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General Laboratory: Blood Gas: Overview Online Training

In life-threatening situations, physicians need to be able to quickly assess a patient’s vital signs. Blood gas analysis is a key component of emergency diagnostic procedures because it allows physicians to quickly assess the patient’s acid-base metabolism and oxygen status.

Identify key parameters included in a blood gas analysis that assess acid-base metabolism and oxygen status Identify the basic principles acid-base metabolism Identify the basic principles of oxygen status Identify the importance of evaluating electrolyte as well as metabolic functions during critical situations and identify tests that allow physicians to assess these areas Welcome to the Blood Gas and Rapid Analysis Tests: Overview Online Training Course. After completing this course, you’ll be able to: Select Next to continue. Acid-base metabolism refers to the body’s ability to maintain our blood at a proper pH to prevent it from becoming overly acidic or overly alkaline. Disorders that affect acid-base metabolism indicate our body’s buffer and regulation systems are no longer capable of maintaining the pH value of the blood at a constant level. Measuring blood gases allows physicians to assess if these changes are due to respiratory or metabolic disorders. pH and pCO2 are the most important blood gas parameters. Other parameters include bicarbonate and base excess levels as well as the oxygen parameters pO2, sO2 and ctO2. Understanding the chemistry and physiology of acid-base metabolism will help you understand the significance of normal and abnormal blood gas analysis results. Key areas include: Chemistry of Acid-Base Metabolism Acids and bases pH value Buffer systems Physiology of Acid-Base Metabolism Development of acids Bicarbonate and non-bicarbonate buffer systems of the blood Let us review the basic principles of acid-base metabolism. You will learn more about the individual tests performed in the Blood Gas: Clinical Significance online training course. Select Next to continue.   L'analyseur de gaz du sang RAPIDPoint® utilise trois cartouches remplaçables pour faire fonctionner le système. Dans cette section, vous apprendrez comment remplacer les cartouches rinçage/poubelle, de mesure et automatique CQ. Based on the definition by Brønstedt, acids are substances that release protons (H+ or hydrogen ions) in aqueous solution and bases (also known as lye) are substances which take up protons. In other words, there is an interaction between the undissociated acid (HA) and the corresponding base (A–) in accordance with: HA = A- + H+ For strong acids, such as HCl, the equilibrium is on the right side; i.e., it is strongly dissociated, while the equilibrium is on the left side for weak acids. To guarantee the electrical neutrality of the solution during dissociation, an equal number of positively charged cations (H+) and negatively charged anions (A–) is always formed. Select Next to continue.   The acidic or alkaline reaction of an aqueous solution depends on the concentration of free protons. The term pH value was introduced with an exponential scale by Sørensen in 1909. It is an expression of very low H+ ion concentrations (pH for potentia hydrogenii). The pH value is the negative decadic logarithm (p) of the hydrogen ion concentration (H+). This negative decadic logarithm allowed the expression of concentrations ranging from 100 to 10–14 with the values 0 to 14. As a result, clean water with an H+ ion concentration of 0.000 000 1 or 10–7 mol had a value of 7 on his scale. At this pH value, the proton concentration corresponds to the one of hydroxide ions [OH–] = [H+]. A pH value of 7 is referred to as neutral pH. Solutions with a pH of < 7 are referred to as acids and solutions with a pH of > 7 are referred to as base. Example of pH values: 0.000 1 mol H+-ions/l ≈ pH 4 → acid 0.000 000 000 1 mol H+-ions/l ≈ pH 10 → base or lye Select Next to continue.   When acid or base is added to an aqueous solution, its pH normally changes. However, if acid or base is added to a buffer solution, most protons are bound. Said buffer mixtures consist of a weak acid and its corresponding alkaline salt. Within certain limits, they are insensitive toward acids and bases. A buffer solution is defined as a solution with a pH that changes only slightly despite the addition of H+- or OH–-ions. As shown in the diagram, neutralizing the acid (HA) with base (A–) at a molar ratio of 10:1 to 1:10 (hatched part) only results in a minor change of the pH: in this example, the pH is elevated from 5 to 7. Buffer mixtures are of particular significance with respect to chemical processes in living organisms, which generally occur within a narrow pH range. For example, the pH range of human blood is maintained at a constant value between 7.3 and 7.5 by active buffer systems. The buffer capacity describes the effectiveness of a buffer system. A 0.1 molar system buffers approximately 5 times less H+ or OH– ions than a 0.5 molar system. Select Next to continue.   