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Question 1
Incorrect
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The whole water content of the body is calculated by multiplying body mass with 0.6. This water is diffused into distinct compartments. Which fluid compartment can be measured indirectly?
Your Answer: Extracellular volume
Correct Answer: Intracellular volume
Explanation:The total body water content of a 70kg man is (70 × 0.6) = 42 litres. For a woman, the calculation is (70 × 0.55) = 38.5 litres.
For a man, it is subdivided into:
Extracellular fluid (ECF) = 14L (1/3)
Intracellular fluid (ICF) = 28L (2/3).The ECF volume is further divided into:
Interstitial fluid = 10.5 litres
Plasma = 3 litres
Transcellular fluid (CSF/synovial fluid) = 0.5 litres.Directly measured fluid compartments:
Heavy water (deuterium) can be used to measure total body water content, which is freely distributed.
Albumin labelled with a radioactive isotope or using a dye called Evans blue can be used to measure Plasma volume . They do not diffuse into red blood cells.
Radiolabelled (Cr-51) red blood cells can be used to measure total erythrocyte volume.
Inulin as the tracer can be used to measure ECF volume as it circulate freely in the interstitial and plasma volumes.Indirectly measured fluid compartments:
Total blood volume can be calculated with the level of haematocrit and the volume of total circulating red blood cells.
ICF volume can be calculated by subtracting ECF volume from total blood volume. -
This question is part of the following fields:
- Basic Physics
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Question 2
Correct
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Concerning the physical principles of temperature measurement by a thermocouple, which of the following best describes it?
Your Answer: The bimetallic strip has a junction potential proportional to temperature
Explanation:A thermocouple, or a thermal junction, is temperature measuring device consisting of a pair of dissimilar metal (bimetallic) wires or strips joined together. Typically, copper and constantan (an alloy of 55% copper and 45% nickel) are used. When there is contact between these metals, a small voltage is generated in the order of millivolts. The magnitude of the thermojunction electromotive force (emf) is proportional to applied temperature (the Seebeck effect). This physical principle is applied in the measurement of temperature. The electromotive force at the measuring junction is proportional to temperature.
Two wires with different coefficients of expansion, joined together, can be used as a switch for thermostatic control.
Semiconductors are NOT used in thermocouple. The resistance of the measuring junction of a thermocouple is irrelevant.
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This question is part of the following fields:
- Anaesthesia Related Apparatus
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Question 3
Correct
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Seven days after undergoing an inguinal hernia repair, a 24-year old male presents with a wound that is erythematous, tender and has a purulent discharge. The most likely cause of this is which of the following?
Your Answer: Infection with Staphylococcus aureus
Explanation:Staphylococcus aureus infection is the most likely cause.
Surgical site infections (SSI) occur when there is a breach in tissue surfaces and allow normal commensals and other pathogens to initiate infection. They are a major cause of morbidity and mortality.
SSI comprise up to 20% of healthcare associated infections and approximately 5% of patients undergoing surgery will develop an SSI as a result.
The organisms are usually derived from the patient’s own body.Measures that may increase the risk of SSI include:
-Shaving the wound using a single use electrical razor with a disposable head
-Using a non iodine impregnated surgical drape if one is needed
-Tissue hypoxia
-Delayed prophylactic antibiotics administration in tourniquet surgery, patients with a prosthesis or valve, in clean-contaminated surgery of in contaminated surgery.Measures that may decrease the risk of SSI include:
1. Intraoperatively
– Prepare the skin with alcoholic chlorhexidine (Lowest incidence of SSI)
-Cover surgical site with dressingIn contrast to previous individual RCT’s, a recent meta analysis has confirmed that administration of supplementary oxygen does not reduce the risk of wound infection and wound edge protectors do not appear to confer benefit.
2. Post operatively
Tissue viability advice for management of surgical wounds healing by secondary intentionUse of diathermy for skin incisions
In the NICE guidelines the use of diathermy for skin incisions is not advocated. Several randomised controlled trials have been undertaken and demonstrated no increase in risk of SSI when diathermy is used. -
This question is part of the following fields:
- Physiology And Biochemistry
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Question 4
Correct
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Which of the following is not used in the treatment of Neuroleptic Malignant Syndrome?
Your Answer: Olanzapine
Explanation:The neuroleptic malignant syndrome (NMS) is a rare complication in response to neuroleptic or antipsychotic medication.
