MRCP 1 Masterclass – Clinical Physiology

An 82-year-old man presented with symptoms of right heart failure and was found to have severe aortic stenosis.

The Bernheim effect describes what phenomenon?

A 74-year-old woman presented with breathlessness, leading to consideration of the diagnosis of congestive cardiac failure.

Which hormone is produced by the heart in response to excessive ventricular stretch?

When an action potential reaches the transverse tubules (T-tubules) in cardiac myocytes, the sarcoplasmic reticulum releases calcium ions.

In order to produce contraction, to what do these ions bind?

A 25-year-old man presented with 1-week history of cough, shortness of breath and fever. He was previously fit and well, with no significant past medical history. He was diagnosed with community-acquired pneumonia and acute kidney injury, and treated initially in the emergency department with intravenous (IV) antibiotics and 500 mL of IV fluid, given quickly. On examination his vital signs included temperature 37°C, pulse 100 beats per minute, blood pressure (BP) 90/50 mmHg and arterial oxygen saturation (SaO2) 96% on air (normal range 94–100). He had warm peripheries and dry mucous membranes.

What is the most appropriate next treatment option?

An 85-year-old man presented with a 2-week history of shortness of breath and increasing leg oedema. His past medical history included myocardial infarction, cardiac failure (ejection fraction <35% on echocardiogram). His medications included aspirin 75 mg od, bisoprolol 5 mg od, ramipril 5 mg od, spironolactone 25 mg od and atorvastatin 80 mg od. He was diagnosed with an exacerbation of heart failure and acute kidney injury. He was given furosemide 40 mg IV, with good effect initially, but his urine output then fell to less than 30 mL/hour. On examination his vital signs included temperature 37°C, pulse 100 beats per minute, BP 90/50 mmHg and SaO2 96% on air (normal range 94–100). He had warm peripheries, an elevated jugular venous pressure (JVP) and oedema up to his knees.

What is the most appropriate next treatment option?

An 80-year-old man presented with complete (third-degree) heart block on an electrocardiogram (ECG), but continued to have an unsupported regular ventricular heart rate of 40 beats per minute on the cardiac monitor. 

Whereabouts in the cardiac conduction system is this rhythm likely to be originating?

A 65-year-old obese woman presented with a 4-month history of progressive shortness of breath on exertion. She had a 50-pack-year smoking history.

A low blood level of which hormone would effectively exclude the diagnosis of heart failure?

A 78-year-old man with severe chronic obstructive pulmonary disease was noted to have an elevated total lung capacity (TLC) during pulmonary function testing.

What is responsible for the increase in TLC?

A 46-year-old woman with severe kyphoscoliosis and breathlessness underwent gas transfer testing. A recent computerised tomography (CT) had shown normal lung parenchyma.

What result would be expected with regard to the transfer factor for CO (TLCO) and transfer coefficient (KCO)?

A 78-year-old man with severe chronic obstructive pulmonary disease (COPD) was brought to the emergency department by ambulance following 3 days of increasing breathlessness and sputum production. His past medical history included atrial fibrillation, depression and chronic back pain. His regular medications included salmeterol/fluticasone, tiotropium, rivaroxaban and sustained-release oral morphine sulphate. He was treated with 15 L/min oxygen via a non-rebreathe mask by the ambulance crew as his initial SpO2 was 75% on air (normal range 94–100). Upon assessment in the emergency department he was drowsy with a Glasgow Coma Scale (GCS) score of 10/15.

Which is the most likely explanation for his depressed GCS score?

A 75-year-old man was seen in the respiratory clinic with a 1-year history of increasing breathlessness, which was most marked if he lay flat. His past medical history included a myocardial infarction followed by coronary artery bypass grafting. On examination he had clear lung fields and paradoxical abdominal movement on inspiration when lying flat.

Which investigation would be most helpful to determine the cause of his breathlessness?

A 38-year-old woman presented with a long history of abdominal discomfort, bloating and irregular stool pattern. After searching on the internet she had come to the conclusion that this was due to an ‘electrical problem’ with the gut.

What is the best-defined electrical activity in the small bowel?

