FRCA Main Flashcards

Question

What are the different parts of a sarcomere?

Answer 1

Z-discs: ends of a sarcomere I band: only actin (thin) filament A band: overlap of actin and myosin filaments H zone: myosin filament only M disc: anchoring point of thick filaments

Answer 2

Calcium stimulates the release of more calcium from the sarcoplasmic reticulum Inhibited by dantrolene

Answer 3

Ryanodine Receptor (CICR) Inositol Triphosphate Receptor (calcium channel) Phospholamban (inhibits sarcoplasmic reticulum calcium ATPase)

Answer 4

Desmosome Junctional Complex: provide structural integrity and tensile strength Gap Junctions: hexameric proteins (connexons) that span the sarcolemma and allow small molecules to pass

Answer 5

Dimers in a staggered helical fashion with globular heads forming six rows Central portion of adjacent filaments joints at M-disc by creatine kinase, M protein and myomesin Tail is made up of light meromyosin (LMM) and heavy meromyosin (HMM) arranged in an alpha helix with a flexible hinge region

Answer 6

Two actin filaments are arranged in a helix Tetramer of alpha-tropomyosin is wound around it (blocking the binding of myosin heads to actin) Inhibitory (TnI), calcium-binding (TnC) and tropomyosin-binding (TnT) troponins are found on tropomyosin

Answer 7

At rest, tropomyosin blocks myosin binding sites on actin Calcium binds to TnC triggering the unbinding of tropomyosin, making the binding sites available for engagement Myosin head binds and fully displaced tropomyosin allowing more heads to bind Once calcium is sequestered, tropomyosin will bing to actin again

Answer 8

The fibres are arranged into a single overlapping and looping band extending from the pulmonary artery to the aorta This explains the ascending, descending and rotational forces during systole

Answer 9

Atrial systole Isovolumetric contraction Rapid ejection Reduced ejection Isovolumetric relaxation Rapid filling Reduced filling

Answer 10

A wave: atrial contraction C wave: isovolumetric contraction causes AV valves to bulge into atria X descent: atrial relaxation + pulling downwards of AV ring during early rapid ejection V wave: ventricular systole Y descent: AV valves open and blood rapidly leaves the atria into the ventricle during diastole

Answer 11

Incisura: sharp downward deflection occurring immediately after the aortic valve closes as blood being ejected from the LV suddenly stops Dicrotic Notch: smaller notch caused by brief backflow of blood as the aortic valve closes and the aorta recoils in on itself

Answer 12

3rd Heart Sound Occurs during early rapid ventricular filling due to tensing of connective tissues that support the valve cusps Occurs in conditions associated with ventricular dilation 4th Heart Sound Occurs during atrial systole Represents vibration of the ventricular wall during atrial contraction Occurs in conditions associated with stiff ventricles

Answer 13

Area within the loop (pressure x volume)

Answer 14

The gradient of the end-systolic pressure volume relationship (ESPVR) and end-diastolic pressure volume relationship (EDPVR) is the reciprocal of the ventricle's compliance Shallower gradient means greater change in volume for a small change in pressure (i.e. more compliant ventricle)

Answer 15

Ejection from the RV begins earlier in systole before peak RV pressure is reached Pulmonary circulation is high capacitance and low pressure, so RV ejection continues whilst RV pressure is falling (up to 60% of stroke volume ejected after peak systolic pressures)

Answer 16

Nernst: predicts transmembrane potential based on one ion at a time Goldman Constant Field: considers all major ions

Answer 17

0: depolarisation, Na channels open allowing Na influx 1: Na channels close and K channels open, allowing K efflux 2: Ca channels open allowing Ca influx to balance K efflux 3: Ca channels close, K efflux continues causing repolarisation 4: Na/K ATPase re-established resting membrane potential and concentration gradients

Answer 18

I and aVF as they are at right angles to each other Should be -30 to +90 degrees

Answer 19

Phase 4: initially at -60 mV, funny sodium channels open allowing sodium influx, at -50 mV T-type Ca channels open, then at -40 mV L-type Ca channels open, reaching threshold potential Phase 0: ongoing flow through L-type Ca channels leads to depolarisation Phase 3: Ca channels close and opening of K channels returns to membrane potential

Answer 20

P wave: < 0.12 seconds PR Interval: 0.12-0.20 seconds QRS Complex: < 0.12 seconds QT Interval Men: < 440 ms Women: < 460 ms

Answer 21

Increases Na and Ca permeability resulting in faster upward drift of pacemaker potential and increased heart rate In myocardial cells, increased calcium influx leads to stronger contraction

Answer 22

Vagus nerve releases acetylcholine to stimulate M2 receptors Leads to opening of K channels that hyperpolarises the cells, thereby slowing the rate at which the threshold potential in pacemaker cells

Answer 23

Atmosphere: 21.2 kPa Alveolus: 14 kPa Arterial: 13.3 kPa Mixed Venous: 5.3 kPa

Answer 24

Conducting Zone - No alveoli - Generations 1-16 (trachea to terminal bronchioles) - Volume: 150 mL - Bulk flow during inspiration and expiration - Warming and humidifying inspired air Respiratory Zone - Has alveoli - Generations 17-23 (bronchioles to alveoli) - Volume: 3000 mL - NO bulk flow, gases move by diffusion  - Function: gas exchange 

Answer 25

Alveolar Minute Ventilation = (Tidal Volume – Dead Space) x Respiratory Rate 

Answer 26

Anatomical: upper airways and conducting zone Alveolar: proportion of minute ventilation that does NOT take part in gas exchange due to entering unperfused or underperfused alveoli

Answer 27

Surface area of the lungs  Diffusion constant for oxygen  Thickness of the alveolar and capillary membrane Difference between the partial pressure of oxygen in the alveoli and the blood

Answer 28

Flow of Gas is directly proportional to: (A/T) x D(P1 - P2) A: surface area T: thickness of interface D: diffusion constant for oxygen P1: partial pressure in alveolus P2: partial pressure in capillary

Answer 29

250 mL/min

Answer 30

0.25 seconds NOTE: red cell transit time through the capillaries is 0.75 seconds

Answer 31

The total proportion of the circulation entering the LEFT side of the heart which has bypassed the oxygenation process of the lungs 

Answer 32

Bronchial circulation and Thebesian drainage (venous drainage from heart muscle into the left ventricle) 

Answer 33

The weight of the lungs compresses the bases meaning that the intrapleural pressure at the bases is less negative This means that the bases have a lower resting volume and require less pressure to bring about a change in volume (i.e. are more compliant)

Answer 34

Zone 1: alveolar pressure greater than arterial pressure so there is no flow (does NOT exist under normal circumstances) Zone 2: arterial > alveolar > venous - flow is dependent on arterial-alveolar pressure gradient Zone 3: arterial > venous > alveolar - flow determined by arterio-venous gradient

Answer 35

Shunt fraction is higher towards the bases Dead space is greater towards the apices

Answer 36

The PO2 at the apex is about 40 mm Hg higher than at the base  due to differences in V/Q The difference in ventilation between the apex and the base is much less than the change in perfusion  Most blood comes from the bases of the lungs which has a lower pO2 and higher pCO2 – this will lower the pO2 and increase the pCO2 of arterial blood when compared to alveolar gas  NOTE: normal alveolar-arterial oxygen difference is 4 mm Hg

Answer 37

High or Low V/Q Ratios Low V/Q Ratio: ventilation is significantly reduced relative to perfusion, leads to fall in PAO2 and even greater fall in PaO2, this can be partially corrected by increasing FiO2 High V/Q Ratio: PAO2 remains stable but PaO2 falls due to reduced perfusion

Answer 38

Qt x CaO2 = (Qs x CvO2) + ((Qt - Qs) x CcO2) Qs/Qt = (CcO2 - CaO2)/(CcO2 - CvO2) Qs = shunt blood flow Qt = total blood flow (cardiac output monitoring) CcO2 = End capillary oxygen content (estimated using alveolar gas equation) CaO2 = arterial oxygen content (from arterial blood gas) CvO2 = mixed venous oxygen content (from pulmonary artery floatation catheter sample)

Answer 39

CaO2 = (Hb x 1.39 x SaO2) + (0.003 x PaO2) NOTE: 1.39 mL of oxygen is carried per gram of fully saturated haemoglobin Hb in grams per 100 mL PaO2 in mm Hg