Buffer systems – with the change of the molar ratio between acid/base (HA/A-) between 10:1 and 1:10, the pH value only changes slightly. The acid-base metabolism expresses the attempt to maintain the pH value as a measure for the degree of acidity. As a result of food intake and metabolism, acidic metabolites such as lactate and “carbonic acid“ constantly accumulate and protons (H+ ions) are continuously released. The maintenance of the pH value at a constant level is particularly important for the organism. The structure of proteins and cell components, the cell membrane permeability as well as the effect of enzymes, are all dependent on a neutral pH value. Larger deviations in the pH value contribute to metabolic disorders, permeability of membranes and displacements in the electrolyte distribution. Blood pH values below 7.0 and above 7.8 are incompatible with life. Based on the regulation of the H+ ion concentration (buffer systems) within specified limits, different mechanisms are responsible for maintaining controlled enzymatic reactions (biochemical reaction sequences) which require a certain pH value. The blood is the responsible transport organ for energy-supplying nutrients and waste products. All generated protons are first buffered in blood and then eliminated mainly via the two most important organs involved in the regulation of the acid-base metabolism of the body, i.e. the lungs and kidneys, as shown in the diagram. The most important acid included in the acid-base metabolism is carbonic acid. However, carbonic acid is not measured by itself, but dissociated into carbon dioxide and water. Carbon dioxide is eliminated by the lungs, while the kidneys secrete all non-volatile acids. The blood is responsible for the: supply of cells with oxygen and nutrients removal of carbon dioxide regulation of the acid-base metabolism Download and print a copy of From Physiology to the Mathematical Basis of Blood Gas Analysis, the Henderson-Hasselbalch Equation. Acid Formation and Proton Development Learn about metabolic processes responsible for formation of acid and development of protons. The quantity of acid produced daily is ~ 20 L from 1 mol/L of hydrochloric acid. The following metabolic processes are responsible for the continuous formation of acid and the development of protons (H+ ions): Breakdown of lipids and carbohydrates Under regular conditions, the lipid and carbohydrate metabolism forms more than 13,000 mmol of carbon dioxide (CO2) a day. With a food intake of 3,000 kcal, the number increases to more than 25,000 mmol of CO2/day. CO2 reacts with water to become carbonic acid (H2CO3). Through dissociation, the latter develops into H+ ions and bicarbonate (HCO3–). Ketogenesis Fatty acids are broken down into diacetic acid and‚ β-hydroxybutyric acid, which completely dissociate into acetoacetate and β-hydroxybutyrate at a physiological pH. Approximately 600 mmol of H+ ions are formed per day during this process. Glycolysis During anaerobic glucose degradation, approximately 1,400 mmol of lactic acid are formed every day which dissociate into lactate and H+ ions at a physiological pH. Breakdown of sulphuric amino acids and phospholipids ~ 80 mmol of H+ ions in the form of nonvolatile acids secreted via the kidneys in urine develop as a result of the breakdown of sulphuric amino acids (e.g. Methionine and Cysteine) and phospholipids. When complete, select the X in the upper-right corner to close the window and continue. Henderson and Hasselbalch Equation Learn more about the Henderson-Hasselbalch equation. The Henderson and Hasselbalch equation allows you to calculate the pH of a buffer solution or the concentration of the acid and base: pH = 6.11 + log [base] / [acid] or pH = 6.11 + log [kidneys] / [lungs] Consequently, the pH value depends on: the renal function (HCO3 –) the pulmonary function (pCO2) When complete, select the X in the upper-right corner to close the window and continue. The buffer system carbonic acid-bicarbonate corresponds to the classical definition of a buffer solution, involving a weak acid with its salts, whereby its change in pH is limited to a minimum. In addition, the key significance of this buffer system consists in the fact that it is not only capable of buffering off H+ ions but that the concentrations of the two buffer components can be modified almost independently from one another: CO2 via respiration influences HCO3- via liver and kidney metabolic influences Let us learn more about respiratory and metabolic influences. Select Next to continue.   