After eating a meal, food passes from the stomach into the duodenum.

Which hormone is released when food contacts the duodenal mucosa?

A 28-year-old man presented with long-standing diarrhoea, for which he had undergone many investigations. Eventually a diagnosis of bile salt malabsorption was made.

Where are bile salts normally reabsorbed?

A 24-year-old woman with systemic lupus erythematosus suffered an acute small bowel vascular event, leading to surgical resection of most of her small bowel. Her nutrition was therefore dependent on the function of her remaining small bowel and colon.

The colon is responsible for reabsorption of which nutrient(s)?

A 23-year-old man presented with pleuritic chest pain. Pulmonary embolism was excluded, but a routine biochemical screen had been requested as part of his work up, and this showed the unexpected finding of an elevated serum bilirubin level. A diagnosis of Gilbert’s syndrome was made.

Impaired function of which enzyme or transporter is the cause of Gilbert’s syndrome?

A 72-year-old man was admitted to hospital with a high fever. A sepsis screen was performed, including measurement of serum C-reactive protein (CRP), which was markedly elevated.

Which cell type produces CRP?

A 44-year-old woman presented with feelings of pins and needles and weakness of her right arm. She had previously had an episode of optic neuritis. A diagnosis of multiple sclerosis was made, which is a demyelinating disorder.

Which is increased by myelination of a nerve fibre?

When an action potential arrives in a nerve terminal it results in influx of calcium ions, which stimulates release of neurotransmitter.

How are neurotransmitters released from nerve terminals?

A 28-year-old woman presented with droopiness of her eyes and double vision. A diagnosis of myasthenia gravis was made.

Which neurotransmitter is released from motor neurons?

A 48-year-old man presented with bilateral carpal tunnel syndrome. He had an appearance suggestive of acromegaly, which was confirmed on investigation.

What are the anabolic actions of growth hormone mediated by?

A 54-year-old woman presented with proximal muscle weakness and easy bruising. She had an appearance that suggested the diagnosis of Cushing’s disease, which was confirmed on investigation.

Which part of the adrenal gland produces cortisol?

A 28-year-old woman presented with weight loss and tremor. A diagnosis of thyrotoxicosis was made.

Thyroxine (T4) is made from what?

A 20-year-old man with insulin-dependent diabetes mellitus was found unconscious (GCS score 6/15). He had very poor veins such that it was not possible to establish intravenous access, and he was given a dose of intramuscular glucagon.

Where is the main site of glucagon action?

A 35-year-old man presented with peripheral oedema and proteinuria. A renal biopsy was planned, and in the meantime he was started on furosemide to reduce his oedema.

Where does furosemide act?

A 24-year-old woman presented with persistent fatigue and biochemical testing revealed serum potassium 2.8 mmol/L (normal range 3.5–5.0). She took no medications, and her blood pressure was 95/50 mmHg.

Which syndrome is she most likely to have?

A 73-year-old man presented with worsening cardiac failure. He was already taking a loop diuretic, ß-blocker and angiotensin-receptor blocker. Spironolactone was added to his medication.

Where does spironolactone act?

A 72-year-old man presented with a 2-day history of recurrent and frequent vomiting. He had been unable to keep down any food or drink.

What is the most likely pattern of electrolyte and acid–base derangement?

A 48-year-old woman underwent a routine hysterectomy for fibroids. She felt nauseated and unwell 24 hours later, and seemed confused. Urgent blood tests revealed serum sodium 112 mmol/L (normal range 135–145). This had been normal at her preoperative assessment.

Why has she developed profound hyponatraemia?

A 68-year-old man attended a routine low clearance renal clinic appointment. Routine blood testing revealed an estimated glomerular filtration rate (eGFR) of 12 mL/min/1.73 m² (normal threshold >60), a low serum calcium, an elevated serum phosphate and that he was anaemic. He complained of anorexia and lethargy.

In which hormone is he deficient?

You are examining a new treatment for blood pressure the route of excretion for which is thought to involve the sodium chloride renal symporter.

Which of the following drugs used in the treatment of hypertension or cardiac failure acts directly on the sodium chloride renal symporter?

