Definitions Flashcards
1
Q
Absorption
A
Absorption - rate & extent to which a drug leaves its site of administration.
The rate and extent of drug movement from the site of administration to the systemic circulation
2
Q
Acid
Arrhenius
Bronsted-Lowry
Lewis
A
Acid – proton donor or substance that increases [H+] of a solution
Arrhenius: a substance which is capable of producing hydrogen ions in an aqueous solution
Bronsted-Lowry: a substance which can donate a hydrogen ion to another substance
Donor = conjugate acid
Acceptor = conjugate base
Lewis: any compound that was a potential electron pair acceptor
3
Q
Additive effect
A
Additive effect - second drug, acting with the first, produces an effect equal to the algebraic sum of the effects of each drug when administered individually (1 + 1 = 2)
4
Q
Afterload
A
Afterload - load the heart is acting against during systole, gives rise to active tension in ventricular wall
- Isolated: force restricting muscle fibre shortening or weight/load that a contracting muscle must overcome prior to shortening.
- Intact: either the stress imposed on the ventricular wall during systole or the arterial impedance to ejection of the stroke volume.
5
Q
Agonist
A
Agonist - A drug that binds to a receptor of a cell and triggers a response by the cell. An agonist often mimics the action of a naturally occurring substance.
Full – able to evoke maximal biological response
Partial – can exert a submaximal response despite high doses
6
Q
Alkaloid
A
Alkaloid – nitrogen containing base of plant origin
7
Q
Antagonistic effect
A
Antagonistic effect - second drug, acting with the first, produces an effect less than the algebraic sum of the effects of each drug administered individually (1 + 1
8
Q
Baricity
A
Baricity – density of one solution compared to another
density (mass / volume) of liquid relative to CSF (CSF baricity = 1)
9
Q
Base
A
Base – proton acceptor or substance that decreases [H+] when added to a solution
10
Q
Bioavailability
A
Bioavailability – the fraction of administered dose which reaches the systemic circulation as intact drug (fraction absorbed x (1-ER)
The rate and extent to which a drug reaches its site of action (or plasma) from its site of administration
11
Q
Bioequivalence
Chemical
Biological
Therapeutic
A
Bioequivalence - refers to two formulations of that yield similar concentrations in blood and Tx’s.
Chemical: meets chemical and physical standards
Biological: yields same concentrations in blood and tissue
Therapeutic: provides equal therapeutic benefit
12
Q
Biophase
A
Biophase – the zone in which the drug comes into intimate contact with its molecular site of action
13
Q
Buffer
A
Buffer – solution containing substances that have the ability to minimize pH changes when an acid or base is added to it
A solution which has the ability to minimise changes in [H+] when an acid or base is added to it.
14
Q
Clearance
A
Clearance – volume completely cleared of a substance per unit time (note total body, organ specific)
- the volume of fluid from which a substance is completely removed per unit time (eg. via passage through an organ).
15
Q
Concentration effect
A
Concentration Effect – the effect of increasing Fi of agent accelerating the equilibrium of PA/PI, consisting of concentrating component and augmentation component.
The effect which the inspired concentration of the anaesthetic agent exerts on the speed with which that agent attains equilibrium
The higher the inspired concentrations, the more rapid the rise in alveolar concentration
16
Q
Context senstive half-time
A
Context sensitive half time – time required following cessation of an infusion designed to maintain a constant plasma concentration, of a given duration (the context) for plasma levels to fall by 50%.
17
Q
Dead space
A
Dead space – part of the tidal volume that does not participate in gas exchange
Physiological dead space is divided into alveolar and anatomical:
- Anatomical - the internal volume of the conducting airways or that part of the inspired TV which is expired unchanged.
- Alveolar - Part of inspired gas which passes through the anatomical dead space and enters the alveoli but is not effective in gas exchange given
Apparatus dead space is volume rebreathed from apparatus before fresh gas enters patient airway.
18
Q
Dependence
A
Dependence
Psychological – Need for a specific psychoactive substance either for its positive effects or to avoid negative psychological or physical effects associated with its withdrawal
Physical – a physiological state of adaptation to a specific psychoactive substance characterized by a withdrawal syndrome during abstinence, which may be relieved in part or in total by readministration of the substance
19
Q
Density
A
Density – weight in grams of 1mL of that solution at STP, mass per unit volume (see universal gas law for gasses)
20
Q
Drug
A
Drug - a chemical substance that produces an effect on a biological tissue.
21
Q
Effect site equilibration time
A
Effect site equilibration time – time taken for equilibration b/w [drug] in plasma and biophase following an IV bolus
22
Q
Elimination half time
A
Elimination half time – time taken for 50% fall in plasma conc during elimination phase – upper limit on how long it will take plasma conc. to fall (0.693 x Cl/VD)_
23
Q
Emulsion
A
Emulsion – stable suspension of small globules of 1 liquid in a 2nd liquid
24
Q
Emulsifier
A
Emulsifier – surface active agent that promotes the formation of an emotion
25
Eutetic mixture
Eutetic Mixture – a mixture of constituents at a ratio that produces the lowest temperature melting point
26
Half life
Half life - time required for elimination of 50% of drug from the body
Time necessary for drug concentration to fall by half whether by redistribution or elimination etc
27
Half time
Half time – time taken for plasma levels of drug to fall by 50% (0.693 x Cl/VD in single compartment model)_
28
Hepatic extraction ratio
Hepatic Extraction Ratio – proportion of drug irreversibly removed from each unit volume of blood during a single passage through the liver (0-1)
29
Hyperactivity
Hyperactivity - usual response achieved at lower than normal dosage (supersensitivity if denervated)
30
Hypersensitivity
Hypersensitivity - usually implies allergy to the drug
Describes an exaggerated or inappropriate immune response that cause tissue damage and even death of the host
Type I: antigen binds to mast cell IgE, resulting in degranulation (eg. Hay fever, anaphylaxis)
Type II: antibody-antigen reaction, resulting in complement activation and antibody-dependent cell-mediated cytotoxicity (eg. Transfusion reactions)
Type III: deposition of antigen-antibody complexes in the host tissue (eg. Serum sickness)
Type IV: (Delayed hypersensitivity) results from antigen presentation to T lymphocytes causing a release of cytokines. (eg. TB)
31
Hyporeactivitiy
Hyporeactivity - usual response achieved at larger than normal dosage
32
Idiosyncrasy
Idiosyncrasy - unusual effect (qualitative difference or extreme quantitative difference) of a drug, usually unrelated to dose, occurring in only a small percentage of patients.
33
Immunity
Immunity - decreased sensitivity as a result of Ab formation
34
Inotrope
Inotrope: drug affecting force of muscle contraction (usually used w/ respect to +ve inotropes). Many (though not all) sympathomimetics are useful as inotropes.
35
Local anaesthetic
Local Anaesthetic - drug producing reversible depression of nerve conduction when placed in close proximity to nerve fibres
Drugs that block, reversibly, the conduction of impulses in the peripheral or central nervous system when applied locally or regionally.
36
Metabolic rate
Metabolic rate – energy expended per unit time (basal equals 12 hours of fasting at rest)
37
MAC
Minimum Alveolar Concentration (MAC) – agent at 1 atm preventing gross purposeful movement to supramaximal stimulus in 50% of patients
Minimum alveolar concentration at one atmosphere of an agent that produces immobility in 50% of those subjects exposed to a noxious stimulus
Qualified clinically by: 100% O2, no premedconversionj to a partial pressure, as percentage of 1atm which then represents the tension of anaesthetic at the site of action in the brain; patient aged 25-35yrs
38
Minimum concentration
Minimum Concentration (Cm) – the minimum conc of LA necessary in vitro to block conduction of all nerve impulses in a given nerve w/n a reasonable time period (usu 10 – 15/60)
39
Mixed venous blood
Mixed venous blood – blood drawn from pulmonary artery, thus containing entire venous return from systemic circulation and attendant oxygen extraction and carbon dioxide addition
40
Mixture
Mixture – physical combination of 2 or more substances, each retaining its own properties
41
Nausea
Nausea – and unpleasant objective sensation referred to the pharynx and upper abdomen assoc with desire to vomit
Unpleasant subjective sensation referred to the pharynx and upper abdomen, associated with a desire to vomit.
42
Opiate
Opiate – drugs derived from opium
| strictly substances derived from Opium ie naturally occurring opioids.
43
Opioid
Opioid – all exogenous substances that bind specifically to any subtype of opioid receptor to produce some agonist effect
Opioid, endogenous – endorphins, dynorphins, enkephalins
44
Opium
Opium – dried powdered mixture of alkaloids from unripe seed capsules of Papaver sominiferum (opium poppy)
45
Pain
Pain - an unpleasant sensory and emotional experience associated with actual or potential tissue damage or described in terms of such damage
Physiological pain – operates as a protective system, warning of contact with potentially damaging stimuli. Different receptors (low threshold for innocuous stimuli, high threshold nociceptors) allow such differentiation.
