Key equations and laws Flashcards
Combine the Beer and Lambert law into one definition
◦ The measured absorbance for a single compound is directly proportional to the concentration fo the compound and the length of the light path through the sample
beer’s law
‣ Beers law deals the the concentration measurement - absorption or attenutation of light is proportional to concentration of the substance
Lamberts law
‣ Lamberts law deals with identification fo the pulsatile signal - ababsorption or attentuation is proportional to the distance the light has ti travel
Oxygen saturation equations (not fractional saturations)
Draw the equation for calculating HCO3 concentration
Joule thomson efffect
A gas changes temperature when it moves from higher pressure to lower pressure, and for most gasses they cool e.g. bike tire pumped = hot
Viscocity
Fluids resistance to flow
Newtonian fluid
Constant viscocity regardless of flow rate
Non newtonian fluid
Viscocity changes with flow rate
Surface tension
The result of attraction between moleciles across the surface of a liquid - as the molecules on the surface have reduced molecules to interact with compared to those deeper they form stronger bonds leaving the surface with the smallest possibel surface area for a given volume
Wall tension
Vessel wall that is an elasticated solid and the attraction between molecules across the surface of the solid (similar ot surface tension)
Laplace’s law
The larger the radius of the vessel the greater the wall tension required to withstand a given internal fluid pressure
What is Laplace’s equation for a spherical bubble
What is Laplace’s law for a cylinder
Work equation
Force applied x distance moved
Amount of energy applied to a system
ie. holding a shopping bag is not work because there is no distance moved
Energy definition
Capacity to do work
Measured in joules - the energy required to exert a force of one newton through a distance of one metre
Power equation
Work done/ time taken
Units watt (1 J/sec)
The rate at which work is done or the rate of transfer of energy
What is pressure by definiition?
Force divided by area
Define compliance
The change of volume with respect to pressure and a measure of the ease of expansion
Units metres/newton
Compliance equation
Change in volume / change in pressure
What is elastance
The opposite, or reciprocal of compliance
Chnage in pressure/change in volume
How to calculate the energy required to move a volume througha tube?
E = pressure x volume
How are power and flow related? (laminar)
If the pressure difference remains constant when E = P x V then
power = pressure x the rate of change of volume (or flow rate)
therefore since pressure is directly related to flow in laminar conditions
Power directly related to flow squared for laminar flow
In turbulent flow how is this related to pressure?
Power is directly proportional to flow ^ 3
Explain pressure as a concept then define it
Gas in a box contains millions of molecules zipping around in all directions bouncing off one antoher and off the walls, the combined effect of these collisions with the walls of the box create pressure
Pressure = force per unit of area
Define flow
the movement of gas through a tube or system
Volume / time
What is the conservation of flow?
Flow remains constant although if cross sectional area changes the velocity will also change to account for flow being conserved therefore
Q = A1 x V1 = A2 x V2
What is laminar flow
Orderly movement of a fluid that complies with a model in which parallel layers have different velocities relative to one another
What is the velocity profile within a blood vessel
Parabolic - fastest at the middle, decreasingly fast either side
Flow occurs when…
There is a difference in pressure between two points
What effect does resistance have on flow?
If resistance is increased a greater driving pressure is needed to maintain a fixed flow rate, BUT it will not prevent flow
Describe the relationship between flow and resistance
Flow = change in pressure or driving pressure / flow resistance of the tube
What is Ohms law
Current = potential difference or voltage/ resistance
Flow has what relationship to pressure
Directly proportional
What is resistance defined by
Hagen Poiseuelle law
What are the assumptions of the hagen Poiseuille equation
liquid is incompressible
Viscosity is stable
Flow is laminar
Hagen poiseuelle equation
What equation is this
Hagen Poiseulle equation
What is the equation for low solved for the Hagen POisuelle equation
Define turbulent flow
Movement of a fluid in which small scale currrents in the fluid move in irregular patterns while the overall flow is one directoin
What is Reynolds number?
A number used to predict whether turbulent or laminar flow would occur in a given system. It has no units
Reynaulds number equation
Reynaulds number equation
What is the unit for density
kg/m cubed
What is the unit for viscocity
newton x seconds/ metres cubed
What are the cutoffs for the Reynolds number
<2000 predominantly laminar
>4000 turbulen flow predominant
2000-4000 transitional with eddies and vortices
What effect does viscocity have on laminar flow?
