Symbols and Units
| Kilde : Poul-Erik_Paulev,MD Originale kilde Textbook in Medical Physiology And Pathophysiology Chapter Symbols and Units |
1. Force is measured in Newton (N). One Newton (kgm s-2) is the force required to accelerate a mass of 1 kg with an acceleration of 1 m s-2. The acceleration due to gravity is generally accepted as g or G = 9.8067 or 9.807 m s-2.
2. Joule established already in 1848 that mechanical work and heat energy were interchangeable. The commonly used unit of energy is the calorie (cal), which is the energy, required to raise the temperature of 1 gram (g) of water from 14.5 to 15.5oC. Work is force times distance, and it is measured as Newton-meter or Joule (J). The Joules equivalent has been determined to be 4.187 J cal-1.
3. Finally, work-rate or power is calculated as work per second (s). The power unit 1 W equals 1 J s-1.
4. Pressure is measured as force per area unit that is in N m-2 or Pascal.
In the gravity field of the earth G or g equals 9.807 m s-2. Blood and sea water has a relative density of 1033 kg m-3. A 10 m high sea water column resting on one square m, corresponds to the following pressure: (10 m × 1033 kg m-3 × 9.807 m s-2) =
101 306.3 (kg m s-2) m-2. This is 101 306.3 N m-2 or 101.3 kPa (= 1 atmosphere). The classical concept is that 1 atmosphere equals 760 mmHg. Accordingly, 1 Torr or 1 mmHg equals (101 306.3 Pa/760 =) 133.3 Pa. In this book pressures are given in Pa (or kPa) together with mmHg.
5. Concentration is mass per volume unit. Squared brackets around a substance or C denote concentration. The international unit is mM = mmol l-1 = mol m-3.
6. A prefix scale for different units is used as follows: milli = m = 10-3; micro = m = 10-6; nano = n = 10-9; pico = p = 10-12; femto = f = 10-15.
<a name="International Symbols">International Symbols</a>
(Fed.Proc. 9: 602-605, 1950).
This is a precise short-cut for intellectual transfer used by all physiologists.
A dash next to any symbol (-) indicates a mean value. A dot next to any symbol (.) denotes a time derivative. Small letters in a suffix denote gas dissolved in blood, whereas large letters denote gas in air. The symbol is often the first letter in the English word.
| A: | ||
| a | = | Solubility: The Bunsen solubility coefficient (ml STPD per ml fluid per 760 mmHg) |
| A | = | Alveolar gas |
| AA | = | arachidonic acid |
| Ach | = | acetylcholine |
| ACTH | = | adrenocorticotropic hormone |
| Ad | = | adrenaline |
| ADH | = | antidiuretic hormone |
| ADP | = | adenine diphosphate |
| AIDS | = | acquired immunodeficiency syndrome |
| AMP | = | adenine monophosphate |
| AMPA | = | special glutamate receptors |
| ANF | = | atrial natriuretic factor |
| ANH/ANP | = | atrial natriuretic hormone/peptide |
| AP | = | action potential |
| AR | = | absolute refractory period |
| ASA | = | acetylsalicylic acid |
| ATP | = | adenine triphosphate |
| ATPS | = | ambient temperature, pressure, saturated with water vapour |
| AV node | = | atrioventricular node |
| B: | ||
| BB | = | buffer base |
| BD | = | base deficit |
| BE | = | base excess |
| BMR | = | basal metabolic rate |
| BSA | = | body surface area |
| BTPS | = | body temperature and ambient pressure, saturated with water vapour |
| C: | ||
| C | = | concentration of gas in blood. Squared brackets around a substance also denote concentration |
| Cal | = | calorie |
| Cv_CO2 | = | concentration of CO2 in mixed venous blood |
| CA | = | carbonanhydrase |
| cAMP | = | cyclic adenine monophosphate |
| CBF | = | cerebral bloodflow |
| CBG | = | corticosteroid binding globulin |
| CCh | = | carbacholine |
| CCK | = | cholecystokinin |
