okay so today we will discuss fluid electrolyte and acid base balance body water content infants have the most water 73 percent of their body weight is water so why the infants have the most water because they have less body fat and less bone mass adult males have about 60 percent water whereas adult females have around 50 percent of water so the adult males have more water because they have more skeletal muscle and less adipose tissue in comparison to females elderly male and female has around 45 percent water so the amount of the water in the body depends upon the age depends upon whether male or female two main flute compartments so intracellular fluid means fluid which is inside the cells so two by third volume of the fluid is located in the in inside the cells so it is intracellular fluid extracellular fluid as the name says it is outside of the cells and one by third volume of the fluid is extracellular fluid plasma which is the fluid part in the blood actually and interstitial fluid is the fluid which is located between those microscopic species between the cells is known as interstitial fluid and lymph cerebral spinal fluid humor of the eye all these are considered iso interstitial fluid so let us see intracellular fluid located inside the cell two by third like volume of the fluid is intracellular fluid whereas one by third is interstitial food water is considered a universal solvent why universal solvent because we can dissolve sugar salt many chemicals in the water so that is the reason it is known as universal solvent electrolyte and non-electrolyte non-electrolyte actually they do not dissociate into ions when they are placed in the water so that is the reason they are called non-electrolyte most of the organic molecules are non-electrolyte such as glucose urea amino acids they do not dissociate in water so they are known as non electrolytes electrolytes like sodium chloride potassium chloride calcium chloride they dissociate into ions in water ions are the charged particles so most of the inorganic salt as i said sodium chloride potassium chloride calcium chloride magnesium chloride they are electro light and those ions conduct the electric current so they are electrolytes electrolytes play a very important role in maintaining the osmotic pressure of the body fluid electrolytes have more greater ability to cause the fluid shift because water moves from low osmolality to higher osmolality it the concentration of the electrolyte is expressed in milli equivalent per liter we need a certain concentration of sodium in our body fluids we need a certain concentration of chloride a certain concentration of potassium so extracellular and intracellular fluid so no extracellular fluid is located outside the cell and the major cation which is found in extracellular fluid is sodium so sodium is found mainly in the extracellular fluid whereas intracellular fluid the major cation is put in here so most potassium is found in the intracellular fluid and more most sodium is found in the extracellular fluid osmotic and hydrostatic pressure they regulate the exchange between the intracellular fluid and the extracellular fluid water always moves from low osmolality towards high osmolarity so as the concentration of extracellular fluid increases means the osmolality of extracellular fluid increases water leaves the cell and water moves into extracellular fluid as the osmolality of extracellular fluid decreases water enters into the cells so like for example if you eat salty pretzel without drinking what happens to the volume of your extracellular fluid so if you eat salty blood cells your extracellular fluid volume will expand even if you do not ingest fluid why because water will flow by osmosis from the intracellular fluid to the extracellular fluid so the as the osmolality of the extracellular fluid increases water leaves the cell and it moves into the extracellular fluid so understand that water intake must equal to water output so now water input and water output is maintained actually we like total intake is about 2.5 liter a day so most of the water intake is through ingested food like fruit vegetables we are eating they have water we are drinking fluids they have water some of the water is formed in the body by metabolism water output most of the water output is through kidneys as kidneys filter the blood 60 percent water from the body goes out through the urine in sensible water loss like there is a continuous water loss through evaporation water evaporates from our skin as we exhale some water goes out with the exhalation perspiration feces so that is the way the water output and water input is maintained osmolality is maintained around like 280 to 300 milli osmo so if the osmolality of extracellular fluid increases we feel thirsty and more adh is released from the posterior lobe of pituitary gland or if the osmolality of extracellular fluid decreases then the thirst center is inhibited and the release of antidiuretic hormone from posterior pituitary is also inhibited so you see here water intake and water output is maintained we like the water intake is about two thousand two point five liter the same way the water output is also two point five liter so normally it is maintained now regulation of water intake so this is important to understand thirst mechanism we feel thirsty and that is the way like is a driving force for water intake so why we feel thirsty for example when the concentration of or osmo leg concentration of extracellular fluid increases we have osmo receptors these osmo receptors are located in the hypothalamus of the brain and osmo receptors detect anything in the osmolality of extracellular fluid so as the concentration or the osmolality of extracellular fluid increases these osmo receptors get activated they get activated by increase of plasma osmolality even if it increases by one or two percent or the osmo receptors are stimulated by dry mouth because when the osmolality of ecf increases thick saliva is produced and we have a dry mouth so it stimulates osmo receptors decreased blood volume or pressure so decreased blood pressure is detected by barrow receptors and the baroreceptors actually stimulate the release of angiotensin second so in this slide the most important thing to understand is where the osmo receptors are located they are located in the hypothalamus how the thirst centered is inhibited the thirst center is inhibited by activation of rese stretch receptors in the stomach so as we drink water we have the stretch receptors in the stomach and the small intestine and they feel stretching so the thirst center or osmore receptors they are inhibited by activation of is stretch receptors in the stomach another thing is is activated when chemoreceptors detect increased solute concentration so the thirst center is activated when the chemoreceptors detect any increased solute concentration of the extracellular fluid and the thirst center is also activated when the blood pressure goes down and more and so when the blood pressure goes down below receptors send the message and angiotensin second is released increased engines said so drinking of water inhibits the thirst center as i talked in the previous slide like as soon as we drink water before the water is absorbed in the blood we quench our thirst why relief of dry mouth the mucosa of the mouth gets wet activation of the stomach as the water goes into the stomach stomach feels like the receptors feels like stretching so the thirst is inhibited by the activation of this stomach stretch receptors solute concentration and volume of urine so now we will talk about solute concentration and volume means dilute urine or concentrated jury that depends on fluid intake our diet and water losses like suppose we are sweating too much then the concentrated urine will be produced so influence of antidiuretic heart antidiuretic hormone is released by the posterior lobe of the pituitary gland and as anti-disuretic