Increasing viscocity reduces the reynolds number proportionally and therefore makes flow more laminar
What effect does density have on laminar flow
the more dense something is the hgiher the reynolds number and the more turbulent the flow will be
What is the COanda effect
fluid or gas stream will hug the convex contour when directed at a tangent to the surface
Explain the coanda effect
As has already been seen with the Venturi effect, when the water leaves the tap at speed, the flowing fluid entrains fluid (in this case air) into the stream of flow. When there is an obstruction, such as the spoon’s surface, this entrainment is dramatically reduced on the spoon side. There is a drop in pressure on the spoon side of the jet and this causes a deflection in the flow towards the spoon.
Define an ideal gas
An ideal gas has 3 conditions
- the molecules are assumed to be so far apart there is no attraction between them
- volume of the molecules themselves is negligible
- moleculears in random motion obeying newtons laws of motion
Avogadros law
equal volumes of gasses at the same temperature and pressure contain the same number of molecules
What is a mole
one mole is 6.02 x 10 ^ 23 atoms/molecules such that it represents a standard amount - it is derived from 12g of carbon
What is molar mass
the mass of 6.02 x 10 ^23 partiicles of the substance measured in g / mol
Daltons law
for a gas the total pressure is simply all the partial pressures added up
Pt = P1 + P2 + P3
How would you calculate the partial pressure of oxygen change between dry air at standard H20 pressures, and alveolar gas pressures?
Boyles law
the volume of gas is inversely proportional to its pressure at a fixed temperature
Describe the relationship between pressure and volume in gasses and draw a diagram to represent the same
What is Charle’s law
at a given pressure the temperature is directly proportional to the volume of the gas - linera relationship
Guy-Lussac’s law
the pressure of a gas is directly proportional to its temperature within a fixed volume
Draw a curve representing Guy Lussacs law
Benedict Roth spirometer - collecting gas passing through an airway opening. It is an expandable compartment consistent of a moveable statically counterbalanced rigid chamber or bell, a stationary base and a dynamic seal between them. The bell can move up and down freely so pressure inside it is close to atmospheric, the seal is often water but dry seals have been used. Changes in internal volume are proportional to displacement
What is the combined gas law
What is the univertsal gas equation
Define diffusion
Passive movemen tof a substance from an area of high concentration to that of lower concentration
Ficks law of diffusion
Add the diffusion constant to Fick’s law of diffusion
What factors lead to a faster rate of diffusion
Large surface area
Large concentration gradient
Small thickness ot diffuse through
High solubility in medium diffusing thorugh
Low molecular weight or density
Grahams law of diffusion
rate at which gasses diffuse are inversely proportional to the square root of their densities
Why is Grahams law of diffusion based on density? How can it be rearranged for molecular mass?
When does solubility of a gas matter to diffusion rate?
When diffusion is moving from a gas through a membrane into a liquid the rate of diffusion is proportional to soliubility of the gas
What two factors does the diffusion constant involve
What is osmotic pressure
the pressure required to stop the flow from one side of a semi permeable membrane to another
Henry’s law
at a cosntant temperature the amount of gas that dissolves in a given type and volume of liquid is directly proportional to the partial pressure of that gas in equilibrium wiht that liquid
Define partition coefficient
the ratio of conentrations of a substance in two phases of a mixture of two immiscible solvents
Blood gas coefficient- what does this mean and reflect?
The ratio fo the concentration of an anaesthetic agent in blood to that in the same volume of gas in contact with that blood at equilibrium
This reflects the solubility of the gas in blood
Oil/gas coefficeint - what does it reflect and why does it matter
the ratio of the concentration of an anaeshtetic agent in oil (adipose) to that in the same volume of gas in contact with that oil at equilibrium
this reflects the solubility of the gas in adipose/brain tissues in comparison to blood - it will reflect how easily it crosses the BBB. If the oil:blood coefficient is >1 (or blood:oil <1) then the concentration or amount of gas dissolved in adipose tissue will be higher than that in blood
What characteristics are ideal in an inhaled agent?
Low solubility in blood
If highly soluble it transfers quickly from the lungs, but has a lower partial pressure in blood once dissolved therefore staying in solution rather than passing to brian tissue therefore taking longer to work, longer to exit the body.