Pathological pain – pain associated with tissue damage or damage to nervous system. Prolonged stimulus causes modification of threshold of nociceptors, hyperalgesia and allodynia.
Acute pain – pain of recent onset and probable limited duration; usually with causal and temporal relationship to injury or disease.
Chronic pain – (usu >3 months) commonly persisting beyond the time of healing of an injury and may not have a clearly identifiable cause.
unpleasant sensory and emotional experience associated with actual or potential tissue damage, or expressed in terms of such damage.
46
Partition coefficient
Partition coefficient – ratios of concentration of dissolved agents present between two phases at a given temperature at equilibrium (equal partial pressures)
Ratio of amount of gases in two phases, at equilibrium, at stated temperature
47
Pharmacogenetics
Pharmacogenetics – study of hereditary (genetic) factors in variability of drug response
48
Preload
Preload - load on the myocardial m’s just prior to the onset of cxn. & determines the end diastolic fibre length prior to onset of contraction.
PRELOAD
- Isolated: load imposed on muscle before contraction, obtained by hanging a small weight at the end of resting muscle.
- Intact: ventricular wall tension at end diastole, determined by EDV, EDP and wall thickness, and approximated by PAWP/CVP.
49
Potentiation
Potentiation - a non-toxic agent ’ing the toxicity of a toxic agent.
50
Receptor
Receptor - the molecules of a biological target with which a drug reacts to produce its biological effect
51
Regurgitation
Regurgitation – passive, not reflex and not forceful
52
Retching
Retching – may precede vomiting, involves rhythmic contraction of same muscle groups, without expulsion of contents
53
Second gas effect
Second gas effect – high volume uptake of one agent (N2O usually) to increase the rate of increase of Fa/Fi of a second gas (classically volatile but also O2).
Uptake of one agent can increase the rate of uptake of a second agent
54
Sensitisation
Sensitization (Reverse tolerance) - acquired hyperactivity due to prior exposure to a drug.
55
Shock
Shock - physiologic state characterized by a significant reduction in systemic tissue perfusion, resulting in decreased tissue oxygen delivery
56
Sleep
Sleep – imperative, natural, periodic state of reversible unconsciousness, rousable by sensory stimuli
57
Solubility
Solubility – amount of specific substance that will dissolve in each vol. of a specified liquid at specified temp and pressure
58
Solution
Solution – homogenous mixture
59
Specific gravity
Specific Gravity – ratio of density of a solution compared to water
60
Suspension
Suspension – heterogenous mixture
61
SVR
SVR - resistance or impediment of the systemic vascular bed to blood flow, mainly from arterioles
62
Synergistic effect
Synergistic effect - second drug, acting with the first, produces an effect greater than the algebraic sum of the effects of each drug administered individually (1 + 1 > 2).
63
Sympathomimetic
Sympathomimetic - sympathomimetic drugs are those which evoke similar responses to those produced by the endogenous activity of the symp. NS.
64
Tachyphylaxis
Tachyphylaxis - acquired hyporeactivity that develops rapidly (mins/hrs) after only a few doses of a drug.
Rapid deterioration in response to repetitive administration of a pharmacologically active substance.
65
Tolerance
Tolerance - acquired hyporeactivity over time (days-wks) due to prior exposure to the drug (or another related drug => cross tolerance)
The demonstration of decreased receptor response to a given concentration of agonist
The need to increase the dose of (opioid) agonist to achieve the same (analgesic) effect previously achieved with a lower dose
66
Vapour
Vapour – gaseous state of a substance that is in equilibrium with the liquid or solid state, which is capable of forming a solid or liquid at the temperature of the vapour (Ie below critical temperature)
The gaseous form of a substance when the ambient temperature is below its critical temperature
67
Viscosity
Viscosity – fluids resistance to flow (ration of shearing stress to velocity gradient), fluids think honey, but gases get more viscous with increasing temperature
68
Vomitting
Vomiting – forceful expulsion of gastric contents via mouth, a survival reflex to expel toxins
69
Volume of distribution
Volume of distribution – the apparent volume which a drug would occupy if all of the drug present in the body distributed uniformly at the concentration present in the blood
70
Absolute humidity
Weight of H2O vapour in one litre of gas
Units: mg/L or gm / m3
0C= 4.8ml/l, 20C = 17mg/l, 37C = 44mg/l
71
Adabiatic change in state of a gas
In an isolated system, occurs when a change in pressure or volume results in a change in temperature.
Eg. If a compressed gas expands adabiatically, cooling occurs
72
Adaption
The temporal progressive reduction in the rate of firing of receptors in response to a continuous sensory stimulus
Eg. Adaption of pressure receptors on bum
73
Ageing
A normal physiological process of degeneration beginning around 30 and proceeding at a variable rate, with obvious changes becoming apparent around 60, and the end point being death.
74
Allodynia
Innocuous stimulus leading to pain
75
Alveolar dead space
That part of the inspired gas, which passes through the anatomical dead space to mix with alveolar gas, but is not perfused with blood and does not contribute to gas exchange. i.e. ventilated but not perfused alveoli
76
Alveolar gas equation
PAO2=PIO2 – PACO2/R + F
77
Ampere
A current which if maintained in two straight parallel conductors of infinite length and negligible cross section, placed one metre apart in a vacuum would produce between these conductors a force equal to 0.20 N/m of length
78
Amphipathic
Part hydrophilic, part hydrophobic
79
Analysis of variance (ANOVA)
A parametric test used to compare the means of two or more groups
80
Anaphylactic reaction
An acute hypersensitivity reaction which occurs in patients previously sensitised to the particular antigen.
Mediated by IgE attached to mast cells
81
Anaphylactoid reaction
Due to direct release of mediators (complement or direct histamine release) from the mast cells by the action of the causative drug or agent
82
Anatomical dead space
Volume of gas in airways excluding alveoli
| Measured by Fowler’s method.
83
Antigen
A substance capable of stimulating the immune system of the host to produce a specific response to it.
84
Apparent volume of distribution
The imaginary volume into which a drug would need to distribute so that it has the same concentration as plasma
85
Autonomic nervous system
Efferent pathway controlling action of involuntary organs and tissues. Main function is homeostasis
86
Avagadro’s hypothesis
Equal volumes of gases at equal condition of pressure and temperature contain equal number of particles
87
Bainbridge reflex
Atrial reflex control of HR
Increase in atrial pressure causes increase in HR – stretch receptors transmit afferent signal through vagus to medulla
- infusion of blood or saline in
normovolemic subject causes reflex increase in HR independent of ↑BP
88
Bartter’s syndrome
Idiopathic hyperplasia of JG cells
| Associated with hypokalaemia and increased levels of renin, AII, and aldosterone, but with normal BP
89
Bezold-Jarisch reflex
Coronary chemoreflex
Injection of vasoactive chemicals into coronary artery leading to apnoea, followed by rapid breathing, hypotension and bradycardia
90
Bias
Systemic deviation from the truth
91
Binomial distribution
Exists if a population contains items which belong to one of two mutually exclusive categories (eg male or female)
92
Biotransformation
The enzymatic conversion of a drug into a more polar, less lipid soluble molecule which is suitable for excretion
Phase I: oxidation, reduction, hydrolysis
Phase II: glucuronidation, sulphation, aceylation
93
Blood/gas solubility or partition coefficient
Also called “Ostwal solubility coefficient”
The ratio of the concentration of dissolved gas to the concentration in the gas phase at equilibrium
Determines the induction time
94
Bohr effect
Alteration of blood pH changes haemoglobins oxygen carrying capacity
rightward shift of the oxyhaemoglobin curve with ↑H+ concentration and ↑PCO2 reflecting lower affinity of Hb for oxygen.
95
Boiling point
The temperature at which its saturated vapour pressure becomes equal to ambient pressure
Temperature at which liquids becomes gases
96
Boyle’s Law
At a constant temperature the volume of a given mass of gas varies inversely with the absolute pressure
for a given mass, provided the temperature is constant, the volume is inversely proportional to pressure
→ V x P = K
97
Buffer power
buffer power = d{B+}/dpH
Here d[B+] = change in concentration of base
dpH = change in pH
98
Bulbs of Krause,
| Ruffini
Krause: cold thermoreceptors in dermis
Ruffini: heat thermoreceptors in dermis
99
Candela
The luminous intensity of a surface of 1/600,000m2of a black body radiator at the temperature of freezing platinum under a pressure of 101,325 kPa
100
Capnography
The graphical measurement of CO2 vs time
101
Carotid chemoreceptor reflex of BP control
Decreased perfusion pressure reduces oxygenation, leading to increased pCO2 and stimulation of the vasomotor center of the brain stem, via Hering’s and vagus nerves.