Answer 40

Alkalosis Hypothermia Decreased 2,3-DPG

Answer 41

Lungs - CO2 is eliminated and pH rises, thereby shifting the curve to the left - This enhances the binding of oxygen to haemoglobin Tissues - Cellular metabolism leads to CO2 and H+ production, thereby shifting the curve to the right - This means that the haem releases oxygen more readily 

Answer 42

Produced as side reaction from glycolysis Binds to beta-globin and reduces haemoglobin's affinity for oxygen Improves oxygen offloading in anaemia and low oxygen states

Answer 43

Protoporphyrin ring (four pyrole rings) and iron in its ferrous (Fe2+) state NOTE: protoporphyrin is synthesised in the mitochondria from glycine and succinyl CoA and combined with ferrous iron

Answer 44

Haemoglobin A: 2 alpha and 2 beta Haemoglobin A2: 2 alpha and 2 delta Haemoglobin F: 2 alpha and 2 gamma

Answer 45

By the reticuloendothelial system Globin chains are broken down into amino acids which are recycled Iron is reused by the bone marrow to make more haemoglobin Protoporphyrin is opened to form biliverdin, which is metabolised to bilirubin

Answer 46

The amount of oxygen (in mL) carried by each gram of haemoglobin  Values in vitro are 1.39 mL/g whereas in vivo its 1.34 ml/G - this is thought to be due to the presence of minor haemoglobin variants like HbA2 and HbF

Answer 47

Refers to the reduced affinity of oxygen for haemoglobin when pH is lower  (and carbon dioxide is higher) This is adaptive – for example, the pH in exercising muscles is low and this helps offload oxygen 

Answer 48

Uptake of foetal CO2 by maternal blood shifts the maternal oxy-haemoglobin curve to the right, and the foetal curve to the left 

Answer 49

Stored blood quickly loses 2,3-DPG and its ability to deliver oxygen 

Answer 50

There are four alpha globin genes on chromosome 14 - Alpha thalassemia results from mutations to 1 to 4 of these genes  There are two beta globin genes on chromosome 11  - Mutations in these genes causes beta thalassemia  - It usually manifests at 6 months of age when HbA takes over from HbF 

Answer 51

Glutamic acid is substituted for valine at position 6 of the beta globin chain

Answer 52

Binding changes the confirmation of haemoglobin making it less likely to release oxygen (I.e. shifting the curve to the left) and it reduces the availability of binding sites for oxygen

Answer 53

20 mL/100 mL

Answer 54

VO2 = CO x (Arterial O2 Content – Mixed Venous O2 Content) = CO(CaO2 – CvO2) 

Answer 55

Normal mixed venous PO2 is around 5.3 kPa - at this pO2, haemoglobin is 75% saturated  Remember, 100% saturated blood contains 20 mL/100 mL of oxygen (meaning that 75% saturation will give 15 mL/100 mL of oxygen) Therefore: VO2 = 5000 x (20-15)/100 = 250 mL/min

Answer 56

Oxygen delivery is insufficient and the oxygen extraction ratio has been increased to compensate NOTE: normal is around 75%

Answer 57

Glucose --> 2 Pyruvate via glycolysis in the cytoplasm 2 Pyruvate --> 2 Acetyl CoA due to oxidative decarboxylation in the mitochondria Free Fatty Acids --> Acetyl CoA via beta oxidation Amino Acids --> Pyruvate + Acetyl CoA + Krebs Cycle Intermediates via oxidation

Answer 58

2 ATP 2 CO2  6 NADH+ 2 FADH

Answer 59

In the mitochondria, reduced enzymes (NADH and FADH) are reoxidised releasing electrons and energy used to convert ADP to ATP 1 NADH2 = 3 ATP 1 FADH2 = 2 ATP Oxygen is the final electron acceptor which combines with hydrogen ions to produce water 

Answer 60

Hypoxia Hypoxia Anaemic Hypoxia Ischaemia/Stagnant Hypoxia Histotoxic Hypoxia

Answer 61

2 mins anoxia = irreversible cell damage  4 mins anoxia = cell death 

Answer 62

LOCAL: acid accumulation from anaerobic respiration leads to right shift of ODC, 2,3-DPG also rises, vasodilation due to low pO2, high pCO2 and low pH VENTILATORY: minute ventilation increases when pO2 < 7 kPa CARDIOVASCULAR: Stimulation of the chemoreceptors results in vasoconstriction and tachycardia resulting in improved tissue perfusion by increasing blood pressure and heart rate

Answer 63

50-150 mm Hg

Answer 64

6.7 kPa NOTE: brain is responsible for 20% of total body oxygen consumption

Answer 65

75% Compared to 25% in other tissues. This can increase to 90% when demand increases (e.g. exercise)

Answer 66

Inhibition of nitric oxide production Local production of vasoconstrictors (e.g. endothelin) Direct effect of hypoxia on vascular smooth muscle 

Answer 67

Due to the mixSting with expired gas from unperfused alveoli

Answer 68

(CO2 x 100)/Alveolar Ventilation = ~5%

Answer 69

Increased inspired pCO2 (rebreathing) Primary respiratory depression (e.g. CNS depression) Increased CO2 production (e.g. sepsis, MH) Compensatory (to metabolic alkalosis)

Answer 70

Increased cerebral blood flow Increased ICP (due to vasodilation) Narcosis (at pCO2 > 12 kPa) Autonomic effects (due to increased circulating catecholamines)

Answer 71

CO2 rapidly crosses the BBB and, in the CSF, dissolves to release H+ (which cannot go back across the BBB leading to a drop in CSF pH) BBB is more permeable to CO2 than it is to H+

Answer 72

Linear increase in minute ventilation Pulmonary vasoconstriction (if PaCO2 > 7) ODC shifts to the right

Answer 73

Impaired heart rate and contractility (due to acidosis) Systemic vasodilation and pulmonary vasoconstriction Arrhythmia Increased catecholamine release (opposes the direct myocardial impairment mentioned above)

Answer 74

Bicarbonate: 18 mmol H+ per L Plasma Proteins: 1.7 mmol H+ per L Haemoglobin: 8 mmol H+ per L Phosphate: 0.3 mmol H+ per L TOTAL: 28 mmol H+ per L

Answer 75

Zinc Zinc hydrolyses water to a reactive Zn-OH species  Nearby histidine removed H+ from Zn and transfers to any buffer molecules near the enzyme Carbon dioxide combined with Zn-OH forming HCO3- The HCO3- dissociates from the zinc atom 

Answer 76

Amino groups of haemoglobin can combine with CO2 to form carbamic acid Deoxyhaemoglobin is about 3.5 times more effective at carbamino carriage than oxyhaemoglobin NOTE: this is a major component of the Haldane effect. Oxygenation reduces its affinity for CO2.

Answer 77

Physiological phenomenon where the binding of oxygen to hemoglobin in the lungs promotes the release of carbon dioxide, and conversely, the release of oxygen from hemoglobin in the tissues facilitates the uptake of carbon dioxide.

Answer 78

Imidazole group of histidine Each Hb tetramer has 38 histidine molecules

Answer 79

Buffering capacity is a measure of a solution's ability to resist changes in pH when acid or base is added  A buffer works best when pKa is close to physiological pH because it means that, at physiological pH, the buffer has significant amounts of both its acid and its conjugate base to be able to neutralise any acid or base that is added to the solution, thereby minimising changes in pH 

Answer 80

In deoxyhaemoglobin, the imidazole group of histidine is more basic As oxygen dissociates, it becomes more basic and binds more H+ Removal of H+ shifts the carbonic acid equilibrium towards H+ and HCO3- generation, thereby 'consuming' CO2 This leads to increased movement of CO2 into the red cells Deoxyhaemoglobin also has increased carbamino carriage

Answer 81

Haldane effect is what happens to pH and CO2 binding because of oxygen, and Bohr effect is what happens to oxygen binding because of CO2 and lower pH.

Answer 82

Haemoglobin buffering (H+ soaked up by histidine residues) Hamburger Shift (HCO3- exchanged for Cl- by Band 3 protein) NOTE: hereditary spherocytosis is caused by inherited defect in Band 3

Answer 83

Paramagnetic gases are attracted by a magnetic field (and can be analysed by a paramagnetic analyser) due to the presence of unpaired outer orbital electrons. Examples: oxygen, nitric oxide

Answer 84

A substance above its critical temperature cannot be liquified irrespective of the pressure applied to it.

Answer 85

-118 degrees

Answer 86

Dynamic compliance is affected by both airway resistance and elastic resistance, while static compliance is affected by elastic resistance alone.

