(for further detais, see thermoregulatory mechanism, chap. 2, sex. XD). Various gastrointestinal secretions (gastric juice.
pancreatic juice etc.) together form about eight liters by volume per day. However, almost the entire quantity (barring about 100 ml. which excreted via feces) of it is reabsorbed so that normally this is not an impotent channel of water loss In some pathological states (severe diarrhea, cholera, severe vomiting) this. however, becomes an important channel of loss It is to be remembered that in diarrhea, the loss of water as accompanied by sodium loss Vomiting causes (in addition to water loss). loss of H+ as well as Cl- ions Distribution of Electrolytes Major electrolytes of the body are cations, Na+, K+, Ca+, and Mg++ among, CL- HC03; phosphate (HP04- ), organic anions and proteins. The concentrations of them in the ECF differ sharply from those in the ICF (table 8. 3 .2). Table: 8. 3.2 The principal inorganic ions of the plasma and ICF Note that :(i) The concentration of the inorganic ions differ sharply between plasma and the ICE (ii) Note also, In the above tale, between the sun totals of anions and cations they is a difference or gap. The gap is called the 'anion gap, The value of anion gap in plasma. In health, is between 10-15 m moles/1 The anion gap is reduced in conditions knowing as metabolic acidosis' (e.g. diabetic coma, where there is accumulator of acid metabolism). (or all practical purposes, anion gap Is measured as Na+ - (Cl-+HC03 the followings are also to he remembered (i) The concentration of inorganic ions. (both cations and ions) in the plasma and intestinal fluid (tissue fluid), although not exactly identical, are remarkably close But protein concentrations are Sharply different Plasma protein concentration is high out The protein concentration in the interstitial fluid is low. (This is because the capillary walls are freely permeable to the inorganic ions but not so to the protein molecules because of their bigger diameters). (ii) Although the compositions of ECF and ICF are vastly different, the osmolality of these two fluids are perhaps same Channels of electrolyte gain and loss Channels of gain under normal circumstances are: (1) food. This is the fundamental channel. However, people vary in their tastes Some persons and indeed some nations are more addicted to common salt (NaCI) and such persons use excess salt in their foods or prefer salty foods An 'average' man usually consumes about 4 gm of sodium in his daily food, (2) drinking water also contains, traces of sodium NaHC03 is a common ingredient of various medicinal mixture used for the treatment of various diseases in gestation of such mixtures therefore becomes additional source of sodium gain. Vegetables and fruits are usually rich in potassium Some medicines are rich potassium salts like KCI. Under normal conditions major channels of electrolyte loss are (1) Kidney and (2) seat Sweating. however. in cold climates is minimum, therefore, in cold climate. for practical purposes, the only Important channel through which Na+ and K+ are lost, is the urine Na+ and K+ loss via kidney are controlled by several factors, lite (i) aldos terone, (II) natriuretic hormone (the third factor) and the (iii) changes in GFR (for further details, see chap 2, sec. (viii) On the other hand, in very hot clmates, sweating may be severe, and can cause loss of as much as 20 gms. of sodium and 2 gms of potassium in a snigle day Under abnormal condtions, heavy amounts of sodium may be lost via feces (as in diarrhea) ABNORMALITIES OF ELECTROLYTIC BALANCE I. Sodium depletion Causes For practical purposes. It may be assumed that sodium deficiency occurs as a result of excessive loss of Na and not due to its diminshed intake. Thus, excess loss can occur through the renal route, examples are (i) Addison disease, where there is lack of aldosterone. (ii) in chronic pyelonephritis (salt losing' nephrrtis) where tubular atrophy may bf remarkable Loss of electrolyte rich fluid through alimentary tract (severe diarrhea), through skin (severe sweating/burn) can also cause heavy sodium depletion. Pathophysiology as the sodium is depleted, the following chain of events develop as a compensatory mechanism.
