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Question 1
Incorrect
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Of the following, which of these oxygen carrying molecules causes the greatest shift of the oxygen-dissociation curve to the left?
Your Answer: Haemoglobin (HbF)
Correct Answer: Myoglobin (Mb)
Explanation:Myoglobin is a haemoglobin-like, iron-containing pigment that is found in muscle fibres. It has a high affinity for oxygen and it consists of a single alpha polypeptide chain. It binds only one oxygen molecule, unlike haemoglobin, which binds 4 oxygen molecules.
The myoglobin ODC is a rectangular hyperbola. There is a very low P50 0.37 kPa (2.75 mmHg). This means that it needs a lower P50 to facilitate oxygen offloading from haemoglobin. It is low enough to be able to offload oxygen onto myoglobin where it is stored. Myoglobin releases its oxygen at the very low PO2 values found inside the mitochondria.
P50 is defined as the affinity of haemoglobin for oxygen: It is the PO2 at which the haemoglobin becomes 50% saturated with oxygen. Normally, the P50 of adult haemoglobin is 3.47 kPa(26 mmHg).
Foetal haemoglobin has 2 α and 2 γchains. The ODC is left shifted – this means that P50 lies between 2.34-2.67 kPa [18-20 mmHg]) compared with the adult curve and it has a higher affinity for oxygen. Foetal haemoglobin has no β chains so this means that there is less binding of 2.3 diphosphoglycerate (2,3 DPG).
Carbon monoxide binds to haemoglobin with an affinity more than 200-fold higher than that of oxygen. This therefore decreases the amount of haemoglobin that is available for oxygen transport. Carbon monoxide binding also increases the affinity of haemoglobin for oxygen, which shifts the oxygen-haemoglobin dissociation curve to the left and thus impedes oxygen unloading in the tissues.
In sickle cell disease, (HbSS) has a P50 of 4.53 kPa(34 mmHg).
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This question is part of the following fields:
- Physiology
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Question 2
Correct
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At 37 weeks' gestation, a 29-year-old parturient is admitted to the labour ward. Her antenatal period was asymptomatic for her. The haematological values listed below are available: Hb concentration of 100 g/L (115-165), 200x109/L platelets (150-400), MCV 81 fL (80-96). Which of the following is the most likely reason for the problem?
Your Answer: Iron deficiency
Explanation:This patient’s limited haematological profile includes mild normocytic anaemia and a normal platelet count.
Iron deficiency is the most common cause of anaemia during pregnancy. It affects 75 to 95 percent of patients. A haemoglobin level of less than 110 g/L in the first trimester and less than 105 g/L in the second and third trimesters is considered anaemia. There will usually be a low mean cell volume (MCV), mean cell haemoglobin (MCH), and mean cell haemoglobin concentration in addition to a low haemoglobin (MCHC). The MCV may be normal in mild cases of iron deficiency or coexisting vitamin B12 and folate deficiency.
To determine whether you have an iron deficiency, you’ll need to take more tests. Low serum ferritin (15 g/L) and less reliable indices like serum iron and total iron binding capacity are among them.
A number of factors contribute to iron deficiency in pregnancy, including:
Insufficient dietary iron to meet the mother’s and foetus’ nutritional needs
Multiple pregnancies
Blood loss, as well as
Absorption of iron from the gut is reduced.The volume of plasma increases by about 50% during pregnancy, but the mass of red blood cells (RBCs) increases by only 30%. Dilutional anaemia is the result of this situation. From the first trimester to delivery, the RBC mass increases linearly, while the plasma volume plateaus, stabilises, or falls slightly near term. As a result, between 28 and 34 weeks of pregnancy, haemoglobin concentrations are at their lowest. The effects of haemodilution will be negated in this patient because she is 37 weeks pregnant.
Vitamin B12 and folate deficiency are less common causes of anaemia in pregnancy. The diagnosis could be ruled out if the MVC is normal.
During pregnancy, the platelet count drops, especially in the third trimester. Gestational thrombocytopenia is the medical term for this condition. It’s due to a combination of factors, including haemodilution and increased platelet activation and clearance. Pre-eclampsia and HELLP syndrome are common causes of thrombocytopenia. Pre-eclampsia isn’t the only cause of anaemia during pregnancy.
A typical blood picture of a haemoglobinopathy like sickle cell disease shows quantitative and qualitative defects, with the former leading to a severe anaemia exacerbated by haemodilution and other factors that contribute to iron deficiency. Microcytic cells are the most common type.
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This question is part of the following fields:
- Pathophysiology
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Question 3
Incorrect
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Which statement is correct about the Mapleson anaesthetic breathing circuits?
Your Answer: Mapleson E is efficient at gas flow equivalent to the patient's minute ventilation
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 4
Incorrect
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Which of the following is the smallest value of pressure?
Your Answer: 1,520 mmHg
Correct Answer: 14.69 psi
Explanation:The SI unit of pressure is the pascal (Pa) and it is equal to one newton (N) per square meter (m2) or N/m2.
1 atmosphere (atm) is the equivalent of:
101325 Pa760 mmHg
1.01325 bar
1033.23 cmH2O.
