Symbols and Units

 Kilde : Poul-Erik_Paulev,MD Originale kilde Textbook in Medical Physiology And Pathophysiology Essentials and clinical problems Chapter Symbols and Units Emne: Fysiologi

<b style="mso-bidi-font-weight:normal"> 1</b>.        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<b style="mso-bidi-font-weight:normal"> </b>= 9.8067 or 9.807 m s-2.

<b style="mso-bidi-font-weight:normal">2.</b>        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.

<b style="mso-bidi-font-weight:normal">3.</b>        Finally, work-rate or power is calculated as work­ per second (s). The power unit 1 W equals 1 J s-1.

<b style="mso-bidi-font-weight:normal"> 4.        </b>Pressure is measured as force per area unit that is in<b style="mso-bidi-font-weight:normal"> </b>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.<b style="mso-bidi-font-weight: normal"> </b>This is 101 306.3 N m-2<b style="mso-bidi-font-weight:normal"> </b>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.

<b style="mso-bidi-font-weight:normal">5.        </b>Concentration<b style="mso-bidi-font-weight:normal"> </b>is mass per volume unit. Squared brackets around a substance or <b style="mso-bidi-font-weight:normal">C</b> denote concentration. The international unit is mM = mmol l-1 = mol m-3.

<b style="mso-bidi-font-weight:normal">6</b>.        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.

<b><a name="International Symbols">International Symbols</a></b>

(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)

<b><a name="Nutritive Equivalents And Enthalpy">Nutritive Equivalents And Enthalpy</a></b>

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.

<b style="mso-bidi-font-weight:normal"><a name=" Essential Atomic And Molecular Weights"> </a><a name=" Essential Atomic And Molecular Weights">Essential Atomic And Molecular Weights</a></b>

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.

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.

<b><a name="Calculated Partial Pressures">Calculated Partial Pressures</a></b>

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).