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Question 1
Correct
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Which of the following is true about number needed to harm?
Your Answer: The number of patients that must receive a particular treatment for one additional patient to experience an adverse outcome.
Explanation:Number needed to harm are a measure of the impact of a treatment or intervention that is often used to communicate results to patients, clinicians, the public and policymakers. It states how many patients need to be treated for one additional patient to experience an adverse outcome (e.g. a death). It is calculated as the inverse of the absolute risk reduction. It can equally well be applied to harmful outcomes as well as beneficial ones, where it becomes numbers needed to treat (NNT) instead.
In this way, they are both calculated the same but NNT usually refers to a therapeutic treatment whereas NNH refers to a risk-factor for disease.
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This question is part of the following fields:
- Statistical Methods
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Question 2
Incorrect
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A 65-year-old man, presents to the emergency department. He explains that an hour ago, he experienced central chest pain, which moved down his left arm.
On ECG, elevation in the ST-segment was noted in the anterior leads. He undergoes emergency percutaneous coronary intervention (PCI) which requires the cardiologist to access the heart via the femoral artery.
Where is the surface marking for identifying the femoral artery?Your Answer: Midway between the ASIS and the pubic tubercle
Correct Answer: Midway between the ASIS and the pubic symphysis
Explanation:The surface marking for locating the femoral artery is the mid-inguinal point, which is the halfway point between the anterior superior iliac spine (ASIS) and the pubic symphysis.
The other mentioned options are not specific for any landmark.
However, it is important to note the difference between the mid inguinal point and the midpoint of the inguinal ligament, which is travels from the ASIS to the pubic tubercle.
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This question is part of the following fields:
- Anatomy
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Question 3
Incorrect
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Calcium homeostasis is regulated by parathormone (PTH).
Which of the following PTH actions is most likely to cause calcium to be released from bone?Your Answer:
Correct Answer: Indirect stimulation of osteoclasts
Explanation:The hormone parathyroid hormone (PTH) and the receptor parathyroid hormone type 1 (PTH1-Rc) are important regulators of blood calcium homeostasis.
PTH can cause a rapid release of calcium from the matrix in bone, but it also affects long-term calcium metabolism by acting directly on bone-forming osteoblasts (by binding to PTH1-Rc) and indirectly on bone-resorbing osteoclasts.
PTH causes changes in the synthesis and/or activity of several proteins, including osteoclast-differentiating factor, also known as TRANCE or RANKL, when it acts on osteoblasts.
RANK receptors are found on the cell surfaces of osteoclast precursors. The osteoclasts are activated when RANKL binds to the RANK receptors. Osteoclasts lack PTH receptors, whereas osteoblasts do. Osteoclasts are activated indirectly when the RANK receptor binds to the RANKL secreted by osteoblasts, resulting in bone resorption. PTH1 receptors are found in osteoclasts, but they are few.
PTH activates G-protein coupled receptors in all target cells via adenylate cyclase.
The PTH2 receptor is most abundant in the nervous system and pancreas, but it is not a calcium metabolism regulator. It is abundant in the septum, midline thalamic nuclei, several hypothalamic nuclei, and the dorsal horn of the spinal cord, as well as the cerebral cortex and basal ganglia. Expression in pancreatic islet somatostatin cells is the most prominent on the periphery.
The distribution of the receptor is being used to test functional hypotheses. It may play a role in pain modulation and hypothalamic releasing-factor secretion control.
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This question is part of the following fields:
- Pathophysiology
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Question 4
Incorrect
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A 73-year-old woman is admitted to the coronary care unit. She has been diagnosed with an acute myocardial infarction and has gone into a cardiogenic shock. As part of her treatment, she is prescribed a dobutamine infusion and placed on full haemodynamic monitoring.
Over the next four days, her measurement are:
Day1 Day2 Day3 Day4
Infusion rate of dobutamine (mcg/kg/min): 5 10 15 25
Cardiac output (L/min): 3.4 3.2 3.1 3.2
Pulse rate (beats/min): 110 112 105 100
Blood pressure (mmHg): 80/60 75/61 83/60 81/56
Haemodynamic changes are noted as a result of response to treatment. What is the most probable cause?Your Answer:
Correct Answer: Tolerance by down-regulation of beta1 receptors
Explanation:Tachyphylaxis is the swiftly declining response to successive drug doses which vastly reduces its effectiveness in a short space of time, mostly as a result of an acute consumption of neurotransmitters.
