Sports and Nutrition Exam 3 guide 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 heavy 2 Know what thermoregulation is and how the body defends against being too hot or cold Let s review all the things that create heat in the body your BMR muscle activity TH and epinephrine Things that loss heat in the body are the process of evaporation radiation convection and conduction What is convection and conduction you ask Conduction is the transfer of heat always hot to cold via contact Convection is when warm air expands and cool air cools Say you are hot The higher than normal blood temperature 37 Celsius 98 6 Fahrenheit will activate the hypothalamus heat loss center which will do two things It will activate the sweat glands to increase heat loss via sweating and it will vasodilate vessels leading to the skin so that blood flow will increase near the surface of the body and heat will be released via radiation This will lower the temperature and then you are good Now if you are too cold Now you will activate the heat promoting center these are brilliant names and this will cause muscles to shiver create heat and cause vasoconstriction to the surface of the body so the blood is drawn to more important organs This will occur till your blood warms up If your body gets too hot it is termed hyperthermia above 105 F Heat stroke starts when the extreme temperature in the body starts to damage the organs Then hypothermia is a too low temperature 3 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 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 Under normal conditions water intake is around 2500ml and is mostly from ingested liquid somewhat food Output is mostly through the urine and skin In exercising conditions intake is obviously greater at 5000ml and is from an increased ingested liquid water from food is the same Output is much greater but urine output is decreases substantially because the body wants to hold onto the water most is lost through the skin 4 Identify which factors regulate fluid balance Describe how each factor influences fluid balance Which is primary hormone response long term response 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 renin system renin 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 Now the opposite will happen if you are not thirsty ADH release will be inhibited and thus you will not absorb more water from the collecting ducts in the kidney This will make your urine very the blood dilute Now for the Renin Angiotension system The second mechanism accomplishes the same end result to increase plasma volume but does it through a different mechanism The renin 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 stimulated when plasma volume decrease and this stimulates the JX cells of the kidney this releases renin renin 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 Angiotensin 2 is also a potent vasoconstrictor that controls blood pressure during exercise Aldosterone also increases potassium