The main features are:
– Elevated creatinine kinase
– Hyperthermia and tachycardia
– Altered mental state
– Increased white cell count
– Insidious onset over 1-3 days
– Extrapyramidal dysfunction (muscle rigidity, tremor, dystonia)
– Autonomic dysfunction (Labile blood pressure, sweating, salivation, urinary incontinence)Management is supportive of ICU care, anticholinergic drugs, increasing dopaminergic activity with Amantadine, L-dopa, and dantrolene, and non- depolarising neuromuscular blockade drugs.
Since Olanzapine is a potential cause of NMS it is not a treatment.
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This question is part of the following fields:
- Pharmacology
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Question 5
Correct
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All of the following statements are false regarding insulin except:
Your Answer: Can be detected in the lymph
Explanation:Insulin is secreted from the β cells of the pancreas. It consists of 51 amino acids arranged in two chains. It interacts with cell surface receptors (not the nuclear receptors and thus mechanism of action is not similar to steroids).
Since insulin can pass from plasma to interstitium and lymphatics, it can be measured in lymph but the concentrations here can be up to 30% less than that of plasma.It decreases blood glucose by stimulating the entry of glucose in muscle and fat (by increasing the synthesis of Glucose transporters)
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This question is part of the following fields:
- Pharmacology
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Question 6
Correct
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A 42 year old lady has acute onset of painless weakness on her left side of the face with a drooping mouth and difficulty speaking. With no significant past medical history and after relevant investigations, you rule out stroke as a possible cause. The lady is suspected to have suffered Bell's palsy, an idiopathic paralysis of the facial nerve. What symptoms are you most likely to find on examination in a patient with Bell's palsy?
Your Answer: Taste impairment of the anterior tongue
Explanation:Bell’s palsy is facial muscle weakness or paralysis that arises from idiopathic damage to the facial nerve. It can occur at any age but is commonly associated with some conditions:
1. pregnancy
2. diabetes
3. upper respiratory ailment
4. GBS
5. ToxinsThe common symptoms of Bell’s palsy are:
1. Abnormal corneal reflex as the facial nerve controls the motor aspect of the corneal reflex.
2. The loss of control of facial muscles and eyelids leads to decreased tear production.
3. mild weakness to total paralysis on one side of the face, occurring within hours to days.
4. Bell’s palsy is a lower motor neuron lesion that usually spares the forehead while the upper motor near lesions, like stroke, involves the entire face.
5. The anterior two-thirds of the tongue is supplied by the chorda tympani branch of the facial nerve, thus resulting in loss of taste.
6. Ptosis can be a feature of Bell’s palsy but Bell’s palsy would typically show unilateral symptoms rather than bilateral. -
This question is part of the following fields:
- Anatomy
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Question 7
Incorrect
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What does therapeutic index in humans mean?
Your Answer: The ED50 divided by the sum of the (LD50 + TD50)
Correct Answer: The TD50 divided by the ED50
Explanation:Therapeutic index is a measure which relates the dose of a drug required to produce a desired effect to that which produces an undesired effect.
In humans, it is usually defined as the ratio of the toxic dose for 50% of the population (TD50) to the minimum effective dose for 50% of the population (ED50) for some therapeutically relevant effect. In animal studies, the therapeutic index can be defined as the ratio of the median lethal dose (LD50) to the ED50.
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This question is part of the following fields:
- Pharmacology
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Question 8
Incorrect
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Which of the following statements is true regarding prazosin?
Your Answer: Causes elevation of renin concentrations.
Correct Answer: Is a selective alpha 1 adrenergic receptor antagonist.
Explanation:Selective α1 -Blockers like prazosin, terazosin, doxazosin, and alfuzosin cause a decrease in blood pressure with lesser tachycardia than nonselective blockers (due to lack of α2 blocking action.
The major adverse effect of these drugs is postural hypotension. It is seen with the first few doses or on-dose escalation (First dose effect).
Its half-life is approximately three hours.
It is excreted primarily through bile and faeces (not through kidneys)
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This question is part of the following fields:
- Pharmacology
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Question 9
Correct
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Out of the following, which anatomical structure lies within the spiral groove of the humerus?
