0:04 [music] I welcome you all to the last part of week 8 which is going to be on water balance and electrolytes. At the end of this session, the student will be able to understand the water balance, the functions of water, regulations of water metabolism and the clinical conditions of over hydration, dehydration and water intoxication in human physiology and clinical nutrition practice and also to explore the types and sources composition of body fluid electrolytes especially sodium potassium balance electrolyte abnormalities and the clinical significance in patient care and nutritional management.
0:50 Water is a major component of our human body and it approximates about 60 to 70%age of total body weight in adults. It is a universal solvent and it is basically referred to as the elixir of our life in which all biochemical reactions of the life occur and is indispensable for every physiological process. When we discuss about the body water distribution, there are different compartments that the body composition of water is constituting which is the compartment is referred to as total body water. Intracellular fluid ICF, extracellular fluid ECF and the percentage of body weight is also depicted here. So total body water is about 60%age of our human body weight
1:38 and ICF which is the intracellular fluid is about 40%age. Extracellular fluid is about 20%age and this extracellular fluid is uh being uh distributed as inter interstial fluid plasma and transcillar fluid. Interstial fluid forms about 15 percentage whereas plasma is about 5 percentage and transcillar fluid is about less than 1% of the total body water. There are lot of conditions where the total body water uh content is being affected. First being the age. As we age the uh percentage of body water content keeps varying. For infants if you see 75 to 80%age of the total body weight is
2:25 about water only. Whereas for the elderly population it's about 50 to 55%age and for gender uh there will be a variation. For women it is uh 50 to 55%age as they have more of adipost tissue. For men it is about 60%age. And uh coming to the body composition also when there is more of muscles it is about 73%age water. If it is only fat, it's only about 10%age water. And for obese individuals, the lower percentage of body water is due to the higher fat mass. So we are going to discuss about the water balance here. If you see the water balance is being accomplished by positive and negative balance. The water
3:11 balance is being uh equalizing the intake to the output over a 24-hour period maintaining the total body water at a constant level. Therefore, positive water balance means the gain is greater than the loss and the negative water balance means the loss is greater than the gain. So that's how it is being depicted. The daily water intake and the output is being referred to as uh different sources that we consume water as drinking water and beverages which is about 1,200 to,500 ml per day and from water from the food is about 700 to,000 ml per day and metabolic water as oxidized is referred to as 200 to 300 ml per day.
3:58 Therefore, the total intake of water would be 2,00 to 2,800 ml per day. And when we talk about the output, it is being uh distributed via urine about 1,00 to,500 ml based on the intake. And there will be insensible skin loss which is contributing to 3 350 to 400 ml per day. Respiratory loss also contributes to 350 to 400 uh ml per day. Sweat is being uh given as 100 to 200 ml per day in the feces about 100 to 200 ml per day. Therefore the total output would be roughly about 1,00 ml per day. We also should know about the obligatory
4:44 water loss. The minimum daily water loss cannot be avoided regardless of the intake. So if you see the minimum urine level would be 500 ml per day to excrete the metabolic waste. [snorts] Insensible loss would be 700 to 800 ml per day. Therefore the total obligatory loss would be 1,00 to,300 ml per day. So talking about the metabolism if you see this particular diagram is clearly depicting the essentiality of the water with regard to the water balance, intake and output. Water is very much essential for maintaining the body temperature and metabolism. Water intake occurs through drinks as you can see in the picture,
5:32 food and metabolic water also. Water output occurs through urine, sweat, lungs and feces. As you can see the picture here, kidneys help in maintaining the water and electrolyte balance in the body. The major functions of water include uh it being an universal solvent. It helps in the temperature regulation. it forms the major transport media structural role also and as well as the chemical reactions. So the first being the universal solvent that means water ma majorly acts as an universal solvent dissolving minerals vitamins amino acids glucose gases which enables all the
