib has the scalenus front muscle joined to the scalene tubercle, isolating the subclavian vein (anteriorly) from the subclavian artery (posteriorly). This anatomical relationship is of major significance with respect to subclavian vein cannulation.
The 1st rib has the following relationships:
superior: lower trunk of the brachial plexus, subclavian vessels, clavicle.
inferior: intercostal vessels and nerves
posterior and inferior: pleura
anterior: sympathetic trunk (over neck)
superior intercostal artery, ventral T1 nerve root.
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This question is part of the following fields:
- Anatomy
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Question 29
Incorrect
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Which statement is correct concerning breathing systems?
Your Answer:
Correct Answer: The reservoir bag can limit the pressure in the breathing system to about 40 cm of water
Explanation:Mapleson classified breathing systems into A, B, C, D and E. Jackson-Rees subsequently modified the Mapleson E by adding a double-ended bag to the end of the reservoir tubing, creating the Mapleson F. A Mapleson E or T-piece does not have a reservoir bag.
A Mapleson A system is a very efficient system for use during spontaneous ventilation. However, it is not suitable for use with patients less than 25 kg, due to the increased dead space at the distal / patient end. This system can be modified into a Lack system or coaxial Mapleson A, where the fresh gas flows through an outer tube (30 mm) and exhaled gases flow through the inner tube (14 mm).
The adjustable pressure limiting valve (APL) or expiratory valve allows exhaled gas and excess fresh gas to leave the breathing system. It is a one-way, adjustable spring-loaded valve, and gases escape when the pressure in the system exceeds the valve opening pressure. During spontaneous ventilation a pressure of less than 1 cm of water (0.1 kPa) is needed when the valve is in the open position (not 2 cm of H2O).
The reservoir bag is highly compliant and when over inflated, the rubber bag can limit the pressure in the system to about 40 cm of H2O.
This is due to the law of Laplace, which states that the pressure will fall as the radius of the bag increases:
Pressure = 2 x tension/radius.
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This question is part of the following fields:
- Anaesthesia Related Apparatus
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Question 30
Incorrect
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Regarding thyroid hormones, one of the following is true.
Your Answer:
Correct Answer: Thyroid binding globulin (TBG) is increased in pregnancy
Explanation:T3 is produced by peripheral de-iodination of T4. It is more active than T4.
TBG, like most binding proteins, is increased in pregnancy. Because of this, measurement of free thyroid hormone concentration is more important than total.
T4 and T3 concentrations are decreased in Illness and starvation.
L-T4 that is the active molecule while D-T4 is inactive.
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This question is part of the following fields:
- Pathophysiology
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