A critically ill patient on the ICU shows evidence of impaired oxygen delivery to the tissues.

The oxygen–haemoglobin dissociation curve is shifted to the left by which one of the following factors?

When taking a history from a 61-year-old woman with disseminated sclerosis, you ascertain that she is intermittently incontinent for liquid stools.

Which one of the following pertains to the clinical physiology of faecal continence?

A patient’s respiratory function is evaluated before lung resection (for a tumour), both at rest and with exertion.

Which one of the following takes place during inspiration at rest?

A 74-year-old male stops smoking after a 50-pack year smoking history. He sees his GP with a marked increase in coughing and sputum production. His GP, after initial assessment and investigations, reassures him that this reflects recovery of the function of his respiratory tract lining.

Which of the following physiological characteristics relates to the lining of the respiratory tract?

A 70-year-old man comes to the Falls Clinic for review. He is monitored in moving from a sitting to a standing position.

On standing for a period of 1 minute or longer, what is an expected normal physiological response?

A 20-year-old man is referred to the Endocrinology Clinic because of delayed puberty. On examination, he has a preadolescent body habitus and no evidence of the development of secondary sexual characteristics. Serum testosterone, luteinizing hormone (LH) and follicle stimulating hormone (FSH) concentrations are all in the prepubertal range. The LH and FSH concentrations increase only slightly following a single injection of gonadotrophin-releasing hormone (GnRH) but a normal response is elicited after GnRH is given daily for seven consecutive days.

Which one of the following is most likely to be the cause of his delayed puberty?

An 18-year-old attempts to climb Mount Everest as a fundraising project during his gap year.

Despite extensive training at sea level, his attempt has to be paused due to a combination of headache, dizziness and shortness of breath. After two days at the same level, his symptoms resolve and he is able to push on to the summit.

Which of the following is involved in high altitude acclimatization?

A 32-year-old man is referred to a dermatologist with soft, fleshy lumps over his elbows.

Examination also reveals that he has yellow fat deposits in his palmar creases. His (fasting) serum cholesterol concentration is 12.4 mmol/l, triglyceride 14.2 mmol/l.

Which one of the following groups of lipoprotein particles is likely to be present in excess?

A 22-year-male student was diagnosed with minimal change nephropathy 4 years previously.

He had received short courses of high-dose steroids each time he had a relapse, and had responded promptly. Currently, his sixth relapse (three in the last 6 months) has manifested as ankle oedema. His urinary protein is 5.1g/24 h with an albumin of 21 g/l.

Which one of the following treatments is most appropriate in the long term?

You are examining the prognostic significance of raised brain natriuretic peptide (BNP) in the management of heart failure.

Where is BNP primarily produced in heart failure?

A 21-year-old man takes advantage of his employer’s health benefits and undergoes a private health screen. Urinalysis is positive for protein on two occasions, once at the health screen and a later repeated sample at the GP. His serum urea and creatinine concentrations are normal.

Which one of the following would be the most important investigations to perform next?

You are interested in a device that measures pulse pressure as a screening tool for cardiovascular disease. You are aware that pulse pressure increases with increasing age.

Which of the following contributes most to increased pulse pressure?

A 17-year-old phenotypic female with no clinical evidence of dysmorphism is referred to the Endocrine Clinic for the investigation of primary amenorrhea. On examination, breast development is normal, the external genitalia are normal female in appearance but pubic hair is sparse. Her karyotype is found to be 46XY.

A defect in which one of the following is most likely to be causing this presentation?

Hypoxia leads to differentiated effects on the vascular beds of the body. Some vascular beds will demonstrate vasoconstriction, others vasodilation.

Which of the following vascular beds vasoconstrict in response to hypoxia?

You are examining the potential for a new thiazide diuretic that is not thought to increase renal potassium loss.

Which one of the following accounts for the increased risk of hypokalaemia with bendroflumethiazide?

A 77-year-old man presents with a history of vomiting undigested food. Routine biochemistry shows a serum bicarbonate concentration of 38 mmol/l.

Which one of the following findings would most strongly suggest that he had a chronic metabolic alkalosis?