102
Case control study
An observational study that begins with a definition of the outcome of interest and then looks backward in time to identify possible exposures, or risk factors, associated with that outcome.
103
Central limit theorem
As the sample size increases, the shape of the sampling distribution approaches normal shape, even if the distribution of the variable in question is not normal.
104
Charle’s Law
At a constant pressure the volume of a given mass varies directly with the absolute temperature
105
Chemoreceptor
Those receptors that are stimulated by a change in the chemical composition of the environment in which they are located
106
Chi square (X2) (Pearson’s)
Used to compare independent groups of categorical data
X^2 = sum (O=E)^2/E
where: O= observed number in each cell; E= the expected number in each cell
107
Chiral molecule
Describes a molecule that has a centre (or centres) of three-dimensional asymmetry (eg. C, N, S)
108
Clark’s occupancy theory
There is a dynamic reversible relationship between drug and receptor
109
Coagulation
Coagulation is a biological amplification system in which a few initial substances activate, by proteolysis, a cascade of circulating precursor enzymes.
110
Cockcroft-Gault formula
Creatinine clearance = ({140-age} x wt in kg)/[814 x serum cr]
multiply 0.85 for females.
111
Coefficient of variation
SD/mean
112
Cohort study
A cohort study observes a group of patients forward in time in order to record their eventual outcome.
113
Colligative properties
Properties of a solution that depend only on the particle concentration.
Ie the number of particles per unit volume
They are: vapour pressure depression, freezing point depression, boiling point elevation, osmotic pressure
properties of a solution that depend only on the number of freely moving particles and not on the nature of those particles. eg osmotic pressure, freezing point depression, vapour pressure.
114
Conduction
Transfer of heat at a molecular level. (cannot occur in a vacuum)
Q=KA(t1-t2)/d
Where: Q=heat loss
A= area of transfer
d= thickness of material over which heat has to travel
K= thermal conductivity of the substance
115
Confidence limits
The lowest and highest values of the CI
116
Confounding
Effect of imbalance and effect on outcome
117
Constitutional or structural isomers
molecules with the same empirical formulae whose atoms are connected to each other in a different sequence.
Eg. Isoflurane, enflurane
118
Contractility
A property of cardiac muscle which defines the work the heart can perform at a specified load.
119
Convection
A process of heat transfer through a stream of fluid. (Cannot occur in vacuum)
120
CP50
Plasma concentration required to produce a response in 50% of the population (or to produce a half-maximal effect)
121
CP95
Plasma concentration required to produce a response in 95% of the population (or to produce 95% of maximal effect)
122
Critical pressure
Minimum pressure for liquefaction at critical temperature
| The vapour pressure of a substance at its critical temperature.
123
Critical temperature
The temperature above which a gas cannot be compressed into a liquid no matter how high the pressure is increased
Nitrous oxide 36.5 dC
O2 -119 dC
CO2 31 dC
124
Cushing reflex
Hypertension, bradycardia secondary to an increased ICP
When ICP is increased, the blood supply to the vasomotor area is compromised, and the local hypoxia and hypercapnoea increases its discharge. The resultant rise in BP restores the blood flow to the medulla, but the HR decreases due to the baroreceptor response.
125
Dalton’s law of partial pressure
In a mixture of gasses the pressure of each gas is the same as that would be exerted if it alone occupied the container.
the pressure exerted by a mixture of gases (or gases and vapour) is equal to the sum of the pressures which each gas would exert if occupying the same space alone.
NB at high pressures, the compressibility of some gases causes deviations in behaviour from predicted values.
126
Defaecation
The active expulsion of rectal contents to the external environment
127
Descriptive statistics
Describe a collection of data (mean, median, standard deviation, variance)
128
Dew point
The dew point is the temperature to which a gas must be lowered in order for water to condense from it. Ie the partial pressure of water vapour equals the saturated vapour pressure
129
Dibucaine number
Refers to the % inhibition of the esterase (in hydrolysing benzoyl choline) by Dibucaine 10-5 (Nupercaine) The D gene is resistant to inhibition.
Normal activity > 70%, atypical activity
130
Diffusional hypoxia
Fink effect
| Returning N2O displaces the alveolar O2 from the lungs, lowering the alveolar O2 concentration
131
Distribution
The movement of drug from the systemic circulation to other body compartments
132
Drug interaction:
Additive
Synergistic
Antagonistic
Additive: the effect of a drug combination is the sum of the effects of each drug (eg potent volatiles)
Synergistic: the effect of a drug combination is greater than the sum of the effects of each drug (eg.opioids and volatiles)
Antagonistic: the effect of a drug combination is less than the sum of the effects of each drug
133
Eaton-Lambert effect
Myasthenic syndrome – muscle weakness caused by antibodies to presynaptic Ca2+ channels at nerve ending, thus preventing ACh release
134
ED50
Dose required to produce a response in 50% of the population (or to produce half-maximal effect)
135
ED95
Dose required to produce 95% depression of the twitch response of the adductor pollicis muscle to stimulation of the ulnar nerve.
136
Efficacy
The strength of the drug-receptor interaction in causing effect. It describes the response to a certain % receptor occupancy.
137
Electroencephalogram (EEG)
A continuous register of the summated electrical activity of the brain recorded by electrodes on the scalp
138
EMF (alternate Nernst equation)
EMF(mv) = +- 61.5log ([] inside/[ ] outside) (at 37 degrees C)
139
enantiomer
(substances of opposite shape)
a pair of molecules existing in two forms that are mirror images of one another (right and left handed) but cannot be superimposed. Eg. S- and R- bupivacaine
enantiomers and diastereoisomers are subtypes of stereoisomers.
140
Endocrine gland
Organs that secrete specific substances (hormones) which are released directly into the circulatory system and which influence metabolism and other body processes.
141
Endocrine system
The system of glands and other structures that elaborate internal secretion (hormones) which are released directly into the circulatory system and which influence metabolism and other body processes
142
Epidemiology
The study of disease in populations
143
Excretion
Irreversible elimination of the drug or its metabolites from the body
144
Exponential function
One where the rate of change of a variable is proportional to the magnitude of the variable
145
Fenn effect
The greater the amount of work performed by the muscle, the greater the amount of ATP that is cleaved
146
FEV1
Fraction of the vital capacity expired during the first second of a forced expiration
147
Fick principle
The amount of a substance taken up by an organ per unit of time is equal to the arterial level of the substance minus the venous level (a-v difference) times the blood flow
148
Fick’s law of Diffusion
rate = permability coefficient x (C1-C2) x (area/thickness)
149
First pass effect
Occurs when orally-administered drugs enter the systemic circulation in concentrations that are much lower than if the drug was administered systemically. Eg. Betablocker doses o vs iv
150
Fisher’s exact test
For use in 2x2 tables, when one or more of the variables
151
Fluoride number
Refers to the % inhibition of the esterase by fluoride 5 x 105M
152
Free water
The amount by which the water content of a solution (eg. Urine) exceeds that needed to form a solution isosmotic with plasma
153
Functional residual capacity
Volume of gas in the lung after a normal expiration
| Equals ERV+RV = 0.7+1.1 = 1.8l = 30ml/kg
154
Gain
The ratio of the secondary change evoked by a given mechanism to the initiating change itself
155
Gas
The gaseous form of a substance when the ambient temperature is above its critical temperature
156
Gastro-ileal reflex
Raised secretory and motor activity in stomach increases ileal activity
157
Gaussian distribution
Normal distribution curve
158
GFR
```
GFR = Uw x V / Pw
Uw = urine conc of W
V = urine volume per unit time
Pw = arterial plasma concentration
```
159
Goldman equation
Used to calculate the magnitude of the resting membrane potential (RMP)
Dependent on the concentrations and the permeability for each ion species present.
160
Graham’s law
Rate of diffusion varies with the inverse of the square root of molecular weight
the ratio of diffusion of gases through certain membranes is inversely proportional to the square root of the molecular weight.
161
Haemopexin
Binds to haem when haptoglobin is saturated
162
Hair hygrometer
A hair is attached to a dial via a system of levers, and lengthening of the hair is linear with increasing humidity. Accurate over the 30-90% range of relative humidity
163
Haldane effect
As Hb releases O2 it can carry more CO2 without a rise in pCO2
Deoxygenation of blood increases its ability to carry CO2 since the reduced form of Hb better buffers H+ (more CO2 transported as bicarbonate) and binds CO2 as carbamino groups.
164
Haptoglobin
An α2-globin. Binds to the globin moiety of free haemoglobin that may be in the plasma
165
Hawthorne effect
The actual process of study (patient explanation, informed consent, measurement, follow-up) may result in more favourable outcomes in such patients.