14.69 pounds per square inch (psi)
1013.25 millibar (mbar) or hectopascals (hPa), and14.69 psi is equal to one atmosphere. The other values are equal to two atmospheres of pressure.
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This question is part of the following fields:
- Basic Physics
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Question 5
Correct
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Noradrenaline is used as an infusion to increase blood pressure in a 43-year-old woman with pneumonia admitted to ICU. Which of the following statements is true regarding Noradrenaline?
Your Answer: Has a short half life about 2 minutes
Explanation:Noradrenaline has a short half-life of about 2 minutes. It is rapidly cleared from plasma by a combination of cellular reuptake and metabolism.
It acts as sympathomimetics by acting on α1 receptors and also on β receptors.
It decreases renal and hepatic blood flow.
Norepinephrine is metabolized by the enzymes monoamine oxidase and catechol-O-methyltransferase to 3-methoxy-4-hydroxymandelic acid and 3-methoxy-4-hydroxyphenylglycol (MHPG).
Natural catecholamines are Adrenaline, Noradrenaline, and Dopamine
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This question is part of the following fields:
- Pharmacology
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Question 6
Incorrect
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Which of the following options is correct regarding the coagulation pathway?
Your Answer: Heparin inhibits the activation of Factor 8
Correct Answer: Tissue factor released by damaged tissue initiates the extrinsic pathway
Explanation:The extrinsic pathway is considered as the main pathway of coagulation cascade.
Heparin is known to inhibit the activation of coagulation factors 2,9,10, and 11.
The extrinsic and intrinsic pathways meet at the activation of coagulation factor 10.
Fibrinogen is converted into Fibrin in the presence of Thrombin. Plasminogen is converted into plasmin during fibrinolysis to breakdown fibrin clot.
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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 is a characteristic of a type 1B antiarrhythmic agent such as Lidocaine?
Your Answer: Inhibits the influx of sodium via voltage-gated channels
Correct Answer: Shortens refractory period
Explanation:The action of class 1 anti-arrhythmic is sodium channel blockade. Subclasses of this action reflect effects on the action potential duration (APD) and the kinetics of sodium channel blockade.
Drugs with class 1A prolong the APD and refractory period, and dissociate from the channel with intermediate kinetics.
Drugs with class 1B action shorten the APD in some tissues of the heart, shorten the refractory period, and dissociate from the channel with rapid kinetics.
Drugs with class 1C action have minimal effects on the APD and the refractory period, and dissociate from the channel with slow kinetics.
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This question is part of the following fields:
- Pharmacology
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Question 8
Incorrect
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The following are the pharmacodynamic properties of a neuromuscular blocking agent: Effective dose 95 (ED95) - 0.3 mg/kg, Time to 95% depression of first twitch of train of four (ToF) - 75 seconds, Time to 25% recovery of first twitch of train of four (ToF) - 33 minutes. Which of the following statements about this neuromuscular blocking agent is the most accurate?
Your Answer: Has a benzylisoquinolinium structure
Correct Answer: Can be reversed by a modified gamma-cyclodextrin
Explanation:The aminosteroid rocuronium is the neuromuscular blocking agent in question.
0.3 mg/kg is the effective dose 95 (ED95) (the dose required to depress the twitch height by 95 percent )
The dose for intubation is 0.6 mg/kg.
75 seconds is the time it takes to reach 95 percent depression of the first twitch of the train of four (ToF) or the onset time.
The clinical duration or time to 25% recovery of the first twitch of the train of four (ToF) is 33 minutes.A modified cyclodextrin can quickly reverse both rocuronium and vecuronium (sugammadex).
It is more fat-soluble than vecuronium, with the liver absorbing the majority of the drug and excreting it in the bile. The only metabolite found in the blood (17-desacetylrocuronium) is 20 times less potent than the parent drug and is unlikely to cause neuromuscular block.
Despite its quick onset of action (60-90 seconds), suxamethonium arguably is still the neuromuscular blocker of choice for a quick sequence induction. Rocuronium is becoming increasingly popular for this purpose.
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This question is part of the following fields:
- Pharmacology
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Question 9
Incorrect
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A 27-year-old woman is admitted to the emergency room with an ectopic pregnancy that has ruptured. The following is a description of the clinical examination: Anxious, Capillary refill time of 3 seconds, Cool peripheries, Pulse 120 beats per minute, Blood pressure 120/95 mmHg, Respiratory rate 22 breaths per minute. Which of the following is the most likely explanation for these clinical findings?