Tolerance or desensitisation is the slow decline in a person’s reaction to a drug due to continued use. It requires a longer time span than tachyphylaxis, usually over days or weeks.
Down- regulation is a reduction in the amount of receptors available on target cells which decreases the affinity of the agent to the cells. For this to occur, the down-regulation of receptors must occur at a rate faster than receptor synthesis. This down-regulation often occurs with beta1 receptors due to:
1) The transportation or receptors from the cell surface to the interior of the cell
2) Degradation of receptors occurring over time.
In this case, dobutamine is prescribed to treat cardiogenic shock. It is able to function by binding to beta1-adrenergic receptors to increase the contraction of the heart, thereby improving cardiac output. It also binds to beta2- and alpha1-adrenergic receptors to balance out the effects produced by binding to beta1 receptors and reduce the risk of system vasculature responses.
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This question is part of the following fields:
- Clinical Measurement
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Question 5
Incorrect
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A 43-year old woman, presented to the emergency department. She has suffered trauma to her right orbital floor.
On examination, it is noted that her right eye is deviated upwards when compared to her left. She also has a deliberate tilt in her head to the left in an attempt to compensate for loss of intorsion.
This clinical sign is caused by damage to which of the following cranial nerves?Your Answer:
Correct Answer: Trochlear nerve
Explanation:The trochlear nerve (CN IV) is the fourth and smallest cranial nerve. It’s role is to provide somatic motor innervation of the superior oblique muscle which is responsible for oculomotion.
Injury to the trochlear nerve will result in vertical diplopia, which worsens when looking downwards or inwards. This diplopia presents as an upward deviation of the eye with a head tilt away from the site of the lesion.
The abducens nerve (CN VI) provides somatic motor innervation for the lateral rectus muscle which functions to abduct the eye. Injury to this nerve will cause diplopia and an inability to abduct the eye, causing the patient to have to rotate their head to look sideways.
The facial nerve (CN VII) provides sensory, motor and parasympathetic innervations. It’s motor aspect controls the muscles of facial expression. Damage will cause paralysis of facial expression.
The oculomotor nerve (CN III) provides motor and parasympathetic innervations. Its motor component controls most of the other extraocular muscles. Damage to it will result in ptosis, dilatation of the pupil and a down and out eye position.
The ophthalmic division of the trigeminal nerve (CN VI) is responsible for sensory innervation of skin, mucous membranes and sinuses of the upper face and scalp.
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This question is part of the following fields:
- Pathophysiology
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Question 6
Incorrect
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All of the following statements about that parasympathetic nervous system (PNS) are true except:
Your Answer:
Correct Answer: The PNS has nicotinic receptors throughout the system
Explanation:With regards to the autonomic nervous system (ANS)
1. It is not under voluntary control
2. It uses reflex pathways and different to the somatic nervous system.
3. The hypothalamus is the central point of integration of the ANS. However, the gut can coordinate some secretions and information from the baroreceptors which are processed in the medulla.With regards to the central nervous system (CNS)
1. There are myelinated preganglionic fibres which lead to the
ganglion where the nerve cell bodies of the non-myelinated post ganglionic nerves are organised.
2. From the ganglion, the post ganglionic nerves then lead on to the innervated organ.Most organs are under control of both systems although one system normally predominates.
The nerves of the sympathetic nervous system (SNS) originate from the lateral horns of the spinal cord, pass into the anterior primary rami and then pass via the white rami communicates into the ganglia from T1-L2.
There are short pre-ganglionic and long post ganglionic fibres.
Pre-ganglionic synapses use acetylcholine (ACh) as a neurotransmitter on nicotinic receptors.
Post ganglionic synapses uses adrenoceptors with norepinephrine / epinephrine as the neurotransmitter.
However, in sweat glands, piloerector muscles and few blood vessels, ACh is still used as a neurotransmitter with nicotinic receptors.The ganglia form the sympathetic trunk – this is a collection of nerves that begin at the base of the skull and travel 2-3 cm lateral to the vertebrae, extending to the coccyx.
There are cervical, thoracic, lumbar and sacral ganglia and visceral sympathetic innervation is by cardiac, coeliac and hypogastric plexi.
Juxta glomerular apparatus, piloerector muscles and adipose tissue are all organs under sole sympathetic control.
The PNS has a craniosacral outflow. It causes reduced arousal and cardiovascular stimulation and increases visceral activity.