Answer 87

The sieving coefficient provides a measure of how different molecules move across a semi-permeable membrane. In renal replacement therapy, it is the ratio of the concentration of a molecule in the ultrafiltrate compared to the concentration in the blood. NOTE: smaller molecules equilibrate across the membrane more readily and have a coefficient around 1

Answer 88

Transpulmonary pressure = pressure in the right side of the heart – pressure in the left side of the heart. NOTE: Pulmonary capillary wedge pressure is often used as a surrogate for left atrial pressure

Answer 89

Blocks post synaptic β1 receptors (part of the autonomic nervous system).

Answer 90

In pulse oximetry, red (660nm) and infrared (940nm) LEDs blink on and off 30 times per second. The degree of absorbance of these wavelengths by a photodetector is measured, and is correlated with known data to provide an estimate of oxygen saturations. Oxygenated haemoglobin absorbs infrared (940nm) light to a greater degree than deoxygenated haemoglobin. The reverse is true of red light. The off:off signal allows for the photodetector to establish the degree of ambient light which is then subtracted from the received signal.

Answer 91

Anterior rami of L2-L4

Answer 92

Closing capacity (the sum of residual volume and closing volume), is the lung volume at which small airways begin to close during expiration. With advancing age, it is increased to the extent that it may exceed FRC. This leads to closure of the small airways during normal tidal breathing.

Answer 93

Convert AC to DC current (knowing as rectification)

Answer 94

Lipid solubility: More lipid soluble, more transfer Ionisation: More ionised, less transfer Protein binding: More protein binding, less transfer pH: Determines degree of ionisation, which in turn affects transfer Molecular weight: Large, bulky molecules, pass less readily.

Answer 95

CO2 is more soluble in water as the temperature decreases such that maintenance of the same PCO2 in the blood when hypothermia requires more total CO2  Decreasing temperature reduces the ionisation of water so pH increases by around 0.016 per degree fall in temperature Therefore, if CO2 production and excretion remain constant, hypothermia would lead to alkalosis

Answer 96

Animals try to maintain blood pH in hypothermia by hypoventilating (this is seen in hibernating animals)

Answer 97

The ionisation state of histidine and, hence, its buffering ability changes with temperature to a similar degree to the ionisation of water  So, as temperature decreases and blood/tissue pH rises, the ionisation of histidine can buffer this change in pH 

Answer 98

Increased inspired CO2: rebreathing Increased production of CO2: hyperthermia, hyperthyroidism, laparoscopic surgery Decreased excretion: increased dead space, failure of respiratory muscle function

Answer 99

The partial pressure of oxygen within the alveolus once the partial pressure of oxygen delivered and the amount consumed to meet the metabolic demands of the body have been considered.

Answer 100

PAO2 = FiO2(Patm - Ph2o) - (PCO2/RQ)

Answer 101

Air becomes 100% saturated with water as it passes through the airways The SVP of water at body temperature is 6.3 kPa As per Dalton's law, as the vapour takes up space within the airways, it must be subtracted from the partial pressure of atmospheric air

Answer 102

It doesn't - the FiO2 remains the same, however, the total atmospheric pressure decreases meaning that the pO2 will decrease

Answer 103

Caused by excessive pulmonary vasoconstriction 

Answer 104

1 atmosphere for every 10 m of depth

Answer 105

Barotrauma in air-filled spaces (e.g. lungs, ear) Arterial air embolus Bubbles forming in vessel poor tissues (e.g. cartilage) with avascular necrosis  Potentially permanent neurological damage

Answer 106

Anaerobic infections CO poisoning Decompression sickness

Answer 107

If hypoxia at sea level, more vulnerable to desaturation and requiring more oxygen at altitude  Pressurisation and depressurisation in planes occurs suddenly which can cause air filled spaces (e.g. pneumothorax, bulla) to expand rapidly Boiling pressure of volatiles falls

Answer 108

Two atoms share one or more outer shell electrons The negatively charged electrons are attracted to both nuclei simultaneously and this overcomes the repulsion which would otherwise exist between two nuclei, thereby forming a strong bond Occurs between non-metals

Answer 109

An outer electron is transferred from one atom to another The electron-accepting atom becomes negatively charged (anion) whilst the other becomes positive (cation) resulting in an electrostatic attraction between them Occurs between metals and non-metals

Answer 110

Energy required to change one unit of mass from liquid to gas (e.g. water boiling)

Answer 111

Energy required to transform matter from one state to another

Answer 112

Energy required to change one unit of mass from solid to liquid (e.g. when ice melts)

Answer 113

Determines the energy needed to raised 1 kg of the substance by a temperature of 1 degree

Answer 114

Q = cmΔT Q: energy required c: specific heat capacity m: mass ΔT: temperature change

Answer 115

4.18 J/g/C

Answer 116

When the water starts becoming a vapour (changing phase), it is absorbing energy (latent heat of vaporisation) and the temperature does not rise

Answer 117

Pressure and temperature where all three states can coexist

Answer 118

Minimum pressure required to liquefy the gas at the critical temperature

Answer 119

Any substance in the gas phase at a temperature lower than its critical temperature This means that vapours can be condensed into a liquid or to a solid by increasing the pressure without reducing the temperature

Answer 120

Solid: A state of matter with a fixed shape and volume, where particles are tightly packed and vibrate in place. Liquid: A state of matter with a fixed volume but no fixed shape, allowing it to flow while particles move more freely than in a solid. Gas: A state of matter with no fixed shape or volume, where particles move rapidly and spread out to fill any container.

Answer 121

CONSTANT VELOCITY: objects move in a straight line at constant speed or remain stationary unless a force acts upon the object

Answer 122

Acceleration of a body is proportional to the force applied and inversely proportional to the mass of the object F = m x a

Answer 123

Force applied to an object per unit area P = F/A

Answer 124

There is a linear relationship between the force applied and the extension of a spring within the elastic limits for that spring F = -kx F: force k: spring constant x: extension

Answer 125

The degree of stiffness or springiness The higher the spring constant the more difficult it is for the spring to extend The amount of displacement from equilibrium can be positive (extension) or negative (compression) - the negative sign, therefore, indicates that the spring exerts a force in the opposite direction to the displacement

Answer 126

Temperature at which the saturated vapour pressure is equal to atmospheric pressure NOTE: At boiling point, further heat does NOT increase the temperature but provides the latent heat of vaporisation which makes gas molecules evaporate from the liquid phase

Answer 127

Atmospheric pressure pushes down on the liquid, preventing vaporisation. When the liquid's saturated vapour pressure matches the atmospheric pressure, the gas molecules inside the liquid can form stable bubbles without being crushed by external pressure. These bubbles rise and escape, leading to boiling. NOTE: this is why the boiling point is lower at higher altitudes

Answer 128

Pressure exerted by the vapour phase of a substance when in equilibrium with the liquid phase (i.e. molecules entering liquid phase are equal to molecules leaving it)

Answer 129

It will shift the equilibrium favouring the movement of molecules out of the liquid phase which increases the initial rate of vaporisation but indirectly leads to a lowering of the temperature, a fall in the saturated vapour pressure and, ultimately, a lower vaporisation rate

Answer 130

A higher SVP means that the agent will more readily vaporise NOTE: a standard temperature must be set when comparing SVP

Answer 131

Boiling Point: 23 SVP at 20 degrees: 89 kPa

Answer 132

Boiling Point: 59 SVP at 20 degrees: 21 kPa

Answer 133

Boiling Point: 49 SVP at 20 degrees: 32 kPa

Answer 134

Boiling Point: 50 SVP at 20 degrees: 33 kPa

Answer 135

Boiling Point: 57 SVP at 20 degrees: 23.3 kPa

Answer 136

Boiling Point: -88 SVP at 20 degrees: 5200

Answer 137

At room temperature, it mainly exists in the vapour phase Tec 6 heats desflurane to 39 degrees and injects it directly into the fresh gas flow Given desflurane's tendency to vaporise, using a standard vaporiser would require a very high fresh gas flow and its high latent heat of vaporisation would lead to cooling and inconsistent vaporisation

Answer 138

High alveolar ventilation = faster onset because more rapid increase in alveolar partial pressure High FRC = slower onset because of dilution of agent S High cardiac output = slower onset because of more rapid removal from the alveoli (alveolar partial pressure cannot build fast)

Answer 139

Halothane: 2.3 Isoflurane: 1.4 Sevoflurane: 0.65 Nitrous Oxide: 0.47 Desflurane: 0.45 NOTE: water solubility decreases as molecular weight decreases

