Sports and Nutrition Exam 3 guide Tony Berardi 1 Describe the average fluid distribution functions of water relative tissue content and daily water balance both under normal and exercise conditions The average male is composed of 60 water and a female is 55 water Out of that 60 2 3 of it is intracellular fluid ICF and 1 3 is extracellular ECF and breaking the EFC down further is 80 interstitial between cells and 20 composes the plasma Water has many essential functions such as thermal heat capacity many reactions lubrication transport and an ionization medium for electrolytes Basically any question involving the function of water is all of the above If you want to look at the content is the tissues the skin organs blood and muscle the most content all are 75 or more water Adipose is only 10 water unless the person is really really really fat Under normal conditions water intake is around 2500ml and is mostly from ingested liquid Output is mostly through the urine In exercising conditions intake is obviously greater at 5000ml and is from an increases ingested liquid water from food is the same Urine output is decreases substantially because the body wants to hold onto the water most is lost through the skin 2 Know the body content functions daily intake and concentrations of electrolytes discussed in class The two important electrolytes are sodium and potassium Sodium is present in the extracellular fluid at about 65g and is involved mainly in the conduction of action potentials and maintaining the electrical gradient It also controls the osmolality and acid base balance as you will see later Since it is an extracellular electrolyte large amounts can be found in the sweat and plasma The AI is 1500mg d and the UL is 2500mg d but of course most Americas consume 1500 5000mg d big factor to cause hypertension and cardiac problems if interested Potassium is an intracellular electrolyte and has the same functions as sodium content of about 180g in the body Most is thus in the cell The AI is 4700 mg d and most people don t actually meet this number and it is readily lost in the body Some things to know that are extra information is that hypercalemia huge excess potassium can cause dangerous arrhythmias and be life threatening it fucks up membrane conduction by lowering the resting potential of the heart and this makes it harder to generate contractions An injection of potassium can kill a person in seconds lethal injection 3 Understand the equation to determine Net Filtration Pressure and be able to use this equation to solve a problem This equation will let you know if the fluid will be filtered leave capillary or absorbed enter capillary Blood always flows from the heart to artery to arteriols then capillarys and based on pressures the water will act accordingly On the arterial end of the capillary the hydrostatic pressure is greater water pressure in capillary and the osmotic pressure is lower proteins and such so it will have a net of water being filtrated with the net filtration pressure heading out of the capillary On the venous end the reverse is true Blood osmotic is high thus net filtration pressure will be going into the cell Now to the formula just plug in the numbers into the formula He will give you the blood hydrostatic pressure the blood osmotic pressure interstitial fluid and interstitial osmotic pressure Those last two are just numbers you will need to determine the net filtration pressure The formula is Hydrostatic interstitial osmotic Osmotic interstitial fluid If the final value is positive then you have filtration and negative is reabsorption 4 Identify which factors regulate fluid balance Describe how each factor influences fluid balance Which is primary response long term etc Fluid balance is regulated in the body by several precise mechanisms The first mechanism is actually dehydration When an individual is dehydrated several things happen their plasma volume drops which decreases their blood pressure this response initiates the rennin system rennin cascades to activate angiotensin 2 this stimulates thirst recepetors in the hypothamus then one drinks and returns fluid level back to normal This is a quick response happens whenever one gets thirsty Now to explain the hormones in detail One thing you that will help you understand is to realize that EVERYTHING in the body happens through a cascade cause and effect one thing always causes another The first hormone is ADH which is released from the posterior pituitary This hormone increase water reabsorption from the collecting ducts in the kidney increasing ones plasma volume So one first gets an increase in osmolarity because water content decreases so it is more concentrated this stimulates osmorereceptors in the hypothalamus they stimulate the posterior pituitary to release ADH ADH then helps reabsorb water in the collecting ducts This will result in concentrated urine super yellow because you are absorbing the water from the kidneys and its osmolarity is increasing More importantly plasma volume is increased osmolarity drops in the blood The second mechanism accomplishes the same end result to increase plasma volume but does it through a different mechanism The rennin aldosterone mechanism works to increase the Na absorption in the collecting ducts and water follows Na because of osmosis thus the end effect is the same to increase plasma volume This is stimulate when plasma volume decrease and this stimulates the JX cells of the kidney this releases rennin rennin cleaves angiotensinogen inactive protein to angiotensin 1 then in the lungs angiotensin 1 is cleaved to angiotensin 2 ACE does this and this is what ACE inhibitors stop angiotensin 2 now acts on the adrenal gland to release aldosterone aldosterone then acts the reabsorb Na vasoconsticts the blood vessels This will result in an increases plasma volume Aldosterone also increases potassium secretion to help maintain that electrolyte balance So through these two mechanisms fluid volume is regulated ADH is more of a short term mechanism and rennin aldosterone is more long term acting slow acting 5 Describe physiologically how dehydration affects fluid balance in the different compartments osmolality sweating and performance at varying levels of hypohydration Are there any differences between men and women Dehydration causes another cascade of events that will lead to decreased performance and possible serious health problems When one gets dehydrated most of