Hydration turns carbon dioxide into carbonic acid. This process is controlled by the lungs, i.e. the respiration. Consequently, carbonic acid can be referred to as the respiratory factor of the buffer pair. Changes in the carbonic acid concentrations can occur within seconds as a reaction to hyper- or hypoventilation. Hypoventilation: The inhaled CO2 quantity is smaller than the quantity produced, resulting in an increase of pCO2 (hypercapnia, > 46 mmHg), the pH value drops (→ respiratory acidosis). Hyperventilation: The eliminated CO2 quantity is greater than the quantity produced, resulting in a decrease of pCO2 (hypocapnia, < 35 mmHg), the pH value rises (→ respiratory alkalosis). Select Next to continue.   The HCO3- buffer system represents the metabolic factor. It is predominantly controlled by the kidneys. Any disorders in this region of the body will result in a deviation of the buffer capacity. A metabolic change cannot occur at the same speed as it can be achieved with respiration. Periods lasting hours and days can be involved. The changes are the result of an altered retention rate, i.e. the tubular reabsorption of H+, HCO3- or the new formation of organic acids in the tissue. As shown in the diagram, the pH value in the blood is indicated by the ratio of HCO3- with the corresponding acid CO2. In healthy subjects, the ratio between base and acid is approximately 24 to 1.2 (20:1). The pH for these “normal values” is 7.41. pH = 6.11 + log 24/1.2 = 7.41 (a) If one of the concentrations is changed, the ratio of 20:1 changes too, causing a change in the pH value. For example, if the carbonic acid concentration rises to double the value due to hypoventilation, i.e. to 2.4 mmol, the pH changes to 7.11. pH = 6.11 + log 24/2.4 = 7.11 (b) However, the same value would be obtained, if the metabolic side would be reduced to half, i.e. 12 mmol. pH = 6.11 + log 12/1.2 = 7.11 (c) Likewise, the pH value changes to the opposite direction if the carbonic acid (H2CO3) content is reduced or bicarbonate (HCO3-) increased. pH = 6.11 + log 48/1.2 = 7.71  (d)   Due to its reciprocal relationship, the metabolic/respiratory buffer pair (HCO3-/ pCO2) is capable of compensating disorders on one side with steps on the other side, resulting in a rapid response to minor pH changes. Select Next to continue.   The group of "non-bicarbonate buffers," which are mainly located in the erythrocytes, are responsible for maintaining the pH value in the blood at a constant level. The bicarbonate buffer HCO3- accounts for 50% of the buffering substance. The ratio of "non-bicarbonate buffers" is mainly composed of hemoglobin, proteins (especially albumin and globulins) and phosphates (in the blood cells). However, the buffer capacities are distributed differently: For HCO3-, the capacity is 75%. For "non-bicarbonate buffers", the capacity is 25%, where hemoglobin accounts for 24%, and proteins and phosphates only account for 1%. With respect to observations of the acid-base metabolism, proteins and phosphates are negligible due to their small buffer capacities. Hemoglobin, with its primary responsibility of transporting gas, requires its complete buffer capacity for the gas exchange. As a result, it is not available as an effective metabolic buffer. In the chart, both bicarbonate and non-bicarbonate buffer systems are included in the term "buffer bases." The total concentration is 48 mmol/L. According to the distribution in the chart: 50% of the concentration is allotted to bicarbonate and 50% to hemoglobin, i.e., 24 mmol/L each Select Next to continue.   