Your Answer: Radial nerve
Explanation:The shaft of the humerus has two prominent features:
1. Deltoid tuberosity – attachment for the deltoid muscle
2. Radial or spiral groove – The radial nerve and profunda brachii artery lie in the grooveMid-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 following parts of the humerus are in direct contact with the indicated
nerves:
Surgical neck: axillary nerve.
Radial groove: radial nerve.
Distal end of humerus: median nerve.
Medial epicondyle: ulnar nerve. -
This question is part of the following fields:
- Anatomy
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Question 10
Correct
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Following an acute appendicectomy, a 6-year-old child is admitted to the recovery unit. Your consultant has requested that you prescribe maintenance fluids for the next 12 hours. The child is 21 kg in weight. What is the most suitable fluid volume to be prescribed?
Your Answer: 732 ml
Explanation:After a paediatric case, you’ll frequently have to calculate and prescribe maintenance fluids. The ‘4-2-1 rule’ should be used as a guideline:
1st 10 kg – 4 ml/kg/hr
2nd 10 kg – 2 ml/kg/hr
Subsequent kg – 1 ml/kg/hrHence
1st 10 kg = 4 × 10 = 40 ml
2nd 10 kg = 2 × 10 = 20 ml
Subsequent kg = 1 × 1 = 1 ml
Total = 61 ml/hr61 × 12 = 732 ml over 12 hrs.
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This question is part of the following fields:
- Physiology
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Question 11
Correct
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What is the number of valves between the superior vena cava and the right atrium?
Your Answer: None
Explanation:The inflow of blood from the superior vena cava is directed towards the right atrioventricular orifice. It returns deoxygenated blood from all structures superior to the diaphragm, except the lungs and heart.
There are no valves in the superior vena cava which is why it is relatively easy to insert a CVP line from the internal jugular vein into the right atrium. The brachiocephalic vein is similar as it also has no valves.
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This question is part of the following fields:
- Anatomy
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Question 12
Correct
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Which of the following anaesthetic agents is most suitable for inhalational induction in an 8-year-old child for inhalational induction of anaesthesia before routine surgery?
Your Answer: Sevoflurane at 4%
Explanation:The ideal agent for this case should have low blood: gas coefficient, pleasant smell, and high oil: gas coefficient (potent with a low Minimum alveolar coefficient (MAC)). Among the given options, Sevoflurane is perfect with 0.692 blood: gas partition coefficient and is low pungency, and is sweet.
Other drugs with their blood: gas partition coefficient and their smell are given as:
Blood/gas partition coefficient MAC Smell
Enflurane 1.8 1.68 Pungent, ethereal
Desflurane 0.42 7 Pungent, ethereal
Halothane 2.54 0.71 Sweet
Isoflurane 1.4 1.15 Pungent, ethereal -
This question is part of the following fields:
- Pharmacology
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Question 13
Correct
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Which of the following statements is true regarding sucralfate?
Your Answer: Has very few side effects
Explanation:Sucralfate is an octasulfate of glucose to which Al(OH)3 has been added. It undergoes extensive cross-linking in an acidic environment and forms a polymer which adheres to the ulcer base for up to 6 hours and protects it from further erosion. Since it is not systemically absorbed it is virtually devoid of side effects. However, it may cause constipation in about 2% of cases due to the Aluminium component in it.
Sucralfate does not have antibacterial action against Helicobacter pylori. However, Bismuth has antibacterial action due to its oligodynamic effect.
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This question is part of the following fields:
- Pharmacology
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Question 14
Correct
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A 74-year-old man presents to a hospital for manipulation of Colles fracture. The patient is 50 kg and the anaesthetic plan is to perform an intravenous regional (Bier's) block. Which of the following is the appropriate dose of local anaesthetic for the procedure?
Your Answer: 0.5% prilocaine (40 ml)
Explanation:Prilocaine is the drug of choice for intravenous regional anaesthesia. 0.5% prilocaine (40 ml) is indicated for this condition.
Lidocaine is another alternative for this condition but volume and dose are likely to be inadequate for the procedure. -
This question is part of the following fields:
- Pharmacology
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Question 15
Correct
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Which of the following statements is true regarding the relation to the liver?
Your Answer: The caudate lobe is superior to the porta hepatis
Explanation:Ligamentum venosum is an anterior relation of the liver: The ligamentum venosum, the fibrous remnant of the ductus venosus of the fetal circulation, lies posterior to the liver. It lies in the fossa for ductus venosus that separates the caudate lobe and the left lobe of the liver.