166
Heat
The energy which can be transferred from an object at a higher temperature to one at a lower temperature
A manifestation of the level of molecular kinetic energy present in a substance
167
Henderson-Hasselbalch equation
```
pH = 6.1 + log ( HCO3-/ {0.03 Pco2})
pH = pKa + log [HCO3]/ (0.03 x pCO2)
```
168
Henry’s law
The concentration of a gas in a liquid is proportional to its partial pressure
169
Hering-Breuer reflex
Inflation reflex: increase in duration of expiration produced by steady lung inflation
170
Hormone
A chemical substance that is secreted into the body fluids by one cell or a group of cells that exerts a physiological control effect on other cells of the body
Peptide hormone: hypothalamus, pituitary, pancreas, parathyroid, gut, heart
Amines: thyroid, adrenal medulla
Steroid: sex hormones, adrenal cortex.
171
Humidity
Amount of water vapour present in air
172
Hyperalgesia
Mildly painful stimulus leading to severe pain
173
Immune system
A series of complex cellular and humoral elements that can interact with many different types of foreign molecular structures (antigens) to provide host defence against foreign substances
174
Incidence
The number of individuals who develop a disease (ie new case) in a given time period
175
Inferential statistics
That branch of statistics where data are collected and analysed from a sample to make inferences about the larger population (using parametric and non-parametric tests.)
176
Inspiratory capacity
Maximal inspiration following passive expiration
| IC=TV+IRV = 7ml/kg + 45ml/kg = ~50ml/kg
177
Inspiratory reserve volume
Air inspired with a maximal inspiratory effort in excess of the tidal volume.
45ml/kg
178
Intestino-intestinal reflex
Over distension of one segment of intestine relaxes the rest of the intestine
179
Intracranial pressure
The pressure within the cranial vault relative to atmospheric pressure (gauge pressure)
180
Intravenous anaesthetic agent
A drug or combination of drugs which will induce anaesthesia, safely and reversibly, when injected in sufficient doses and which could also be given intermittently or by infusion for maintenance
181
Ionic permeability
Net quantity of ion that will diffuse across each unit area of the membrane per unit [ ] gradient
182
Isohydric principle
An assessment of the concentrations of any one acid-base pair can be utilised to provide a picture of overall acid-base balance in the body.
183
Isomer
Constitutional: compounds with the same empirical formulae whose atoms are connected to each other in a different sequence. Eg. Isoflurane, enflurane
Stereoisomers: molecules that not only have the same empirical formula but which also have the atoms attached in the same sequence. They differ, however, in the three-dimensional arrangement of those atoms.
Enantiomers: mirror images: eg. S- and R- bupivacaine
Diastereoisomers: oriented around a carbon double bond: eg. Atracurium.
184
Kelvin
The fraction 1/273.16 of the triple point of water (that temperature at which water can exist as solid and gas = 0.16 dC
185
Kilogram
The mass of the international prototype kilogram kept at the international Bureau of Weights and measures in France
186
Kruskal-Wallis test
A non-parametric equivalent of ANOVA
187
La Chatelier Effect
Shift in equilibrium of carbonic anhydrase reaction to CO2
| H+ + HCO3= H2O + CO2
188
Lambert-Beer Law
There is a non linear, power relationship between the light intensity transmitted, and the incident light intensity
It=Iie-A
the intensity of light passing through a solution decreases exponentially with the concentration of solute and distance traveled through solution
I trans = I incident e^-A
A = DEC
(A = absorption)
D = distance, E = extinction coefficient, C= concentration
189
Laminar flow
Q proportional to [pi (P1-P2) r^4] / 8nl
n = viscosity (poises)
l = length of tube in cm
Q = flow of gas (ml/sec)
Note that flow is proportional to pressure drop, and to the radius to the power of 4, and inversely proportional to viscosity and length.
190
Laplace’s law
The equilibrium relationship between transmural pressure difference, wall tension, and radius of curvature in a concave surface, for a sphere: dP=2T/R; for a cylinder: dP=T/R
In a cylinder, for a constant internal pressure, wall tension varies directly with the radius
In a sphere, for a constant internal pressure, wall tension increases at twice the rate as the radius.
191
Latency
Time from drug introduction to onset of action
192
Latent heat
The amount of heat required to change the state of a substance, when it is at the temperature required to change state.
193
Latent heat of vapourization
The amount of heat required to change a liquid to the gaseous phase.
194
Lissauer’s tracts
Collections of axons that can travel up or down 1-2 segments
195
MAC awake
MAC at which consciousness is regained or at which 50% of patients will respond to a simple command.
Useful to predict recovery, usually ~0.6 MAC
196
MAC-95
MAC absolving 95% of the reflex response
197
MAC-BAR
MAC that blocks adrenergic response in 50% of patients
NA used, measuring BP & HR
MAC required to block adrenalin response (BP and HR increase mediated by catecholamines) in 50% of patients exposed to standard stimulus.
198
MAC-hr
Duration of exposure to 1 MAC of agent
199
Mann-Whitney U test
A non-parametric equivalent to the unpaired t-test
200
Mayer waves
Slow oscillations in arterial pressure that occur at the rate of about one per 20-40 seconds during hypotension.
Hypoxia stimulates chemoreceptors, stimulation raises BP, removing the stimulus to the chemoreceptors, and initiating a new cycle
201
Meta-analysis
Process of combining the results of different trials to derive a pooled estimate of effect.
202
Metre
The distance that light travels in a vacuum in 1/299,792,458 of a second
203
Molality
The number of moles of a solute per kilogram of solvent = this is independent of temperature
204
Mole
The amount of a substance which contains as many elemental entities as there are in 0.012Kg of carbon12
205
Monro-Kellie doctrine
The intracranial volume is fixed and for the intracranial pressure to remain constant reciprocal changes must occur between the volumes of the individual components of the intracranial contents.
206
Motor unit
Consists of an anterior horn cell, a motor neuron and the muscle fibres which it supplies.
207
Nebulisation
The breaking up of liquid water into tiny droplets, that can be held in air in suspense
208
Nernst equation
E = RT/FZ ln []o/[]i
```
where:
E=equilibrium potential
R= gas constant
T= absolute temperature
F= faraday (no of coulombs per mole of charge)
Z= valence of the ion +/-
```
209
Nernst potential
The potential level across the membrane that will exactly prevent net diffusion of an ion in either direction
210
Newtonian fluid
Those fluids for which the shear rate is proportional to the shear stress.
211
Null hypothesis
There is no difference between the population variables in question
212
Number needed to treat
(NNT) the reciprocal of the absolute risk reduction
| describes the number of patients who need to be treated in order to avoid one adverse event.
213
Odds ratio
The ratio of odds of an outcome in those treated vs. those not treated – usually a case-control study
OR 1 = no change
An estimate of the risk ratio (The proportion of patients with an outcome who were exposed to a risk factor vs. the proportion not exposed.)
214
Oil / Gas partition coefficient
The amount of gas in equal volume of two phases at stated temperature, independent of pressure at equilibrium
215
Oncotic pressure
Colloid osmotic pressure
| That part of the osmotic pressure of plasma or interstitial fluid which is due to protein
216
One-tailed t-test
Used to look for a difference between two groups in only one direction (ie larger or smaller)
217
Opsonization
Coating of a target cell with certain complement proteins
218
Osmolality
Number of osmoles of solute per kilogram of solvent. One osmole contains Avogrado’s number of particles This is independent of temperature
219
Osmolarity
Number of osmoles of solute per litre of solution. This is altered by temperature changes because of the expansion of the solution.
220
Osmole
The mass of a substance which yields 6.02 x 1023 osmotically active particles
221
Overdrive suppression
The automaticity of pacemaker cells is depressed after a period of high frequency excitation
Eg. Firing of the SAN tends to suppress the automaticity in the other foci
222
Oxygen flux
Amount of oxygen delivered to the peripheral tissues per minute
223
P value
The probability of the event occurring by chance if the null hypothesis is true
224
P50
The PO2 at which the haemoglobin is half saturated with O2
| P50 = 27. (HbF P50 = 20.)
225
Parameter
Summaries of population data (compared to statistics, which are summaries of sample data)
Defined by Greek letters (μ,σ, etc.)
226
Partial pressure of a gas in a liquid
That pressure which in the gaseous phase in equilibrium with the liquid would produce the concentration of gas molecules found in the liquid.
227
Pathological / clinical pain
Usually due to tissue or nerve damage and if unchecked, leads to sensitisation of the peripheral and central nervous system.
228
Pearson correlation coefficient
(r) a measure of how closely the data points on a scatterplot assume a straight line (value lies between –1 & 1)
It is a measure of association.
