Membership of the Royal College of Surgeons (MRCS) Physiology and Applied Surgical Science Syllabus

Physiology and Applied Surgical Science syllabus — full chapter and topic list

Expand any chapter to see its topics and sub-topics. This is the whole examinable outline for Physiology and Applied Surgical Science in Membership of the Royal College of Surgeons (MRCS), not a summary of it.

1. 1

   Cardiovascular and Respiratory Physiology

   4 topics

   • Cardiac cycle and output
     • Preload, afterload and contractility
     • Starling's law and pressure-volume loops
   • Circulatory regulation
     • Baroreceptor and chemoreceptor reflexes
     • Microcirculation and capillary exchange
   • Respiratory mechanics and gas exchange
     • Lung volumes and compliance
     • Oxygen-haemoglobin dissociation curve
     • Ventilation-perfusion matching
   • Acid-base balance
     • Buffer systems and the Henderson-Hasselbalch equation
     • Interpretation of arterial blood gases
2. 2

   Renal, Fluid and Electrolyte Physiology

   4 topics

   • Glomerular filtration and tubular function
     • GFR, clearance and autoregulation
     • Sodium and water handling
   • Body fluid compartments
     • Distribution of crystalloids and colloids
     • Osmolality and tonicity
   • Electrolyte disorders
     • Sodium and potassium imbalance
     • Calcium, magnesium and phosphate disorders
   • Acute kidney injury in the surgical patient
     • Pre-renal, renal and post-renal causes
     • Perioperative fluid optimisation
3. 3

   Endocrine and Metabolic Physiology

   4 topics

   • Endocrine pancreas and glucose control
     • Insulin and glucagon regulation
     • Perioperative diabetes management
   • Adrenal and pituitary function
     • Cortisol and the HPA axis
     • Catecholamines and phaeochromocytoma
   • Thyroid and calcium homeostasis
     • Thyroid hormone action
     • PTH and vitamin D regulation
   • Metabolic response to surgery and trauma
     • Ebb and flow phases
     • Starvation, catabolism and nutritional support
4. 4

   Haematology and Immunology

   4 topics

   • Haemostasis and coagulation
     • Coagulation cascade and fibrinolysis
     • Platelet function and bleeding disorders
   • Blood groups and transfusion
     • ABO and Rh systems and crossmatching
     • Transfusion reactions and massive transfusion
   • Innate and adaptive immunity
     • Inflammatory cells and mediators
     • Antigen presentation and T/B cell responses
   • Transplant immunology
     • HLA matching and rejection
     • Immunosuppression principles
5. 5

   Cellular Physiology and Neurophysiology

   4 topics

   • Cell membrane and transport
     • Membrane potentials and ion channels
     • Active and passive transport
   • Nerve and muscle physiology
     • Action potential and synaptic transmission
     • Skeletal and smooth muscle contraction
   • Gastrointestinal physiology
     • Secretion, motility and absorption
     • Hepatic and biliary function
   • Thermoregulation and shock physiology
     • Temperature control and hypothermia
     • Classification and compensation in shock

Physiology and Applied Surgical Science flashcards for Membership of the Royal College of Surgeons (MRCS)

20 of 64 cards from the Physiology and Applied Surgical Science deck — real questions with worked answers.

1. What is the formula for cardiac output, and what are typical resting values?

   $CO = SV \times HR$. With a stroke volume $SV \approx 70\ \text{mL}$ and heart rate $HR \approx 70\ \text{bpm}$, $CO \approx 5\ \text{L/min}$.

2. Define ejection fraction and give the normal range.

   $EF = \frac{SV}{EDV} \times 100\%$, where $SV = EDV - ESV$. Normal $EF \approx 55\text{--}70\%$.

3. What are the three main determinants of stroke volume?

   Preload (ventricular end-diastolic volume/stretch), afterload (resistance/aortic pressure the ventricle ejects against), and contractility (intrinsic inotropic state).

4. State the Frank-Starling law of the heart.

   Within physiological limits, increased ventricular end-diastolic volume (preload/myocardial fibre stretch) increases the force of contraction and therefore stroke volume.

5. List the phases of the cardiac cycle in order.

   Atrial systole, isovolumetric ventricular contraction, rapid ejection, reduced ejection, isovolumetric relaxation, rapid filling, and reduced filling (diastasis).