Raoults law
the fall in vapour pressure of a solvent is proportional to the molar concentration of the solute
Mathematics of the Beer-Lambert law
Define current
the flow of an electric charge - this can be electrons or flow of charged particles e.g. ions
Wire resistance is proportional to?
Increases with length
Decreases with cross sectoinal area increases
Conduct better at lower temperatures
What is voltage
an informal term for electrical potential difference - this is the amount of energy required to move a unit of charge between two points.
1 volt is if 1 coulomb were to move through a potential differenceof 1 volt it would require 1 joule of energy ; or the electrical potential required to move 1 ampere through 1 ohm resistor
Ohms law
the potential difference between two points is the product of the resitance and the current flowing
Draw the Ohm;s law pyramid
Kirchoffs first law
current in = current out
Or the sum of all currents going in and out is zero
Kirchoffs second law
closed loop netowrk the total voltage around the loop is equal tot he sum of all voltage drops within the same loop - this is also equal to zero (as the battery produces the voltage gain)
What is power in electircal terms
the rate of electrical energy usage/transferrance per second measured in watts - 1 watt is 1 joule transfered per second
Power in electrical terms =
Voltage x current
voltage squared / resistance
Current squared x resistance
Resistance in series calculation
the total resistance is greater than the largest reisstors
Resistors in parallel equation
the total resisstance is smaller than the smallest resistor
Impedence
the resistance to thef low of an alternating current - instead of resistance using in DC
Calculations for power remain the same
What is capacitance
a measure of the charge a device can hold measured in Farads
The cpacitance = charge stored in coulombs/ potential difference in volts
Energy stored = 1/2 capacitance x voltage squared
The charge Q in a capacitor is given by what equation
Q = C x Vc
C is caacitance
Vc is appplied voltage
How do you calculate distance in the pulse echo principle
2d = v x t
What is the equation for natural frequency
What is the Windkessel effect and how does it apply to arterial lines?
◦ The reflected wave in the upper aorta is more prominent however they merge as you progress down the vascular tree, amplification increases as the vascular tree becomes less compliant and more and more reflection waves accumulate —> windkessel effect as the stored energy
In the simple flow model of dye calculation of cardiac output what equation is used to calculate the rate of dye removal from a tank?
rate of dye removal = liquid flow x dye concentration
In the simple flow model of dye dilution cardiac output calculation what is flow rate equal to
amount of dye added / area under the graph
What is cardiac output equal to in the circulatory flow model diagram dye dilution technique
Amount of dye injected / area under graph
Describe the Fick principle in words where oxygen is the substrate
- Total uptake of oxygen by the body is equal to the product of the cardiac output and the arterial-venous oygen content difference
FICK EQUATION
- CO = VO2/ Ca - Cv
◦ Blood flow to an organ = rate of uptake or excretion of a substance / arterio-venous concentration difference
How is VO2 measured in the direct Fick method
- VO2 measurement
◦ patients breaths through a spirometer containing a known volume of 100% oxygen and a CO2 absorbed, after a minute the volume of O2 remaining in the spirometer allows the calculation of O2 uptake
What is the Stewart Hamilton equation
How is the Fick principle used indirectly?
- Measured of cardiac outptu using the Fick equation but substituting estimated values for the some of the measured variables
- Estimations
◦ Uses age/weight and sex based nomogram to estimate VO2 - especially inaccurate if morbidly obese, paralysed, thyrotoxicosis, burns, sepsis, hypothermia where metabolically not normal patients. Additionally pulmonary O2 consumption can be dramatically increased in pnumonia overestimating cardiac output
◦ Mixed venous blood assumed on the basis of normal vlues or estimated from CVC samplws; or from end tidal
◦ Arterial oxygen content can be estimated from pulse oximetry
What is the equation for cardiac output when an indicator dye is used?
What is the equationf or cardiac output when temperature change is used?
How is stroke volume derived from pulse contour analysis? How is it calibrated? What is the calibration factor?
What is the doppler equation for measuring velocity? How does velocity relate to flow?
◦ V = F (d)c / 2 F(O) cos (theta)
‣ V = velocity of blood in descending aorta
‣ F(d)c = change in frequency of the reflected ultrasound x speed of ultrasound in tissue
‣ F(O) = transmitted ultrasound freqeuncy
◦ Blood flow is then determined by velocity x cross sectional area of the descending aorta (thoracic) estimated from patients height and weight
What is the equation for SVR
BSA calculation
What is cardiac index? How is it calculated? What are its normal values?