Your Answer: Reduction in blood volume of 40-50%
Correct Answer: Reduction in blood volume of 15-30%
Explanation:The following is the Advanced Trauma Life Support (ATLS) classification of haemorrhagic shock:
Class I haemorrhage:
It has blood loss up to 15%. There is very less tachycardia, and no changes in blood pressure, RR or pulse pressure. Usually, fluid replacement is not required.Class II haemorrhage:
It has 15-30% blood loss, equivalent to 750 – 1500 ml. There is tachycardia, tachypnoea and a decrease in pulse pressure. Patient may be frightened, hostile and anxious. It can be stabilised by crystalloid and blood transfusion.Class III haemorrhage:
There is 30-40% blood loss. It portrays inadequate perfusion, marked tachycardia, tachypnoea, altered mental state and fall in systolic pressure. It requires blood transfusion.Class IV haemorrhage:
There is > 40% blood volume loss. It is a preterminal event, and the patient will die in minutes. It portrays tachycardia, significant depression in systolic pressure and pulse pressure, altered mental state, and cold clammy skin. There is need for rapid transfusion and surgical intervention. -
This question is part of the following fields:
- Physiology
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Question 10
Correct
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Which of the following factors significantly increases the risk of hepatotoxicity and fulminant hepatic failure in halothane administration?
Your Answer: Multiple exposure
Explanation:Hepatotoxicity due to halothane administration is relatively common and is a major factor in its rapidly declining use. Type 1 hepatotoxicity has an incidence of 20% to 30%. A comprehensive report in 1969 demonstrated an incidence of type 2 hepatotoxicity (hepatitis) of 1 case per 6000 to 20000 cases, with fatal cases occurring approximately once in 35000 patients following a single exposure to the anaesthetic. This incidence of fatal cases increases to approximately 1 in 1000 patients following multiple exposures. Following this study was a large-scale review in the United Kingdom, which showed similar results. To put this into perspective, there is only a single case of hepatotoxicity confirmed after the administration of desflurane and 2 cases per 1 million after enflurane. By the 1970s, halothane was the most common cause of drug-induced liver failure.
Halothane-induced hepatotoxicity has a female to male ratio of two to one. Younger patients are less likely to be affected; 80% of the cases are typically in patients 40 years or older. Other risk factors include obesity and underlying liver dysfunction. Medications such as phenobarbital, alcohol, and isoniazid may play a role in affecting CYP2E1 metabolism, increasing one’s risk.
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This question is part of the following fields:
- Pharmacology
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Question 11
Incorrect
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One of the following sets of arterial blood gases best demonstrates compensated respiratory acidosis?
Your Answer: pH=7.24, PaCO2=3.5kPa, PaO2=8.5kPa, HCO3- =18mmol/L
Correct Answer: pH=7.36, PaCO2=8.5kPa, PaO2=7.5kPa, HCO3- = 43mmol/L
Explanation:pH=7.36, PaCO2=8.5kPa, PaO2=7.5kPa, HCO3- = 43mmol/L is the correct answer.
Since the pH is the lower limit of normal, it is compensated despite a raised PaCO2. Retention of bicarbonate ions by the renal system suggests this process is chronic.
pH=7.24, PaCO2=3.5kPa, PaO2=8.5kPa, HCO3- =18mmol/L represents an acute uncompensated metabolic acidosis
The remaining stems are degrees of uncompensated respiratory acidosis and therefore incorrect.
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This question is part of the following fields:
- Pathophysiology
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Question 12
Incorrect
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Which statement is correct concerning breathing systems?
Your Answer: In a coaxial Mapleson A system (or Lack) the inner tube has a diameter of 20 mm and the outer tube has a diameter of 30 mm
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 13
Incorrect
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The production of carbon dioxide and water occurs during cellular respiration, which involves an energy substrate and oxygen. For a patient, the respiratory quotient is calculated as 0.7. Which of the following energy substrate combinations is the most likely in this patient's diet?
Your Answer: Low carbohydrate, low fat and high protein
Correct Answer: Low carbohydrate, high fat and low protein
Explanation:The respiratory quotient (RQ) is the proportion of CO2 produced by the body to O2 consumed per unit of time.
CO2 produced / O2 consumed = RQ
CO2 is produced at a rate of 200 mL per minute, while O2 is consumed at a rate of 250 mL per minute. An RQ of around 0.8 is typical for a mixed diet.
The RQ will change depending on the energy substrates consumed in the diet.
Granulated sugar is a refined carbohydrate that contains 99.999 percent carbohydrate and no lipids, proteins, minerals, or vitamins.
Glucose and other hexose sugars – RQ = 1
Fats – RQ = 0.7
Proteins – RQ is 0.9
Ethyl alcohol – RQ = 0.67 -
This question is part of the following fields:
- Pathophysiology
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Question 14
Correct
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A 45-year old gentleman is in the operating room to have a knee arthroscopy under general anaesthesia. Induction is done using fentanyl 1mcg/kg and propofol 2mg/kg. A supraglottic airway is inserted and the mixture used to maintain anaesthesia is and air oxygen mixture and 2.5% sevoflurane. Using a Bain circuit, the patient breathes spontaneously and the fresh gas flow is 9L/min. Over the next 30 minutes, the end-tidal CO2 increase from 4.5kPa to 8.4kPa, and the baseline reading on the capnograph is 0kPa. The most appropriate action that should follow is:
Your Answer: Observe the patient for further change
Explanation:Such a high rise of end-tidal CO2 (EtCO2) in a patient who is spontaneously breathing is often encountered.
Close observation should occur for further rises in EtCO2 and other signs of malignant hyperthermia. If this were to rise even more, it might be wise to ensure that ventilatory support is available.