A 25-year-old man, previously rather sedentary in his habits but alarmed by his increasing weight, is persuaded by his girlfriend to join a gym, and begins an exercise program. Although there are several similar people enrolled in the program, he finds that he is unable to keep up with them because of muscle pain, particularly in his legs. Within a few minutes of resting, however, the pains resolve. Investigation revealed a slight fall in blood lactate concentration during exercise.

Which one of the following is most likely to be the cause of his complaint?

A 56-year-old woman presents to the emergency department with a 2-hour history of central, crushing chest pain radiating to her jaw. As a myocardial infarction is suspected, an ECG is immediately taken. ST elevation and Q waves are present in leads V –V, I and AVL.

Which one of the following aspects of the heart is most likely to have been involved in the infarct?

A 54-year-old male, with a suspected new diagnosis of chronic obstructive pulmonary disease (COPD), is sent for pulmonary function tests. During the tests he is required to inhale a small volume of carbon monoxide. He is told that this is to measure his diffusing capacity, or how well his lungs exchange gases.

Which of the following physiological principles best describes pulmonary gas exchange?

A 32-year-old woman on nasogastric aspiration for paralytic ileus following surgery develops a metabolic alkalosis.

Which one of the following intravenous fluids would be the preferred treatment for the alkalosis?

A 54-year-old male is brought to his GP by his wife. She states that his facial features have changed, describing coarsening. On direct questioning he admits to an increasing shoe size and being no longer able to wear his wedding ring. After appropriate investigations a growth hormone-secreting adenoma is found.

In health, the secretion of growth hormone is increased by which one of the following?

You are called to see a 56-year-old man 2 h after a cardiac catheterization. He is actively bleeding from his catheter site and his dressings and bedclothes are soaked with blood.

Which one of the following statements is true?

Some 24 h after sustaining severe skeletal and soft tissue trauma in a road traffic collision, a 19-year-old man becomes oliguric.

Which one of the following would be least likely to present if acute tubular necrosis (ATN) were the likely diagnosis?

A 46-year-old female teacher presented with increasing breathlessness over 9 months, occasional haemoptysis and severe arthralgia. She was found to have impaired renal function with an active urinary sediment. Her chest X-ray showed bilateral alveolar shadowing with loss of lung volume. The p-ANCA was positive and she was started on prednisolone and cyclophosphamide. Her symptoms and renal function both improved, but 2 months later her breathlessness worsened considerably. She had a cough productive of non-purulent sputum and oximetry showed an oxygen saturation of 84%.

What investigation is essential to guide further management?

A 21-year-old woman presents to the clinic with a collapse. On further questioning she admits to problems with fainting over the past few years and her sodium is at the lower end of the normal range. Cortisol is below the lower limit of normal and you wonder about an inherited defect in cortisol  production and plan to measure metabolic precursors to cortisol.

What is the immediate precursor in the production of cortisol?

A 38-year-old woman, with a raised BMI, presents to the GP with symptoms of severe heartburn. Focused history revealed copious NSAID use, but no ‘red flag’ symptoms. No other medical or surgical history is available. Upper GI endoscopy revealed mucosal breaks extending between the tops of two mucosal folds, involving 60% of the mucosal circumference in the oesophagus. Manometry revealed a reduced mean lower oesophageal sphincter (LOS) pressure.

Which of the following clinical conditions best fits these findings?

A 52-year-old man comes to the Well Man Clinic for review of his blood pressure, cholesterol and diabetes management. He is advised about a low-sugar, low-salt, low-fat diet.

Which of the following is the UK recommended daily maximum for salt in the diet?

You review a 68-year-old gentleman with chronic obstructive pulmonary disease (COPD) in the respiratory clinic. Despite optimization of his inhaled therapy, he has required daily high dose steroid all winter to keep his symptoms under control. On examination you note a moon face, copious striae and early limb muscle wasting. His BP is 155/90 mmHg.

Which of the following is the likely status of his endogenous corticosteroid axis?

Some 4 h after sustaining major trauma in a road traffic collision, a 22-year-old man, not known to have diabetes, is found to have a high blood glucose concentration.