Cardiac output / BSA
COmparison between cardiac output of patients of a different size
Normal 2.5 - 4 L/min/metre squared
Define stroke volume
the volume of blood pumped out fo the L of the heart during each systolic contraction
How is stroke volume determined using cardiac measurement devices
cardiac output / HR –> i.e. average SV over 1 minute
SVI define? Normal values
CI / HR x 1000
Indexed for body size
33 - 47 mL/metre squared / beat
SVR calculation and normal values
80 x (MAP - CVP) / cardiac output
Normal 800 - 1200 dynes-sec/cm ^ -5
SVRI - Define?
SVR indxed to body size
80 x (MAP - CVP) / CI
Normal vlue 1970 - 2390 dynes-sec/cm^-5 x metres squared
Pulmonary vascular resistance calculation
80 x (MPAP - PAWP) / cardiac output
Normal value <250 dynes - sec / cm^ -5
Hagen Poiseuille law
Turbulent flow is proportional to? and inversely proportional to?
Reynolds number
What affects flow
Define absorption
movement of drug from site of administration into central compartment
Define afterload
impedance to ventricular ejection/ventricular wall tension/stress to eject stroke volume (as per
Laplace’s law)
What does drug affinity refer to
attraction of a drug to a receptor
Define anaphylactoid
clinical indistinguishable from anaphylaxis, cause by complement/indirect histamine release
from mast cell. Dose dependent
Anode
negative electrode (donates electrons)
Avogadros hypothesis
equal volume of gases at same temp and pressure contains equal number of molecules.
(One mole of gas = 6 x1023 molecules occupies 22.4L at STP)
Bainbridge reflex
increased intravascular volume in normovolemic pts causes reflex tachycardia independent
of increased blood pressure
Baricity
density of liquid in relation with CSF
Basal metabolic rater
minimal metabolic rate, amount of energy liberated per unit time to maintain basal
cellular function (J/s or W) at defined conditions (rest, room temperature, 12hr post-meal)
Define base excess
blood sample equilibrated to PaCO2 40mmHg (titrated with acid/base until pH is normal)
beer lamert law
intensity of light passing through a solution decreases exponentially with concentration
(Beers) and distance (Lambert)
I Trans = I Incident.e-A A=absorption (A= distance x extinction coefficient x concentration)
Define bernoulli effect
decreased pressure in tube as velocity of flow increases
Define bioavailability
proportion of drug which reaches systemic circulation FB=FA x (1-HER)
Blood volume distribution in veins
65%
55% if supine
% of blood in arteries at any one time
13%
% of blood in capillaries at baseline
5%
% of blood in arterioles at baseline
2%
% of blood centrally aat baseline?
15%
25% when supine (the only source from which veinous redistribution goes to)
Blood gas partition coefficient
Blood Gas Partition Coefficient – ratio of anaesthetic agent in equilibrium at 37oC contain same partial pressure
between the 2 phases
Bohr effect
Bohr Effect – the variable affinity of Hb to O2 in the variable concentration of H+ and PCO2
Bohr equation
amount of physiological dead space in lung Vd/Vt=PaCO2 – PeCO2/PaCO2
Bourdon gauage
coiled metal where a rise in temperature cause the tube to uncoil
Define buffer
substance which to receive or donate H+ in solution preventing the change in pH
Calorie
heat energy necessary to raise the temp of 1g of H2O by 1oC
% of blood flow to heart? % of VO2?
5% - 70% LCA
10% of VO2
Renal % of blood flow? % of VO2?
25% of blood flow
90% of which goes to cortex, 5% medulla
7% of VO2
Brain blood flow? O2 extraction?
15% of CO
65% grey matter
20% VO2
L:iver blood flow? VO2?
25-30% CO
1/3 hepatic artery
25% VO2
Skeletal muscle cardiac output? VO2
20% for both
What is bathmotropy?
Bathmotropy: excitability, ease of myocyte depolarise by stimulus (slope phase 0)
Cardaic properties?