| cGMP | = | cyclic guanosine monophosphate |
| CNS | = | central nervous system |
| CSF | = | cerebrospinal fluid |
| COLD | = | chronic obstructive lung disease |
| COMT | = | catechol-O-methyl transferase |
| C peptide | = | connecting peptide |
| CRH | = | corticotropin releasing hormone |
| CVP | = | central venous pressure |
| D: | ||
| D | = | diffusion capacity |
| Da | = | Daltons (MW units) |
| DAG | = | diacylglycerol |
| 1, 25-D3 | = | 1,25-dihydroxy-cholecalciferol |
| 25-OH-D | = | 25-hydroxy-cholecalciferol |
| DIT | = | di-iodine-thyronin |
| DM | = | Diabetes mellitus |
| DMNV | = | dorsal motor nucleus of the vagus |
| DMPP | = | dimethylphenylpiperazine |
| DNA | = | deoxyribonucleic acid |
| DOPA | = | dihydroxy-phenylalanine |
| 2,3-DPG | = | diphosphoglycerate |
| DPPC | = | dipalmitoyl phosphatidylcholine |
| E: | ||
| E | = | expiration |
| Enet | = | mechanical net-efficiency of external work |
| EAA | = | excitatory amino acids |
| ECG | = | electrocardiogram |
| ECF | = | extracellular fluid |
| ECV | = | extracellular fluid volume |
| EDIP | = | end-diastolic intraventricular pressure |
| EDRF | = | endothelium-derived relaxing factor |
| EDTA | = | ethylene-diamine-tetra-acetate |
| EEG | = | electroencephalogram |
| EF | = | excretion fraction |
| EGF | = | epidermal growth factor |
| e.p. | = | equilibrium potential |
| EPSP | = | excitatory postsynaptic potential |
| ER | = | endoplasmic reticulum |
| ERBF | = | effective renal blood low |
| ERPF | = | effective renal plasma flow |
| ERV | = | expiratory reserve volume |
| ESV | = | end systolic volume |
| F: | ||
| F | = | fraction of gas in dry air or force |
| f | = | respiratory frequency (breath/min) |
| FABP | = | fatty acid binding protein |
| FAD | = | flavine adenine dinocleotide |
| FADH2 | = | flavine adenine dinucleotide (reduced) |
| FFA | = | free fatty acids |
| FGF | = | fibroblast growth factor |
| FRC | = | functional residual capacity (= RV + ERV) |
| FSH | = | follicle stimulating hormone |
| FU | = | Flow units in ml of blood (100 g tissue)-1 min-1 |
| G: | ||
| G | = | Gibbs energy (free, chemical energy) |
| GABA | = | gamma-aminobutyric acid |
| GFF | = | glomerular filtration fraction |
| GFR | = | glomerular filtration rate (normal 118-120 ml min-1) |
| GH | = | growth hormone |
| GHIH | = | growth hormone inhibiting hormone |
| GHRH | = | growth hormone releasing hormone |
| GIP | = | gastric inhibitory peptide or glucose-dependent insulin-releasing peptide |
| GLP | = | glucagon-like peptide |
| GnRH | = | gonadotropin releasing hormone |
| GLUT | = | glucose transporter |
| GRP | = | gastrin releasing peptide |
| GTP | = | guanosine triphosphate |
| H: | ||
| H | = | heat content (enthalpy; all energy when the pressure-volume work is zero) |
| Hb | = | haemoglobin (haemoglobin F = foetal haemoglobin) |
| HBF | = | hepatic blood flow |
| hCG | = | human chorionic gonadotropin |
| HDL | = | high density lipoprotein |
| HGF | = | hepatocytic growth factor |
| HGH | = | human growth hormone |
| HIP | = | hydrostatic indifference point |
| HIV | = | human immunodeficiency virus |
| hPL | = | human placental Lactogen |
| HPLC | = | high pressure liquid chromatography |
| HSS | = | hepatocyte stimulating substance |
| I: | ||
| I | = | inspired gas |
| ICSH | = | interstitial cell stimulating hormone |
| ICV | = | intracellular fluid volume |
| IDDM | = | insulin-dependent diabetes mellitus |
| IDL | = | intermediate density lipoprotein |
| IGF | = | insulin-like growth factor |
| IGF-BP | = | IGF-binding protein |
| IP3 | = | inositol triphosphate |
| IRV | = | inspiratory reserve volume |