In the blood, 98% of the oxygen is chemically bound to hemoglobin. Oxygen plays a major role with respect to the vitality of all body cells and hence the viability of the human organism. Based on the simplified formula, Nutrition + O2 → energy + CO2 + H2O oxygen is constantly metabolized for energy recovery (ATP synthesis), but it cannot be stored in the organism. As a result, the continuous re-supply must be guaranteed at any time. An interruption of the oxygen supply, for example as a result of respiratory or cardiac arrest lasting 5 to 10 minutes can lead to irreversible organ damage (in particular brain damage) and lead to death. On the other hand, excess oxygen can be equally toxic and damage the endothelial membrane of the lung. The oxygen supply is dependent on: heart and metabolism lungs blood transport (in particular the carrier properties of hemoglobin). In other words, oxygen covers a long distance from the ingestion to the mitochondria. Download and print  a copy to view the Correlation between Oxygen Uptake and Transport: The Oxygen Dissociation Curve (ODC). Select Next to continue.   Exterior respiration refers to the pulmonary gas exchange. The most important function of the lungs consists in the uptake of oxygen from the inspired air and the supplies to the organism via the blood as the transport organ. At the same time, the metabolic product carbon dioxide is going the opposite way, namely from venous blood to air in the lungs. Interior respiration describes the release of oxygen into the cells and the oxidation of food according to C6H12O6 + 6 O2 → 6 CO2 + 6 H2O Pulmonary gas exchange is based on the following four basic functions: Ventilation, Perfusion, Distribution, Diffusion. Respiratory regulation: Elevated pCO2 values in the arterial blood lead to an increased urge to inspire and deepening of the respiration. A decreased pH value of < 7.37 (acidosis) has the same effect. Thirdly, a lack of O2 causes an increased respiratory activity, although manifested in acceleration rather than a deepening.   Inspiration Gas Learn more about Inspiration Gas and Dalton’s Law. Depending on the diagnosis and type of malfunction, it is possible to introduce procedures to support the regular function, such as increasing the O2 concentration of the inspired air or using a respirator to assume the natural function. Inspiration gas The gas mixture available in the atmosphere serves as gas for spontaneous respiration. Room air contains ~78% of nitrogen and ~21% of oxygen in addition to minor quantities of CO2 and other gases, generally noble gases. Partial pressure is allocated to each individual gas according to its volume ratio as a result of air pressure (1 atm. = 760 mmHg). This pressure is referred to as partial pressure (p) and is equal to the product of total pressure and volume fraction of the gases (Dalton’s law): Dalton’s law: Partial pressure = % of ratio in the gas mixture x 760 Example: pO2 = 21% (= 0.21) x 760 = 160 mmHg/21.17kPa When complete, select the X in the upper-right corner to close the window and continue. Functions of Pulmonary Gas Exchange Learn more about pulmonary gas exchange. Tab TitleTextVentilation Ventilation (ventilation of the alveoli) refers to oxygen transport based on the flow of gas to areas with a lower pressure than the atmosphere to the pulmonary alveoli. The pressure difference is the result of the periodic enlargement and reduction of the thoracic cavity caused by the contraction of the diaphragm and the intercostal and abdominal musculature. A major gradient in the partial pressure of oxygen occurs en route to the alveoli, reducing it from initially 160 mmHg in room air to 100 mmHg in the alveolar region. The decrease is caused by the relative humidity of the inspired air during its passage through the nose and bronchi which serves to protect the alveoli from drying out (the water vapor pressure (47 mmHg at 37°C) does not depend on the total pressure, but only on the temperature). Tracheal pO2 = (760 - 47 mmHg) x 0.21 = 150 mmHg       In addition, the so-called dead space (nasal area, mouth, neck, trachea, bronchial tree and terminal bronchi) in which no gas exchange takes place is ventilated. The inspired air is mixed with the functional residual capacity contained in the lungs, resulting the two important consequences: the pressure in the alveoli is largely constant (pO2 = 100 mmHg and pCO2 = 40 mmHg). the blood temperature is kept constant as a result of the dilation and mixing effect. pCO2 is the most important parameter with respect to the respiratory center – via chemoreceptors in the wall of the aorta and carotid aorta. PerfusionPerfusion (of the lungs): To achieve an optimal gas exchange, the lung requires adequate perfusion with blood. In a resting state, 5 L of alveolar air are renewed by ventilation every minute; at the same time, 5 L of blood flow through the lungs (cardiac output). In this ideal case, the ventilation-perfusion ratio (VPR) ranges from 0.8 to 1.0 (5/5). When exercising, the ventilation increases faster (up to 20 times) than the perfusion (up to 5 times); the