6:19 biochemical reactions. The temperature is being regulated with having a high specific heat capacity. Absorbing more of body heat. Sweating and evaporation dissipates the heat preventing the overheating uh process. [snorts] Water becomes a carrier for nutrients to cells via the blood. Removes the metabolic waste via urine, sweat and breath. The structural role is being maintained by cell tur and shape. It cushions the brain and spinal cord with the cerebrospinal fluid majorly forming as a component and it also helps in the lubricating process with joints especially it's also in the sinovial
7:06 fluid. Water is involved in the chemical reactions like hydrarolysis, condensation, oxidation reaction substrates and all that. That's the major functions of water and also it is involved in digestion like excretion acid base balance. So under digestion if you see uh it is hydraying the carbohydrate protein and fat in the gastrointestinal tract and forms as a medium for digestive enzymes as well. It dissolves and transports a metabolic waste products like ura creatinine for renal excretion. An acidbased balance is acting as a buffer via carbonic acid bio biccarbonate system and ionization of
7:52 water provides hydrogen and hydroxile ion as a part of lubricant. uh mucus, waterbased lub uh lubricants, lubricates the gastrointestinal tract, respiratory tract and reproductive organs. There will be an electrolyte imbalance that is observed for example is a medium in which electrolytes are dissolved and maintained at precise concentrations. Even for fetal production amniotic fluid uh forms a base and it protects the fetus. So everywhere water plays an important role. So a lot of functions if you see as an universal solvent temperature regulation as a transport
8:37 medium structural role chemical reaction and also for the digestion excretion acid base balance lubrication elect balance and fetal pro protection. The regulation of water balance is taking place by uh antidiuretic hormone which is also called as ADH. ADH helps in maintaining the water balance in the body. [snorts] Hypothalamus stimulates the pituitary gland to release ADH. ADH increases the water reabsorption in the kidneys and they reduce the urine output. This helps maintain the normal blood volume and osmotic pressure. So if you see the uh antidiurotic
9:24 hormone regulation, it starts with hypothalamus where uh in the transport it transports the signals to the pituitary gland which will release the antidiuretic hormone here. Antidioturotic hormone will cause more resorption of water in the kidneys thereby releasing the high sodium uh restoring the high sodium levels in the normal as a normal sodium to normal sodium. uh SIADH is syndrome of inappropriate secretion of antidiuretic hormone which occurs in a condition called diabetes incipidus where there will be a urine secretion is going to be very high.
10:10 Antidiurotic hormone regulation is represented in figure 6.2 which is being given here. And if you see how the brain uh hypothalamus is activating the hypoolmic condition where it increases the ECF sodium and colloidal osmotic pressure. Here the hypothalamus will stimulate and signal the pituitary gland. Thereby this increases the secretion of antidiurotic hormone. Therefore, the ADH will conserve water and increase the kidney reabsorption of water and decreases the urine output. It also increases the extracellular fluid volume and increases the extracellular uh fluid with the sodium concentration
10:56 and osmotic pressure and thereby this will uh bring the normal ECF colloidal osmotic pressure and blood volume. If we see uh coming to the uh food part, it triggers or stimulates the thirst and in increases the fluid intake. Thereby stimulation of thirst is always linked with sodium concentration in the body. Mechanism of ADH regulation and water balance is being activated by these things. First the stimulus, next detection, then signaling and then uh responsing then action then effect result and then goes to the negative feedback and this is how it goes. So
11:43 coming to the stimulus increase in extracellular fluid osmolality will cause or u makes a stimuli here and the osmo receptors in the hypothalamus will detect this and then it signals the posterior pituitary gland and [snorts] thereby the response is ADH is released and ADH is therefore acting on the distal tubular uh uh duct collecting ducts of the kidneys and thereby the effect is increasing the reabsorption of water and uh also the electrolytes like sodium and the result is they conserve the water and uh also they will uh decrease the osmolality and
12:30 also they raise the fluid balance and also they uh bring the blood volume into normalization. This again goes as a negative feedback. So that that's the process if you see with ADH there will be a low concentration and uh without ADH there will be an um more uh diluted urine here. So the supporting regulatory system includes uh RA which is the an angotensinogen renine angotensin aldoststerone system where angotensin 2 will stimulate the thirst and aldoststerone will lead to the sodium and water retention. arterial anti- natriotic peptide uh
