FMGE Physiology questions, system by system

1. Q1. In the carotid body, a fall in arterial PO2 depolarises the glomus cell. This happens because hypoxia inhibits which channel?

   • A. Oxygen-sensitive potassium channels
   • B. Voltage-gated sodium channels
   • C. L-type calcium channels
   • D. Epithelial chloride channels

   Answer: A. Oxygen-sensitive potassium channels

2. Q2. CFTR is a cyclic-AMP-regulated channel. Which ion does it conduct, and what follows in the airway when it is lost?

   • A. Sodium, with excess airway surface liquid
   • B. Potassium, with a depolarised epithelium
   • C. Chloride, with reduced airway surface liquid and thick secretions
   • D. Calcium, with impaired ciliary beating

   Answer: C. Chloride, with reduced airway surface liquid and thick secretions

1. Q1. What is the approximate glomerular filtration rate in a healthy young adult, and what fraction of renal plasma flow does it represent?

   • A. About 60 ml/min, roughly a tenth of renal plasma flow
   • B. About 125 ml/min, roughly a fifth of renal plasma flow
   • C. About 125 ml/min, roughly half of renal plasma flow
   • D. About 600 ml/min, essentially all of renal plasma flow

   Answer: B. About 125 ml/min, roughly a fifth of renal plasma flow

2. Q2. Renal clearance of a substance is calculated as UV/P. What does the resulting figure represent?

   • A. The mass of the substance excreted per unit time
   • B. The fraction of the filtered load that is reabsorbed
   • C. The volume of plasma completely cleared of the substance per unit time
   • D. The rate at which urine is formed

   Answer: C. The volume of plasma completely cleared of the substance per unit time

1. Q1. A child being treated for diabetic ketoacidosis deteriorates six hours into treatment with headache and a falling conscious level. What is the most likely cause, and the main risk factor?

   • A. Hypoglycaemia, from an excessive insulin infusion
   • B. Cerebral oedema, associated with over-rapid fluid replacement and a fast fall in osmolality
   • C. Hypokalaemia, from the insulin-driven potassium shift
   • D. Sepsis, from an unrecognised precipitant

   Answer: B. Cerebral oedema, associated with over-rapid fluid replacement and a fast fall in osmolality

2. Q2. Why does creatinine clearance slightly overestimate the true glomerular filtration rate?

   • A. Creatinine is reabsorbed in the distal tubule
   • B. Creatinine is metabolised within the kidney
   • C. A small amount of creatinine is secreted by the proximal tubule in addition to being filtered
   • D. Creatinine binds plasma protein and is incompletely filtered

   Answer: C. A small amount of creatinine is secreted by the proximal tubule in addition to being filtered

1. Q1. If the radius of an arteriole falls to one third of its original value, by what factor does its resistance to laminar flow increase?

   • A. 9 times
   • B. 27 times
   • C. 81 times
   • D. 3 times

   Answer: C. 81 times

2. Q2. A patient has profuse watery diarrhoea that persists during fasting, with hypokalaemia and achlorhydria. Which pancreatic neuroendocrine tumour is responsible?

   • A. Insulinoma
   • B. Glucagonoma
   • C. Gastrinoma
   • D. VIPoma

   Answer: D. VIPoma

1. Q1. After resection of the terminal ileum, which substance is most likely to become deficient, and why can body stores delay the deficiency for years?

   • A. Folate, because the jejunum also absorbs it
   • B. Iron, because the duodenum compensates
   • C. Vitamin B12, because it is absorbed only in the terminal ileum and hepatic stores last several years
   • D. Calcium, because vitamin D compensates

   Answer: C. Vitamin B12, because it is absorbed only in the terminal ileum and hepatic stores last several years

2. Q2. Which change shifts the oxygen-haemoglobin dissociation curve to the left, and what is the functional consequence?

   • A. A rise in 2,3-BPG, releasing more oxygen to tissues
   • B. A fall in pH, releasing more oxygen to tissues
   • C. A rise in temperature, releasing more oxygen to tissues
   • D. Alkalosis, so haemoglobin binds oxygen more tightly and releases less to tissues

   Answer: D. Alkalosis, so haemoglobin binds oxygen more tightly and releases less to tissues

1. Q1. In a dehydrated adult, which nephron segment reabsorbs the largest absolute volume of filtered water, and is that reabsorption regulated by ADH?