A lot would depend on whether surgery was almost completed. At this stage of anaesthesia, it would be inappropriate to administer opioid antagonists or respiratory stimulants.
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This question is part of the following fields:
- Physiology
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Question 15
Correct
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From the following electromagnetic waves, which one has the shortest wavelength?
Your Answer: X rays
Explanation:Electromagnetic waves are categorized according to their frequency or equivalently according to their wavelength. Visible light makes up a small part of the full electromagnetic spectrum.
Electromagnetic waves with shorter wavelengths and higher frequencies include ultraviolet light, X-rays, and gamma rays. Electromagnetic waves with longer wavelengths and lower frequencies include infrared light, microwaves, and radio and televisions waves.
Different electromagnetic waves according to their wavelength from shorter to longer are X-rays, ultraviolet radiations, visible light, infrared radiation, radio waves. X-ray among electromagnetic waves has the shortest wavelength and higher frequency with wavelengths ranging from 10*-8 to 10* -12 and corresponding frequencies.
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This question is part of the following fields:
- Anaesthesia Related Apparatus
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Question 16
Correct
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Concerning platelets one of the following is true
Your Answer: Are formed in the bone marrow from megakaryocytes
Explanation:Platelets are fragments of megakaryocytes and they are encapsulated by membrane.
They have no nucleus but are metabolically active and are able to express membrane receptors and release stored substances when triggered. adenosine diphosphate and serotonin are 2 of its content.
Because they have no nucleus, they are not able to produce new proteins. This is why aspirin and other drugs affect function for their entire lifespan after exposure. Its lifespan is approximately 9-10 days in normal individuals.
Platelets does NOT PRODUCE prostacyclin but are able to produce nitric oxide, prostaglandins and thromboxane.
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This question is part of the following fields:
- Pathophysiology
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Question 17
Incorrect
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Drug toxicity when using bupivacaine is most likely to occur when this local anaesthetic technique is performed.
Your Answer: Brachial plexus block
Correct Answer: Intercostal nerve block
Explanation:An intercostal nerve block is used for therapeutic and diagnostic purposes. Intercostal nerve blocks manage acute and chronic pain in the chest area. Common indications are chest wall surgery and shingles or postherpetic neuralgia.
An intercostal nerve block is also an effective option for the management of pain associated with chest trauma and rib fractures. These blocks have been shown to improve oxygenation and respiratory mechanics, and offer pain relief that is comparable to that of epidural analgesia.
This technique, however, is limited by the relatively large doses of local anaesthetic required, and relatively high intravascular uptake from the intercostal space, increasing risk of local anaesthetic toxicity.
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This question is part of the following fields:
- Pharmacology
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Question 18
Correct
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A 68-year old man, is admitted in hospital. He is scheduled to undergo a femoro-popliteal bypass graft, for which he has been administered a spinal-epidural anaesthetic. Intrathecal heavy bupivacaine (0.5%) was injected at L3-4 with good effect. On insertion of the epidural catheter, he remained asymptomatic. During surgery, 5000 I.U. of IV heparin was given. The surgery is successful and required no epidural top-ups. Six hours later, he complains of a severe back pain with weakness in his lower limbs. What is the most important first step?
Your Answer: A full neurological examination to establish the nature of the problem
Explanation:The most likely diagnosis is a spinal epidural haematoma, a neurological emergency. A full examination must be carried out to determine the nature of the neurological problem before conducting any investigations or imaging.
The effects of spinal anaesthesia should have worn off by this time point, and the severe back pain is a red flag.
The patient will also require an urgent neurological team referral as a spinal epidural haematoma requires immediate evacuation for spinal decompression. Analgesics may be prescribed for pain management.
Heparin would have been fully metabolised and so a reversal is unnecessary.
A spinal epidural haematoma is a pooling of blood in the epidural space, which can cause compression of the spinal cord. Its presenting symptoms are:
Usually begins with severe backpain and percussion tenderness
Cauda equina syndrome
Paralysis of the lower extremities.
If infected, a fever occurs in 66% of cases
Lower limb weakness developing after stopping an epidural infusion or weakness of the lower limbs which does not resolve within four hours of cessation of infusion of epidural local anaesthetic
Meningism. -
This question is part of the following fields:
- Pathophysiology
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Question 19
Incorrect
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A study of blood pressure measurements is being performed in patients with chronic kidney disease. Considering that the results are normally distributed, what percentage of values lie within two standard deviations of the mean blood pressure reading?
Your Answer: 98.30%
Correct Answer: 95.40%
Explanation:Normal distribution, also called Gaussian distribution, the most common distribution function for independent, randomly generated variables, and describes the spread for many biological and clinical measurements.
Properties of the Normal distribution
symmetrical i.e. Mean = mode = median
68.3% of values lie within 1 SD of the mean
95.4% of values lie within 2 SD of the mean
99.7% of values lie within 3 SD of the mean
The empirical rule, or the 68-95-99.7 rule, tells you where most of the values lie in a normal distribution: Around 68% of values are within 1 standard deviation of the mean.