13:19 where it gets released when atria is overstretched leading to promoting sodium and water excretion. Aldo also promotes the sodium reabsorption in the kidney and that thereby the water uh is uh being uh retained following the sodium. Kidneys form a primary organ of water regulation adjusting the urine volume to 500 to 20,000 ml per day. So when we talk about renin angotensin aldoststerone system. So this is the mechanism like how it is being uh happening when there is a low blood pressure in the body that gets stimulated and they will release the
14:04 renin from the kidneys. The renin will convert the angotensinogen into angotensin one. If you see that happens here and acce converts the angotensin one into angotensin 2 here. So aldoststerone therefore increases the sodium and water uh reabsorption raising the blood pressure here. If you see in the kidneys it happens that's the major mechanism here. So when the blood pressure uh is getting uh you know uh dropped so that's how the reninine is released and then renin converts angotensinogen to one and two
14:49 and then angotensin 2 will also have a role to play and then aldoststerone will increase the sodium and water reabsorption and then it raises the blood pressure. So this is the mechanism via RAS system which is the renin angotensin aldoststerone system. There are conditions where you can see that uh when there is a body uh water is lost or the intake is uh getting uh low and the water loss is exceeding the water intake. we lead to a condition called dehydration resulting in insufficient body water to maintain normal physiological functions. It is the most common fluid disorder which is encountered clinically. So [snorts] the
15:37 classification is going by uh this particular way where you can see that there is a mild dehydration. You can see about 1 to 2 percentage which is being uh identified by thirst, dry mouth, decreased urine output and dark urine is present. Can you see here? So moderate levels are from three about 3 to 5 percentage. Headache dizziness fatigue reduced skin tar and tachicardia is absorbed. Severe dehydration includes confusion, sunken eyes, rapid weak pulse, hypotension and ooligura. If the uh dehydration is very much critical about greater than 10%age, it leads to delirium, anura, circulatory failure and
16:23 death also. So the classification of uh water can be with regard to different ways with totonicity also it's being uh classified as isotonic, hypotonic and hypotonic. Isotonic is when the normal uh sodium levels are between 135 to 145 and there will be equal water and sodium loss that happens via diarrhea and vomiting. So thereby ECF volume gets decreased and hypertonic is a condition where you can see that uh the sodium levels are greater than 145. So more water it's getting lost than sodium. So it happens with fever, diabetes incipidus where the
17:10 shells get shrunken. You can see over here hypotonic is a condition where uh the sodium levels are low that is less than 135 m equivalents per liter. So more sodium is lost than water which is including uh diuretics where more usage of diuretics sweating there will be a water replacement in this condition swell cells will swell. So the causes and clinical assessment of dehydration includes causes will be inadequate intake and the loss of uh more of body fluids like vomiting, diarrhea, excessive sweating, fever, burns, diabetes condition, diuretics
17:57 usage and there is hemorrhage. How do we assess them? Using a skin ter test. So you can see the skin is being uh taken and pinched and if it is taking a long time to retract we call it as poor skin tugger capillary refill urine specific gravity is also checked serum osmolarity bun [snorts] creatin ratio everything is being looked into. Next we move on to a condition called overhydration where it is also referred to as hyperolmia. It's a condition in which the total body water is excessively increased either from excessive intake or impaired excretion leading to fluid accumulation in tissues and cellular system
18:43 circulatory system. There [snorts] are different types of de overhydration which includes isotonic overhydration, hypotonic overhydration and hypertonic overhydration. Isotonic condition includes excessive IV uh normal saline, heart failure and renal failure. The uh conditions or features that we could observe is edema, hypertension and pulmonary congestion. So hypotonic uh is could be uh seen as hyponetriia, cerebral edema and confusion. The mechanism could be because of syndrome of inappropriate antidiuretic hormone, excessive plain water intake and um if it is uh hypertonic
19:30 overhydration could be uh same as uh that which leads to hyperatriia cellular dehydration and the mechanism could be excessive IV hypertonic saline injection mineralcorticoid when that is excess in the quantity. So the signs and symptoms include with regard to different organs. So when it comes to cardiovascular it leads to hypertension, bounding pulse, raised GVP and S3 gallop. In respiratory condition we could find out pulmonary edema, dispnneia crackles on the oscultation. For renal we could observe oligura in renal failure or polyura in as a
20:17 compensatory mechanism. [snorts] Peripheral uh levels it leads to pitting edema in ankle sacrum perorbital region. uh neurological conditions. It includes headache confusion seizures.