Answer 140

The lower the blood: gas partition coefficient the faster the onset of action because the gas is better able to achieve high alveolar partial pressures as it does not transfer into the blood as readily

Answer 141

The minimum alveolar concentration of an anaesthetic agent that prevents movement in response to a standard skin incision in standard conditions in 50% of subjects when breathing 100% oxygen in the absence of other analgesic or anaesthetic agents NOTE: inversely related to potency (smaller MAC means more potent)

Answer 142

Nitrous Oxide: 104 Desflurane: 6.6 Sevoflurane: 2 Isoflurane: 1.1 Halothane: 0.75

Answer 143

Potentiate GABA-A and glycine receptor, and may inhibit NMDA receptors

Answer 144

MAC increases with oil: gas partition coefficient

Answer 145

Young age Chronic alcohol consumption Hyperthermia Hyperthyroidism Cocaine and amphetamine use

Answer 146

Neonates and elderly Acute alcohol intoxication Hypothermia Hypothyroidism Other sedatives Pregnancy

Answer 147

Liquid at room temperature Stable at room temperature and in light Non-flammable Inert in contact with metal, rubber and soda lime Inexpensive Environmentally safe Low latent heat of vaporisation High saturated vapour pressure

Answer 148

Pleasant smell No respiratory irritation Low blood: gas partition coefficient (fast onset/offset) Potent (high oil: gas partition coefficient so low MAC) Minimal metabolism Excretion via the lungs Cardiovascular stability Analgesic properties Non-epileptogenic No increase in intracranial pressure

Answer 149

Cerebral vasodilation (resulting in raised ICP) Excitatory phenomena (agitation/delirium - most common with sevoflurane)

Answer 150

Reduced alveolar ventilation (due to reduced tidal volume and only slight increase in respiratory rate) Bronchodilation (sevoflurane and isoflurane)

Answer 151

Decreased MAP (usually by decreasing SVR though halothane reduces cardiac output) Sevoflurane can prolong QTc NOTE: desflurane and sevoflurane cause an increase in HR

Answer 152

CYP450 pathways produce a toxic metabolite called trifluoroacetic acid which led to some patients going into acute fulminant hepatitis NOTE: most other volatile agents are excreted unchanged by the lungs

Answer 153

Rare autosomal dominant (chromosome 19) condition that can be triggered by volatile agents and suxamethonium Incidence of 1 in 10,000

Answer 154

Muscle rigidity Tachycardia Rising ETCO2 Rising oxygen requirement Hyperpyrexia Metabolic and respiratory acidosis

Answer 155

Triggering agents (volatiles or suxamethonium) causes uncontrolled release of free calcium from the sarcoplasmic reticulum due to a mutation in the ryanodine receptor of the sarcoplasmic reticulum

Answer 156

Consider using regional anaesthesia Avoid suxamethonium and volatiles Use TIVA Use a clean machine (no volatiles used by machine beforehand) Have dantrolene to hand Monitor temperature and ETCO2 closely

Answer 157

A measure of a fluid's resistance to flow.

Answer 158

Constant viscosity regardless of flow rate NOTE: non-Newtonian fluids can become more or less viscous with increasing flow rate

Answer 159

Hydrogen bonds between water molecules on the surface of a liquid are stronger than those in the middle as there are fewer surrounding molecules This pulls neighbouring molecules as close to each other as possible (causing the bubble shape)

Answer 160

The larger the radius of the vessel, the greater the wall tension required to withstand a given internal fluid pressure

Answer 161

Sphere: ΔP = 2T/R Cylinder: ΔP = T/R NOTE: wall tension and surface tension are measured in force per unit length (N/m)

Answer 162

Initially, it looks like a cylinder and the increase in radius leads to increasing wall tension in a vicious cycle If it bulges towards a more cylindrical shape, the tension will decrease because the wall tension of a sphere is half that of a cylinder for the same difference in pressure and radius.

Answer 163

ΔP = 2T/R Smaller alveoli have a higher pressure for a given surface tension. This means that smaller alveoli are harder to inflate and would empty into larger alveoli. Surfactant reduces surface tension and is present in greater concentrations in smaller alveoli.

Answer 164

Product of the force applied and the distance the object is moved Work = Force x Distance

Answer 165

Capacity for doing work

Answer 166

Rate at which energy is being done (or the rate of energy transfer) Power = Work Done/Time Taken

Answer 167

The amount of energy required to exert a force of one newton through a distance of one metre A calorie is another unit for energy and is approximately 4.2 J

Answer 168

Watt 1 watt = 1 joule per second

Answer 169

Work Done = Force x Distance Force = Pressure x Area Work Done = Pressure x Area x Distance Volume = Area x Distance Work Done = Pressure x Volume

Answer 170

Energy is lost due to airway resistance At end inspiration and end expiration, the pressure between the lungs and ventilator will temporarily equilibrate because there is no air flow meaning that there can be no resistance

Answer 171

Elastic hysteresis - different volumes for identical pressures during inspiration and expiration This occurs because lung tissue resists stretching during inspiration and recoils more readily during expiration Surfactant dilutes during inspiration leading to increasing surface tension

Answer 172

Change of volume with respect to pressure (a measure of ease of expansion) C = ΔV/ΔP Measured in metres per Newton

Answer 173

Elastance is the reciprocal of compliance

Answer 174

Age Emphysema

Answer 175

Your lungs need to be compliant enough to expand relatively easily during inspiration They also need to be elastic enough to deflate during expiration without requiring too much work from the expiratory muscles

Answer 176

The work of one inspiration is around 0.36 J NOTE: for 15 breaths/min Power = 0.36 x 15/60 = 0.09 J/s = 90 mW As the respiratory muscles are only 90% efficient, the power required for resting breathing is around 900 mW The total metabolic rate of a subject at rest is 80-90 W so respiratory power is about 1% of energy consumed by the body

Answer 177

Rapid breathing causes higher flow rates resulting in more turbulence Turbulent flow (as per the relationship described above) requires more power than laminar flow for a given flow rate resulting in higher energy consumption by the respiratory muscles The oxygen demands of the hyperactive respiratory muscles can exceed the supply of oxygen resulting in hypoxia

Answer 178

At rest, the mechanical output power of the heart is 1.3 W Efficiency of the Heart 10% of energy supplied to the heart is converted into mechanical energy 90% is converted to heat This means the heart requires 13 W of power to function at rest

Answer 179

A supraglottic airway device used for ventilation during general anesthesia, designed to seal the upper airway and facilitate breathing The COBRA airway has a ramp which helps to guide tracheal tubes towards the larynx.

Answer 180

Unidirectional valves are between the patient and the reservoir bag on both inspiratory and expiratory limb. Fresh gas flow introduced between soda lime and the inspiratory valve. APL valve between expiratory valve and soda lime. The ventilator is typically located between the unidirectional valve in the expiratory limb and the soda lime

Answer 181

Gastric Acid: Parietal Cells Gastrin: G-Cells Pepsinogen: Chief Cells Somatostatin: D-Cells

Answer 182

Rate of change in the plasma concentration per unit time.

Answer 183

Time taken for the plasma concentration to reach zero, had it continued at its initial rate. This is also the time for the plasma concentration to reach 1/e of its original value, which is roughly 37%.

Answer 184

t1/2 = 0.693 x Vd/Cl t1/2 = 0.693/k t1/2 = 0.693 x time constant

Answer 185

20-30 cm H2O

Answer 186

Thiopentone is buffered at a pH of 10.5 at which point the water-soluble enol form is favoured At physiological pH, it becomes a more lipid soluble keto form which can cross the blood-brain barrier

Answer 187

A long inlet port into the vaporising chamber ensures that the bypass channel is not contaminated by retrograde flow (creates increased resistance to backflow) Downstream flow restrictors maintain vaporiser at a pressure greater than at the gas outlet. Downstream pressure relief valves act to prevent back pressure being transmitted to the ventilator. Anti-spill valves prevent contamination of the breathing circuit. Wicks and baffles are used to ensure gas leaving the vaporisation chamber is fully saturated with vapour.

Answer 188

A supramaximal stimulus of 50mA is used in peripheral nerve stimulators. This is 25-50% higher than that needed to produce a maximal response which ensures all motor fibres depolarise simultaneously and eliminates variation due to impedance and position of electrodes.

Answer 189

Sweat glands NOTE: the rest uses noradrenaline

Answer 190

Advantages: no sampling tube, reduced chance of obstruction, no lag time, no pollution, no effect due to changes in water vapour pressure. Disadvantages: sensor windows clog with secretions, bulky, increased risk of patient cross-contamination.