VPR increases up to 4 times.DistributionDistribution summarizes the ventilation and perfusion which are matched to one another. The VPR of 0.8 – 1.0 mentioned above applies to the whole lung and is, on principle, valid for all pulmonary segments up to and including the individual alveoli. However, different distribution ratios occur in the various pulmonary segments even under regular conditions, and the VPR varies as a result. For example, it is possible that certain regions are less ventilated, while the perfusion is not reduced (ventilation distribution impairment). On the other hand, the irregular blood distribution in the lung is possible, while the ventilation is not altered (circulatory distribution impairment).Diffusion Diffusion refers to the movement of molecules along a certain concentration gradient due to their temperature-dependent, kinetic energy. This concentration gradient occurs between alveoli and mixed-venous blood: The partial pressure differences for oxygen (D = 60 mmHg), and carbon dioxide (D = 6 mmHg) are the driving forces for the pulmonary gas exchange. The diffusion path (alveolar epithelium – interstitium – capillary endothelium – plasma – erythrocyte membrane) is approximately 1 mm. To balance the smaller partial pressure difference, carbon dioxide is capable of overcoming the diffusion path 23 times easier compared to oxygen (better diffusion conductivity). Consequently, respiratory gases are transported alternating by convection across long distances (ventilation, circulation) and diffusion on thin interfaces (gas/fluid in the case of alveoli and blood/tissue at the periphery).     When complete, select the X in the upper-right corner to close the window and continue. Good laboratory practice dictates that a quality control program be established in all laboratories. Run controls under the following conditions: at regular intervals determined by the laboratory procedures, when using a new shipment of reagents, when using a new lot number of reagent, each time a calibration card is scanned, whenever test results are in doubt, or when training new operators. Refer to your laboratory quality assurance program to ensure quality throughout the entire testing process. Follow the manufacturer's storage and handling instructions for quality control material. Improper storage and handling of control materials can cause erroneous results. Refer to the control material package insert for proper handling instructions.   When working with biohazardous materials, always use universal precautions. Wear personal protective equipment, including safety glasses, and gloves. Composition and properties of hemoglobin The main responsibility of the blood as a transport system consists in the supply of all cells and tissue of the body with oxygen and the simultaneous elimination of the metabolic product carbon dioxide. In the blood, 98% of oxygen is chemically bound to hemoglobin. The hemoglobin molecule (Hb) consists of four protein chains (2 α-, 2 β-chains) with a pigment component each (heme). The bivalent charged iron ion in the heme structure is relevant with respect to the oxygen transport. An oxygen molecule is co-ordinatively absorbed in the pulmonary capillaries. As a result, 1 mol of Hb is capable of binding 4 mol of oxygen. The process of oxygen absorption is referred to as oxygenation and the product as oxyhemoglobin (O2Hb). Conversely, deoxygenation yields deoxyhemoglobin (HHb). A proton (H+) is reversibly absorbed in the free bonding site of the Hb molecule. The term "Oxygenation" indicates that the O2 absorption takes place without a change in the oxidation numbers; i.e., iron remains bivalent and oxygen remains at oxidation level "0".              HHb + 4 O2 ⇔ Hb(O2)4 Deoxyhemoglobin          Oxyhemoglobin The bonding capability (capacity) of hemoglobin with oxygen is described by means of Hüfner’s number and amounts to 1.34 mL of O2  per g of Hb (in the practice, the theoretical value of 1.39 is never achieved due to the presence of non-oxygenizable hemoglobins). For a hemoglobin concentration of 15 g/dL, it is 20 mL of O2 per 100 mL of blood. A maximum of 1 L of oxygen can be transported with a blood volume of 5 L. The oxygen binding capability of hemoglobin depends on the pH, pCO2, pO2, the erythrocyte metabolite 2,3-Diphosphoglycerate (DPG) and the temperature (see oxygen dissociation curve). In addition, hemoglobin is capable of binding part of the carbon dioxide that develops during the cellular metabolism and of releasing it again in the lungs. Consequently, hemoglobin plays a central role in the transport chain for respiratory gases and is a unique example for an energy supplier that directly recycles the accumulated waste product. Select Next to continue.     