Around 95% of values are within 2 standard deviations of the mean. Around 99.7% of values are within 3 standard deviations of the mean.
the standard deviation (SD) is a measure of how much dispersion exists from the mean.SD = square root (variance)
The empirical rule, or the 68-95-99.7 rule states where most of the values lie in a normal distribution. Around 68% of values fall within 1 S.D of the mean, about 95% within 2 S.D of the mean, and about 99.7% of values within 3 S.D of the mean. Therefore, 95.4% is the most reasonable answer if results are normally distributed.
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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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A measuring system's response to change is complex, yet it can be mathematically modelled. Which of the following terms best characterises a pressure transducer's responsiveness to blood pressure changes?
Your Answer: Dynamic first-order response
Correct Answer: Dynamic second-order response
Explanation:The static-response defines how a measuring system behaves while it is in equilibrium (i.e. when the measured values are not changing). If the value being measured changes over time, the reaction of a measuring system will change as well which would be a dynamic response.
The dynamic response of a measuring system can be subdivided into zero-order, first-order and second-order responses:Zero-order:
Consider a thermometer that has been left in a room for a week. The thermometer will display the current ambient temperature when you enter the room.First-order:
Consider the use of a mercury thermometer to check a patient’s temperature. It is comprised of a mercury column that expands as it warms up. The scale’s initial temperature is room temperature, but when it’s placed under the patient’s tongue, the temperature readings rise until they reach body temperature.Second-order
Consider putting weights on a mechanical weighing scale. The weight as reported on the measuring dial, will wobble around the correct value at first until reaching equilibrium. An example of this is in clinical practice is the direct measurement of arterial pressure with a transducer. The value of the input fluctuates around a central point.Drift is the progressive deterioration of a measurement system’s precision. With time, the measurement deviates from the genuine, calibrated value. The graph between this measurement and the real value should, ideally, be linear (e.g. on the y-axis the measured end-tidal CO2 against true value of the end-tidal CO2). Drift is split into three types: zero-offset, gradient, and zonal drift.
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This question is part of the following fields:
- Anaesthesia Related Apparatus
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Question 21
Correct
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Which of the following combinations of signs seen in a patient would most likely confirm ingestion of substances with anticholinesterase effects?
Your Answer: Bradycardia and miosis
Explanation:An acetylcholinesterase inhibitor or anticholinesterase is a chemical that inhibits the cholinesterase enzyme from breaking down acetylcholine (ACh) therefore increasing the level and duration of action of the neurotransmitter acetylcholine(ACh).
ACh stimulates postganglionic receptors to produce the following effects:
Salivation
Lacrimation
Defecation
Micturition
Sweating
Miosis
Bradycardia, and
Bronchospasm.Since these effects are produced by muscarine, they are referred to as muscarinic effects, and the postganglionic receptors are called muscarine receptors.
SLUD (Salivation, Lacrimation, Urination, Defecation – and emesis) is usually encountered only in cases of drug overdose or exposure to nerve gases. It is a syndrome of pathological effects indicating massive discharge of the parasympathetic nervous system.
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This question is part of the following fields:
- Pathophysiology
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Question 22
Incorrect
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Which of the following statement regarding Adrenaline (Epinephrine) is not true?
Your Answer: Inhibits insulin secretion by the pancreas
Correct Answer: Inhibits glycolysis in muscle
Explanation:Adrenaline acts on α1, α2, β1, and β2 receptors and also on dopamine receptors (D1, D2) and have sympathomimetic effects.
Natural catecholamines are Adrenaline, Noradrenaline, and Dopamine
Adrenaline is a sympathomimetic amine with both alpha and beta-adrenergic stimulating properties.
Adrenaline is the drug of choice for anaphylactic shock
Adrenaline is also used in patients with cardiac arrest. The preferred route is i.v. followed by the intra-osseous and endotracheal route.Adrenaline is released by the adrenal glands, acts on α 1 and 2, β 1 and 2 receptors, and is responsible for fight or flight response.
It acts on β 2 receptors in skeletal muscle vessels-causing vasodilation.
It acts on α adrenergic receptors to inhibit insulin secretion by the pancreas. It also stimulates glycogenolysis in the liver and muscle, stimulates glycolysis in muscle.
It acts on β adrenergic receptors to stimulate glucagon secretion in the pancreas
It also stimulates Adrenocorticotrophic Hormone (ACTH) and stimulates lipolysis by adipose tissue -
This question is part of the following fields:
- Pharmacology
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Question 23
Incorrect
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One of the causes of increased pulse pressure is when the aorta becomes less compliant because of age-related changes. Another cause of increased pulse pressure is which of the following?
Your Answer: Impaired ventricular relaxation
Correct Answer: Increased stroke volume
Explanation:Impaired ventricular relaxation reduces diastolic filling and therefore preload.
Decreased blood volume decreases preload due to reduced venous return.
Heart failure is characterized by reduced ejection fraction and therefore stroke volume.
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 (is increased by stroke volume) = 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
Aortic stenosis would decrease stroke volume as end systolic volume would increase.