Answer 191

Advantages: easy to connect, no problem with sterilisation, can be used in awake patients, easy to use in unusual patient position e.g. prone, light weight, robust. Disadvantages: lag time, possible sampling tube obstruction, water vapour pressure can change ETCO2 concentrations, sampled gas vented to atmosphere or returned to circle system, moisture trap required to dry gas, pressure drop along sampling tube affects ETCO2 concentrations.

Answer 192

A mainstream analyser would add minimal dead space and be able to rapidly display changes in carbon dioxide with a high respiratory rate and small tidal volume. A rapid response time is desired, and this is less possible with side stream capnography.

Answer 193

It makes it impossible to deliver an oxygen concentration below 25% E.g. when nitrous oxide is turned up to 9 L/min, the oxygen flow rate will increase to 3 L/min to achieve a concentration of 25%

Answer 194

Digoxin Spironolactone Isoniazid Cimetidine

Answer 195

Coherent bundle (to transmit image) Non-coherent/illumination bundle (to transmit light) NOTE: a working channel surrounded by a flexible steel braid, angulation wires and a protective sheath

Answer 196

The coherent sheath can consist of as many as 10’000 fibres of diameter 5-20 μm.

Answer 197

2,6-diisopropylphenol

Answer 198

Dermatome: anterior aspect of thigh Myotome: hip flexion

Answer 199

Low penetration rate Effective bidirectionally Small internal volume (minimise dead space) Minimal resistance to gas flow Effective when wet or dry Disposable Cheap Transparent and lightweight

Answer 200

1/Rtot = 1/R1 + 1/R2 + 1/R3 + … 1/Rn, where n is the number of parallel branches.

Answer 201

Loading dose (mg) = concentration (mg/ml) x volume of distribution (ml)

Answer 202

90-95% calcium hydroxide. 2-5% sodium hydroxide. Silica and zeolite – varying amounts. Indicator dye NOTE: pH is 13.5 with a moisture content of 14-19%. Calcium carbonate is formed during the series of reactions between carbon dioxide and the constituents of soda lime.

Answer 203

Pressure and temperature are directly proportional

Answer 204

Volume and temperature are directly proportional

Answer 205

Product of pressure and volume is constant (k=PV). Therefore, P1V1 = P2V2 in a closed system.

Answer 206

Describes how the amount of gas dissolved in a liquid is proportional to its partial pressure above said liquid.

Answer 207

Describes how the rate of a diffusion of a substance is inversely proportional to its molecular weight.

Answer 208

ECG SpO2 NIBP a Capnography (if airway device in place)

Answer 209

Protein Binding 98%

Answer 210

Protein Binding 80%

Answer 211

Protein Binding 25%

Answer 212

Protein Binding 75%

Answer 213

Non-competitive NMDA antagonist

Answer 214

150 mL NOTE: total volume of CSF produced per day is 450 mL

Answer 215

5 second tetanic stimulus (50 Hz) followed by a 3 second pause and then 20 stimuli at a rate of 1 Hz. During the period of stimulation, pre-synaptic receptors are activated which leads to the synthesis and mobilisation of additional acetylcholine. This explains why twitches appear following tetanic stimulation, yet did not appear with the conventional train of four. NOTE: used for deep neuromuscular block

Answer 216

Decrease in the amplitude of an oscillation as a result of energy loss in a system due to frictional or resistive forces. The damping coefficient gives a measure of how quickly an oscillating system will come to rest at a new value.

Answer 217

250 ml/min to meet basal oxygen consumption

Answer 218

Highly lipid soluble (600 x morphine) meaning that it enters and accumulates in tissues This gives it a high context-sensitive half-time meaning that a timely wake up is impractical.

Answer 219

Inhibits nitric oxide induced cGMP activity resulting in vasoconstriction

Answer 220

The amount of charge that passes a given point, per second, when 1 ampere of current is flowing.

Answer 221

Children: C2/C3 Adults: C5/C6

Answer 222

Ensures that only one vaporiser % control dial may be turned on at any time through the use of interlocking extension rods

Answer 223

Hepatic artery Portal vein Branch of biliary tree

Answer 224

Hepatic portal vein 60% flow 40% oxygen NOTE: common hepatic artery is a branch of the coeliac trunk

Answer 225

Reduced protein concentration in CSF limits buffering capacity allowing changes in pH to occur This affects central chemoreceptors which controls ventilation

Answer 226

Levetiracetam (30-60 mg/kg over 5 minutes, maximum 3g) Phenytoin (20 mg/kg by slow IV infusion over 20 minutes with ECG monitoring) Phenobarbital (20 mg/kg IV over 5 minutes)

Answer 227

680 L Pressure of 137 bar

Answer 228

Dibucaine number Patient's plasma is added to a mixture of benzylcholine Emitted light is measured Dibucaine (inhibits plasma cholinesterase if cholinesterase is normal) is then added Dibucaine reduces the emission of light if pseudocholinesterase is normal Normal reduction in light emission with dibucaine is 80% NOTE: with other subtypes of pseudocholinesterase, the dibucaine number is lower because there is less inhibition of pseudocholinesterase by dibucaine

Answer 229

Cricothyroid muscle Innervated by the external laryngeal nerve (which is a branch of the superior laryngeal nerve, which is a branch of the vagus nerve)

Answer 230

Resistance describes the opposition to flow of direct current Reactance is used when the current is alternating Impedance (Z) is the sum of resistive and reactive components NOTE: all are measured in ohms

Answer 231

If two thermodynamic systems are in equilibrium with a third then they are also in equilibrium with each other

Answer 232

Energy can neither be created or destroyed only converted from one form to another

Answer 233

Entropy (i.e. a measure of unavailable energy) tends to increase with time.

Answer 234

As a system approaches absolute zero (-273.15ºc) all processes cease and entropy approaches a minimum

Answer 235

Partial pressure at which aerobic metabolism is no longer possible. This is normally around 0.3 kPa

Answer 236

Cells are unable to utilise oxygen despite an adequate supply This leads to reduced cellular consumption and venous oxygen saturations may be elevated

Answer 237

Allows compensation for wide variations in thoracic impedance by electronically adjusting waveform magnitude and duration Lower peak current delivered Less energy required for defibrillation Improved safety profile NOTE: biphasic means that current flows in one direction before reversing

Answer 238

1: sodium deoxycholate haemolyses erythrocytes releasing Hb 2: sodium nitrite converts Hb to MetHb which then reacts with sodium azide to give azidemethaemoglobin 3: absorbance is measured at two wavelengths (570 nm and 880 nm). Degree of absorbance is relative to Hb concentration so estimate is generated 4: after each reading, photometer zeros itself and checks the intensity of the light source and photocell

Answer 239

Small, compact device used to measure tidal volume and minute volume of expiratory flow.

Answer 240

25 L of CO2

Answer 241

Class 1: a mains powered device enclosed within an earthed metal casing to ground any leakage current Class 2: double insulated electrical device, this mitigates the need for an earth wire Class 3: SELV (safety extra low voltage) of typically 24-50V. These devices may be battery powered or connected to mains via a transformer.

Answer 242

Type B: touches skin but does not penetrate (e.g. ECG) Type BF: part that touches the patient is electrically isolated from the rest of the device (e.g. thermometer) Type CF: for equipment that touches the heart or is inserted into the body (e.g. pacing wires)

Answer 243

This is a compensatory mechanism where the hepatic artery vasodilates in response to reduced portal venous flow Adenosine is secreted at a constant rate into the space of Mall (periportal space) via oxygen-independent mechanisms. Reduced portal blood flow leads to reduced clearance of adenosine and the accumulating adenosine has a direct vasodilatory effect on the hepatic artery.

Answer 244

Glycopeptide antibiotic Inhibit cell wall synthesis by binding to and interfering with the ongoing synthesis of peptidoglycan cell wall.

Answer 245

Muscle spindles are stretch transducers that maintain a constant muscle length despite a change in load. Golgi tendon organs are found in muscle tendons and function to limit tension generated within the muscle.

Answer 246

Where a resistor and capacitor are placed in series as a circuit. It acts as a low pass filter i.e. allows frequencies below a certain value to pass

Answer 247

(age/2) + 12

Answer 248

Tyrosine kinase linked receptor

Answer 249

Equal volumes of an ideal gas at standard temperature and pressure will contain an equal number of molecules, and that one mole of an ideal gas at standard temperature and pressure occupies 22.4 litres.