| ISF | = | interstitial fluid (tissue fluid) |
| Iso | = | isoprenaline |
| ISS | = | interpreted signal strength |
| i.v. | = | intravenous |
| J: | ||
| J | = | flux of a substance (mol min-1) through an area unit |
| J | = | Joule |
| JG | = | juxtaglomerular |
| K: | ||
| K | = | Kelvin degrees of temperature |
| L: | ||
| LAT | = | lactic acid threshold |
| LBNP | = | lower-body-negative-pressure |
| LES | = | lower oesophageal sphincter |
| LH | = | luteinizing hormone |
| LHRH | = | luteinizing hormone releasing hormone |
| LPL | = | lipoprotein-lipase |
| LDL | = | low density lipoprotein |
| LTH | = | prolactin |
| LVET | = | left ventricular ejection time |
| M: | ||
| MAO | = | monoamine oxidase |
| MAP | = | mean arterial pressure/mean aortic pressure |
| MeCH | = | metacholine |
| MEOS | = | microsomal ethanol oxidation system |
| MG | = | monoglycerides |
| 2MG | = | 2-monoglyceride |
| MIH | = | Muller inhibiting hormone |
| MIT | = | mono-iodine-thyronin |
| mM | = | mmol l-1 |
| MR | = | metabolic rate |
| MSH | = | melanocytic stimulating hormone |
| MW | = | molecular weight (in Daltons) |
| N: | ||
| N | = | Newton |
| NA | = | noradrenaline |
| NAD | = | nicotinamide adenine dinucleotide |
| NADH2 | = | nicotinamide adenine dinucleotide (reduced) |
| NANC | = | non-adrenergic, non-cholinergic |
| NBB | = | normal buffer base/neutral brush border |
| NGF | = | nerve growth factor |
| NIDDM | = | non-insulin-dependent diabetes mellitus |
| NMDA | = | N-methyl-D aspartate |
| NOS | = | nitric oxide synthase |
| NSAID | = | non-steroid anti-inflammatory drug |
| P: | ||
| P | = | partial pressure of gas in air or blood |
| PAH | = | para-amino hippuric acid |
| PCV | = | packed cell volume |
| PDE | = | phosphodiesterase |
| PDGF | = | platelet derived growth factor |
| PEF | = | peak expiratory flow |
| PG | = | prostaglandins |
| PG2 | = | prostacyclin |
| PGE2 | = | prostaglandin E2 |
| PIF | = | prolactin inhibiting factor |
| PIP2 | = | phosphatidyl-inositol diphosphate |
| PB | = | barometric pressure |
| Pc'CO2 | = | partial pressure of CO2 in end-capillary blood |
| PIO2 | = | partial pressure of O2 in inspired air in trachea |
| PaO2 | = | partial pressure of O2 in arterial blood |
| POMC | = | pro-opiomelanocortin |
| PP | = | pancreatic polypeptide/ pulse pressure amplitude |
| PRL | = | prolactin |
| PRU | = | pressure resistance unit |
| PTH | = | parathyroid hormone |
| PVR | = | pulmonary vascular resistance |
| Q: | ||
| Q° | = | Cardiac output (l min-1) |
| QRS | = | the ventricle complex of the ECG |
| R: | ||
| R | = | ventilatory exchange ratio (pulmonic) |
| R | = | Gas constant |
| RAS | = | reticular activating system |
| RBF | = | Renal bloodflow |
| RC | = | respiratory controller/ respiratory centres |
| REM | = | rapid eye movements |
| RES | = | reticulo-endothelial system |
| RIA | = | radio-immuno assay |
| RMP | = | resting membrane potential |
| RNA | = | ribonucleic acid |
| RPF | = | renal plasma flow |
| RPM | = | revolutions per minute |
| RQ | = | respiratory quotient (metabolic) |
| RR | = | relative refractory period |
| RV | = | residual volume |
| S: | ||
| S | = | entropy (the tendency to spread in a maximum space) |
| S | = | saturation degree |
| SA | = | specific activity |
| SAmode | = | sinoatrial node |
| SB | = | standard bicarbonate concentration |
| SBE | = | standard base excess |
| SDA | = | specific dynamic activity |
| SR | = | sarcoplasmic reticulum |
| SS | = | steady state/ stimulus strength |
| STPD | = | standard temperature and pressure, dry (0oC, 760 mmHg) |
| STN | = | solitary tract nucleus |