229
Perfect Gas Law
Absolute pressure at a given volume varies directly with the absolute temperature
230
Peristalsis
Progressive contraction of successive sections of circular muscle
231
pH
Negative log of the active hydrogen concentration
Introduced by Sorensen in 1909
or equivalently: aH+=10(-pH)
where aH+ = activity of hydrogen ion.
232
Pharmacodynamics
The study of the biochemical and physiological effects of drugs on the body
233
Physiological dead space
Sum of the alveolar and anatomical dead spaces.
Measured by the Bohr equation.
INSERT BOHR EQUATION
the ratio of the physiological dead space to the tidal volume can be estimated by measurement of the PCO2 in arterial blood and mixed expired gas.
234
Physiological pain
The normal protective response to noxious stimuli and warns of impending tissue damage
235
pKa
The negative logarithm (to the base 10) of the dissociation constant: HA↔H++A-
At pH equal to pKa, the acid is 50% dissociated (ie there are equal amounts of HA and A-)
Ionisation of acids is greatest at alkaline pH, ionisation of bases is greatest at acidic pH.
236
Poiseuille’s law
```
Q = pi(P1-P0)r^4 / 8nl
Q = flow
pi/8 = constant of proprtionality
v = viscosity
l = length
r = radius
P1-P0 = pressure gradient
```
237
Poisson distribution
Describes (rare) random processes, where there is no knowledge of how much did not occur. Eg. Given a rate that events occur (at random), how many events occur in a set time?
238
Potency
The (reciprocal) relationship between the therapeutic effect of a drug and the dose necessary to achieve that effect
239
Power (statistics)
The likelihood of detecting a difference between groups if one exists (ie preventing a type II error)
240
Pressure interconversion – 1atm
1 atm = 101.325 kPa = 1013.250 mbar = 760mmHg = 1035.08cm H2O = 14.696 psi (lb/in2)
241
Prevalence
The current number of cases (pre-existing and new)
242
Probability
A theory of uncertainty that is used as a rational means of dealing with an uncertain world
243
Protein binding
The percentage of a chemical that binds to proteins
244
Pulmonary chemoreflex
Juxtacapillary receptors in the lung respond to intravenous administration of chemicals. The reflex response is apnoea, followed by rapid breathing, bradycardia and hypotension.
245
Racemic mixture
Two enantiomers are present in equal proportions
Eg bupivacaine, ketamine. (the S form of ketamine is more potent and less likely to cause emergence delirium than the R form)
246
Radiation
Loss of energy from the body by electromagnetic radiation. Occurs through a vacuum, and does not require physical contact
Q=kT4
247
Rate
Measure of frequency of an event
248
Receptor potential
The alteration in membrane potential, generated by the stimulus, at the nerve ending associated with the receptor
249
Referred pain
Pain felt not at the site of origin (viscous or deep somatic) but in a somatic structure some distance away
250
Regurgitation
The effortless passive movement of gastric contents into the oesophagus and possibly the pharynx and oral cavity
251
Relative humidity
The ratio between the actual vapour content that exists to the maximum possible water content at the same temperature
Relative humidity = actual vapour pressure/saturated vapour pressure
252
Renal clearance
The volume of plasma from which that substance is completely cleared by the kidneys per unit time
253
Residual volume
The gas remaining in the lung after a maximal expiration
| 15-20ml/kg = 1.2l in adult male
254
Respiratory dead space
The space in the conducting zone of the airways occupied by gas that does not exchange with blood in the pulmonary vessels.
255
Reticular activating syste
A functional area of CNS, anatomically based on the reticular formation in the mid brain and medulla, responsible for the alert, conscious state and involved in vegetative functions
256
Risk ratio
Incidence rate of an event (outcome) in an exposed population versus the incidence rate in a non-exposed population.
Usually associated with a prospective cohort study
If the risk ratio is greater than 1.0, there is an increased risk with that exposure.
257
Rosenthal Correction Factor
Deltaph/deltaT = -0.015 pH units/degree C
| i.e. temp = pH
258
Sample
A group taken from a population
259
Saturated vapour pressure
Equilibrium pressure point at which number of molecules leaving equals the number of molecules entering the liquid phase
This is independent of atmospheric pressure, dependent only on the temp and the physical characteristics of the liquid
Water at 20C 17gm/m3, at 37C is 44gm/m3 (ie 2.5 times)
260
Second
The time for 9,162,631,770 vibrations of a cesium133 atom
261
Second gas effect
Uptake of one agent can increase the rate of uptake of a second agent
262
Seebeck effect
If in a circuit made from two dissimilar metals, the junctions are set at different temperatures, there is a current generated in proportion to the temperature difference
263
Sequential analysis
A collection of valid statistical methods used to repeatedly compare the outcome of two groups while a trial is in progress. This allows a clinical trial to be stopped as soon as a significant difference between groups is identified.
264
Sleep
A temporary state of unconsciousness which can be overcome by sensory stimulation
265
Specific heat
The number of joules of energy required to raise the temperature of 1 Kg of a substance by 1K (Units kJ/kgK)
Water: 4.19kJ/kgK
Blood: 3.6kJ/kgK
266
Splay
Apperance of a substance in the urine before the Tm is reached
267
Staircase effect (treppe)
Progressive increase in strength in contractions of skeletal muscle when starting from at rest. Thought to be due to increased concentration of calcium ions in cytosol
268
Standard deviation
insert image
269
Standard error
insert image
270
Statistic
defines a sample
271
Stereoisomers
molecules that not only have the same empirical formula but which also have the atoms attached in the same sequence. They differ, however, in the three-dimensional arrangement of those atoms – i.e. have a chiral centre.
Enantiomers: mirror images: eg. S- and R- bupivacaine
Diastereoisomers: oriented around a carbon double bond: eg. Atracurium.
272
Student’s t-test
A parametric test used to compare the means of two groups
273
Summation
Adding together of individual twitch contractions to increase the intensity of overall muscle contraction.
274
Swallowing
The active movement of oral or pharyngeal contexts into the stomach
275
Synaptic transmission
The transmission of nerve signals from one neuron to another through interneuronal junctions called synapses
276
Temperature
A measure of the tendency of heat to travel between substances
277
Thermoneutral zone
The environmental temperature in which body temperature is normal and remains normal while heat production and evaporative heat loss both remain at a minimum.
278
Tidal volume
Normal inspiration to passive expiration
| 7ml/kg = 500ml in adult male
279
Time constant
The time constant is the time at which the process would have been complete had the initial rate of change continued
280
Tonicity
The effective osmolality of a solution
281
Total (physiological) dead space
Volume of gas not equilibrating with blood i.e. wasted ventilation
282
Transducer
A device that changes a signal from one form of energy to another
283
Transport maximum Tm
The limit of the amount of material a particular active reabsorptive system can transport per unit time because of saturation of the membrane transport proteins.
Eg. Glucose = 375gm/minute
284
Traube Hering waves
Fluctuations in BP associated with respiration
285
Type 1 error
| Type 2 error
Type I: α error. Where one rejects the null hypothesis incorrectly – false conclusion of effect
(eg. More likely with multiple testing)
Type II: β error. Where one accepts the null hypothesis incorrectly– false conclusion of no effect
(more likely with inadequate sample size)
286
Universal law of constant proportion
As Y declines it does so at a rate proportional to its own magnitude
287
Unpaired T-test
Used to compare two independent groups
288
Van't Hoff equation
```
Used to calculate osmotic pressure
Osmotic pressure = n x (c/M) x RT
N= number of particles into which the solution dissociates
C = concentration in g/l
M = molar weight of the molecules
R = universal gas constant = 0.082
T = absolute temperature (K)
```
289
Vapour pressure
The pressure exerted by the molecules escaping from the surface of a liquid to enter the gaseous phase
290
Vapour pressure of water
Partial pressure of water vapour in a gas mixture. When vapour pressure equals atmospheric pressure, boiling occurs
291
Variance
google
292
Vascular compliance (eqn)
Vascular compliance = increase in volume/increase in pressure
Compliance = distendibility x volume
293
Vascular distensibility (eqn)
Vascular distensibility = increase in volume / (increase in pressure x original volume)
294
Viscosity
Ratio of shear stress to shear rate of fluid (dimensions dyne/cm2 = 1 Poise)
Shear stress: force applied in the direction of motion to the contact area.
