25/6 MCQ LOs Flashcards
List the chamber sequence in order of when they contract.
Why does RV ejection occur before LV?
RA -> LA -> LV -> RV
PAP < Aortic root pressure.
List the hormone that the lung inactivates.
Serotonin Noradrenaline Bradykinin Leukotrienes Adenosine
What is the time to peak effect and t1/2ke0 of midaz?
Peak effect 2.8 mins
T1/2 ke0 4 mins
Describe the mechanism of action of adenosine
Adenosine -> A1 receptors at SAN / AVN -> Gi effect -> opens adenosine-sensitive K channels to increase K+ current -> hyperpolarisation
Is aspirin more or less active than its metabolite
Principle metabolite salicylic acid.
Both are active (no comparison given)
Salicylic acid lasts 2-4 hours as opposed to aspirin 15 mins
Describe aspirin toxicity
Results from saturation of hepatic glycine conjugation for salicylic acid metabolism becomes zero-order kinetics.
Uncoupling oxidative phosphorylation
Tinnitus, vertigo, glucose imbalance, hyperventilation, coma, agitation (penetrates BBB), resp alkalosis and meta acidosis
What is the effect of vWF on Factor VIII
note that Factor VIII is a cofactor for factor IXa to activate factor X. It is inactivated by Protein C.
Protein C is activated by protein S. Warfarin early stage inactivates protein C and S, which is procoagulant as it gives unchecked factor V and VIII
vWF protects factor VIII from proteolysis by protein C
what is the main metabolite of amiodarone
desmethylamiodarone
List the adverse effects of lignocaine at different concentrations (microg/ml)
2 - anti-arrhythmic 5 - dysarthria, tinntus, tingling 8 - visual disturbance 10 - convulsions 12 - LOC 20 - resp depression 25 - CVS depression
Why does bupivacaine cause greater toxicity in neonates
decreased level of AAG
List the CV changes with exercise
AV O2 difference increases to 20mls/dl Mild increase of MAP to ~90-100mmHg O2 consumption increases by 60 folds SV increases then decreases SVR drops by a third
Describe fuel cell
Similar to clark electrode converts potential energy from a fuel into electricity Anode - lead Cathod - gold mesh KOH solution
Presence of oxygen creates a current
What is the last part of the heart to be depolarised?
the epicardial surface of LV wall at base of heart
How much of diclofenac is absorbed and how much is protein bound
50% absorption
99% protein bound
Describe codeine in relation to morphine
Codeine is methylmorphine - methyl sub at OH group on position 3 of morphine
10% of drug is O-desmethylated to morphine
Codeine is 10% analgesic potency of morphine
Describe the effects of different GPCR on myosin light chain
Gq - IP3 - Ca -> Increases MLCK effect -> contraction
Gs - cAMP -> inhibits MLCK -> relaxation
Gi - inhibits cAMP -> potentiates MLCK -> contraction
List the actions of metformin
Increase insulin sensitivity via increased receptors amount and affinity of receptors
Increase glucose uptake and utilisation in SKM
Reduce hepatic gluconeogenesis
Decrease LDL and vLDL synthesis
Decrease glucose absorption from gut`
List in order the effect of volatile agent on cerebral blood flow.
Halothane > desflurane > enflurane > isoflurane > sevoflurane
For iso, up to 1 MAC, CBF is auto regulated.
Write down the characteristics of esmolol
B1 selective No ISA or MSA Protein binding 55% broken down by RBC esterase T1/2 of 9 mins
Why does pulmonary vascular resistance change with lung volume
Lowest PVR at FRC
Below FRC, PVR increases due to reduced calibre of extra alveolar vessels.
Above FRC, PVR increases due to reduced calibre of alveolar capillaries.
What is the absolute humidity of air saturated at 37 degrees?
44 g/m^3
What is the flow rate of oxygen flush on the circle?
35-75 L /min
What is the content of O2/CO2/N2 in air?
78% N2
21% O2
0.03% CO2
Describe the volume control ventilation profile.
Flow sensors terminate the inspiration when the predetermined volume has been delivered.
Pressure and volume profile look like shark fins
Flow profile is squared
Describe the pressure control ventilation profile
Constant inspiratory pressure delivered.
Pressure waveform is squared.
Flow shows a decelerating profile to maintain a constant pressure
Volume waveform looks like a shark fin
What are the assumptions from estimating LVEDV from PCWP?
Normal MV - abnormal MV overestimates LVEDV
Normal LV compliance - underestimates if non-compliant
Normal airway pressure - PCWP overestimates with high PEEP
What does carotid massage achieve?
Increased vagal outflow to AV nodal tissue and thus increases the refractoriness
Which LA has faster metabolism
Prilocaine vs. procaine.
Prilocaine - amide LA
Procaine - ester LA
Procaine faster than prilocaine
Describe the changes in cardiac output for an elite athlete
Increased LVEDV (baseline 120ml, to 160-220ml) due to eccentric hypertrophy. Exercise/training is associated with larger blood volume.
Resting stroke volume from 70ml to 100-125 ml
End systolic volume of 60-95ml (from baseline of 50ml)
Compensates by reduced baseline heart rate.