The cranial outflow consists of
1. The oculomotor nerve (CN III) to the eye via the ciliary ganglion,
2. Facial nerve (CN VII) to the submandibular, sublingual and lacrimal glands via the pterygopalatine and submandibular ganglions
3. Glossopharyngeal (CN IX) to lungs, larynx and tracheobronchial tree via otic ganglion
4. The vagus nerve (CN X), the largest contributor and carries ¾ of fibres covering innervation of the heart, lungs, larynx, tracheobronchial tree parotid gland and proximal gut to the splenic flexure, liver and pancreasThe sacral outflow (S2 to S4) innervates the bladder, distal gut and genitalia.
The PNS has long preganglionic and short post ganglionic fibres.
Preganglionic synapses, like in the SNS, use ACh as the neuro transmitter with nicotinic receptors.
Post ganglionic synapses also use ACh as the neurotransmitter but have muscarinic receptors.Different types of these muscarinic receptors are present in different organs:
There are:
M1 = pupillary constriction, gastric acid secretion stimulation
M2 = inhibition of cardiac stimulation
M3 = visceral vasodilation, coronary artery constriction, increased secretions in salivary, lacrimal glands and pancreas
M4 = brain and adrenal medulla
M5 = brainThe lacrimal glands are solely under parasympathetic control.
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This question is part of the following fields:
- Physiology And Biochemistry
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Question 7
Incorrect
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Which of the following statement is true about Loop diuretics?
Your Answer:
Correct Answer: Are useful in the treatment of acute heart failure
Explanation:Loop diuretics act by causing inhibition of Na+ K+ 2Cl– symporter present at the luminal membrane of the ascending limb of the loop of Henle.
Furosemide, torsemide, bumetanide, ethacrynic acid, furosemide, piretanide, tripamide, and mersalyl are the important members of this group
The main use of loop diuretics is to remove the oedema fluid in renal, hepatic, or cardiac diseases. Thus they are useful in the treatment of acute heart failure. These can be administered i.v. for prompt relief of acute pulmonary oedema (due to vasodilatory action).
Hypokalaemia, hypomagnesemia, hyponatremia, alkalosis, hyperglycaemia, hyperuricemia, and dyslipidaemia are seen with both thiazides as well as loop diuretics
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This question is part of the following fields:
- Pharmacology
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Question 8
Incorrect
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A 5-year old male has ingested a peanut and has developed urticaria, vomiting and hypotension. The pathogenesis of this condition is derived from predominant cells of which cell line?
Your Answer:
Correct Answer: Common myeloid progenitor
Explanation:A is correct. Common myeloid progenitor cells are involved in the anaphylaxis reaction.
B is incorrect. The common lymphoid lineage gives rise to T-cells, B-cell and NK cells.
C is incorrect as megakaryocytes give rise to platelets.
D is incorrect – Neural crest cells give rise to various cells throughout the body, including melanocytes, enterochromaffin cells and Schwann cells. However, they do not give rise to mast cells.
E is incorrect. Reticulocytes give rise to erythrocytes.This is a classic case of anaphylaxis. In this situation, IgE previously raised against antigens (in this case peanut antigen) bind to mast cells, and this causes them to degranulate.
There is release of vasoactive substances like histamine into the blood, and this is responsible for the symptoms seen. Therefore, the main type of cells involved in the pathogenesis of the disease is mast cells. -
This question is part of the following fields:
- Physiology And Biochemistry
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Question 9
Incorrect
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A 72-year-old long-term rheumatoid arthritis patient is having shoulder replacement surgery.
He has chronic obstructive pulmonary disease with a limited exercise tolerance. He agrees to the procedure being performed with an interscalene brachial plexus block.
Which of the following neurological complications puts this patient at the greatest risk?Your Answer:
Correct Answer: Phrenic nerve block
Explanation:An ipsilateral phrenic nerve block will result from a successful interscalene block (ISB).
The phrenic nerve is the diaphragm’s sole motor supply, and ipsilateral hemidiaphragmatic paresis affects up to 100% of patients who receive ISBs. Phrenic nerve palsy is usually well tolerated and goes unnoticed by healthy people. However, forced vital capacity decreases by approximately 25%, which can produce ventilatory compromise in patients with limited pulmonary reserve, requiring assisted ventilation.
Vocal cord palsy occurs when the recurrent laryngeal nerve is inadvertently blocked, causing hoarseness and possibly acute respiratory insufficiency. Unless bilateral laryngeal nerve palsy occurs, which can cause severe laryngeal obstruction, this complication is usually of little consequence.