Sodiium loss from the ECF fall of the osmolality of the ECF stoppage of ADH secretion eilmnation of large volume of water by excessively dilute urine This restores the osmolality of the ECF no doubt but causes a shnkage of The volume of the ECf (plasma * interstitial flud) The signs and symptoms are largely due to this shrinkage if me loss of sodium continues, further compensatory mechanisms are called into ancon Thus, fall of osmofalrry of the ECF Dmovement of ECF water to Inside of the ceils swelling of the cells. Many late stage signs and symptoms of sodium depletion are due to cellular swelling Therefore, the conclusion is sodium depletion, as a rule, is associated with water depletion, so that the clinical picture is a combined depletion of sodium and water Clinical features. The clinical features is a severe case are In the expected lines Owing to The shrinkage of the plasma. (i) the blood pressure falls, The patient might develop visual black outs on attempts to stand As the BP falls, compensatory mechanism, in order to combat with the falling BP, appear, as explained In hemorrhagic shock (chap 12. sec V), signs of these ate tachycardia, pillar and cold extremities The GFR falls (provided that fall of BP is sufficient ally severe so as to override the renal autoregulalron) - this leads to original/anuria and uremia, (11) (he plasma sodum concentrator surprisingly, may remain within normal limit This is because of the operatun of the compensatory met ha nems trying to keep the osmolality of the plasma normal Only in very severe conflrtons plasma sodum values become subnormal Thirst not a prominent symptom, because the plasma does not become hypertonic. Only in exceptional circumstances, a picture of pure sodium deficiency can be fomd Assume, there has been heavy sodium loss due to, say. excessive sweating and the subject has taken repeated excess amounts of plain drnung water, this causes a compensate of water crass but no compensation of sodium loss Severe degree sodium loss. as a rule, causes loss Of K+ ions also In addition, there is also disturbances of add base balance These will be discussed later Pure water depletion The condition is rare in adults Children are more susceptible, as their ability to concentrate the urine is rather less satisfactory in adults, lying in a state of coma, this condition may be seen Pathophysiology The chain of even will be loss
pancreatic juice etc.) together form about eight liters by volume per day. However, almost the entire quantity (barring about 100 ml. which excreted via feces) of it is reabsorbed so that normally this is not an impotent channel of water loss In some pathological states (severe diarrhea, cholera, severe vomiting) this. however, becomes an important channel of loss It is to be remembered that in diarrhea, the loss of water as accompanied by sodium loss Vomiting causes (in addition to water loss). loss of H+ as well as Cl- ions Distribution of Electrolytes Major electrolytes of the body are cations, Na+, K+, Ca+, and Mg++ among, CL- HC03; phosphate (HP04- ), organic anions and proteins. The concentrations of them in the ECF differ sharply from those in the ICF (table 8. 3 .2). Table: 8. 3.2 The principal inorganic ions of the plasma and ICF Note that :(i) The concentration of the inorganic ions differ sharply between plasma and the ICE (ii) Note also, In the above tale, between the sun totals of anions and cations they is a difference or gap. The gap is called the 'anion gap, The value of anion gap in plasma. In health, is between 10-15 m moles/1 The anion gap is reduced in conditions knowing as metabolic acidosis' (e.g. diabetic coma, where there is accumulator of acid metabolism). (or all practical purposes, anion gap Is measured as Na+ - (Cl-+HC03 the followings are also to he remembered (i) The concentration of inorganic ions. (both cations and ions) in the plasma and intestinal fluid (tissue fluid), although not exactly identical, are remarkably close But protein concentrations are Sharply different Plasma protein concentration is high out The protein concentration in the interstitial fluid is low. (This is because the capillary walls are freely permeable to the inorganic ions but not so to the protein molecules because of their bigger diameters). (ii) Although the compositions of ECF and ICF are vastly different, the osmolality of these two fluids are perhaps same Channels of electrolyte gain and loss Channels of gain under normal circumstances are: (1) food. This is the fundamental channel. However, people vary in their tastes Some persons and indeed some nations are more addicted to common salt (NaCI) and such persons use excess salt in their foods or prefer salty foods An 'average' man usually consumes about 4 gm of sodium in his daily food, (2) drinking water also contains, traces of sodium NaHC03 is a common ingredient of various medicinal mixture used for the treatment of various diseases in gestation of such mixtures therefore becomes additional source of sodium gain. Vegetables and fruits are usually rich in potassium Some medicines are rich potassium salts like KCI. Under normal conditions major channels of electrolyte loss are (1) Kidney and (2) seat Sweating. however. in cold climates is minimum, therefore, in cold climate. for practical purposes, the only Important channel through which Na+ and K+ are lost, is the urine Na+ and K+ loss via kidney are controlled by several factors, lite (i) aldos terone, (II) natriuretic hormone (the third factor) and the (iii) changes in GFR (for further details, see chap 2, sec. (viii) On the other hand, in very hot clmates, sweating may be severe, and can cause loss of as much as 20 gms. of sodium and 2 gms of potassium in a snigle day Under abnormal condtions, heavy amounts of sodium may be lost via feces (as in diarrhea) ABNORMALITIES OF ELECTROLYTIC BALANCE I. Sodium depletion Causes For practical purposes. It may be assumed that sodium deficiency occurs as a result of excessive loss of Na and not due to its diminshed intake. Thus, excess loss can occur through the renal route, examples are (i) Addison disease, where there is lack of aldosterone. (ii) in chronic pyelonephritis (salt losing' nephrrtis) where tubular atrophy may bf remarkable Loss of electrolyte rich fluid through alimentary tract (severe diarrhea), through skin (severe sweating/burn) can also cause heavy sodium depletion. Pathophysiology as the sodium is depleted, the following chain of events develop as a compensatory mechanism.
Sodiium loss from the ECF fall of the osmolality of the ECF stoppage of ADH secretion eilmnation of large volume of water by excessively dilute urine This restores the osmolality of the ECF no doubt but causes a shnkage of The volume of the ECf (plasma * interstitial flud) The signs and symptoms are largely due to this shrinkage if me loss of sodium continues, further compensatory mechanisms are called into ancon Thus, fall of osmofalrry of the ECF Dmovement of ECF water to Inside of the ceils swelling of the cells. Many late stage signs and symptoms of sodium depletion are due to cellular swelling Therefore, the conclusion is sodium depletion, as a rule, is associated with water depletion, so that the clinical picture is a combined depletion of sodium and water Clinical features. The clinical features is a severe case are In the expected lines Owing to The shrinkage of the plasma. (i) the blood pressure falls, The patient might develop visual black outs on attempts to stand As the BP falls, compensatory mechanism, in order to combat with the falling BP, appear, as explained In hemorrhagic shock (chap 12. sec V), signs of these ate tachycardia, pillar and cold extremities The GFR falls (provided that fall of BP is sufficient ally severe so as to override the renal autoregulalron) - this leads to original/anuria and uremia, (11) (he plasma sodum concentrator surprisingly, may remain within normal limit This is because of the operatun of the compensatory met ha nems trying to keep the osmolality of the plasma normal Only in very severe conflrtons plasma sodum values become subnormal Thirst not a prominent symptom, because the plasma does not become hypertonic. Only in exceptional circumstances, a picture of pure sodium deficiency can be fomd Assume, there has been heavy sodium loss due to, say. excessive sweating and the subject has taken repeated excess amounts of plain drnung water, this causes a compensate of water crass but no compensation of sodium loss Severe degree sodium loss. as a rule, causes loss Of K+ ions also In addition, there is also disturbances of add base balance These will be discussed later Pure water depletion The condition is rare in adults Children are more susceptible, as their ability to concentrate the urine is rather less satisfactory in adults, lying in a state of coma, this condition may be seen Pathophysiology The chain of even will be loss
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