Automaticity: ability to initiate own beat
Dromotropy: speed of conduction via AV node
Inotropy: contractility
Lusitropy: active relaxation
Bathmotropy: excitability, ease of myocyte depolarise by stimulus (slope phase 0)
Irritability: size of stimulus required to depolarise cell in context to resting phase
(difference between threshold and RMP
Cathode
Cathode – positive electrode which receives electron
Define chiral
Chiral – asymmetric in which the structure and its mirror image is not superimposable
Clearance
volume of plasma clear of a drug per unit time
Closing capacity
the lung volume at which dependant airways begin to close (CV+RV)
Colligative properties
properties of a solution that depends only on the number of freely moving particles and
not on the nature of those particles
i.e. – Osmotic pressure, Boiling point elevation, Freezing point depression, Vapour pressure depression
Colloid
substances unable to pass semipermeable membrane (suspension of solutes)
Compliance
change in volume over change in pressure. (Normal 200ml/cmH2O) affected by lung elastic
recoil/lung volume/disease/pulmonary blood volume
Static compliance
patient inspiring sequentially to different known volume, relaxing against a closed
glottis (time for equilibrium to occur) =VT/(Pplateau-PEEP)
Dyanamic compliance
against normal breathing, volume and pressure at point of no flow =VT/(Ppeak-
PEEP)
Specific compliance
compliance divided by FRC (Normal: 0.05/cmH2O)
Context sensitive half time
time for plasma concentration of a drug to decrease by 50% after stopping the
infusion designed to maintain steady state
Dependant on: Duration of infusion/Distribution/Clearance
Define contractility
Contractility – myocardial performance factor that is independent of heart rate and loading factors
Define convection
mode of heat transfer via bulk movement of liquid or gas in contact
Coronary perfusion pressure
Diastolic BP-LVEDP
Counter current exchange
provides circulatory perfusion to LOH and CD while maintaining hypertonic
interstitial medullary gradient
Counter current multiplier
concentrating effect of the medullary interstitium multiplied by the counter
current flow of tubular fluid within LOH
Critical pressure
pressure required to liquefy a vapour at its critical temperature
Critical temperaturw
temperature above which substance cannot be liquefied however much pressure applied
Critical velocity
velocity above which laminar flow become turbulent
Major cross match
part of blood compatibility testing (to prevent haemolysis post transfusion)
Major – patient serum + donors’ RBC
Saline agglutination: reconfirms ABO grouping
Indirect Coombs: reconfirms presence of minor antibodies
Minor cross match
Minor – patient RBC + donors’ serum
Define crystalloid
substances able to pass semipermeable membrane
Daltons law
the pressure exerted by a mixture of gas = the sum of pressures of each individual gasses
Damping?
resistance to free oscillation
Under damping: overshoot common, system oscillates
Over damping: slow signal response with inability to respond to rapid change
Critical damping: point of overshoot is just avoided
Optimal damping: 64% critical damping, minimal overshoot and minimal response reduction
Under damping
resistance to free oscillation
Under damping: overshoot common, system oscillates
Over damping: slow signal response with inability to respond to rapid change
Critical damping: point of overshoot is just avoided
Optimal damping: 64% critical damping, minimal overshoot and minimal response reduction
Overdamping
resistance to free oscillation
Under damping: overshoot common, system oscillates
Over damping: slow signal response with inability to respond to rapid change
Critical damping: point of overshoot is just avoided
Optimal damping: 64% critical damping, minimal overshoot and minimal response reduction
Critical damping
resistance to free oscillation
Under damping: overshoot common, system oscillates
Over damping: slow signal response with inability to respond to rapid change
Critical damping: point of overshoot is just avoided
Optimal damping: 64% critical damping, minimal overshoot and minimal response reduction
Optimal damping
resistance to free oscillation
Under damping: overshoot common, system oscillates
Over damping: slow signal response with inability to respond to rapid change
Critical damping: point of overshoot is just avoided
Optimal damping: 64% critical damping, minimal overshoot and minimal response reduction
Dead space and its components
tidal volume that does not take part in ventilation
Physiological – alveolar + anatomical (Bohr’s equation)
Anatomical – volume of conducting airways (Fowler’s method)
Alveolar – volume beyond conducting airways that do not take part in ventilation (V/Q mismatch)
Decontamination
process which removes/destroys contaminants
Cleaning