ISB can also cause cranial nerve X and XII palsy (Tapia’s syndrome). One-sided cord paralysis, aphonia, and the patient’s tongue deviating toward the block’s side are all symptoms.
When a local anaesthetic spreads to the stellate ganglion and its cervical sympathetic nerves, Horner’s syndrome can develop. Ptosis of the eyelid, miosis, and anhidrosis of the face are all symptoms. Horner’s syndrome, on the other hand, may not indicate that the brachial plexus is sufficiently blocked.
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This question is part of the following fields:
- Pathophysiology
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Question 10
Incorrect
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You draw a patient's blood sample from the median cubital vein in the antecubital fossa.
Which of the following veins also connects to the cephalic vein other than the median cubital vein?Your Answer:
Correct Answer: Basilic vein
Explanation:The upper limb venous drainage is divided into superficial and deep. The superficial veins are accessible to draw blood for investigations. The cephalic, basilic, and median cubital veins are superficial veins.
The median cubital vein connects the cephalic vein and basilic vein. It is located anteriorly in the antecubital fossa and is preferred for venepuncture due to its palpability and ease of access.
The basilic vein and cephalic vein are the primary veins that drain the upper limb. They begin as the dorsal venous arch. The basilic vein originates from the ulnar side, while the cephalic vein originates from the radial side of the dorsal arch of the upper limb.
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This question is part of the following fields:
- Anatomy
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Question 11
Incorrect
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Regarding amide local anaesthetics, which one factor has the most significant effect on its duration of action?
Your Answer:
Correct Answer: Protein binding
Explanation:When drugs are bound to proteins, drugs cannot cross membranes and exert their effect. Only the free (unbound) drug can be absorbed, distributed, metabolized, excreted and exert pharmacologic effect. Thus, when amide local anaesthetics are bound to ?1-glycoproteins, their duration of action are reduced.
The potency of local anaesthetics are affected by lipid solubility. Solubility influences the concentration of the drug in the extracellular fluid surrounding blood vessels. The brain, which is high in lipid content, will dissolve high concentration of lipid soluble drugs. When drugs are non-ionized and non-polarized, they are more lipid-soluble and undergo more extensive distribution. Hence allowing these drugs to penetrate the membrane of the target cells and exert their effect.
Tissue pKa and pH will determine the degree of ionization.
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This question is part of the following fields:
- Physiology
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Question 12
Incorrect
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What is the percentage of values that lie within 3 standard deviations of the mean?
Your Answer:
Correct Answer: 99.70%
Explanation:99.7% of the values within 3 standard deviations of the mean.
For 99.7% confidence interval, you can find the range as follows:
1. Multiply the standard error by 3.
2. Subtract the answer from mean value to get the lower limit.
3. Add the answer obtained in step 1 from the mean value to get the upper limit.
For a confidence interval of 68%, multiply the standard error with 1 and repeat the process. For a 95% confidence interval, Standard Error is multiplied by 1.96 to get the interval.
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This question is part of the following fields:
- Statistical Methods
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Question 13
Incorrect
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Which statement is correct about the Mapleson anaesthetic breathing circuits?
Your Answer:
Correct Answer: Mapleson A is most efficient for spontaneous ventilation
Explanation:Mapleson breathing system (or circuit) analysed five different arrangements of components of the breathing system:
Mapleson A – It is the most efficient for spontaneous respiration. The flow of fresh gas required is 70-85 ml/kg/min, i.e., approximately 5-6 lit./min fresh gas flow for an average adult.
Mapleson B and C – inefficient for both SV and PPV; requires gas flow of two to three times minute volume (100 ml/kg/min). Not commonly used but category C may be used for emergency resuscitation.
Mapleson D – efficient for PPV at gas flow equivalent to patient’s minute volume; the Bain’s circuit is a coaxial version of the Mapleson D
Mapleson E and F – for paediatric use; requires gas flow at two to three times the patient’s minute volume. The Mapleson F consists of an open-ended reservoir bag (Jackson-Rees modification). -
This question is part of the following fields:
- Anaesthesia Related Apparatus
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Question 14
Incorrect
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Anaesthetic gas concentrations can be measured using a refractometer. The main principal which allows it to be used for this purpose is which of the following?
Your Answer:
Correct Answer: Refraction
Explanation:Refractometers measure the degree to which the light changes direction, called the angle of refraction. A refractometer takes the refraction angles and correlates them to refractive index (nD) values that have been established. Using these values, you can determine the concentrations of solutions.