Shear rate: ratio of the velocity of the plate to the depth of the liquid
295
Vital capacity
Maximal inspiration followed by a maximal expiration
| VC=ERV+TV+IRV =1.0+0.5+3.3 = 4.8l in adult male (15+7+45=~60ml/kg)
296
Water content
Total amount of water present per unit volume of a gas. (vapour + fine suspended drops) Units are mg/l
297
Yate's correction
For five or less values in a chi-squared test
298
Z transformation
Converts any normal distribution curve to a standard normal distribution curve, with mean = 0, SD = 1
299
Zymogen
Pro-enzymes requiring proteolytic cleavage to become active
300
Acidemia
arterial blood pH 44 nmol/L
301
ACIDOSIS
an abnormal process or condition which tends to lower arterial pH if there are inadequate secondary changes in response to the primary disease process
- Respiratory - 1º change in CO2
- Metabolic - 1º change not in CO2
302
ACTIVITY
the effective concentration of a substance in a reacting system
303
ADIABATIC HEAT
heat produced when a gas is compressed
304
Affinity
Avidity with which a drug binds to a receptor (analogous to potency), or ability to bind to a receptor and form a stable complex.
305
Alkalemia
arterial blood ph > 7.45 or [H+]
306
ALKALOSIS
an abnormal process or condition which tends to raise arterial pH if there are inadequate secondary changes.
307
AMPLITUDE LINEARITY
amplifications of the signal should be equal throughout the entire signal range to prevent distortion.
308
ANAESTHESIA
without sensation.
| -General: controlled production of unconsciousness
309
ANALOGUE SIGNAL
where the output of the transducer in either volts or amps varies directly with the input signal
310
ANAPHYLAXIS
clinical syndrome produced by IgE type I hypersensitivity resulting from antigen-antibody reaction at surface of mast cells. The syndrome manifests as red rash/flush, bronchospasm, collapse, angioedema, GIT symptoms. Requires prior exposure to antigen.
311
Andoe
positive electrode to which negative ions attract
312
ANREP EFFECT
- intrinsic regulatory mechanism of the heart whereby an abrupt increase in afterload produces transient increase in LVEPD and decrease in SV allowing prompt restoration to near baseline values.
313
Atenuate
Reduce
314
ATPS
Ambient tempreature and pressure, saturated with water vapour (Tamb, Pb, PH2O)
315
AUTOREGULATION
ability of organ/body to maintain homeostasis in the presence of altering physiological conditions.
316
AVOGADRO’S HYPOTHESIS
- equal volumes of different gases at the same temperature and pressure contain equal number of molecules. One mole of any gas comprises 6.022 x 1023 molecules and occupies 22.4 L at STP
317
AZEOTROPE
a mixture of two substances that cannot be separated by fractional distillation given each component shares same boiling point (the boiling point of each is altered by the presence of the other). eg mixture of ether and halothane in the ratio of 1:2
318
BASAL METABOLIC RATE
- energy liberated by catabolism of food per unit time determined by measurement of heat produced by subject: I. in morning II. fasted III. resting supine IV. at normal body temp V. in thermic comfort
319
BASE EXCESS
- blood sample equilibrated to PaCO2
| 40mmHg is titrated with acid or base until the pH is normal (is negative in acidosis).
320
BECQUEREL
one becqueral is the amount of radioactivity produced when one nucleus disintegrates per second
321
BERNOULLI EFFECT
- lateral pressure in a tube decreases as fluid accelerates through a constriction given increased propagating kinetic energy. The total pressure in a cylinder or tube conducting fluid equals the lateral pressure plus the kinetic energy of its forward velocity.
322
BICARBONATE ACTUAL
- true [HCO3-] in whole blood calculated by blood gas analyser by substituting pH and pCO2 into Henderson-Hasselbalch equation.
323
BICARBONATE STANDARD
- [HCO3-] in whole blood equilibrated at 37ºC with plasma PCO2 40mmHg reflects acid/base status of plasma if lung function is normal.
324
BIMETALLIC STRIP
- two dissolver metals arranged in a coil with different coefficients of expansion.
325
Binomical distribution
distribution in which there are two possible outcomes for each measurement.
326
BIOTRANSFORMATION
enzymic conversion of a drug in general to a more polar and less lipid soluble molecule.
327
BELL-MAGENDIE LAW
in the spinal cord the dorsal roots are sensory and the ventral roots motor.
328
BOURDON GAUG
- coiled type of metal where rises in temp pressure cause tube to uncoil.
329
BREATHING
- the alternate inspiration and expiration of air into and out of the lungs.
330
BTPS
Body Temperature Pressure Saturated
| (310K, Pb, P H2O 47mmHg)
331
BUFFER BASE
- sum of all buffer anions in the blood including deoxyHb, HCO3- and intracellular/extracellular proteins and phosphates, normally totaling 44 -48mmol L¯¹.
332
BULK FLOW
- net solvent movement in one direction.
333
BUNSEN SOLUBILITY COEFFICIENT
- the volume of gas dissolved in a unit volume of solvent at a stated temperature and one atmosphere of pressure.
334
CALIBRATION
(1) Zero point
(2) Linearity
(3) Gain
335
CALORIE
- heat energy necessary to raise the temp of 1g of H2O by 1°C from 15 to 16°C
336
CATHODE
negative electrode of galvanic battery to which cations migrate and are reduced and into which electrons are fed from their source.
337
CENTRAL LIMIT THEORY
- even when a variable is not normally distributed the sample mean will tend to be normally distributed
338
CENTRAL TENDENCY
- describes centre of normal distribution, with the terms mode, mean, and median.
339
CHARLES LAW
- for a given mass of gas at a constant pressure, volume is directly proportional to absolute temperature.
340
CHELATE
- to incorporate a metal into an organic complex whereby a metallic ion is sequestered and firmly bound into a ring within the chelating molecule.
341
CHEMICAL EQUIVALENT
weight of a substance that will combine with or replace 8 grams of oxygen (replaced by mole).
342
CHIRAL
not superimposable on its mirror image, hence a centre for mirror image isomerism.
343
CLOSING CAPACITY
the lung volume at which dependent airways begin to close during expiration.
344
COLLOID
substance unable to pass through a semipermeable membrane, or substance present in solution in the colloidal state.
345
COLLOIDAL STATE
a system of particles in suspension rather than being in true solution due to the larger size of the particles.
346
COMPLIANCE
change in volume per unit change in pressure.
347
CORONARY PERFUSION PRESSURE
= diastolic BP - LVEDP
348
CORRELATION
describes the strength of association between variables, expressed as the Pearson correlation coefficient (r). An r of +1or -1 indicates complete positive or negative association, and r = 0 indicates no association.
349
Cross match
- serum of patient’s blood is mixed with each donor unit to ascertain if agglutination is present.
350
CURRENT
1 Ampere = movement of 6.24 x 10 18 electrons(e-) per second past some point.
-Direct current: steady flow of e- in one direction only.
-Alternating current: Root Mean Square (RMS) - take mean of squared AC voltage then take square root of this
RMS AC = equivalent AC
351
DAMPING
- Under: overshoot common - the system oscillates prior to
stabilizing.
- Over: slow signal response with inability to respond to rapid
change.
- Critical: point at which overshoot is just avoided.
- Optimal: 64% of critical damping => minimal overshoot (6-7%)
with only slight reduction in speed of response => compromise
between speed and accuracy
352
DATA
- results for analysis
- Nominal: qualitative value eg gender
- Ordinal: relative value between points eg ASA
- Ratio: continuous data including zero value eg mmol/L, Kelvin
- Interval: continuous data with no absolute zero ie where zero is
arbitrary point eg temp in Celcius
353
DEGREES OF FREEDOM
- number of observations in a sample that can vary independently of other observations.
354
DESENSITIZATION
- same as tolerance
- Homologous - responsiveness lost to agonists of same class only.
- Heterologous- Loss of responsiveness to a whole range of stimuli.
355
DEXTRANS
- any of a range of glucose polymers of varying sizes formed during the hydrolysis of sucrose.
356
DEXTROSE
D-Glucose
357
DIBUCAINE NUMBER
- % inhibition of plasma cholinesterase activity after addition of 10 -5 M solution of dibucaine (cinchocaine)
358
DIFFUSION
movement of substances down an activity gradient for that substance.
359
DOPPLER EFFECT
alteration in frequency of signal when source moves in relation to observer. Hence, waves reflected from moving substance will be picked up as lower in frequency (and pitch) when substance moves away and higher when substance approaches detector.
360
DOUBLE BOHR EFFECT
fetus unloads CO2 and H+ to maternal blood at placenta so that maternal oxyHb curve shifts to right causing decreased O2 affinity => unloads O2 to fetus. Concurrently, fetal blood CO2 and H+ decrease, shifting fetal oxyHb to left causing increased affinity for O2.
361
DOUBLE BURST STIMULATION
- two short bursts of tetanus (2-4 pulses at 50 Hz) separated by 0.75sec. The tetanus bursts fatigue the NMJ more than two single twitches.
362
DOWN REGULATION
- reduction in receptor number which usually occurs with chronic exposure to an agonist. It is associated with reduced sensitivity to the agonist and increased sensitivity to the antagonist.