Illustration of the hemoglobin structure. Each of the 4 protein chains contains a heme structure consisting of 4 pyrrole rings and an iron (II) ion in the middle. Selecione o link abaixo para visualizar ou imprimir o diagrama de fluidos do IMT. Lembre-se que este diagrama também pode ser encontrado no Apêndice do Guia do Operador e em seu instrumento. The hemoglobin analysis supplies important information for the evaluation of the function of the oxygen transport system. The requirement to determine the hemoglobin levels leads to the development of various methods to concentrate the total hemoglobin, hemoglobin types and dyshemoglobins. The hemoglobin capacity and hence the transport capability of oxygen is altered by the presence of dyshemoglobins and toxins. Human hemoglobin consists of: 97–98% of HbA1 (2 α- and 2 β-protein chains) < 3% of HbA2 (2 α- and 2 Δ-chains) < 1% of HbF (2 α- and 2 γ-chains) and reacts with various substances to become complexes or fractions Dyshemoglobins impair the bonding capability of oxygen. You will learn more about hemoglobin derivatives in the Blood Gas: Clinical Significance online training course. Hemoglobin Derivatives Learn about the types of hemoglobin fractions. Tab TitleTextO2HbOxyhemoglobin The process of oxygen absorption is referred to as oxygenation and the product as oxyhemoglobin (O2Hb).HHbDeoxyhemoglobin Deoxygenation yields deoxyhemoglobin (HHb). A proton (H+) is reversibly absorbed in the free bonding site of the hemoglobin molecule.HbFFetal Hemoglobin Up to the 3rd month of pregnancy, embryos have almost 100% of fetal hemoglobin (HbF), while the number for a five month old infant is only 10%. The oxygen affinity of HbF is higher compared to the adult hemoglobin HbA1 found in the blood of adults.MetHbMethemoglobin In addition to oxygenation, oxidation of iron (Fe++) with iron (Fe+++) is also possible; as a result, this so-called methemoglobin (MetHb) is no longer available for oxygen transport. The content of methemoglobin in human blood is normally very small (approximately 1%); exposure to certain toxins and medications or certain illnesses can cause cyanosis or hypoxemia.COHbCarboxyhemoglobin  Carbon monoxide is bound to hemoglobin at the same position as the oxygen molecule to form carboxyhemoglobin (COHb). However, the affinity of carbon monoxide to hemoglobin is greater compared to oxygen. When inhaling a gas mixture containing CO in addition to O2, the formation of oxy- and carboxyhemoglobin depends on the ratio of the partial pressures of both gases according to: COHb/O2Hb = M x pCO/pO2 where M = 300 (according to Haldane), meaning that the affinity of CO to Hb is 300 times greater compared to O2. CO bound to hemoglobin is released from the hemoglobin bond much slower compared to O2. The CO affinity is pH-dependent and peaks at pH 7.35. Carbon monoxide intoxication is very dangerous because CO is odorless and the early symptoms such as headache, nausea and dizziness are unspecific. As little as 0.5% of carbon monoxide in the surrounding air (inspiration air) can block 90% of the hemoglobin for oxygen transport. When complete, select the X in the upper-right corner to close the window and continue. Nesta seção, você aprenderá como eletrólitos são medidos no multissensor QuikLYTE® após as amostras serem movidas até a torre. The following blood gas parameters are available to evaluate the sufficient oxygen supply and hence the optimal function of the organism: pO2 (oxygen partial pressure, indicator for the oxygen uptake in the lungs) sO2 (oxygen saturation, oxygen transport indicator) ctO2 (oxygen concentration, oxygen supply indicator) determination of the hemoglobin derivatives (indicator for the hemoglobin/oxygen affinity of the tissue): oxyhemoglobin, deoxyhemoglobin, carboxyhemoglobin, and methemoglobin. You will learn more about each of these tests in the Blood Gas: Clinical Significance online training course. Select Next to continue.   Parabéns! Você concluiu o treinamento do módulo de Tecnologia de Multissensor Integrado (IMT) do sistema integrado de Química Clínica Dimension® RxL Max®. Depois de ter revisto o conteúdo desta página, você pode proceder para a avaliação. In life-threatening situations, in addition to ordering a blood gas analysis to immediately assess a patient’s acid-base metabolism and oxygen status, physicians also order tests to quickly evaluate the patient’s electrolyte and metabolic functions. Let us get an overview of these areas. You will learn more about the individual tests performed in the Blood Gas: Clinical Significance online training course. Select Next to continue.   