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This question is part of the following fields:
- Basic Physics
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Question 15
Incorrect
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Which of the following is true regarding a laryngoscope?
Your Answer:
Correct Answer: The Wisconsin and Seward are examples of straight blade laryngoscopes
Explanation:Direct laryngoscopy are performed using laryngoscopes and they can be classed according to the shape of the blade as curved or straight.
Miller, Soper, Wisconsin and Seward are examples of straight blade laryngoscopes. Straight blades are commonly used for intubating neonates and infants but can be used in adults too.
The tip of the miller blade is advanced over the epiglottis to the tracheal entrance then lifted in order to view the vocal cords.
The RIGHT-SIDED Macintosh blade is used in adults while the left-sided blade may be used in conditions that make intubation with standard blade difficult e.g. facial deformities.
The McCoy laryngoscope is based on the STANDARD MACINTOSH blade not Robertshaw’s. It has a lever operated hinged tip, which improves the view during laryngoscopy.
Polio blade is mounted at an angle of 120-135 degrees to the handle. Originally designed for use during the polio epidemic in intubation patients within iron lung ventilators, it is now useful in patients with conditions like breast hypertrophy, barrel chest, and restricted neck mobility.
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This question is part of the following fields:
- Anaesthesia Related Apparatus
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Question 16
Incorrect
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Which of the following antihypertensive drugs is an alpha-blocker?
Your Answer:
Correct Answer: Doxazosin
Explanation:Doxazosin is selective alpha 1 blocker (it causes less tachycardia than a non-selective alpha-blocker) and is the drug of choice for a patient with hypertension and benign hyperplasia of the prostate (BHP).
The major adverse effect of an alpha-blocker is first-dose hypotension.
Atenolol and Labetalol are beta blockers. It works by relaxing blood vessels and slowing heart rate to improve blood flow and decrease blood pressure.
Clonidine is an α2A-adrenergic agonist used to treat high blood pressure, ADHD, drug withdrawal (alcohol, opioids, or nicotine), menopausal flushing, diarrhea, spasticity, and certain pain conditions.
Methyldopa is a centrally-acting alpha-2 adrenergic agonist used to manage hypertension alone or in combination with hydrochlorothiazide, and to treat hypertensive crises.
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This question is part of the following fields:
- Pharmacology
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Question 17
Incorrect
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Many of the processes we deal with in anaesthesia are exponential.
What is the underlying mathematical principle of an exponential process?Your Answer:
Correct Answer: The rate of change of x is dependent on the magnitude of x
Explanation:The magnitude of x determines the rate of change of x. First-order drug kinetics is a good example. Most drugs’ plasma levels are controlled by an exponential process. The rate of change in drug metabolism is proportional to the current plasma concentration (so-called non-linear kinetics).
A tear-away function is just one type of exponential relationship (y = ex), in which e is Euler’s number, x is the power, and e is the base. Natural logarithms rely on Euler’s number.
Euler’s number is a mathematical constant, not a mathematical principle. It’s referred to as an irrational number. This is a number that cannot be expressed as a simple fraction or a ratio.
A line or curve that acts as the limit of another line or curve is known as an asymptote. A washout exponential curve, for example, where the value y represents the plasma concentration of a drug in a single compartment model against time on the x axis. This descending curve approaches but never touches the x axis. This curve is asymptotic to the x axis, which is the curve’s asymptote. An asymptote isn’t just a characteristic of exponential curves.
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This question is part of the following fields:
- Basic Physics
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Question 18
Incorrect
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Which of these structures will cause the biggest reduction in hepatic blood flow when occluded surgically?
Your Answer:
Correct Answer: Portal vein
Explanation:The portal vein arises from the splenic and mesenteric veins, and is the biggest vessel in the portal venous system, accounting for about 75% of the hepatic blood flow.
It is responsible for draining blood from parts of the gastrointestinal system, the spleen, the pancreas and the gallbladder into the liver.
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This question is part of the following fields:
- Anatomy
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Question 19
Incorrect
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Anaesthetic awareness is most probable in general anaesthesia for which surgical operation?
Your Answer:
Correct Answer: Emergency surgery for major trauma
Explanation:Awareness during general anaesthesia is a frightening experience, which may result in serious emotional injury and post-traumatic stress disorder.
The incidence of awareness during general anaesthesia with current anaesthetic agents and techniques has been reported as 0.2-0.4% in nonobstetric and noncardiac surgery, as 0.4% during caesarean section, and as 1.5% in cardiac surgery.