The portal triad contains three important tubes: 1. Proper hepatic artery 2. Hepatic portal vein 3. Bile ductules It also contains lymphatic vessels and a branch of the vagus nerve.
The bare area of the liver is a large triangular area that is devoid of any peritoneal covering. The bare area is attached directly to the diaphragm by loose connective tissue. This nonperitoneal area is created by a wide separation between the coronary ligaments.
The porta hepatis is a fissure in the inferior surface of the liver. All the neurovascular structures (except the hepatic veins) and hepatic ducts enter or leave the liver via the porta hepatis. It contains the sympathetic branch to the liver and gallbladder and the parasympathetic, hepatic branch of the vagus nerve. The caudate lobe (segment I) lies in the lesser sac on the inferior surface of the liver between the IVC on the right, the ligamentum venosum on the left, and the porta hepatis in front.
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This question is part of the following fields:
- Anatomy
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Question 16
Incorrect
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Question 17
Incorrect
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Bioelectric potentials that have been measured have an optimum bandwidth and typical frequency. For a standard 12-lead ECG, which of the following bandwidth and voltage combinations is the best?
Your Answer: Bandwidth 0.5-50 Hz, voltage 0.5-10 millivolts
Correct Answer: Bandwidth 0.05-150 Hz, voltage 100-4000 microvolts
Explanation:The potential difference (amplitude) and bandwidth frequencies of bioelectric signals are typical.
These are the following:
ECG: A bandwidth of 0.5-50 Hz is usually sufficient in monitoring mode, but a typical diagnostic bandwidth is 0.05-150 Hz (up to 200 Hz) with a typical voltage range of 0.1-4 millivolts (100-4000 microvolts).
EEG has a frequency range of 0.5-100 Hz and a voltage range of 0.5-100 microvolts.
EMG has a frequency range of 0.5 to 350 Hz and a voltage range of 0.5 to 30 millivolts.Prior to display, these small signals will need to be amplified and processed further.
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This question is part of the following fields:
- Anaesthesia Related Apparatus
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Question 18
Correct
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A 75-year-old man, visits his general practitioner. He complains of changes to his bowel habit and unexpected weight loss in the last 6 months. He is scheduled for a colonoscopy and biopsy where he is diagnosed with a transverse colon malignancy. The transverse colon is one of many organs tethered to the posterior wall of the abdominal cavity by a double fold of the peritoneum. Which of the listed organs is also tethered to the peritoneum in a similar way?
Your Answer: The stomach
Explanation:The peritoneal cavity is made up of the omentum, the ligaments and the mesentery.
The section of the peritoneum responsible for tethering organs to the posterior abdominal wall is the mesentery.
These tethered organs are classified as intraperitoneal, and these include the stomach, spleen, liver, first and fourth parts of the duodenum, jejunum, ileum, transverse, and sigmoid colon.
Retroperitoneal organs are located posterior to the peritoneum and include: the rest of the duodenum, the ascending colon, the descending colon, the middle third of the rectum, and the remainder of the pancreas.
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This question is part of the following fields:
- Anatomy
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Question 19
Correct
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Which of the following is true about the bispectral index (BIS)?
Your Answer: Sevoflurane lowers BIS more than ketamine
Explanation:The bispectral index (BIS) monitors works to determine the level of consciousness of a patient by processing electroencephalographic (EEG) signals to obtain a value between 0 and 100, where 0 reflects no brain activity, and 100 reflects a patient is completely awake.
The general meaning of BIS values are:
>95: Patient is in an awake state.
65-85: Patient is in a sedated state.
40-65: Patient is in a state that is optimal for general surgery.
<40: Patient is in a deep hypnotic stateIt is important in measuring the depths of anaesthesia to prevent haemodynamic changes or patient awareness during surgery.
The nature of anaesthetic agent used is a determinant factor in resultant BIS values. Intravenous agents, such as propofol, thiopental and midazolam, result in a deeper hypnotic state, whilst inhalation agents have a lesser hypnotic effect at the same BIS values. Certain agents result in inaccurate BIS values such as ketamine and nitrous oxide (NO). These two agents appear to increase the BIS value, whilst putting the patient in a deeper hypnotic state, and should therefore not be used with BIS monitoring.
Hypothermia also affects the BIS value as it causes a 1.12 per °C decrease in body temperature.