This is because of an increase in afterload, an increase in resistance that the heart must pump against due to a hard stenotic valve. -
This question is part of the following fields:
- Physiology And Biochemistry
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Question 24
Correct
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Levels of serum potassium in around 1000 patients that were on ACE inhibitor were measured. The mean value was calculated to be 4.6mmol/L and a standard deviation of 0.3mmol/L was recorded. Which among the given options is correct?
Your Answer: 68.3% of values lie between 4.3 and 4.9 mmol/l
Explanation:Its known that 68.3% of the total values of a normally distributed variable are found within a range of 1 standard deviation from the mean which makes the range to be 4.3 to 4.9 mmol/L.
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This question is part of the following fields:
- Statistical Methods
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Question 25
Incorrect
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Which statement best describes the bispectral index (BIS)?
Your Answer: It predicts the response to surgical incision
Correct Answer: It decreases during normal sleep
Explanation:The bispectral index (BIS) is one of several systems used in anaesthesiology as of 2003 to measure the effects of specific anaesthetic drugs on the brain and to track changes in the patient’s level of sedation or hypnosis. It is a complex mathematical algorithm that allows a computer inside an anaesthesia monitor to analyse data from a patient’s electroencephalogram (EEG) during surgery. It is a dimensionless number (0-100) that is a summative measurement of time domain, frequency domain and high order spectral parameters derived from electroencephalogram (EEG) signals.
Sleep and anaesthesia have similar behavioural characteristics but are physiologically different but BIS monitors can be used to measure sleep depth. With increasing sleep depth during slow-wave sleep, BIS levels decrease. This correlates with changes in regional cerebral blood flow when measured using positron emission tomography (PET).
BIS shows a dose-response relationship with the intravenous and volatile anaesthetic agents. Opioids produce a clinical change in the depth of sedation or analgesia but fail to produce significant changes in the BIS. Ketamine increases CMRO2 and EEG activity.
BIS is unable to predict movement in response to a surgical stimulus. Some of these are spinal reflexes and not perceived by the cerebral cortex.
BIS is used during cardiopulmonary bypass to measure depth of anaesthesia and an index of cerebral perfusion. However, it cannot predict subtle or significant cerebral damage.
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This question is part of the following fields:
- Physiology
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Question 26
Incorrect
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One of the following neuromuscular blocking agents is the most potent:
Your Answer: Mivacurium
Correct Answer: Vecuronium
Explanation:The measure of drug potency or therapeutic response is the ED95. This is defined as the dose of a neuromuscular blocking drug required to produce a 95% depression of muscle twitch height. The ED50 and ED90 describe a depression of twitch height by 50% and 90% respectively.
The ED95 (mg/kg) of the commonly used neuromuscular blocking agents are:
suxamethonium: 0.27
rocuronium: 0.31
vecuronium: 0.04
pancuronium: 0.07
cisatracurium: 0.04
mivacurium: 0.08 -
This question is part of the following fields:
- Pharmacology
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Question 27
Incorrect
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A global cerebral blood flow (CBF) of 35 ml/100 g/min (Normal CBF = 54 ml/100 g/min) can lead to which of the following?
Your Answer: More damage than complete ischaemia
Correct Answer: Poor prognostic EEG
Explanation:CBF is defined as the blood volume that flows per unit mass per unit time in brain tissue and is typically expressed in units of ml blood/100 g tissue/minute. The normal average CBF in adults human is about 50 ml/100 g/min, with lower values in the white matter (,20 ml/100 g/min) and greater values in the gray matter (,80 ml/100 g/min).
Low CBF levels between 30-40 ml/100 g/min may begin to show poor prognostic EEG. EEG findings consistently associated with a poor outcome are isoelectric EEG, low voltage EEG, and burst suppression (specifically burst suppression with identical bursts), as well as the absence of EEG reactivity.
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This question is part of the following fields:
- Physiology
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Question 28
Incorrect
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All of the following statements about calcium channel antagonists are incorrect except:
Your Answer: Nifedipine acts on the SA and AV nodes to slow the heart rate
Correct Answer: May cause potentiation of muscle relaxants
Explanation:Calcium channel blocker (CCB) blocks L-type of voltage-gated calcium channels present in blood vessels and the heart. By inhibiting the calcium channels, these agents decrease the frequency of opening of calcium channels activity of the heart, decrease heart rate, AV conduction, and contractility.
Three groups of CCBs include
1) Phenylalkylamines: Verapamil, Norverapamil
2) Benzothiazepines : Diltiazem
3) Dihydropyridine : Nifedipine, Nicardipine, Nimodipine, Nislodipine, Nitrendipine, Isradipine, Lacidipine, Felodipine and Amlodipine.Even though verapamil as good absorption from GIT, its oral bioavailability is low due to high first-pass metabolism.
Nimodipine is a Cerebro-selective CCB, used to reverse the compensatory vasoconstriction after sub-arachnoid haemorrhage and is more lipid soluble analogue of nifedipine
Calcium channel antagonist can potentiate the effect of non-depolarising muscle relaxants.
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This question is part of the following fields:
- Pharmacology
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Question 29
Incorrect
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Which of the following statement is true or false regarding to the respiratory tract?