Answer 250

Prostaglandin analogue used in management of PPH It can precipitate bronchospasm

Answer 251

Potassium channel activator Activation of ATP-sensitive potassium channels within the walls of arterioles causes hyperpolarisation, which reduces intracellular calcium. In turn, this leads to arteriolar vasodilation and subsequent reduced blood pressure.

Answer 252

Previous cardiac arrest due to VF or unstable VT VT with structural heart disease Non-ischaemic dilated cardiomyopathy Severely impaired ejection fraction (< 35%) despite 3 months of optimal medical management

Answer 253

Skin Subcutaneous tissue Supraspinous ligament Interspinous ligament Ligamentum flavum Epidural space

Answer 254

L-tyrosine --> L-Dopa by tyrosine hydroxylase L-Dopa --> dopamine by dopa decarboxylase Dopamine --> noradrenaline by dopamine hydroxylase Noradrenaline --> adrenaline by PNMT (phenylethanolamine N-methyltransferase)

Answer 255

Anticholinergic effects – dry mouth, dry nose, blurred vision, constipation, urinary retention, sweating, increased body temperature. CNS effects – drowsiness, confusion, myoclonus, seizure, coma. Cardiovascular effects: tachycardia, arrhythmias, hypotension, transient hypertension, VT, VF and prolonged QT interval.

Answer 256

273.16 K, and sub-atmospheric pressure (611 Pa) NOTE: this is the point at which it exists in solid, liquid and gas phases at equilibrium

Answer 257

pKa: 7.7 Protein Binding: 55% Solubility: 50 times the solubility of procaine

Answer 258

Phrenic nerve palsy The phrenic nerve runs on the anterior aspect of the anterior scalene

Answer 259

Aminoglycosides (the higher the concentration, the greater the bactericidal action) NOTE: beta-lactams are time-dependent

Answer 260

1) Inflation in diastole – higher early diastolic blood pressure (via reduction of apparent internal volume of aorta) leading to improved end organ perfusion, particularly the heart. 2) Deflation as late as possible – results in reduced end diastolic pressure in the aorta, reducing afterload and myocardial O2 demand.

Answer 261

Intercostal space > caudal > epidural > brachial plexus > femoral > subcutaneous

Answer 262

Area under velocity time graph x aortic cross-section x heart rate NOTE: area under the velocity-time graph is referred to as stroke distance

Answer 263

Anode: Silver Cathode: Platinum

Answer 264

Radiofrequency (RF) energy is applied perpendicularly to the applied magnetic field at the Larmor frequency which rotates the net magnetisation of hydrogen ions in tissue. When the RF energy is switched off, net magnetisation returns to equilibrium and energy is lost to surrounding tissue. This is relaxation.

Answer 265

Frequency of the current (at 50-60 Hz the sensitivity of biological tissues to unwanted electrical stimulus is maximal)

Answer 266

900-1200 dynes.sec.cm-5

Answer 267

1-4 hours NOTE: clearance of 6-10 mL/kg/min

Answer 268

Alpha intercalated cells in the collecting duct

Answer 269

Momentum of the vanes can cause an overestimation

Answer 270

Minimise dead space and prevent rebreathing. NOTE: tidal volume should be at least 5 times the internal filter volume

Answer 271

Cori cycle

Answer 272

Aspirin – continue. Clopidogrel and prasugrel – 7 days. Ticagrelor – 5 days. Tirofiban – 8 hours. Abciximab – 2 days.

Answer 273

More potent Leads to less histamine release Similar duration of action

Answer 274

Clindamycin, gentamicin and tetracycline inhibit protein synthesis. Clindamycin and erythromycin inhibit the 50S ribosomal subunit. Gentamicin and tetracycline inhibit the 30S ribosomal subunit.

Answer 275

Mapleson A (Magill) FGF is near the reservoir bag and APL valve is near the patient

Answer 276

Mapleson D FGF near the patient APL valve near the bag

Answer 277

Carbon dioxide maximally absorbs IR radiation at 4.3 μm and nitrous oxide at 4.5 μm, however these spectra can overlap leading to an overestimation of end-tidal CO2 measured by IR spectroscopy.

Answer 278

Nausea/vomiting, a coarse tremor, oligouria, ataxia, hyper-reflexia, nystagmus, and convulsions/coma.

Answer 279

Ratio of dead space volume (Vd) to tidal volume (Vt) is equal to: (PaCO2 - PeCO2)/PaCO2 Pa = arterial Pe = expired

Answer 280

M1: brain and secretory glands M2: heart, affects pacemaker M3: smooth muscle of bronchioles and arterioles, also found in the bladder M4: CNS M5: regulate dopamine release in the CNS

Answer 281

Radiation (loss via infrared radiation): 40% Convection (loss to air currents): 30% Evaporation (loss of heat energy due to vaporisation): 20% Respiratory losses: 5-10% Conduction (loss to direct transfer to surfaces): 5%

Answer 282

Ethyl violet – white to purple. Phenolphthalein – pink/red to white. Clayton yellow – pink/red to yellow/cream. Ethyl orange – orange to yellow. Mimosa Z – red to white.

Answer 283

Sensory: medial 1.5 digits Motor: majority of small muscles in the hand except LOAF (median nerve)

Answer 284

Patients admitted for elective surgery should have a BP below 160/100 mm Hg in primary care On the day of surgery, you can proceed if blood pressure is below 180/110 mm Hg

Answer 285

Ketamine: phencyclidine Propofol: phenol Thiopentone: barbituric acid Etomidate: imidazole

Answer 286

pKa 8.7 Relative lipid solubility: 30 x morphine Relative potency: 0.1 x morphine Vd: 4 L/kg Protein binding: 60%

Answer 287

Aminosteroids: rocuronium and vecuronium

Answer 288

Desflurane has a low boiling point, and therefore fluctuations in temperature lead to significant fluctuations in saturated vapour pressure (SVP), which unless accounted for, would lead to substantial variation in the concentration of desflurane to the patient. To avoid this, the Tec 6 vapouriser is heated to 39 degrees and therefore the delivery of desflurane is predictable.

Answer 289

Air is passed through a constriction leading to an increase in velocity and decrease in pressure (conservation of energy) as described by the Bernoulli effect. This reduction of pressure leads to entrainment of water via the Venturi effect.

Answer 290

Pentameric ligand gated ion channel 2 alpha, 1 beta, 1 delta, 1 epsilon NOTE: gamma instead of epsilon in foetus

Answer 291

Due to the increased parasympathetic tone in children compared to adults, they are prone to significant bradycardia under vagal stimulation

Answer 292

Usually 16G Huber tip with blunt leading edge and angled tip to allow catheter to be passed Lee's lines to allow measurement of depth Macintosh wings to stabilise the needle Stylet introducer to prevent coring of tissue A loss of resistance syringe is used when performing an epidural, but is not a feature of the Tuohy needle.

Answer 293

At steady state - input = output Infusion Rate = Elimination Rate Elimination Rate = Clearance (L/min) x Steady State Conc Infusion Rate/Clearance = Steady State Conc

Answer 294

Prolonged R Time: anticoagulant or clotting factor deficiency Low Max Amplitude + Long K Time: weak clot suggestive ineffective platelet or fibrinogen action Short Lysis Time + High CL30: overactivity of fibrinolytic system

Answer 295

0.22 micron mesh to prevent the passage of bacteria, viruses and foreign bodies into the epidural space.

Answer 296

Absolute: mass of water vapour in a given volume of gas at a given temperature and pressure (g/m3) Relative: ratio of actual mass of water vapour compared to maximum amount of water vapour the gas could contain at the same temp and pressure

Answer 297

NF is proportional to √(r²/clρ), where r = radius of the tubing, c = compliance, l = length and ρ = density of the fluid

Answer 298

Has a natural frequency 10x higher than the fundamental frequency (sine wave 1-2 Hz, corresponds to heart rate 60-120 bpm), Frequency range of 0.5 to 40 Hz to include the first 10 harmonics of the heart rate

Answer 299

A resonant sine wave will be superimposed on the pressure wave. This will raise the systolic blood pressure, reduce the diastolic blood pressure, but should have no effect on the mean arterial pressure.