physical removal of foreign material
Disinfection
process of eliminating most pathogenic organism except spores
Disinfectant
chemical used to disinfect non-living surfaces
Antiseptic
chemical used to disinfect living surfaces
Sterilisation
process of killing all microbes
Dependence
psychophysical requirement of continued supply of substance
Physical dependence: characterised by withdrawal symptoms after discontinuation of a drug or after
administration of an antagonist
Psychological dependence: a chronic state, characterised by the compulsive use of a substance resulting
in harm (physical, psychological or social) and continued use despite harm
What are 2 examples of desensitisation
Tachyphylaxis: acute decrease in response to repeated dose of a drug
Tolerance: chronic decrease in response to repeated dose of a drug
Tachyphylaxis
Tachyphylaxis: acute decrease in response to repeated dose of a drug
Tolerance: chronic decrease in response to repeated dose of a drug
Tolerance
Tachyphylaxis: acute decrease in response to repeated dose of a drug
Tolerance: chronic decrease in response to repeated dose of a drug
Dibucaine number
% inhibition of plasma cholinesterase activity after addition of dibucaine (quality of plasma
cholinesterase)
Diffusion
movement of substances down its concentration gradient (obeys Fick’s law of diffusion)
Diffusion hypoxia
reduced alveolar O2 concentration from dilution by N20 leaving the blood stream and
entering the alveoli
Doppler effect
frequency shift effect where the frequency and wavelength of a signal changes in relation to
changes in soundwaves when source moves in relation to stationary observer
ECG
graphical presentation of surface recording of electrical activity of heart
EEG
graphical presentation of surface recording of electrical activity of neural cells (specifically the postsynaptic
potentials of subcortical neurons perpendicular to electrode)
Efficacy
maximal effect attainable by drug
Elimination
amount of drug excreted by the body
Emulsion
pair of immiscible fluid (droplet disperse throughout another) inherently unstable and tend to coalesce
so need emulsifier to improve solubility
Enzyme
biological catalyst
Eutectic
mixture in which the physicochemical properties are different to that of its individual component
Evaporation
mode of heat transfer via vaporisation of H2O from surface
Fick prinicple
blood flow to an organ equals rate of substrate uptake/removal divided by A-V concentration
difference for that substance
Laminar flow
Laminar: organised, parabolic, flow proportional to pressure
Turbulent: disorganised, eddies, flow2 proportional to pressure
Turbulent flow
Laminar: organised, parabolic, flow proportional to pressure
Turbulent: disorganised, eddies, flow2 proportional to pressure
Fouriers analysis
construction of complex waveform from multiple basic sine waves of different frequency
Slowest component: fundamental frequency
Faster component: harmonics
Define FRC
lung volume at the end of normal tidal expiration, equilibrium point where the
chest wall expand outwards and the lung collapsing
Boyles law
Boyle’s Law (1st gas law): at a constant temperature, volume of gas is inversely proportional with
absolute pressure (PV=k, T constant)
Charles law
Charles’ Law (2nd gas law): at a constant pressure, volume of gas is directly proportional to absolute
temperature (V~T, P constant
Amontons law
Amonton’s Law (3rd gas law): at a constant volume, pressure is directly proportional to temperature (P~T,
V constant)
Daltons law
Dalton’s Law: the pressure exerted by a mixture of gas = the sum of pressures of each individual gasses
Henry’s law
Henry’s Law: at given temperature, amount of a given gas dissolved in a given liquid is directly
proportional to the partial pressure of the gas in equilibrium with the liquid
Poynting effect: formation of a gaseous mixture of O2 and N2O when O2 is bubbled
Gibbs Donnan
distribution of charged diffusible ions in the presence of non-diffusible ions across a
semi-permeable membrane
Responsible for: Oncotic pressure
Cell volume stability (double Donnan)
RMP
Define haldane effect
Deoxygenated Hb has increased ability to carry CO2
Define half life
the time necessary for drug concentration to decrease by 50%
Haemostasis
physiological process of maintaining blood in a fluid clot free-state in normal vessel or producing
rapid localised coagulation at site of injured vessel
Evaporation
Evaporation – via vaporisation of water (0.56kcal energy for 1g H2O
Heat capacity
amount of heat required to raise the temperature of a given object by 1 Kelvin
Hormones
chemical messenger produced by ductless glands and transported to act on distant target sites via
circulation in trace amount
Peptides
Amines
Steriods
Peptide examples
Peptides – glucagon, insulin, PTH, ACTH, LH, FSH
Amines – derived from tyramine (T3/T4, NAdr, Adr) or tryptophan (5HT, Melatonin)
