Core pharmacology. What causes macrocytosis?
Question.
Which one of the following is NOT a cause of macrocytic anaemia ?
- Alcohol abuse
- Hyperthyroidism
- Methotrexate
- Phenytoin
- Gastrectomy
Core pharmacology. Is a benediction in order?
Question.
A young patient’s median nerve is injured by a supracondylor fracture of the humerus. The resulting motor deficits may include all of the following EXCEPT which one?
- Weakness of pronation
- Weakness of ulnar deviation of the wrist
- Loss of thumb opposition
- Loss of abduction of the index and middle fingers
- Loss of index and middle finger flexion
Core Anatomy : Where does all your K+ go?
Question.
Potassium excretion by the kidney is increased by which one of the following?
- Aldosterone
- Reduced renal tubular flow
- Falling serum pH (acidaemia)
- Spironolactone
- ACE inhibitors
Core Physiology: Cerebral blood flow
Question.
Which one of the following is NOT correct regarding the cerebral circulation?
- Cerebral oxygen consumption is about 20% of total body oxygen consumption
- The brain uses glucose as its main energy source
- Autoregulation maintains a constant cerebral blood flow for mean arterial pressures (MAP) between 60-160mmHg.
- Cerebral blood flow is very sensitive to arterial pO2
- Local metabolites, ADP, K+ and H+ ions, all increase cerebral blood flow
Core Physiology: Gentamycin – static or synergistic?
Question.
Which one of the following is true regarding the use of gentamicin?
- It is bacteriostatic
- It has synergistic effects when used along with penicillin
- It is effective against anaerobes
- Nephrotoxicity is dose related
- Ototoxicity is rare
Core Physiology: Laryngeal anatomy.
Question.
Regarding the anatomy of the larynx, which one of the following statements is FALSE?
- It joins the top of the trachea at the level of C6
- The vocal cords lie inferior to the epiglottis
- The glossopharyngeal nerve (CN IX) provides both motor and sensory innervation to the larynx
- The vocal cords abduct during respiration but adduct during phonation
- The cricoid cartilage lies below the thyroid cartilage
Answer.
C
Explanation.
The anatomy of the larynx is complicated. It lies inferior to the hyoid bone, anterior to the lower pharynx and joins to the top of the trachea at C6 level.
Three unpaired cartilages make up its external form:
(1) epiglottis (a flap of elastic cartilage covered by mucous membrane which is attached to the anterior thyroid cartilage)
(2) thyroid cartilage; and
(3) cricoid cartilage (most inferior and separated from the thyroid cartilage above by the cricothyroid membrane).
The three paired cartilages (the arytenoids, corniculate and cuneiform) are smaller, located posteriorly within the larynx, and function in movement of the vocal cords.
The extrinsic muscles of the larynx (infrahyoid, suprahyoid and stylopharangeus) move the larynx as a whole during swallowing. The intrinsic muscles (the arytenoids, cricoarytenoids, thyroarytenoids and cricothyroid) abduct, adduct, relax and tense the vocal cords during speech and respiration. The vocal cords are relaxed and abducted during respiration and adducted and tensed during phonation.
During swallowing the backward movement of the tongue and upward movement of the larynx forces the epiglottis down over the superior laryngeal opening to prevent swallowed matter from entering the trachea.
The vagus nerve (CN X) provides motor and sensory innervation to the larynx via its superior laryngeal branch (motor to cricothyroid and sensory to the superior larynx above the vocal cords), and its recurrent laryngeal branch (motor to all the intrinsic muscles of the larynx except cricothyroid and sensory to the larynx below the vocal cords).
FRCEM Primary Revision Essentials: Five and five useful FOAMed articles for your FRCEM Primary revision!
FRCEM Primary Revision
Below is a list of ten educational modules, five from RCEM learning and five from Doctors.net.uk Education, which have a basic science focus and are useful for FRCEM primary revision. If you haven’t found RCEM learning before, it is a great free resource from the College and found at www.rcemlearning.co.uk/landing/. Modules take about an hour to complete and can be added to your CPD folder! If you are not a member already you will need to register to view the Doctors.net.uk education modules.