Answer 300

As temperature increases, resistance through a thin piece of metal increases linearly Slow response time and fragile Needs Wheatstone bridge to increase sensitivity

Answer 301

Consists of a semiconductor for which there is a non-linear relationship between resistance and temperature Cheap and small so can be used for invasive monitors (e.g. pulmonary artery flotation catheter) Respond quickly to changes but can have calibration error

Answer 302

A material whose electrical conductivity is is between an conductor and an insulator Conductivity can be controlled by adding impurities (doping), applying electrical fields or increasing the temperature

Answer 303

In a semiconductor, electrons exist in two energy bands: - Valence Band: electrons are bound tightly to atoms and can't move freely - Conduction Band: electrons are free to move enabling conduction At room temperature, most electrons are in the valence band, however, applying energy (e.g. heat) enables the electrons to jump across the band gap to the conduction band so it can conduct electricity

Answer 304

Thermocouples rely on the Seebeck (thermoelectric) effect. At the junction of two dissimilar metals, a voltage will be produced in proportion to the temperature difference between two such junctions. Typically copper and constantan are the metals used. The response is nearly linear and passes through the origin as a temperature difference of zero produces zero output voltage. Multiple thermocouples in series produce a thermopile which will increase sensitivity.

Answer 305

Oculomotor Nerve Trochlear Nerve Ophthalmic Nerve (Nasociliary, Lacrimal, Frontal) Abducens Nerve Superior Ophthalmic Vein Branch of inferior ophthalmic vein

Answer 306

PHASE 1 Oxidation Reduction Hydrolysis Dealkylation Deamination

Answer 307

All twitches present < 70% occupancy 1 twitch lost = 70% 2 twitches lost = 80% 3 twitches lost = 90% All twitches lost = 95-100%

Answer 308

Q = (πr4ΔP)/8nl where r = radius, ΔP = pressure gradient, n = viscosity, l = length, Q = flow rate.

Answer 309

Q = (πr4ΔP)/8nl This is analogous to Ohm’s law (V = IR –> I = V/R), where voltage is represented by the pressure gradient, current is represented by the flow rate, and resistance is given by 8nl/πr4.

Answer 310

At the bottom (low-flow), the space between the bobbin and wall is narrow. Gas flow is laminar and dependent on viscosity. At the top (high flows) the space between the bobbin and wall is wider. Gas flow is more turbulent and dependent on density. The pressure difference across the bobbin is constant at all points in the rotameter.

Answer 311

At the bottom of a rotameter, the gap between the bobbin and tube is narrow, so flow is laminar and mainly affected by viscosity — the internal friction of the gas. At the top, the gap is wider, flow becomes turbulent, and is mainly influenced by density, which affects the inertia and turbulence of the gas.

Answer 312

They bind more readily to inactivated or open sodium channels and so affect nerves with a rapid firing rate (e.g. sensory nerves) compared to motor nerves

Answer 313

Enflurane and Isoflurane

Answer 314

Dihydrocodeine

Answer 315

1: Bolus Dose at 1.5 ml/kg over 1 min 2: Infusion at 15 mL/kg/hour 3: Second Bolus + Increase Infusion to 30 mL/kg/hour (if cardiovascular instability not sorted)

Answer 316

History of ischaemic heart disease Active GI bleeding Active GI ulceration Cerebrovascular disease CABG IBD Heart failure Peripheral vascular disease

Answer 317

Low PaO2 High PaCO2 Low pH High [H+]

Answer 318

NOT Absorbed: magnesium and aluminium Absorbed: sodium bicarbonate and sodium citrate NOTE: aluminium causes constipation whereas magnesium causes diarrhoea

Answer 319

30 mL in circuit draw-over variable bypass vaporiser NOT temperature compensated Small, cheap, lightweight Variable output

Answer 320

Variable bypass draw-over vaporiser NOT actively temperature compensated but incorporates an ethylene glycol heat sink Any anaesthetic agent can be used by changing a removable scale on the dial

Answer 321

State Entropy: calculated from low frequency range waves Response Entropy: calculated from high frequency waves including EMG activity from frontalis muscle As a patient wakes, the difference between SE and RE increases due to diminishing effect of drugs affecting the central nervous system and the increased contribution of EMG values from the frontalis muscle. RE increases more quickly than SE.

Answer 322

12 ml/kg i.e. 840 ml for a 70kg adult.

Answer 323

Derived from medial cord of brachial plexus which is comprised of nerve roots C8-T1

Answer 324

Lumbricals 1+2 Opponens Pollicis Abductor Pollicis Brevis Flexor Pollicis Brevis

Answer 325

Requires a blood sample to be taken and spectrophotometric techniques are then performed that are able to provide information regarding oxyhaemoglobin, deoxyhaemoglobin, methaemoglobin and carboxyhaemoglobin

Answer 326

Increase the boiling point by 0.51ºc (ebullioscopic constant) Decrease the freezing point by 1.86ºc (cryoscopic constant) Increase the osmotic pressure.

Answer 327

Boiling occurs when vapour pressure = atmospheric pressure Solute particles get in the way of water molecules escaping into the gas phase, thereby lowering the vapour pressure for a given temperature This means you have to heat the solution to a higher temperature to boil

Answer 328

Freezing happens when water molecules arrange into a solid crystal structure Solute particles disrupt this orderly arrangement, making it harder for water to freeze. Therefore, you must lower the temperature further to freeze the solution → freezing point goes down.

Answer 329

Median, ulnar, radial and musculocutaneous nerves at the level of the axillary artery The musculocutaneous nerve lies separately between corocobrachialis and biceps brachii, and needs significant redirection of the needle to anaesthetise it.

Answer 330

Class Ia – blocks fast Na+ channels in cardiac myocytes and prolong refractory period e.g. procainamide, quinidine, disopyramide. Class Ib – blocks fast Na+ channels in cardiac myocytes and shortens refractory period e.g. lidocaine, phenytoin, mexiletine. Class Ic – blocks fast Na+ channels in cardiac myocytes and no effect on refractory period e.g. fleicanide, propafenone. Class II – β adrenoreceptor blockade e.g. atenolol, propranolol, esmolol. Class III – K+ channel blockade e.g. amiodarone, sotalol. Class IV – Ca++ channel blockade e.g. verapamil, diltiazem.

Answer 331

Pressure generator, time-cycled, minute volume divider. Two knobs are able to change from controlled to manual and to adjust the inspiratory time. The inflation pressure is adjusted by sliding a weight to a different position on top of the main bellows. Fresh gas flow drives the ventilator. In inspiration a small bellows receives FGF and the main bellows deliver their content to the patient. During expiration the small bellows delivers their content to the main bellows until a predetermined tidal volume is reached.

Answer 332

Sevoflurane (200 g/mol)

Answer 333

Centrally acting ganglion blocking drug Functions centrally to reduce blood pressure by competitive antagonist of nicotinic acetylcholine receptors in the parasympathetic and sympathetic ganglia

Answer 334

Physical properties that are dependent on number of dissolved particles rather than the identity of the solute. Includes elevation of boiling point, reduction of freezing point, reduction in vapour pressure and change in osmotic pressure. NOTE: this is how an osmometer works

Answer 335

Clear Fluid: 20 drops Blood: 15 Drops

Answer 336

Method of continuous, non-invasive blood pressure measurement. A small cuff placed around the finger is inflated or deflated by a controller system to keep the blood volume in the finger constant (as measured by plethysmography). The applied pressure to keep blood volume constant is comparative to arterial blood pressure.

Answer 337

If it was added earlier to the mixture, a crack in an adjacent flowmeter will mean that the oxygen follows the path of least resistance and escapes via the cracked flowmeter rather than to the patient - thereby delivering a hypoxic mixture

Answer 338

15% of cardiac output at rest Which is around 750ml/min

Answer 339

Supraventricular only: digoxin, verapamil, adenosine. Ventricular only: lidocaine, phenytoin. Both: amiodarone, beta-blockers, disopyramide, procainamide, fleicanide.

Answer 340

Avoid the risk of inducing ventricular fibrillation Risk is highest around 50-60Hz, which is the frequency of mains electricity

Answer 341

Chloride - 115-125 mmol/L

Answer 342

VENOUS: 10% dissolved, 60% bicarbonate, 30% carbamino ARTERIAL: 5% dissolved, 90% bicarbonate, 5% carbamino

Answer 343

Potency: lipid solubility (more lipid soluble, more potent) Duration of Action: protein binding (higher protein binding, longer duration) Speed of Onset: pKa (lower pKa, faster speed of onset)

Answer 344

36.5 degrees

Answer 345

95% protein boud Vd of 2-70 L/kg Half-life of 20-100 days

Answer 346

The pump used to generate vacuum should be able to generate a negative pressure of -400 mmHg or 53 kPa. The minimum requirement of suction is to generate a vacuum of 500 mmHg in 10 seconds with a displacement of air of 25 L/min as such it is considered a high pressure, low flow system.