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This question is part of the following fields:
- Clinical Measurement
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Question 20
Correct
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Which of the following is a correct match for reflex and their root value?
Your 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 21
Incorrect
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Which of the following statement is true regarding the mechanism of action of doxycycline?
Your Answer: Inhibit 50S subunit of ribosomes
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 22
Correct
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With regards to the repolarisation phase of the myocardial action potential, which of the following is responsible?
Your Answer: Efflux of potassium
Explanation:Cardiac conduction
Phase 0 – Rapid depolarization. Opening of fast sodium channels with large influx of sodium
Phase 1 – Rapid partial depolarization. Opening of potassium channels and efflux of potassium ions. Sodium channels close and influx of sodium ions stop
Phase 2 – Plateau phase with large influx of calcium ions. Offsets action of potassium channels. The absolute refractory period
Phase 3 – Repolarization due to potassium efflux after calcium channels close. Relative refractory period
Phase 4 – Repolarization continues as sodium/potassium pump restores the ionic gradient by pumping out 3 sodium ions in exchange for 2 potassium ions coming into the cell. Relative refractory period
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This question is part of the following fields:
- Physiology And Biochemistry
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Question 23
Correct
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Which of the following is a correctly stated fundamental (base) SI unit?
Your Answer: A metre is the unit of length
Explanation:The international system of units, or system international d’unites (SI) is a collection of measurements derived from expanding the metric system.
There are seven base units, which are:
Metre (m): a unit of length
Second (s): a unit of time
Kilogram (kg): a unit of mass
Ampere (A): a unit of electrical current
Kelvin (K): a unit of thermodynamic temperature
Candela (cd): a unit of luminous intensity
Mole (mol): a unit of substance. -
This question is part of the following fields:
- Clinical Measurement
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Question 24
Correct
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An 80-year-old man has a swelling in his left groin with moderate pain and discomfort complaints. Diagnosed with an inguinal hernia, he is scheduled for elective surgery to repair the defect. Of the following, which nerve runs in the inguinal canal and is at risk of being damaged during surgery?
Your Answer: Ilioinguinal nerve
Explanation:The inguinal canal is a passage in the lower anterior abdominal wall just above the inguinal ligament. It transmits the following structures:
1. genital branch of genitofemoral nerve
2. ilioinguinal nerve
3. spermatic cord (males only)
4. round ligament of the uterus (females only)The ilioinguinal is a direct branch of the first lumbar nerve. The ilioinguinal nerve enters the inguinal canal via the abdominal musculature (and not through the deep (internal) inguinal ring) and exits through the superficial (or external) inguinal ring.
The openings for the other nerves in the answer options are:
Sciatic nerve – exits the pelvis via the greater sciatic foramen
Obturator nerve – descends into pelvis via the obturator foramen
Femoral nerve – descends from the abdomen through the pelvis behind the inguinal canalThe Iliohypogastric nerve also arises from the first lumbar root with the ilioinguinal nerve but pierces the transversus abdominis muscle posteriorly, just above the iliac crest, and continues anteriorly between the transversus abdominis and the internal abdominal oblique muscles.
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This question is part of the following fields:
- Anatomy
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Question 25
Correct
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The solutions that contains the most sodium is?
Your Answer: 3500 mL 0.9% N saline
Explanation:Sodium concentration for different fluids
3% N saline 513 mmol/L
5% N saline 856 mmol/L
0.9% N saline 154 mmol/L
Hartmann’s solution 131 mmol/L
0.45% N saline with 5% glucose 77 mmol/LThis means that:
500 mL 5% N saline contains 428 mmol of sodium
1000 mL 3% N saline contains 513 mmol of sodium
3500 mL 0.9% N saline contains 539 mmol of sodium
4000 mL Hartmann’s contains 524 mmol of sodium
6000 mL 0.45% N saline with 5% glucose contains 462 mmol of sodium. -
This question is part of the following fields:
- Physiology
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Question 26
Correct
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Which of these thyroid hormones is considered the most potent and most physiologically active?
Your Answer: T3
Explanation:Triiodothyronine (T3) is more potent than thyroxine (T4). It is able to bind to more receptors (90%) compared to T4 (10%), and the onset of action is more immediate (within 12 hours) than T4 (2 days).
Ninety-three percent of thyroid hormones synthesized is T4, and the remaining 7% is T3. The half-life of T3 is shorter (1 day), and its affinity for thyroxine-binding globulin is lower than T4.