Your Answer: The trachea starts at the lower end of the thyroid cartilage at the level of the sixth cervical vertebra
Correct Answer: The sympathetic innervation of the bronchi is derived from T2 - T4
Explanation:The diaphragm has three opening through which different structures pass from the thoracic cavity to the abdominal cavity:
Inferior vena cava passes at the level of T8.
Oesophagus, oesophageal vessels and vagi at T10.
Aorta, thoracic duct and azygous vein through T12.
Sympathetic trunk and pulmonary branches of vagus nerve form a posterior pulmonary plexus at the root of the lung. Fibres continue posteriorly from superficial cardiac plexus to form Anterior pulmonary plexus. It contains vagi nerves and superficial cardiac plexus. These fibres then follow the blood vessel and bronchi into the lungs.
The lower border of the pleura is at the level of:
8th rib in the midclavicular line
10th rib in the lower level of midaxillary line
T12 at its termination.
Both lungs have oblique fissure while right lung has transverse fissure too.
The trachea expands from the lower edge of the cricoid cartilage (at the level of the 6th cervical vertebra) to the carina.
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This question is part of the following fields:
- Physiology
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Question 30
Incorrect
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A 27-year old man loses 1000ml blood after being stabbed on his thigh. The most impactful physiological response occurring at the start to combat the decline in the intravascular blood volume of this man is?
Your Answer: Arteriolar constriction
Correct Answer: Venoconstriction
Explanation:In contrast to the arterial system, which contains 15% of the circulating blood volume, the body’s veins contain 70% of it.
In severe haemorrhage, when sympathetic stimulation causes venoconstriction, venous tone is important in maintaining the return of blood to the heart.
Because the liver receives about 30% of the resting cardiac output, it is a very vascular organ. The hepatic vascular system is dynamic, which means it can store and release blood in large amounts – it acts as a reservoir within the general circulation.
In a normal situation, the liver contains 10-15% of total blood volume, with the sinusoids accounting for roughly 60% of that. The liver dynamically adjusts its blood volume when blood is lost and can eject enough blood to compensate for a moderate amount of haemorrhage.
In the portal venous and hepatic arterial systems, sympathetic nerves constrict the presinusoidal resistance vessels. More importantly, sympathetic stimulation lowers the portal system’s capacitance, allowing blood to flow more efficiently to the heart.
Net transcapillary absorption of interstitial fluid from skeletal muscle into the intravascular space compensates for blood loss effectively during haemorrhage. The decrease in capillary hydrostatic pressure (Pc), caused by reflex adrenergic readjustment of the ratio of pre- to postcapillary resistance, is primarily responsible for fluid absorption. Within a few hours of blood loss, these fluid shifts become significant, further diluting haemoglobin and plasma proteins.
Albumin synthesis begins to increase after 48 hours.
The juxtamedullary complex releases renin in response to a drop in mean arterial pressure, which causes an increase in aldosterone level and, eventually, sodium and water resorption. Increased antidiuretic hormone (ADH) levels also contribute to water retention.
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This question is part of the following fields:
- Physiology
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Question 31
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 32
Correct
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According to the statements given which one is most correct concerning the spinal cord?
Your Answer: There are 31 pairs of spinal roots
Explanation:The cylindrical structure(spine), starts from the foramen magnum in medulla oblongata at the skull’s base. Its length varies in gender with men having 45cm and women having up to 43 cm. The spine contains 31 pairs of spinal nerves, named according to the spinal region:
– 8 cervical nerve pairs ( C1-C8)
– 12 thoracic nerve pairs ( T1-T12)
– 5 lumbar nerve pairs (L1-L5)
– 5 sacral nerves (S1-S5) and
– 1 coccygeal nerve pair.
These spinal nerves are classified as the peripheral nervous system though they branch from the spinal cord and central nervous system. They interact directly with the spinal cord to modulate the motor and sensory information from the peripheral’s region. As the nerves emerges form the spinal cords they are known as rootlets. They join to form nerve roots, and depending on their position, we have anterior nerve roots and posterior.The spinal cord is supplied by two posterior and one anterior spinal arteries which anastomoses caudally, at the conus medullaris.
The anterior spinal artery supplies the anterior two-thirds of the spinal cord and medulla. Disruption of the anterior spinal artery supply is characterised by ischaemia or infarction of motor tracts (corticospinal) and loss of pain and temperature sensation below the level of the lesion.
The posterior spinal arteries supply the posterior columns (posterior third of the spinal cord). Infarction of the posterior columns results in the loss of proprioceptive, vibration and two-point discrimination.
The spinal cord normally ends at the level of L1 or L2 in an adult and L3 in a newborn.
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This question is part of the following fields:
- Anatomy
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Question 33
Incorrect
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Standard error of the mean can be defined as:
Your Answer: Number of patients / square root (standard deviation)
Correct Answer: Standard deviation / square root (number of patients)
Explanation:The standard error of the mean (SEM) is a measure of the spread expected for the mean of the observations – i.e. how ‘accurate’ the calculated sample mean is from the true population mean. The relationship between the standard error of the mean and the standard deviation is such that, for a given sample size, the standard error of the mean equals the standard deviation divided by the square root of the sample size.
