2021 - Multiple Choice Questions

Which of the following organs has the highest oxygen extraction ratio?
  1. Brain
  2. Heart
  3. Kidneys
  4. Liver
Which subunit of G-proteins function as a GTP-ase?
  1. Alpha
  2. Beta
  3. Gamma
  4. Delta
Handbook of the Behavioral Neurobiology of Serotonin
The Gibbs-Donnan Effect:
  1. Causes an equalisation of the electrical potential on both sides of a semi-permeable membrane
  2. Explains why Haemoglobin binds hydrogen ions in RBCs
  3. Counteracts movement of fluid from the capillary into the extracellular space
  4. Explains why anions bind to Albumin in the plasma
  • The Gibbs-Donnan Effect is the predictable and unequal distribution of permeant charged ions on either side of a semipermeable membrane, in the presence of impermeant charged ions (e.g. proteins).
 
  • The permeant ions distribute themselves so that at equilibrium, the ratios of their concentrations are equal:

  • The total electrical potential remains unequal however due to presence of impermeant charged proteins.
 
  • At the capillary endothelium, the Gibbs-Donnan effect contributes to the oncotic pressure. Charged plasma proteins (primarily Albumin) lead to the arrangement of permeant charged ions (Na and Cl) so that their concentration is higher in the plasma. This increases the osmotic pressure of plasma relative to the ECF and counteracts the hydrostatic pressure in the capillary.
Stenotrophomonas species are:
  1. Gram positive cocci
  2. Gram positive bacilli
  3. Gram negative cocci
  4. Gram negative bacilli
Reference (Not the diagram)
Aspergillus fumigatus is:
  1. A yeast
  2. A mold
  3. A dimorphic fungus
  4. A gram negative cocci
2 broad clinical classifications for fungi:
  • On the basis of growth form:
    • Yeasts – ovoid or spherical single cells that multiply by budding (e.g. Cryptococcus)
    • Filamentous (moulds) – multi-nucleate, branching hyphae -> forms a mycelium (e.g. Aspergillus, Trichophyton)
    • Dimorphic – form hyphae at environmental temperatures and yeast cells within the body (e.g. Histoplasma)
      • Candida is dimorphic in the other direction – unusual (from yeasts in the environment and hyphae in the body)
 
  • By the type of infection:
    • Superficial mycoses (superficial skin, hair, mouth, vagina)
      • Candida albicans (Vaginal candidiasis)
    • Subcutaneous mycoses (nails, deeper skin)
      • Mycetoma spp.
      • Sporothricosis
    • Deep mycoses
      • Aspergillus
      • Candida
      • Coccidioides
      • Cryptococcus
      • Histoplasma
Relative humidity:
  1. Is the mass of water vapour present in a given volume of air
  2. Remains constant if the temperature of the air changes
  3. Increases as the temperature of the air increases
  4. Increases as the temperature of the air decreases
  • Absolute humidity is the mass of water vapour present in a given mass/volume of air (g/kg)
  • Relative humidity is the ratio of the mass of water vapour in a given volume of air to the mass required to saturate that given volume of air at the same temperature.
  • i.e. Current absolute humidity/absolute humidity if saturated at the current temperature
      Effect of temperature
  • Warmer air is able to hold more water vapour – i.e. is able to have a higher absolute humidity
  • Colder air holds less water vapour – i.e. able to have a lower absolute humiditiy
  When the temperature of the air decreases:
  • Saturated absolute humidity drops, current absolute humidity remains the same
  • Therefore – the ratio of current absolute humidity : saturated absolute humidity increases
I.e. Relative Humidity Increases
Which muscle of the larynx abducts the vocal cords?
  1. Posterior cricoarytenoid
  2. Lateral cricoarytenoid
  3. Thyroarytenoid
  4. Cricothyroid
  • Laryngeal Muscles
  • The posterior cricoarytenoids are the ONLY muscles to abduct the vocal folds
In smooth muscle contraction, what does Ca2+ bind to?
  1. Troponin C
  2. Calmodulin
  3. Calbindin
  4. Myosin
Which pattern of nerve stimulation is most useful in monitoring very deep neuromuscular blockade?
  1. Train-of-Four Ratio
  2. Train-of-Four Count
  3. Post-tetanic Count
  4. Double Burst Stimulation
  • Post-tetanic count
  • During profound non-depolarizing neuromuscular block, there may be no response to TOF or single twitch stimulation. In such circumstances, a post-tetanic count (PTC) may be useful.
  • Occurs due to post-tetanic facilitation (ACh mobilisation and increased synthesis)
  • Effects can last up to 6 min – should not be repeated in this period
Where do nerve impulses arise from to cause pupillary dilatation?
  1. Ciliary Ganglion
  2. Edinger-Westphal Nucleus
  3. Superior Cervical Ganglion
  4. Occipital Cortex
What is the plasma protein binding of Propofol?
  1. <5%
  2. 35-45%
  3. 75-85%
  4. >95%
The thermoneutral zone is:
  1. The range of core temperatures that do not trigger a physiological response to alter the temperature of the body
  2. The range of ambient temperatures which do not trigger a change in thermal behaviour
  3. 25 – 30°C
  4. 36.0 – 37.5°C
  1. The range of core temperatures that do not trigger a physiological response to alter the temperature of the body (Inter-threshold Temperature)
  2. The range of ambient temperatures which do not trigger a change in thermal behaviour (Thermal Comfort Zone)
  3. 25 – 30°C (Usual Thermoneutral Zone)
  4. 36.0 – 37.5°C (Normal Core Body Temperature)
 
  • TNZ: The range of ambient temperatures where the body can maintain its core temperature solely through regulating dry heat loss, i.e. Skin blood flow (conduction and radiation).
    • Range (unclothed): 25-30°C
    • Range(clothed): 20-22°C
    • Neonates: 32-34°C (unclothed), 24-30°C (clothed)
 
  • Within the TNZ, the rate of heat loss is equal to the basal metabolic rate
A fluid with a large strong ion difference will cause a:
  1. Hyperchloraemia
  2. Metabolic Alkalosis
  3. Metabolic Acidosis
  4. Low CO2
Which of these is true for Rocuronium:
  1. Less potent than Vecuronium
  2. 90% plasma protein binding
  3. Half-life of 10 minutes
  4. Eliminated primarily in urine
  1. Less potent than Vecuronium
    • Increased potency -> lower dose used
    • ED95 Rocuronium = 0.3mg/kg
    • ED95 Vecuronium = 0.05mg/kg (more potent)
  2. 90% plasma protein binding (10% bound to plasma proteins)
  3. Half-life of 10 minutes (Half life of ~80 mins)
  4. Eliminated primarily in urine (Excreted in bile (60%) and unrine (40%) )
What percentage of total body Magnesium is in the intracellular fluid?
  1. 60%
  2. 40%
  3. 15%
  4. 5%
What is the mechanism of action of docusate as an aperient?
  1. Stimulant
  2. Bulk-forming
  3. Osmotic effect
  4. Stool softener
The plasma protein binding of Vecuronium is:
  1. 30%
  2. Unknown
  3. 60-90%
  4. 15-30%
Explanation:
  1. 30% (Rocuronium)
  2. Unknown
  3. 60-90% (Vecuronium)
  4. 15-30% (Pancuronium)