   • A. The proximal convoluted tubule, reabsorbing about two thirds isosmotically and independently of ADH
   • B. The thin descending limb, under ADH control
   • C. The distal convoluted tubule, under ADH control
   • D. The collecting duct, which reabsorbs the largest volume

   Answer: A. The proximal convoluted tubule, reabsorbing about two thirds isosmotically and independently of ADH

2. Q2. On the left ventricular pressure-volume loop, which event marks the end of isovolumetric contraction and the start of ejection?

   • A. Closure of the mitral valve
   • B. Opening of the aortic valve
   • C. Closure of the aortic valve
   • D. Opening of the mitral valve

   Answer: B. Opening of the aortic valve

1. Q1. A patient's mouth droops to the left. The forehead wrinkles normally on the right and the right eye closes fully. Which lesion is this?

   • A. A right lower motor neurone facial palsy
   • B. A left lower motor neurone facial palsy
   • C. A left upper motor neurone facial palsy
   • D. A right upper motor neurone facial palsy, since bilateral cortical input spares the forehead

   Answer: D. A right upper motor neurone facial palsy, since bilateral cortical input spares the forehead

2. Q2. Which cutaneous receptor detects high-frequency vibration, and what adaptation property allows this?

   • A. Merkel discs, which are slowly adapting
   • B. Ruffini endings, which are slowly adapting
   • C. Pacinian corpuscles, which are rapidly adapting with a layered capsule
   • D. Free nerve endings, which are non-adapting

   Answer: C. Pacinian corpuscles, which are rapidly adapting with a layered capsule

1. Q1. Which of the following causes hypoxic hypoxia, in which arterial oxygen tension itself is reduced?

   • A. Carbon monoxide poisoning
   • B. Cyanide poisoning
   • C. Severe anaemia
   • D. A right-to-left intracardiac shunt

   Answer: D. A right-to-left intracardiac shunt

2. Q2. What does the PR interval on the electrocardiogram represent, and what prolongs it?

   • A. Atrial and AV nodal conduction, prolonged by first-degree AV block
   • B. Ventricular depolarisation, prolonged by bundle branch block
   • C. Ventricular repolarisation, prolonged by hypokalaemia
   • D. Atrial repolarisation, prolonged by ischaemia

   Answer: A. Atrial and AV nodal conduction, prolonged by first-degree AV block

1. Q1. What produces the dicrotic notch on the aortic pressure trace?

   • A. Passive ventricular filling
   • B. The rapid ejection phase
   • C. Closure of the aortic valve with brief backflow against the cusps
   • D. Isovolumetric contraction

   Answer: C. Closure of the aortic valve with brief backflow against the cusps

2. Q2. Which statement about isovolumetric relaxation is correct?

   • A. Both the aortic and mitral valves are closed while ventricular pressure falls at constant volume
   • B. The semilunar valves are open
   • C. It corresponds to the QRS complex
   • D. It produces the 'a' wave of the jugular venous pulse

   Answer: A. Both the aortic and mitral valves are closed while ventricular pressure falls at constant volume

1. Q1. Which ion is present at the lowest free concentration inside the cell, and why does this matter?

   • A. Free calcium, kept at about 100 nanomolar so that small influxes act as an effective second messenger
   • B. Magnesium, kept low to permit ATP binding
   • C. Potassium, kept low to maintain the resting potential
   • D. Protein, kept low to prevent oncotic swelling

   Answer: A. Free calcium, kept at about 100 nanomolar so that small influxes act as an effective second messenger

2. Q2. What is the resistance of a muscle to passive stretch when the patient is relaxed, and how does it differ from spasticity?

   • A. Spasticity, which is constant through the range
   • B. Tone, which is the normal baseline resistance, whereas spasticity is velocity-dependent and increases with rapid stretch
   • C. Rigidity, which is velocity-dependent
   • D. Clonus, which is rhythmic

   Answer: B. Tone, which is the normal baseline resistance, whereas spasticity is velocity-dependent and increases with rapid stretch

Every FMGE session paper, all 19 subjects together, is on our previous year questions page.