The incidence during major trauma surgery is higher. Incidence of recall has been reported to be as high as 11-43% in major trauma cases.
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This question is part of the following fields:
- Physiology
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Question 20
Incorrect
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A 28-year-old girl, Sam, has suffered a road traffic accident. She is brought to the emergency department and undergoes investigations and treatment.
On X-ray of the humerus, she has a mid-shaft fracture.
What structure is at the highest risk of damage with a mid-shaft humeral fracture?Your Answer:
Correct Answer: Radial nerve
Explanation:Mid-shaft fractures of the humerus usually occur after a direct blow to the upper arm, which can occur after a fall or RTAs.
The most important clinical significance of a mid-shaft humeral fracture is an injury to the radial nerve. The radial nerve originates from the brachial plexus and has roots of C5-T1. It crosses the spiral groove on the posterior side of the shaft of the humerus.
On examination, the patient may have a wrist drop, loss or weakness of finger extension, and decreased or absent sensation to the posterior forearm, digits 1 to 3, and the radial half of the fourth digit.The humeral shaft has two compartments:
1. Anterior:
Brachial artery and vein
Biceps brachii, brachialis, coracobrachialis
Musculocutaneous, median, and ulnar nerves
2. Posterior:
Radial nerve
TricepsOther significant nerve injuries are:
1. Axillary nerve – surgical neck fracture of the humerus
2. Brachial Artery – supracondylar fracture of the humerus
3. Axillary artery – surgical neck fracture of the humerus, but is relatively uncommon -
This question is part of the following fields:
- Anatomy
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Question 21
Incorrect
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Which of the following statements is true regarding ketamine?
Your Answer:
Correct Answer: Can be used in the management of refractory status epilepticus
Explanation:Ketamine is a phencyclidine (hallucinogenic) derivative that is administered in a dose of 2 mg/kg and acts by blocking NMDA (N-methyl-D-aspartate) receptors of glutamate.
It is a powerful bronchodilator agent and is, therefore, an intravenous anaesthetic of choice in bronchial asthma (halothane is an inhalational anaesthetic agent of choice for bronchial asthma). It is also used in the management of refractory status epilepticus.
It is an acid solution with an elimination half-life of three hours.
It has S (+) enantiomer and R (-) enantiomer. the S(+) enantiomer is two to four times more potent than the R(-) and is less likely to produce hallucinations.
Its use is contraindicated in patients with ischaemic heart disease because it increased sympathetic outflow leading to tachycardia and increased cardiac output which in turn increases the myocardial oxygen demand.
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This question is part of the following fields:
- Pharmacology
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Question 22
Incorrect
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The cardiac tissue type that that has the highest conduction velocity is:
Your Answer:
Correct Answer: Purkinje fibres
Explanation:Potassium maintains the resting potential of cardiac myocytes, with depolarization triggered by a rapid influx of sodium ions, and repolarization due to efflux of potassium. A slow influx of calcium is responsible for the longer duration of a cardiac action potential compared with skeletal muscle.
The cardiac action potential has several phases which have different mechanisms of action as seen below:
Phase 0: Rapid depolarisation – caused by a rapid sodium influx.
These channels automatically deactivate after a few ms.Phase 1: caused by early repolarisation and an efflux of potassium.
Phase 2: Plateau – caused by a slow influx of calcium.
Phase 3 – Final repolarisation – caused by an efflux of potassium.
Phase 4 – Restoration of ionic concentrations – The resting potential is restored by Na+/K+ATPase.
There is slow entry of Na+into the cell which decreases the potential difference until the threshold potential is reached. This then triggers a new action potentialOf note, cardiac muscle remains contracted 10-15 times longer than skeletal muscle.
Different sites have different conduction velocities:
1. Atrial conduction – Spreads along ordinary atrial myocardial fibres at 1 m/sec2. AV node conduction – 0.05 m/sec
3. Ventricular conduction – Purkinje fibres are of large diameter and achieve velocities of 2-4 m/sec, the fastest conduction in the heart. This allows a rapid and coordinated contraction of the ventricles
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This question is part of the following fields:
- Physiology And Biochemistry
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Question 23
Incorrect
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Which term among the following is used for the proportion of a particular disease that would be eradicated from a population if the rate of disease were to be reduced to that of the group that has not been exposed to it?
Your Answer:
Correct Answer: Attributable proportion
Explanation:The attributable risk is the rate of a disease in an exposed group to that of a group that has not been exposed to it. It involves the measure of association that is pertinent to making decisions for the individuals.