363
DRUG ABUSE
persistent or sporadic excessive use inconsistent with or unrelated to acceptable medical practice.
364
DRUG DEPENDANCE
- a state psychic or sometimes physical resulting from the interaction between a living organism and a drug, characterized by behavioural and other responses that always include a compulsion to take the drug on a continuous or periodic basis in order to experience its psychic effects, and sometimes to avoid the discomfort of its absence.
365
DYNE
- force needed to accelerate 1g by 1cm per sec per sec Dyne/cm² = 0.1 Pa.
366
ECG
Graphic recording of the changes occurring in the electrical potential (in mV) between different sites on the skin as a result of cardiac activity.
367
ELECTICAL EQUIVALENT:
= gram molecular weight/valance
368
Entrainment ratio
entrained flow/driving flow
369
Enzyme
biologial catalyst
370
Force
mass x acceleration (unit is Newton)
371
FOURIER ANALYSIS
any complex waveform can be constructed from multiple sine waves of different frequencies. The slowest component is the fundamental frequency, and higher frequency multiples of the fundamental frequency are termed harmonics.
372
FREE RADICAL
extremely reactive radical which carries an unpaired election (where radical is fundamental constituent of molecule).
373
F-TEST
a test to compare two variances to see if two samples represent the same population (divide larger variance by smaller and refer to F tables)
374
FUNCTIONAL PLASTICITY
implies dynamic alterations in response of neurons can occur.
375
Functional SaO2
HbO2x100 / [HbO2 + Hb]
376
GAIN STABILITY
gain is the ratio of output to input signal amplitude; the degree of signal gains should be the same and should remain constant over time.
377
GALVANOMETER
- measures current, usually by deflection of wire in a magnetic field.
378
GIBBS-DONNAN EFFECT
- in the presence of a non-diffusible ion, the diffusible ions distribute themselves so that at equilibrium their concentration ratios are equal.
379
GOLD STANDARD
- the standard by which new tests are compared, thought to generally have high accuracy (sensitivity and specificity).
380
GLYCOL
alcohol compounds with two or more hydroxyl (OH) groups.
381
HAPTEN
- small molecule that assists in immunological response but cannot produce response on its own.
382
HEAD’S PARADOXICAL REFLEX
- lung inflation produces a paradoxical further increase in inspiration.
383
HEAT CAPACITY
The amount of heat required to raise the temperature of a given object by 1 Kelvin. Specific heat capacity is the amount of heat required to raise the temperature of 1kg of a substance by 1 Kelvin.
384
HETEROMETRIC AUTOREGULATION
improved ventricular function that is dependant upon changes in myocardial fibre length.
385
HOMEOMETRIC AUTOREGULATION
compensatory mechanisms that result in improved ventricular performance independent of changes in myocardial fibre length.
386
HYPOTHALAMUS
the portion of the diencephalon (posterior forebrain) lying beneath the thalamus and forming the floor of the third ventricle. Concerned with:
- neuroendocrine, control of pituitary hormone sectretion
- Autonomic NS control
- thermoregulation
- control of motion, thirst
387
HYSTERESIS
value of one phenomena depends on whether another has been rising or falling eg transpulmonary pressure required to hold constant lung volume after expiration vs inspiration.
388
IDEAL GAS LAW
- an ideal gas is one which has negligible intermolecular attraction and the molecular volume is small in comparison to the space between molecules.
PV = nRT
389
INTRINSIC ACTIVITY
analogous to efficacy.
390
IMPEDENCE
resistance to a pulsatile/alternating flow/current.
391
INTRAOCULAR PRESSURE
pressure of aqueous humour. Normal is 12-20mmHg and it is raised by:
1. increased choroidal blood volume/flow
2. aqueous humour production/ absorption
3. Intraocular mass/bleeding/hypoxemia
4. CVP, transient ABP changes
5. Extravascular muscle tone
6. Direct external pressure
392
ISOTOPE
different form of same element.
393
JOULE
Work done when a force of one neutron moves its point of application one metre in the direction of the force.
394
KIDNEY FUNCTION:
1. H20 and electrolyte balance/regulation
2. Acid-base balance
3. Removal waste and foreign chemicals
4. Metabolism
5. BP regulation
6. Erythropoetin/Vitamin D activation
7. Gluconeogenesis
395
KRUSKALL WALLIS
non-parametric equivalent of ANOVA
396
LIVER FUNCTIONS:
1. Storage - Glycogen, fat, Cu/Fe, vitamins
2. Bile production and disposal
3. Metabolism - fat, CHO, proteins (including enzymes), hormones
4. Detoxification
5. Immunity
397
LUNG FUNCTIONS:
1. Gas/respiration exchange
2. Filtration
3. Metabolism and deactivation (eg angiotensin, 5HT)
4. Storage
5. Surfactant
6. Immunity
398
MANOMETER
device to measure pressure of a gas.
399
METABOLISM
literally means change, referring to all types of chemical and energy transformations that occur in the body.
- Catabolism: breakdown
- Anabolism: formation
400
MOLALITY
number of moles of solute per kg of solvent.
401
MOLARITY
number of moles of solute per litre of solution.
| Dependant on temperature, density of solvent, and volume of solute.
402
MOLE
molecular weight of a substance in grams.
403
MOTOR UNIT
consists of anterior horn cell, motor axon, and muscle fibres supplied by it.
404
MULLER MANOUVRE
strong inspiratory effort against a closed glottis.
405
MUSCLE SPINDLE
- intrafusal muscle fibres (~10 in capsule) which are concerned with proprioception.
406
NATURAL FREQUENCY
- frequency at which a system resonates or oscillates at a greater amplitude than seen above or below this frequency.
407
NEGATIVE PREDICATIVE VALUE
likelihood of avoiding an outcome, equal to proportion of true negatives (TN) given a negative test result: TN/ (TN + FN). Depends on prevalence.
408
NEUROLEPTICS
- inhibit the following via Dopamine receptor blockade:
- learned conditioned behaviour
- amphetamine induced arousal
- opioid induced vomiting
409
NEUROMUSCULAR BLOCKADE:
Non-depolarizing / Competitive
- no fasciculation
- fade (T4/T1 0.7 (no fade)
- no post tetanic facilitation
- Phase II Block / Partial Non-Depolarizing: repeated doses of depolarizing relaxant can produce similar characteristics to non-depolarizing block, but this occurs via different mechanism and is difficult to reverse with neostigmine.
410
NOCICEPTION
the phase which initiates human pain experiences; the detection of tissue damage by receptors in the body and the transmission of this input to the CNS.
411
NON PARAMETERIC METHODS
used when data is not normally distributed eg nominal or ordinal data.
412
NORMALITY
- the number of chemical gram equivalents of solute per litre of solution.
413
OHM
the resistance which will allow one ampere of current to flow under the influence of a potential of one volt.
414
OHM’S LAW
V = IR
415
OVERTON-MEYER THEORY
olatile agents with the highest oil solubility are found to have the greatest potency as anaesthetics.
416
PARAMETER
a measurement which characterizes/summarizes population data distribution and hence defines a population. Uses Greek letters (c.f. statistics which uses Roman letters)
417
PERIPHERAL NERVE STIMULATOR (IDEAL)
- waveform: unpolar square 0.2 - 0.3msec
- current: supramaximal 20-60mA into 2.5 k Ω
- adjustable
- maintained with changing Ω
- positive electrode proximal
- stimulus: - T.O.F (2 Hz)
- single batch 1.0 Hz
- tetanus 50 Hz, 3-5sec (painful in awake patient)
- double burst, 2 short titanic 50 Hz for 60msec
418
POST TETANIC COUNT
- number of responses to 1 Hz stimulation for 3 seconds after 5 sec of 50 Hz tetanus.
- PTC 8-10 = first TOP
- PTC 0 = no buck or cough
- fade = NDR (c.f. DR)
419
Power (electrical)
Work/Unit time (unit = W, watt)
420
PRESSURE
force per unit area (unit = Pa.)
421
PSEUDO-CRITICAL TEMPERATURE -
temperature at which a gas mixture will separate out into its constituent components.
422
RAOULTS LAW
- an empirical result which describes the lowering of the vapour pressure of a solvent by the presence of a solute. Solute molecules reduce the concentration of solvent molecules in the liquid phase and hence reduce the number of solvent molecules which leave the liquid phase per unit time. If solvent and solute are chemically similar, Raoults law accurately describes the reduction in vapour pressure.
423
RECOVERY
Reversal of anaesthetized state to consious state including reversal of induction and recovery of neuromuscular function.
424
REDUCTION
- removal of O2 or gain of e-
425
REFLEX
basic unit of integrated neural activity or the sum total of any particular automatic response mediated by the nervous system.
426
REGRESSION
mathematically describes relationship between two variables and hence allows prediction of one variable given another.