| sv | = | stroke volume |
| T: | ||
| T | = | tension (force) |
| T | = | temperature |
| T3 | = | Tri-iodo-thyronine |
| T4 | = | tetra-iodo-thyronine |
| TBA | = | thyroxine-binding albumin |
| TBG | = | thyroxine-binding globulin |
| TBPA | = | thyroxine-binding prealbumin |
| TBV | = | total blood volume |
| TCA | = | tri-carboxylic acid |
| TEV | = | total erythrocyte volume |
| TFGF | = | transforming growth factor |
| TG | = | triglycerides |
| TGF | = | tubuloglomerular feedback |
| TH | = | total haemoglobin content |
| TLC | = | total lung capacity (=RV+VC) |
| TP | = | threshold potential |
| TPVR | = | total peripheral vascular resistance |
| TRH | = | thyrotropin-releasing hormone |
| tRNA | = | transfer RNA |
| TSH | = | thyroid-stimulating hormone |
| TV | = | tidal volume |
| TxA2 | = | thromboxane A2 |
| V: | ||
| v dash | = | linear mean velocity |
| V° | = | volume velocity of gas |
| V | = | volume |
| V°A | = | expired alveolar ventilation (l min-1) |
| VC | = | vital capacity (=IRV+TV+ERV) |
| VD | = | dead volume |
| W | = | Watts (J s-1) |
| W | = | external work (with pressure-volume work zero) |
<a name="Nutritive Equivalents And Enthalpy">Nutritive Equivalents And Enthalpy</a>
Nutritive equivalents for oxygen are:
Carbohydrate 37 mmol oxygen g-1, fat 91 mmol oxygen g-1 , and protein 43 mmol oxygen g-1. On a mixed diet 20 kJ of energy is transferred per litre STPD of oxygen used; the RQ is 0.8.
Nutritive equivalents for carbon dioxide are:
Carbohydrate 37 mmol g-1, fats 64 mmol g-1, and protein 34 mmol g-1.
Metabolic enthalpies (heat energy liberated in the body per g combusted nutrient) in kJ g-1 substance: Protein 17, fat 39 and carbohydrate 17.5.
<a name=" Essential Atomic And Molecular Weights"> </a><a name=" Essential Atomic And Molecular Weights">Essential Atomic And Molecular Weights</a>
These are given in g mol-1 (or Daltons, Da) throughout the text. Calcium 40; Carbon 12; Glucose 180; Helium 4; Hydrogen 1; Nitrogen 14; Oxygen 16; PAH 194.2; Phosphorus 31; Potassium 39; Sodium 23; Xenon 131.
Physical Constants And Conversion Factors
Acceleration due to gravity (standard 1 G): 9.81 m/s2.
Avogadro's constant: 6.02 1023 molecules mol-1 .
Diffusion coefficients for most molecules: 10-10 m2 s-1 per molecule.
Energy (J = N m = Volts Coulomb): 1 cal = 4.187 J.
Farad = Coulomb/Volts.
Faraday's constant: 96 487 (104) Coulomb/mol monovalent ion.
Molar gas constant (R): 8.31 J mol-1 per degree Kelvin (K).
Specific heat capacity of the human body: 3.47 kJ kg-1 oC-1.
Energy transfer by evaporation of 1 kg of water at the usual skin temperature: 2436 kJ.
Pressure (Pascal = Pa = N m-2): 1 mmHg = 1 Torr = 133.3 Pa.
Surface tension of body warm water: 0.07 N m-1.
Temperature conversion between degrees of Fahrenheit (oF) and degrees of Celsius (oC): (oF) = 9/5 (oC) + 32.
<a name="Calculated Partial Pressures">Calculated Partial Pressures</a>
The partial pressures of respiratory gasses are calculated in the alveoli and in the surrounding air of a healthy person, resting at sea level (101.3 kPa = 760 mmHg or Torr = 1 atmosphere).
The water vapour tension in a fluid (air or liquid) of the temperature 310 K (37oC) is 6.27 kPa or 47 mmHg. At 293 K (20oC) the tension is 2.4 kPa or 18 mmHg. The alveolar gas fractions are: FAO2 = 0.15, and FACO2 = 0.056. The composition of atmospheric air is: FIO2 = 0.2093 and FICO2 = 0.0003.
PO2 = FO2 (101.3 - 6.27) kPa.
PAO2 = 13.3 kPa (100 mmHg); PaO2 = 12.7 kPa (95 mmHg); PvO2 = 6 kPa (45 mmHg).
PACO2 = 5.3 kPa (40 mmHg) ; PaCO2 = 5.3 kPa (40 mmHg); PvCO2 = 6.1 kPa (46 mmHg).
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