Answer 347

PCT: carbonic anhydrase inhibitors Ascending limb loop of Henle: osmotic and loop diuretics Early DCT: thiazide diuretics DCT: potassium sparing diuretics Late DCT and Collecting Duct: aldosterone antagonists

Answer 348

Flow is proportional to the radius squared Flow is proportional to the square root of the pressure gradient Flow is inversely proportional to the length and density of the fluid

Answer 349

Carotid artery Internal jugular vein Vagus nerve

Answer 350

184.5 NOTE: it is a structural isomer of isoflurane

Answer 351

Initially a high output of 1-3 mA is chosen and the needle advanced slowly towards the nerve until contraction is noted. The output is then reduced until maximal stimulation is achieved with minimum output from the nerve stimulator. Typically 0.3-0.5 mA suggests the needle tip is touching or very close to the nerve. If contraction occurs at ≤ 0.2mA it suggests that the needle tip is intraneural and should be withdrawn.

Answer 352

Heat energy lost When a ferromagnetic material is placed in a magnetic field, it will become magnetised (O to A) When the field is removed, it remains weakly magnetised (A to B) Area within the loop is heat loss

Answer 353

PV = nRT P = pressure (Pa) V = volume of gas (m³) n = number of moles (mole) R = ideal gas constant (8.31 J/K/mol) T = temperature (Kelvin)

Answer 354

Rate of Diffusion is proportional to: Area x Concentration Gradient/Thickness

Answer 355

EMF describes the driving voltage of a battery Voltage is known as potential difference and represents the difference in electric potential between two points in a circuit

Answer 356

Process of rendering an object free from all pathogenic organisms excluding bacterial spores

Answer 357

Method of disinfection that uses temperatures of 70 °c for 30 minutes

Answer 358

At least hourly

Answer 359

CPP = DBP – LVEDP

Answer 360

Low dose (< 5 µg/kg/min): increased renal blood flow through agonism of D1 and D2 Moderate dose (5-10): beta adrenoceptor agonist with positive inotropy High dose (> 15): alpha agonist causing vasoconstriction

Answer 361

Prilocaine

Answer 362

Increased sodium and calcium permeability, which favours a more rapid depolarisation towards threshold potential during phase 4

Answer 363

Mapleson D

Answer 364

Absorption of energy by an oscillating or precessing system. Precession refers to the movement of nuclei around a magnetic field.

Answer 365

All block fast Na channels in cardiac myocytes Class Ia – PROLONGS the refractory period e.g. procainamide, quinidine, disopyramide. Class Ib – SHORTENS the refractory period e.g. lidocaine, phenytoin, mexiletine. Class Ic – NO EFFECT on the refractory period e.g. fleicanide, propafenone.

Answer 366

Oesophageal barrier pressure = lower oesophageal sphincter pressure – intragastric pressure

Answer 367

Needle contacts the anterior tubercle of C6 (Chassaignac's tubercle) NOTE: the stellate ganglion lies at C7 formed by the fusion of the inferior cervical and T1 ganglia

Answer 368

Between the second and third tracheal cartilage rings

Answer 369

Measurement of total magnetic field passing through a given area NOTE: when divided by the size of the area, it is called magnetic flux density

Answer 370

Magnetic Flux: Weber (Wb) Magnetic Flux Density: 1 Tesla = 10,000 Gauss NOTE: 1 Tesla = 1 Wb/m²

Answer 371

The point at which inspired air reaches 37ºc and a relative humidity of 100%. This is normally achieved a few centimeters distal to the carina.

Answer 372

Stewart-Hamilton equation

Answer 373

Normal saline is pressurised to 300 mmHg and runs at a rate of 2-4 ml/hr via a flushing device. This prevents clot formation, keeping the arterial line patent and reducing damping.

Answer 374

Removes a specific frequency from a signal

Answer 375

Ergometrine can cause coronary vasospasm and hypertension and therefore is contraindicated in pre-eclampsia.

Answer 376

It neutralises upstream circuit noise (i.e. rejects signals common to both inputs)

Answer 377

Obstruction of the common gas outlet can cause rising pressure within the circuit that can transmit gases back into the anaesthetic machine causing damage and contamination This valve opens at 35-40 kPa of pressure

Answer 378

Atlantoaxial instability Atlas = C1 Axis = C2

Answer 379

The absorption spectra of carboxyhaemoglobin and oxyhaemoglobin are similar at 660 nm. This leads to an overestimation via spectrophotometric methods of SpO2.

Answer 380

The fluid requirement in the first 24 hours is equal to 4ml x weight (kg) x %burns Half of this is given in the first 8 hours, and the remainder in the remaining 16 hours.

Answer 381

Air: 4-5 hours 100% Oxygen: 1 hour

Answer 382

4-10 mg/kg

Answer 383

Autosomal recessive mutation on chromosome 3

Answer 384

Originates as a continuation of the sigmoid sinus Exits the jugular foramen Runs through the neck to subclavian vein

Answer 385

Probenecid is a renal tubular blocking agent. Penicillins are normally excreted via tubular secretion in the nephron. Blocking this secretion increases plasma levels approximately 2-4 times.

Answer 386

Z = d/fa Where Z = impedance, d = distance between the plates, f = frequency of current and a = area of plates.

Answer 387

Flow of 35-75 L/min Pressure of 4 bar Bypassing the flowmeters and vaporiser

Answer 388

Yellow – breathing filters for viruses, bacteria and particulate matter. Blue – heat and moisture exchange. Green – heat and moisture exchange and filter.

Answer 389

Calculates the electrical potential for an INDIVIDUAL ion, and thus allows for the estimation of how each ion affects the membrane potential.

Answer 390

Membrane potential = RT/ZF x ln (extracellular concentration/intracellular concentration) where R = universal gas constant T = temperature (kelvin) Z = Valency F = Faraday’s constant ln = natural logarithm

Answer 391

Phenoxybenzamine Non-selective irreversible alpha antagonist (new receptors must be synthesised to overcome the effect)

Answer 392

Mu-1 = analgesic + physical dependance Mu-2 = respiratory depression, reduced peristalsis, euphoria and meiosis

Answer 393

Brain Leads to analgesia, antidepressant effect and physical dependence

Answer 394

Brain and spinal cord Leads to spinal analgesia, sedation and miosis

Answer 395

Brain and spinal cord Leads to anxiety, depression, appetite modulation, and is thought to be involved in tolerance

Answer 396

Apixaban, rivaroxaban and edoxaban

Answer 397

The theory that mechanical work may be transferred to heat energy and heat energy to work, the magnitude of one being proportional to the other. This is the principle used in the generation of electricity in coal power stations.

Answer 398

PVR = 80 x (Mean pulmonary artery pressure – Left atrial pressure)/Cardiac output.

Answer 399

1 – neonates up to 5 kg, cuff volume 4 ml. 1.5 – infants 5-10 kg, cuff volume 7 ml. 2 – children 10-20 kg, cuff volume 10 ml. 2.5 – children 20-30 kg, cuff volume 14 ml. 3 – adults 30-50 kg, cuff volume 20 ml. 4 – adults 50-70 kg, cuff volume 30 ml. 5 – adults 70-100 kg, cuff volume 40 ml. 6 – adults over 100 kg, cuff volume 50 ml.

Answer 400

Uncoupling of opioid receptors from their G-protein, which underpins the decreased receptor sensitivity that is observed

Answer 401

pCO2 in blood Consists of a measuring electrode (silver/silver chloride) and reference electrode (mercury/mercury chloride) surrounded by film of NaHCO3 and permeable teflon membrane allowing CO2 to diffuse from sample to solution In solution, CO2 is converted to H+ via CA H+ interact with buffer around reference electrode leading to potential difference between two electrodes which leads to voltage that correlates with pCO2

Answer 402

Carotid bodies have high flow so get all of their oxygen from dissolved O2 - therefore mainly responds to changes in pO2 (ventilatory) Aortic bodies have lower flow and respond to changes in both oxygen tension and oxygen content

Answer 403

13700 kPa (137 bar) + 101 kPa (≈1 bar) = 13800 kPa NOTE: once filled, if taking up Mount Everest, the absolute pressure does not change because it is sealed

Answer 404

Stimulation causes increased adenylate cyclase activity Increased cAMP Activation of PKA Activation of myosin light chain phosphatase Smooth muscle relaxation

FRCA Main Flashcards

(479 cards)