427
RESPIRATORY EXCHANGE RATIO
estimation of Respiratory Quotient, derived from ratio of expired CO2 to inspired O2. Depends on ventilation and not necessarily at steady state.
428
RESPIRATORY QUOTIENT
the ratio in the steady state of the volume of CO2 produced to the volume of O2 consumed per unit time (1 for CHO, 0.7 for fat, 0.82 for protein).
429
Reynolds number
Re = rvd/n
Flow of fluid with velocity v, viscosity n, and density d through tube of radius r, becomes turbulent at ~Re > 2000
430
RHEOLOGY
The science dealing with the flow and deformation of matter.
431
SARCOMORE
the contractile unit of a myofibril delineated by Z bands.
432
SENSITIVITY
- the proportion of true positives that are correctly identified.
= TP/ (TP + FN)
433
SOLUTE
a substance dissolved in a solvent to form a solution.
434
SOLUTION
a homogenous molecular mixture of two or more substances of dissimilar molecular structure. Usually refers to solids in liquids.
435
SOLVENT
a substance (usually a liquid) having the power to dissolve other substances in it.
436
SOLVENT DRAG
solvent, moving by bulk flow, tends to drag along some molecules of solute.
437
Specific compliance
= lung compliance/lung volume
438
SPECIFICITY
the proportion of true negatives that are correctly identified.
= TN/(TN + FP)
439
STARCH
any of a group of polysaccharides of the general formula (C6 H10 O5)n
440
STARLINGS LAW OF THE HEART
the force of contraction is dependant on the end-diastolic muscle fibre length; the heart pumps whatever blood is returned to it.
441
STATISTICS
rganisation and mathematical manipulation of data. Defines a sample.
- Descriptive: describes the characteristics studied .
- Inferential: used to make decisions.
442
STAVERMAN REFLECTION COEFFICIENT
a measure of how impermeable the capillary is to proteins eg l = completely impermeable.
443
STPD
standard temperature pressure density
| (273K, 1 atm, PH2O = 0)
444
STROKE VOLUME
LVED - LVESV
445
SUPRAMAXIMAL STIMULUS
the point where the force of contraction fails to increase rapidly despite an increase in delivered current (~ 2.75 x initial threshold)
446
SURFACTANT
urface active mixture of phospolipids (P I, D L, S) secreted by alveolar type II cells to decrease surface tension of pulmonary fluids and thus contribute to elastic properties of lung.
447
SYNERGISM
mplies two drugs interact to produce an effect greater than the additional effect.
448
SYSTEME INTERNATIONALE-
```
s Sec
M,m Mol, metre
A Ampere
C Candela
K,k Kelvin, Kilogram
```
449
TONOMETER
measures pressure of a liquid.
450
TOTAL LUNG CAPACITY
maximum volume that the lungs can contain.
451
TRAIN OF FOUR
4 pulses of supramaximal stimulus at 2.0 Hz.
452
TRANSDUCER
a device which changes a signal from one energy form to another. The ability of a transducer to respond to a change in the signal depends on
- frequency of the signal
- natural undamped frequency
- degree of damping
453
THERAPEUTIC INDEX:
Toxic dose SD/therapeutic dose SD
454
UP REGULATION
- increased receptor number (and reponse) which usually occurs with chronic exposure to the antagonist. Associated with increased sensitivity to the agonist but resistance to the antagonist.
455
VALSALVA MANOUVRE
forced expiration against a closed glottis.
456
VENOUS ADMIXTURE
theoretical amount of mixed venous blood needed to add to pulmonary capillary blood to create arterial gas tensions (ie O2).
457
VENTILATION
the process of exchange of air between the lungs and ambient air.
- Total: total volume leaving lung each minute.
- Alveolar: effective ventilation of the alveoli, where gas exchange with the blood takes place.
458
VITAMIN
an organic substance found in foods and essential in small quantities for growth, health , and preservation of life.
459
VOLT
the potential difference which produces a current of one ampere in a substance when the rate of energy dissipation is one volt.
460
VOMITING
forceful expulsion of gastric contents via the mouth.
461
WHEATSTONE BRIDGE
set of four resistors in series, an electrical source and a galvanometer, with one of the resistors often used as part of a strain guege or resistance thermometer.
462
WIND UP
Hyperexcitable state of pain transmission that may lead to pain memory establishment.
463
WORK
Force x distance or pressure x volume (unit= Joule)
464
WINDKESSEL EFFECT
hydraulic filtering which converts the intermittent output of the heart to a steady flow through the capillaries.
465
X-RAYS
- electromagnetic radiation produced when a beam of electrons is accelerated from a cathode to strike an anode (usually tungsten).
466
ZERO STABILITY
ability to maintain zero.
467
*EUTECTIC
mixture in which the melting point is lower than each individual constituent.
468
* LINDQUIST EFFECT-
Describes axial streaming of RBC in vessel
469
*LYOPMILISOD-
Creation of a stable preparation of a biologic substance by rapid freezing and dehydration under high vacuum.
470
*SEBBECK EFFECT
At any junction of two dissimilar metals, a small voltage is produced, the magnitude of which depends on the temperature of the junction.
471
Osmosis
Diffusion of a solvent down it’s concentration gradient across a semi permeable membrane
472
Absolute pressure
Gauge pressure + atmospheric pressure
473
Third perfect gas law
At constant volume, the absolute pressure of a given mass of gas varies directly with absolute temperature.
474
Tare weight
Of a cylinder is the weight when empty.
475
Specific latent heat
The heat required to convert 1kg of a substance from one phase to another at a given temperature.
476
Gauge Pressure
Measures pressure relative to ambient pressure, being the pressure above ambient pressure. Equals absolute pressure minus ambient pressure.
477
Micelle
Spherical aggregates of lipid molecule surrounded by bile salts rendering them water soluble.
478
Von Willebrand’s factor
Large plasma protein synthesized by endothelial cells & megakaryocytes which functions as an adhesive protein to bind platelets to each other & damaged endothelium.
479
ED95 NMBD
The dose of a neuromuscular drug required to produce 95% depression of a single twitch response at adductor pollicis under N20-barbiturate-opioid anaesthetic.
480
NMDA receptor
Multi-unit transmembrane protein forming an ligand gated cation channel, requiring partial membrane depolarization to release a magnesium ion ‘plug’ and the presence of glycine before it can be activated by glutamate and produce an EPSP.
481
Optical isomers
Have a chiral centre, Can be distinguished by the rotation of polarized light (dextro & laevo, d & l) absolute configurations (R & S)
482
Diastereoisomers
Have more that one chiral centre, and multiple possible stereoisomers; not all mirror images so cannot be called enantoimers.
483
Tautomerism
Refers to the dynamic interchange between two forms of a molecular structure, often precipitated by a change in the physical environment. Eg, midazolam.
484
Spare receptors
A maximal tissue response is produced receptor occupancy is less than 100%.
485
EC50
Measure of potency. The dose that will cause a response that is 50% of the maximum.
486
quantal dose-response curves
Used when the effect being measured is an all or none phenomenon - presence or absence of a response is plotted for a population. ED50, TD50, LD50.
487
Therapeutic window
Is the dose range between the minimum therapeutic concentration and maximum toxic concentration.
488
Shunt
Refers to blood which enters the arterial system without passing through the ventilated areas of the lung.
489
Anatomical dead space
Volume of the conducting airways.
| 2.2ml/kg or 150ml for 70kg adult. Measured by Fowler’s method.
490
Physiological dead space
Part of the tidal volume that does not participate in gas exchange. Equal to anatomical plus alveolar dead space and is measured by the Bohr equation.
491
Alveolar dead space
Part of the inspired gas which passes through the conducting airways to mix with gas at the alveolar level but does not participate in gas exchange.
492
Haemoglobin
Metalloprotein consisting of four globin chains each with it’s own haem group. The haem contains iron in it’s ferrous form (Fe2+), which forms loose reversible bond with O2.
493
Interthreshold range
Is the range of core temperature over which no autonomic thermoregulatory response occurs.
494
Malignant Hyperthermia [hyperpyrexia]
is an inherited (pharmacogenetic)
disorder of skeletal muscle, characterised by a hypermetabolic state, triggered
by all volatile anaesthetics and sux.
495
zero order kinetics
a constant amount of drug is eliminated per unit time. Occurs with high dosage phenytoin, salicylates, theophylline, and thiopentone (v. large doses).
496
Acute porphyria
Rare genetic diseases caused by errors in the pathway of haem biosynthesis resulting in the toxic accumulation of porphobilinogen and porphyrin precursors.
497
CPP
Cerebral Perfusion pressure is the driving pressure of blood flow through the brain. Equal to MAP mminus greater of ICP or cerebral venous pressure.