Increased secretion of which one of the following substances is most likely to be responsible?

In your role as the Renal Registrar, you are reviewing pathologies involved in chronic renal dysfunction.

Which of the following correctly describes one of the principal actions of endothelin on the kidney?

A patient on enteral nutrition develops constipation.

What could explain the underlying clinical physiology?

A 59-year-old man has sustained damage to the hypothalamus after a road traffic accident and period of hypotension associated with blood loss. He is suffering from hyperphagia.

Which of the following structures is most likely to have been damaged?

A 19-year-old girl is seen in the clinic with profound menorrhea. Initial hormonal blood tests are sent.

Which one of the following statements applies to the physiology of the normal menstrual cycle?

You are doing a stint as the chemical pathology reviewer for the local hospital. You are doing random quality control on the results.

Which one of the following sets of results is most likely to be the result of an analytical error

A healthy medical student performs a series of pulmonary investigations as part of the respiratory physiology lab.

Which one of the following is higher at the apex of the lung than at the base when he is standing?

A 41-year-old patient complains of a persistent ringing in the right ear, which no one else can hear. You presume a diagnosis of tinnitus.

Which one of the following statements is correct regarding the clinical physiology of the ear?

You are reviewing the results of arterial blood gases in the chemical pathology laboratory.

Which one of the following results is most likely to be a laboratory error?

A 40-year-old man with known chronic liver disease presents with exertional dyspnoea. On examination his blood pressure is 130/80 mmHg and his jugular venous pressure (JVP) is slightly elevated. He has bilateral pleural effusions, ascites and marked pitting oedema, for which his GP has prescribed furosemide. Investigations reveal: plasma sodium 136 mmol/l, K 3.5 mmol/l, bicarbonate 30 mmol/l and chloride 99 mmol/l.

Which one of the following is the most characteristic physiological activity that results in retention of sodium in the face of salt and water overload?

A 24-year-old man is being provided with long-term parenteral nutrition for Crohn’s disease.

His energy requirement is estimated to be approximately 2500 kcal/24 h.

Which one of the following combinations of lipid emulsion and dextrose solutions would be most appropriate to provide his energy requirements?

A 19-year-old man presents with a three-month history of diarrhoea with stools that float and are difficult to flush away. He has also been tiring easily and complains of abdominal bloating.

On direct questioning he admits to 6kg of weight loss. These features are suggestive of malabsorption.

Which one of the following investigations would have the potential to indicate a single cause for this?

A 58-year-old patient is reviewed 2 weeks after discharge from a prolonged hospital stay, when a road traffic collision resulted in multiple rib fractures, complicated by the development of a left sided pneumonia. On review in the clinic, he appears to be recovering. His BP is 122/70 mmHg, pulse is 70/min and regular. There is residual left sided chest bruising, but air entry is normal on both sides. He has lost a few kg in weight since his admission.

Which of the following are you likely to find on hormone testing?

A patient who had a myocardial infarction 6 months ago presents with firm, minutely lobulated enlargement of his gums. This is not associated with pain. On examination, it is most pronounced in the maxillary and mandibular anterior regions. He is diagnosed as having drug induced gingival hypertrophy.

Which drug is most likely to be responsible for this?

What is the frequency of alpha waves on an electroencephalography (EEG)?

A 47-year-old man with a long history of alcohol abuse is admitted to hospital with acute abdominal pain and is diagnosed clinically as having acute pancreatitis. This is confirmed by finding a high serum amylase activity and by the results of an ultrasound scan. He has not had a similar illness before. His serum is seen to be lipaemic: serum triglyceride concentration is 26 mmol/l.

Which one of the following is the most likely cause of the hypertriglyceridemia?

As a hormone, steroids produce their catabolic effects on human body cells via which of the following?

Vasoconstriction in response to hypoxia occurs in which one of the following vascular beds?

Which one of the following inhibits aldosterone secretion?

Which one of the following statements is true regarding vasopressin?

A 59-year-old woman presented to the emergency department having collapsed while waiting at a bus stop. An ECG showed a prolonged QT interval.

Which one of the following is the most likely underlying cause for her ECG changes?