Core Physiology: A shunt too far.
Question.
Which one of the following statements is true regarding the pathophysiology of pulmonary shunts?
a. Alveolar ventilation and the alveolar–arterial (A-a) gradient are both increased
b. Alveolar ventilation and gas exchange are both reduced
c. Alveolar ventilation is decreased and dead space is increased
d. Alveolar ventilation is normal while perfusion is decreased
e. Alveolar ventilation and the alveolar–arterial (A-a) gradient are both unaffected.
Answer.
The answer is b. Alveolar ventilation and gas exchange are both reduced in a pulmonary shunt, while the alveolar-arterial (A-a) gradient is increased.
Explanation.
A pulmonary shunt is a volume of lung with adequate perfusion but poor or absent ventilation. This creates regions of little or no gas exchange so that blood leaving the shunt remains de-oxygenated. When the deoxygenated blood from the shunt mixes with the oxygenated blood from rest of the lung, it lowers the overall arterial oxygen concentration (PaO2) and if the shunt is large enough, cause systemic arterial hypoxia. Shunts may be as small as a few alveoli in a tiny patch of atelectasis or large as an entire lung. A common cause of pulmonary shunting is pneumonia where the alveoli fill with inflammatory fluid (consolidation).
The alveolar-arterial (A-a) gradient is a measure of the difference between the alveolar concentration of oxygen (PAO2) and the arterial concentration of oxygen (PaO2): A-a gradient = PAO2 – PaO2. Now, the ‘ideal’ alveolar oxygen concentration (PAO2) calculated by the alveolar gas equation is largely unaffected by pulmonary shunts while the arterial oxygen concentration (PaO2) measured by blood gas analysis is markedly reduced, resulting in an increase in the A-a gradient.
Dead space refers to areas of lung that are ventilated but not perfused (the opposite of a shunt) and therefore shunts do not affect dead space.
Revision essentials: Five and five useful FOAMed articles for your FRCEM Primary revision!
Below is a list of ten educational modules, five from RCEM learning and five from Doctors.net.uk Education, which have a basic science focus and are useful for FRCEM primary revision. If you haven’t found RCEM learning before, it is a great free resource from the College and found at www.rcemlearning.co.uk/landing/. Modules take about an hour to complete and can be added to your CPD folder! If you are not a member already you will need to register to view the Doctors.net.uk education modules.
Core Pharmacology: Understanding the adverse effects of Lithium.
Question.
Which one of the following statements regarding lithium (Li) is FALSE?
a. It has a narrow therapeutic range
b. Lithium levels are increased by drugs which induce cytochrome p450
c. Serum lithium levels for monitoring should be measured 12 hours after the last dose
d. Lithium inhibits the action of anti-diuretic hormone (ADH)
e. Hypothyroidism is a frequent adverse effect of lithium therapy
Answer.
The answer is b.
Explanation.
Lithium is a monovalent cation used in the treatment of bipolar disorder, depression and Schizoaffective disorders.
When administered orally it is fully absorbed from the gut with peak levels 4 hours after ingestion. It has a narrow therapeutic index and toxicity is common. Hence patients on lithium require monitoring with blood taken for serum lithium levels 12 hours after the last dose.
Lithium is not metabolised at all by the liver and so enzyme inducers and inhibitors have no effect on levels. It is, however, almost entirely eliminated via the kidneys so that pre-existing renal impairment as well as concomitant use of nephrotoxic drugs (diuretics, ACE inhibitors and NSAIDS) are causes of lithium accumulation and toxicity. Symptoms of lithium toxicity are mostly GI (nausea, vomiting and diarrhoea) and, with more serious poisoning, neurological (tremor, ataxia, confusion and coma).
Lithium inhibits the action of anti-diuretic hormone (ADH) in the collecting duct of the kidney and is a well-recognised cause of nephrogenic diabetes insipidus. It also causes hypothyroidism of varying degrees in around 1 in 5 patients.