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This question is part of the following fields:
- Statistical Methods
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Question 24
Incorrect
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Which of the following is a correct match for reflex and their root value?
Your Answer:
Correct Answer: Knee reflex: L3/L4
Explanation:Reflexes are a routine part of clinical examination. Hyperreflexia (abnormally brisk reflexes) is the sign of upper motor neuron damage whereas diminished or absent jerks are most commonly due to lower motor neuron lesions. Reflexes may be Monosynaptic (deep tendon reflexes) or polysynaptic (superficial reflexes)
Here are deep tendon reflexes with their nerve root
Biceps = C5, C6
Supinator (Brachioradialis) = C5, C6
Triceps = C6, C7
Knee reflex = L3,L4
Ankle reflex = S1Polysynaptic superficial reflexes with their nerve root are listed below
Planter response = S1-2
Abdominal reflexes = T8-12
Cremasteric reflex = L1-2 -
This question is part of the following fields:
- Anatomy
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Question 25
Incorrect
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Venepuncture is being performed on the basilic vein in the cubital fossa. At which of the following points does the basilic vein pass deep under the muscle?
Your Answer:
Correct Answer: Midway up the humerus
Explanation:The basilic vein is one of the primary veins that drain the upper limb, like the cephalic vein. It begins as the dorsal venous arch. The basilic vein originates from the ulnar side of the dorsal arch of the upper limb passes along the posteromedial aspect of the forearm, moving towards the anterior surface of the elbow.
The basilic vein pierces the deep fascia at the elbow and joins the venae commitantes of the brachial vein to form the axillary vein.
The basilic vein passes deep under the muscles as it moves midway up the humerus. At the lower border of the teres major muscle, the anterior and posterior circumflex humeral veins feed into it.
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This question is part of the following fields:
- Anatomy
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Question 26
Incorrect
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Which one of the following pharmacokinetic models is most suitable for target-controlled infusion (TCI) of propofol in paediatric patients?
Your Answer:
Correct Answer: Kataria
Explanation:Marsh (adult) model, when used with children caused over-estimation of plasma concentration. To address this issue Kataria et al developed a three-compartmental model for propofol in children. The pharmacokinetic models used by Target controlled infusion (TCI) systems are used to calculate the relative sizes of the central (vascular), vessel-rich peripheral, and vessel-poor peripheral compartments. The relative volumes of these compartments are different in young children when compared to adults.
Kataria, therefore, is the correct option as described above.
The Maitre model is a three-compartmental model for alfentanil TCI.
The Marsh model describes a propofol TCI model for adults
The Minto model applies to TCI remifentanil.
The Schnider model is also an adult model for propofol that incorporates age and lean body mass as covariates.
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This question is part of the following fields:
- Pharmacology
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Question 27
Incorrect
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The mandibular division of the trigeminal nerve passes through which anatomic structure?
Your Answer:
Correct Answer: Foramen ovale
Explanation:The mandibular branch of the trigeminal nerve passes through the foramen ovale. Other structures that pass through this foramen are the accessory meningeal artery, and occasionally, the lesser petrosal nerve.
These are the structures that pass through the other openings in the cranial fossa:
Foramen rotundum – Maxillary branch of the trigeminal nerve
Foramen lacerum – Greater petrosal nerve, traversed by the internal carotid artery
Superior orbital fissure – Oculomotor nerve; trochlear nerve; lacrimal, frontal and nasociliary branches of the ophthalmic branch of the trigeminal nerve; abducens nerve, superior ophthalmic vein
Stylomastoid foramen – facial nerve
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This question is part of the following fields:
- Anatomy
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Question 28
Incorrect
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An 80-year-old female presents to the emergency department with symptoms consistent with mesenteric ischemia. She is quickly shifted to the operation theatre for an emergency laparotomy.
On exploration, the segment of the colon from the splenic flexure down to the rectum is ischemic.
The artery blocked in this scenario arises at what vertebral level from the aorta?Your Answer:
Correct Answer: L3
Explanation:The hindgut is from the distal third of the transverse colon down to the upper one-third of the anal canal. The inferior mesenteric artery supplies the hindgut.
The inferior mesenteric artery arises from the aorta behind the inferior border of the third part of the duodenum 3–4 cm above the aortic bifurcation, at the third lumbar vertebra level.