6. What causes the first ($S_1$) and second ($S_2$) heart sounds?

   $S_1$ is closure of the mitral and tricuspid (atrioventricular) valves at the onset of systole; $S_2$ is closure of the aortic and pulmonary (semilunar) valves at the onset of diastole.

7. Give the formula for mean arterial pressure (MAP).

   $MAP = DBP + \frac{1}{3}(SBP - DBP)$, equivalently $MAP \approx DBP + \frac{1}{3}\,\text{pulse pressure}$. Also $MAP = CO \times SVR$.

8. How does the baroreceptor reflex respond to a fall in blood pressure?

   Reduced stretch of carotid sinus and aortic arch baroreceptors decreases afferent firing, increasing sympathetic and decreasing parasympathetic output, raising heart rate, contractility and systemic vascular resistance to restore MAP.

9. What is the relationship between flow, pressure and resistance (and how does radius affect it)?

   $Q = \frac{\Delta P}{R}$, and by Poiseuille's law $R \propto \frac{1}{r^{4}}$, so halving vessel radius increases resistance 16-fold.

10. What is the tidal volume and the equation for minute ventilation?

    Tidal volume $V_T \approx 500\ \text{mL}$. Minute ventilation $\dot{V}_E = V_T \times RR$ (respiratory rate).

11. Define anatomical dead space and give the equation for alveolar ventilation.

    Anatomical dead space ($V_D \approx 150\ \text{mL}$) is conducting airway volume not participating in gas exchange. Alveolar ventilation $\dot{V}_A = (V_T - V_D) \times RR$.

12. State the alveolar gas equation for alveolar oxygen tension.

    $P_AO_2 = P_iO_2 - \frac{P_aCO_2}{R}$, where $P_iO_2 = F_iO_2(P_{atm} - P_{H_2O})$ and $R$ is the respiratory quotient ($\approx 0.8$).

13. What is compliance of the lung and how is it expressed?

    Compliance is the change in lung volume per unit change in pressure: $C = \frac{\Delta V}{\Delta P}$. It reflects distensibility; it is reduced in fibrosis and increased in emphysema.

14. Describe the shape and significance of the oxyhaemoglobin dissociation curve.

    It is sigmoid. A right shift (decreased $O_2$ affinity) occurs with increased $CO_2$, $H^+$ (low pH), temperature and 2,3-DPG (Bohr effect), promoting $O_2$ unloading at tissues; a left shift increases affinity.

15. In what forms is carbon dioxide transported in blood, and in what proportions?

    As bicarbonate $\ce{HCO3^-}$ (~70%), bound to haemoglobin as carbamino compounds (~23%), and dissolved in plasma (~7%).

16. State the Henderson-Hasselbalch equation as applied to the bicarbonate buffer system.

    $pH = 6.1 + \log_{10}\left(\frac{[\ce{HCO3^-}]}{0.03 \times P_aCO_2}\right)$.

17. What is the normal arterial pH range, and the normal values for $P_aCO_2$ and $[\ce{HCO3^-}]$?

    pH $7.35\text{--}7.45$; $P_aCO_2$ $4.7\text{--}6.0\ \text{kPa}$ ($35\text{--}45\ \text{mmHg}$); $[\ce{HCO3^-}]$ $22\text{--}26\ \text{mmol/L}$.

18. How do you calculate the anion gap, and what is its normal value?

    $\text{Anion gap} = [\ce{Na+}] - ([\ce{Cl-}] + [\ce{HCO3^-}])$. Normal is approximately $8\text{--}16\ \text{mmol/L}$.

19. Classify the four primary acid-base disturbances by primary change and compensation.

    Metabolic acidosis (low $\ce{HCO3^-}$, respiratory compensation by hyperventilation lowering $P_aCO_2$); metabolic alkalosis (high $\ce{HCO3^-}$, hypoventilation); respiratory acidosis (high $P_aCO_2$, renal retention of $\ce{HCO3^-}$); respiratory alkalosis (low $P_aCO_2$, renal excretion of $\ce{HCO3^-}$).

20. What is the normal glomerular filtration rate (GFR) and the equation linking it to clearance?

    Normal GFR $\approx 120\ \text{mL/min}$. GFR $= $ clearance of a freely filtered, non-secreted, non-reabsorbed substance: $C_x = \frac{U_x \times V}{P_x}$ (inulin is the gold standard).

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