Steroids – synthesised from cholesterol (androgens, sex hormones, vit D)
Amines examples
Peptides – glucagon, insulin, PTH, ACTH, LH, FSH
Amines – derived from tyramine (T3/T4, NAdr, Adr) or tryptophan (5HT, Melatonin)
Steroids – synthesised from cholesterol (androgens, sex hormones, vit D)
Steriods examples
Peptides – glucagon, insulin, PTH, ACTH, LH, FSH
Amines – derived from tyramine (T3/T4, NAdr, Adr) or tryptophan (5HT, Melatonin)
Steroids – synthesised from cholesterol (androgens, sex hormones, vit D)
Huffners number
1.34 is amount of oxygen which can combine with 1g of Hb when fully saturated
Absolute humidity
Absolute: mass of H2O in a given volume of air (mg/L)
Relative: ratio of mass of H2O vapour in a given volume of air to the mass required to saturate
the volume at the same temperature
Relative humidity
Absolute: mass of H2O in a given volume of air (mg/L)
Relative: ratio of mass of H2O vapour in a given volume of air to the mass required to saturate
the volume at the same temperature
Interthreshold range
range of body temperature where ANS is not triggered
Innate immunity components
Innate immunity: Humoral – complement system
Cellular – macrophages, neutrophils, barrier
Acquired immunity components
Acquired immunity: Humoral – B-cell, immunoglobulins
Cellular – T-cell mediated
Define isomer
compounds with the same molecular weight but different structural or spatial arrangement
Types of isomers
Structural
Stereoisomers
Structural isomer types
Structural isomers: positional/tautomers
Types of stereoisomers
Stereoisomers: enantiomers/diastereomers/geometric isomers
Latent heat
heat required to convert 1kg of a substance from one phase to another at a given temperature
Manometers measure?
Manometer – decide to measure pressure of gas
MAP =
Mean Arterial Pressure (MAP) – the product of CO x SVR
=DBP+1/3(SBP-DBP)
Monro Kellie doctrine
Monro-Kellie Doctrine – the cranium is a rigid closed vault. Total volume is fixed, any increase in intracranial
content will result in large increase in pressure (blood/brain/CSF)
Muscle spindle
Muscle Spindle – intrafusal muscle fibre (10 in a capsule) which are concerned with proprioception
Define osmotic pressure
Osmotic Pressure – minimum pressure necessary to prevent the movement of solvent
Osmosis
Osmosis – diffusion of solvent (H2O) down its concentration gradient
Osmolality
Osmolality – number of osmole per kg of solute non dependant on temperature
Osmolarity
Osmolality – number of osmole per kg of solute non dependant on temperature
Osmolarity
Osmolarity – number of osmole per litre of solvent dependant on temperature
p50
P50 – PO2 at which Hb is 50% saturated. Relates to Hb affinity
26.6 for HbA
pKa
pKa – negative log of acid dissociation constant (Ka), where Ka = (H+) (A-)/ (HA), buffering capacity of the buff
(pKa +/- 1 for closed system) or degree of ionisation (50% @pH=pKa)
Primary hyperalgesia
Primary hyperalgesia – peripheral sensitisation, stimulus at site produces more pain
Secondary hyperalgesia – central sensitisation, increased responsiveness in surrounding site
Secondary hyperalgesia
Primary hyperalgesia – peripheral sensitisation, stimulus at site produces more pain
Secondary hyperalgesia – central sensitisation, increased responsiveness in surrounding site
Allodynia
previously non-painful stimulus now painful
Wind up in the context of pain
central sensitisation to pain which impulse strengthens with repetitive stimulation (includes
long term potentiation)
Partition coefficient
ratio of concentration of substance in 2 phases in equilibrium (equal volume and pressure)
at stated temperature (normally 37oC), related to solubility of substances in different phases
BGPC (blood: gas) inversely proportional to speed of onset/offset
OGPC (oil: gas) proportional to potency and metabolism
TGPC (tissue: gas) proportional to tissue uptake/offset
Piezoelectric
ability to interconvert between mechanical energy and electrical energy
Post tetanic count
number of responses to 1Hz stimulation for 3 seconds after 5sec of 50Hz tetanus
PTC 8-10: first TOF
PTC 0: no buck or cough
potency
Potency – drug dose required to achieve certain response, related to receptor affinity (PD) and PK
Define preload
Isolated: initial fibre length prior to contraction = amount of stretch of ventricular muscle fibre at the end
of ventricular filling
Intact: compliance x transmural pressure (filling pressure – extrinsic pressure)
Pressure
force per unit area (Pascal or N/m2)
Gauge Pressure – pressure above/below atmospheric pressure
Absolute Pressure – gauge + atmospheric pressure
Reduction
removal of O2 or gaining e-
Residual volume
volume of gas in the lings at end of maximal expiration
Resonance
tendency at which system oscillates at greater amplitude at certain frequency
Respiratory quotient? How and why does it vary?