The important landmarks of vessels arising from the abdominal aorta at different levels of vertebrae are:
T12 – Coeliac trunk
L1 – Left renal artery
L2 – Testicular or ovarian arteries
L3 – Inferior mesenteric artery
L4 – Bifurcation of the abdominal aorta
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This question is part of the following fields:
- Anatomy
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Question 29
Incorrect
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A 20-year old male was involved in an accident and has presented to the Emergency Department with a pelvic crush injury.
The clinical exam according to ATLS protocol revealed the following:
Airway-patent
Breathing - respiratory rate 25 breaths per minute. Breath sounds are vesicular and there are no added sounds.
Circulation - Capillary refill time - 4 seconds. Peripheries are cool. Pulse 125 beats/min. BP - 125/95 mmHg.
Disability - GSC 15, anxious and in pain.
Secondary survey reveals no other injuries. The patient is administered high flow oxygen and IV access is established.
The most appropriate IV fluid regimen in this case will be which of the following?Your Answer:
Correct Answer: Judicious infusion of Hartmann's solution to maintain a systolic blood pressure greater than 90mmHg
Explanation:These clinical signs suggest that 15-30% of circulating blood volume has been lost.
Pelvic fractures are associated with significant haemorrhage (>2000 ml) that can be concealed. This may require aggressive fluid resuscitation which is initially with crystalloids and then blood. What is also important is including stabilisation of the fracture(s) and pain relief.
The Advanced Trauma Life Support (ATLS) classification of haemorrhagic shock is as follows:
Class I haemorrhage (blood loss up to 15%):
<750 ml of blood loss
Minimal tachycardia
No changes in blood pressure, RR or pulse pressure
Patients do not normally not require fluid replacement as will be restored in 24 hours, but in trauma, this needs to be correct.Class II haemorrhage (15-30% blood volume loss):
Uncomplicated haemorrhage requiring crystalloid resuscitation
Represents about 750 – 1500 ml of blood loss
Tachycardia, tachypnoea and a decrease in pulse pressure (due to a rise in diastolic component due action of catecholamines).
There are minimal systolic pressure changes.
There may be associated anxiety, fright or hostilityClass III haemorrhage (30-40% blood volume loss):
Complicated haemorrhagic state – crystalloid and probably blood replacement are required
There are classical signs of inadequate perfusion, marked tachycardia, tachypnoea, significant changes in mental state and measurable fall in systolic pressure.
Almost always require blood transfusion, but decision based on patient initial response to fluid resuscitation.Class IV haemorrhage (> 40% blood volume loss):
Preterminal event patient will die in minutes
Marked tachycardia, significant depression in systolic pressure and very narrow pulse pressure (or unobtainable diastolic pressure)
Mental state is markedly depressed
Skin cold and pale.
Needs rapid transfusion and immediate surgical intervention.A blood loss of >50% results in loss of consciousness, pulse and blood pressure.
Fluid resuscitation following trauma is a controversial area.
This clinical scenario points to a 15-30% blood loss. However, further crystalloid and blood replacement may be required after assessing the clinical situation. There is increasing evidence to suggest that transfusion of large volumes of crystalloid in the hospital setting are likely to be deleterious to the patient and hypotensive resuscitation and judicious blood and blood product resuscitation is a more appropriate option. A ratio of 1 unit of plasma to 1 unit of red blood cells is used to replace fluid volume in adults.
This patient does not require immediate transfusion of O negative blood and there is time for a formal crossmatch. The argument about colloids versus crystalloids has existed for decades. However, while they have a role in fluid resuscitation, they are not first line.
There is a risk of anaphylaxis, Hypernatraemia, and acute renal injury with colloidal solutions.
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This question is part of the following fields:
- Physiology
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Question 30
Incorrect
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Concerning forced alkaline diuresis, which of the following statements is true?
Your Answer:
Correct Answer: Can be used in a barbiturate overdose
Explanation:In situations of poisoning or drug overdose with acid dugs like salicylates and barbiturates, forced alkaline diuresis may be used.
With regards to overdose with alkaline drugs, forced acid diuresis is used.
By changing the pH of the urine, the ionised portion of the drug stays in the urine, and this prevents its diffusion back into the blood. Charged molecules do not readily cross biological membranes.
The process involves the infusion of specific fluids at a rate of about 500ml per hour. This requires monitoring of the central venous pressure, urine output, plasma electrolytes, especially potassium, and blood gas analysis.
The fluid regimen recommended is:
500ml of 1.26% sodium bicarbonate (not 200ml of 8.4%)
500ml of 5% dextrose and
500ml of 0.9% sodium chloride. -
This question is part of the following fields:
- Physiology
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