The distribution of the electrolytes in the body and hence their concentration (osmolarity in [mmol/l] or osmolarity in [mmol/kg]) represents a sensitive balance that is crucial to a number of biological control mechanisms, the induction of enzymatic activities, transfer of action potentials via nerve fibers, etc. The electrolyte and water metabolisms are intrinsically tied to one another. Na+, Cl–  and HCO3- are more prevalent in extracellular fluid (blood plasma and interstitial fluid) K+, hydrogen phosphate and proteins are more prevalent in intracellular fluid. The electrolyte and water metabolism can be impaired in a life-threatening manner by various illnesses. Generally, water deficit causes dehydration and too much water causes hyperhydration. The concentration of sodium ions in the body is by far the greatest; consequently, their influence is the highest. Download and print a copy of the Distribution of Electrolytes and Water in the Human Body. Download and print a copy of the Electrolyte Concentrations. Impaired Electrolyte Metabolism Learn more about impaired water and electrolyte metabolism with regard to sodium concentration. The concentration of sodium ions in the body is by far the greatest; consequently, their influence is the highest. Depending on the concomitant sodium loss or excess, the disorders are further divided into three types each: Isotonic disorder refers to regular osmolarity (loss and excess of sodium and water are balanced). Hypotonic disorders cause reduced osmolarity (sodium concentration is decreased compared to the available water supply). Hypertonic disorders result in increased osmolarity (the sodium concentration. When complete, select the X in the upper-right corner to close the window and continue. Carbohydrates, fats and proteins are the three most important nutrients we ingest in our diets. They are the main energy suppliers and key components for the organism. During not physically challenging work, half of the energy requirement is provided by carbohydrates. Their digestion (decomposition into simple sugar molecules) starts in the mouth with the help of Ptyaline (commonly known as salivary amylase), an enzyme produced by the salivary glands. Those metabolically converted substances are referred to as metabolites. They include the intermediate products of the intermediary metabolism or compounds synthesized by the organism. One of these metabolites is glucose, the most important energy source and molecule of the carbohydrate group. It is generated during the enzymatic cleavage of more complex carbohydrates and resorbed in the small intestine. From here, three basic metabolic paths are possible: if energy is not required immediately, glucose can be stored in the liver and musculature as glycogen. In addition, glucose can be converted into other sugars or into intermediate products linked to the metabolism of fatty acids and triglycerides, or the formation of amino acids. Lactate is the salt of lactic acid and an end product of the glucose metabolism. Download and print a copy of Lactate: Biochemistry, Physiology, and Pathophysiology. Download and print a copy of Glucose: Biochemistry, Physiology, and Pathophysiology. Download and print a copy of Total bilirubin in neonates: Biochemistry, Physiology, and Pathophysiology. Glycolysis Learn more about glycolysis. To obtain its key position within the energy metabolism of the human body, the metabolite glucose is decomposed. Aerobic Glycolysis The oxidative glucose decomposition takes place under aerobic conditions, yielding energy and the end products carbon dioxide and water: C6H12O6 + 6 O2 → 6 CO2 + 6 H2O + Energy (36 mol ATP) Anaerobic Glycolysis An alternative decomposition path under anaerobic conditions exists too: it generates lactate and a much smaller energy recovery: C6H12O6 → 2C3H6O3 + Energy (2 mol ATP) C3H6O3 ⇔ C3H5O3- + H+ Anaerobic glycolysis represents the main energy supply of cells and tissue, which sometimes require large amounts of energy under anaerobic conditions (skeletal musculature) or are poorly supplied with oxygen (retina, cartilage). Glycolysis is especially important for the erythrocytes, because they are lacking the cell organelles (mitochondria) required for the aerobic energy recovery.   When complete, select the X in the upper-right corner to close the window and continue.