A man's water intake is sufficient. However his blood concentration is always too concentrated as it passes through his hypothalamus. Why?
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A man's water intake is sufficient. However his blood concentration is always too concentrated as it passes through his hypothalamus. Why?
Ā
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It took the diagnosis of high blood pressure (hypertension) at theage of 45 to shock Max into taking better care of himself. A formercollege football player, he had let himself go, eating too muchjunk food, drinking too much alcohol, sitting on his chubby bottomfor the majority of the last two decades, and even indulging in thefrequent habit of smoking cigars. Max's physician had to prescribetwo different antihypertensive medications in order to get hisblood pressure under control. She also prescribed regular exercise,a low-salt diet, modest alcohol intake, and smoking cessation. Maxwas scared, really scared. His father had hypertension at a youngage as well, and ended up on dialysis before dying fromcomplications of kidney failure.
Fortunately for Max, he took his doctor's advice and began adramatic lifestyle change that would bring him to his present-daysituation. Now, at the age of 55, he was a master triathlon athletewho routinely placed among the top five tri-athletes of the sameage group in the country. Max's competitive spirit had been ignitedby this, but at the same time he wanted to be first among hispeers. To that end, he hired Tracey, a Certified Clinical ExerciseSpecialist, to help him gain the edge he needed to win at the endof the race. His most immediate concern was that he wasexperiencing problems with dehydration and fatigue because hehadn't found an effective way to drink enough fluids whileexercising.
Tracey showed Max an impressive array of assessment tools forquantifying and analyzing his physiological state before, during,and after his workouts. One of the tools was urinalysis, which Maxfound a bit odd, but he dutifully supplied urine samples on aregular, prescribed basis. Tracey explained that Max's hydrationstatus was tricky due to the medication he took to control hishypertension, and that renal status (as measured in the urinalysis)was one of the tools she could use to evaluate his physiologicalstate. Tracey logs the following results of Max's urinalysisimmediately after, and six hours after, a rigorous 2-hour run.
| Time | Color | SpecificGravity | Protein | Glucose | pH |
| Before exercise | pale yellow | 1.002 | absent | absent | 6.0 |
| Immediately afterexercise | dark yellow | 1.035 | small amount | absent | 4.5 |
| Six hours afterexercise | yellow | 1.025 | absent | small amount | 5.0 |
| Max'surine is most concentrated before exercise. | |
| Max'surine is most dilute immediately post-exercise. | |
| Max'surine is least concentrated six hours post-exercise. | |
| Max'surine is most dilute before exercise. |
| True | |
| False |
| highestsix hours after Max exercises | |
| highestbefore Max exercises | |
| lowestimmediately after Max exercises | |
| lowestbefore Max exercises |
| Mostproteins pass through the glomerular membrane and are present invarying amounts in urine. | |
| Fewproteins are small enough to pass through the glomerular membrane,but the few that do are reabsorbed. So, proteins are not usuallypresent in urine. | |
| Allproteins are negatively charged and too large to pass through theglomerular membrane. So, proteins are not normally present inurine. | |
| Mostproteins pass through the glomerular membrane and are reabsorbed.So, proteins are not present in urine. |
| Glucoserequires a transport protein to get through the glomerularmembrane, so glucose in the filtrate cannot increase even whenblood glucose concentration is high. | |
| Theglomerular membrane prevents glucose from entering the filtrateunless blood glucose concentration is abnormally high. | |
| Thehigher the blood glucose concentration, the more glucose isfiltered through the glomerular membrane. | |
| Onlysmall glucose molecules can filter through the glomerular membrane,but high blood glucose concentration increases the amount ofglucose in the filtrate. |
| Thetubule cells are unable to reabsorb any glucose that enters thefiltrate. | |
| Tubulecells inhibit glucose production when blood levels areelevated. | |
| Reabsorption of glucose is limited by transport proteins. | |
| Thetubule cells actively secrete excess glucose into thefiltrate. |
| generating new bicarbonate | |
| reabsorbing bicarbonate | |
| secretinghydrogen | |
| reabsorbing hydrogen |