SEM = SD / square root (n)
where SD = standard deviation and n = sample size
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This question is part of the following fields:
- Statistical Methods
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Question 34
Correct
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A double-blinded randomised controlled trial is proposed to assess the effectiveness of a new blood pressure medication. Which type of bias can be avoided by ensuring the patient and doctor are blinded?
Your Answer: Expectation bias
Explanation:Observers may subconsciously measure or report data in a way that favours the expected study outcome. Therefore, by blinding the study we can eliminate expectation bias.
Recall bias is a systematic error that occurs when the study participants omit details or do not remember previous events or experiences accurately.
Verification can occur during investigations when there is a difference in testing strategy between groups of individuals, which might lead to biasness due to differing ways of verifying the disease of interest.
Nonresponse bias is the bias that occurs when the people who respond to a survey differ significantly from the people who do not respond to the survey.
A distortion that modifies an association between an exposure and an outcome because a factor is independently associated with the exposure and the outcome. Randomization is the best way to reduce the risk of confounding.
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This question is part of the following fields:
- Statistical Methods
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Question 35
Correct
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When there is a relation between two variables due to the existence of a confounding factor, this association is termed as:
Your Answer: Indirect
Explanation:When the association among any two classes of object is defined by the presence of a third entity it is termed as indirect association. For an instance, the age of the employee may affect the rate of pay, which would have implications on job satisfaction. So, in this example, an indirect relationship between age and job satisfaction exists due to a third party i.e. rate of pay.
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This question is part of the following fields:
- Statistical Methods
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Question 36
Incorrect
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When compared to unipolar diathermy, which of the following is more specific to bipolar diathermy?
Your Answer: Requires an isolating capacitor
Correct Answer: Has a power output of up to 140 joules per second
Explanation:Electrocautery, also known as diathermy, is a technique for coagulation, tissue cutting, and fulguration that uses a high-frequency current to generate heat (cell destruction from dehydration).
The two electrodes in bipolar diathermy are the tips of forceps, and current passes between the tips rather than through the patient. Bipolar diathermy’s power output (40-140 W) is lower than unipolar diathermy’s typical output (400 W). There is no earthing in the bipolar circuit.
A cutting electrode and a indifferent electrode in the form of a metal plate are used in unipolar diathermy. The high-frequency current completes a circuit by passing through the patient from the active electrode to the metal plate. When used correctly, the current density at the indifferent electrode is low, and the patient is unlikely to be burned. Between the patient plate and the earth is placed an isolating capacitor. This has a low impedance to a high frequency current, such as diathermy current, and is used in modern diathermy machines. The capacitor has a high impedance to current at 50 Hz, which protects the patient from electrical shock.
High frequency currents (500 KHz – 1 MHz) are used in both unipolar and bipolar diathermy, which can cause tissue damage and interfere with pacemaker function (less so with bipolar diathermy).
The effect of diathermy is determined by the current density and waveform employed. The current is a pulsed square wave pattern in coagulation mode and a continuous square wave pattern in cutting mode.
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This question is part of the following fields:
- Anaesthesia Related Apparatus
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Question 37
Correct
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Which of the following is the best marker of mast cell degranulation in a patient with suspected anaphylaxis who became hypotensive and developed widespread urticarial rash after administration of Augmentin?
Your Answer: Tryptase
Explanation:Mast cell tryptase is a reliable marker of mast cell degranulation. Tryptase is a protease enzyme that acts via widespread protease-activated receptors (PARs).
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This question is part of the following fields:
- Pharmacology
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Question 38
Correct
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An experiment is designed to investigate that how three diets having different sugar content affect the body weight to a different level. Which one of the following test will determine a statistically significant difference among the diets?
Your Answer: ANOVA
Explanation:Chi-square test is used to determine the statistically significant different between categorical variables. It also determines the difference between expected frequencies and the observed frequencies.
Mann Whitney U test is used to determine the statistically significant different between two independent groups.
Wilcoxon’s test is the test of dependency. it determines the statistically significant difference between two dependent groups.
Student t-test is one of the most commonly used method to test the hypothesis. It determines the significant difference between the means of two different groups.
ANOVA (analysis of variance) is similar to student’s t-test.
ANOVA is a statistical method used to determines the statistically significant difference between the mean of more than two group. In this experiment as we are dealing with three different group, ANOVA is most suitable test to determine the difference between each groups.
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This question is part of the following fields:
- Statistical Methods
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Question 39
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: Myoglobin
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 40
Correct
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What can you see within the tunica media of a blood vessel on examination?
Your Answer: Smooth muscle
Explanation:The blood vessel well is divided into 3 parts, namely:
The tunica intima, which is the deepest layer. It contains endothelial cells separated by gap junctions
The tunica media, primarily consisting of the involuntary smooth muscle fibres, laid out in spiral layers with elastic fibres and connective tissue.
The tunica adventitia, which is the most superficial layer. It consists of the vasa vasorum, fibroblast and collagen.
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This question is part of the following fields:
- Anatomy
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