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This question is part of the following fields:
- Pathophysiology
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Question 27
Correct
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Which of the following would most likely explain a failed post-operative analgesia via local anaesthesia of a neck abscess?
Your Answer: pKA
Explanation:For the local anaesthetic base to be stable in solution, it is formulated as a hydrochloride salt. As such, the molecules exist in a quaternary, water-soluble state at the time of injection. However, this form will not penetrate the neuron. The time for onset of local anaesthesia is therefore predicated on the proportion of molecules that convert to the tertiary, lipid-soluble structure when exposed to physiologic pH (7.4).
The ionization constant (pKa) for the anaesthetic predicts the proportion of molecules that exists in each of these states. By definition, the pKa of a molecule represents the pH at which 50% of the molecules exist in the lipid-soluble tertiary form and 50% in the quaternary, water-soluble form. The pKa of all local anaesthetics is >7.4 (physiologic pH), and therefore a greater proportion the molecules exists in the quaternary, water-soluble form when injected into tissue having normal pH of 7.4.
Furthermore, the acidic environment associated with inflamed tissues favours the quaternary, water-soluble configuration even further. Presumably, this accounts for difficulty when attempting to anesthetize inflamed or infected tissues; fewer molecules exist as tertiary lipid-soluble forms that can penetrate nerves.
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This question is part of the following fields:
- Physiology
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Question 28
Correct
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How many unpaired branches leave the abdominal aorta to supply the abdominal viscera?
Your Answer: Three
Explanation:The abdominal arteries are divided into 3 branches;
– 3 main unpaired trunks (celiac trunk, superior mesenteric, inferior mesenteric arteries)
– 6 paired branches
– unpaired median sacral artery.We can group the abdominal aorta as follows;
-Ventral which includes: Coeliac trunk, superior mesenteric and inferior mesenteric arteries
-Lateral: Inferior phrenic, middle suprarenal, renal and gonadal arteries
-Dorsal: Lumbar and median sacral arteries
-Terminal : Right and left common iliac arteriesThe celiac trunk (L1) takes blood the foregut and its found posterior to the stomach. The unpaired superior mesenteric artery supplies blood to the mid-gut.
The paired renal arteries form the inferior suprarenal arteries. The renal arteries arise around L1/L2 and takes blood to either side of the kidneys.
The median sacral artery supplies blood to the lumbar vertebrae the L4 and L5.
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This question is part of the following fields:
- Anatomy
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Question 29
Correct
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Which of following statements is true regarding the comparison of fentanyl and alfentanil?
Your Answer: Fentanyl is more potent than alfentanil
Explanation:Fentanyl is a pethidine congener, 80€“100 times more potent than morphine, both in analgesia and respiratory depression. Fentanyl is ten times more potent than alfentanil.
Alfentanil has a more rapid onset than fentanyl even if fentanyl is more lipid-soluble because both are basic compounds and alfentanil has lower pKa, so a greater proportion of alfentanil is unionized and is more available to cross membranes.
Elimination of alfentanil is higher than fentanyl due to its lower volume of distribution.
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This question is part of the following fields:
- Pharmacology
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Question 30
Correct
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General anaesthesia is administered to a patient in a hospital in Lhasa which is one of the highest cities in the world (at 11,975 feet). An Anaesthetic rotameter is normally calibrated at 20 C and 1 bar pressure and is known to be underread at altitude. The temperature of the theatre was 10 C. Which one of the following physical properties is responsible for the rotameter inaccuracy in these conditions?
Your Answer: Density of the gas
Explanation:Since the gas is less dense at higher altitudes, the density of a gas influences flows when passing through the orifice. Due to this reason, for a given flow rate, the bobbin will not be forced as far up the rotameter tube.
At higher altitudes, the volume of a fixed mass of gas increases, and therefore the molecules of gas are widely spaced resulting in a decrease in density with an increase in altitude.
Viscosity is simply termed as friction of gas. The viscosity of a gas is important only at low flow rates when the flow characteristic of the gas is laminar.
Charle’s law stated that the volume occupied by a fixed amount of gas is directly proportional to its absolute temperature (T) provided the pressure remains constant.
Boyle’s law for a fixed amount of gas at constant temperature, the pressure (P) and volume (V) are inversely proportional.
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This question is part of the following fields:
- Basic Physics
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