the ratio in steady state of volume of CO2 produced per volume of O2 consumed per
unit time (Carbohydrate: 1, Protein: 0.8, Fat: 0.7)
Reynolds number equation
Re = PʋD/η turbulent if Re >2000
Sarcomere
contractile unit of a myofibril separated on each ends by Z lines
Saturated vapour pressure
the pressure of a vapour which is in equilibrium with its liquid phase, indicator of
volatility
Second gas effect
uptake of large volume of primary gas accelerates the rate of rise of second gas given
concurrently
Shunt
blood entering the arterial system without passing through ventilated lung
Causes of shunt
Physiological Shunt:
True Shunt: Thebesian veins & bronchial arteries
Others: V/Q mismatch (V/Q ratio <1)
Pathological Shunt: patent foramen ovale, atelectasis, pneumonia
Macro and micro shock
Macroshock: current >10mA or current passes through the trunk/heart in electrocution
Microshock: low current passes through cardiac muscles sufficient to cause cardiac arrhythmias
Sleep
physiological decrease level of consciousness and awareness but easily rousable
Specific heat capacity
amount of heat required to raise the temperature of 1kg of a substance by 1 Kelvin
Starlings law of the heart
Starling’s Law of the Heart – the force of contraction is dependent on the end-diastolic muscle fibre length
Temperature
thermal state of a substance which determines whether it will give heat to another substance or
receive heat (unit SI – Kelvin)
Therapeutic index
ratio of drug dose causing adverse effect over dose causing desirable effect (LD50/ED50)
Thermoneutral zone
range of ambient temperature at which VO2 (metabolic rate) is at minimum
(thermoregulation can occur via changes to skin blood flow alone)
Adult: 25-30oC
Term: 32-34oC
Prem: 34-36oC
Time constant
the time it would take for an exponential process to be completed should the initial rate of
change remains the same 1τ: 63% completed
Tonicity
effective osmolality of a solution
Tubuloglomerular feedback
renal autoregulation to ensure constant GFR (via detection of Na/Cl by macula
densa)
Ultrafiltration
process which water is removed from blood during various forms of dialysis. Water passing
through a semi-permeable membrane as a result of positive pressure on the blood side of membrane
Valsalva manouvre
forced expiration against a closed glottis (standardised, forced expiration against a closed
glottis for 10-15secs at 40mmHg)
Vapour
substance in gaseous phase below its critical temperature
Vapour pressure
pressure exerted by molecules in vapour phase
Viscocity
property of liquid which creates resistance/impendence to free flow, given by shear stress/shear rate
Vital capacity
maximum volume of gas that can be exhaled following maximum inspiration
Vitamin
organic substance, not produced in the body, small amount essential for life, for biochemical reactions
(non-energy substrate)
Volume of distribution
apparent volume in which a given amount of substance must be dispersed to give the
resultant plasma concentration
Wheatstone bridge
often incorporated as part of a transducer circuit to amplify signals, composed of a set of
four resistors in series, an electrical source and a galvanometer, with one of the resistors often part of a strain
gauge or resistance thermometer
Work of breathing
Force (N) x Distance (m) = Pressure x Volume
Elastic Resistance 60% (Surface Tension 70%; Elastic Tissue 30%)
Non Elastic Resistance 40%
Windkessel effect
hydraulic effect of large elastic arteries which converts the intermittent output of heart to a
steady flow through capillaries (maintain perfusion of organ during diastole when cardiac ejection cease)
