Renal Lab on urine specific gravity and urine flow rate: How does fasting lead t
ID: 3517005 • Letter: R
Question
Renal Lab on urine specific gravity and urine flow rate:
How does fasting lead to high urine specific gravity? How does Coke lead to a higher urine specific gravity than water or Gatorade?
Why do water and Gatorade have a low urine specific gravity?
Why does Gatorade have a higher specific gravity than water?
How does gatorade lead to higher urine flow rate than water? Why is the urine flow rate of Coke lower than water or gatorade?
Please answer these questions using the physiological function of the renal system and what horomes like ANP or ADH do
Explanation / Answer
Fasting leads to dehydration which leads to improper fluid intake. In that case, kidneys reabsorb as much water as possible back into circulation in order to maintain blood pressure. This leaves less water per amount of solute being excreted by the kidneys, thereby raising specific gravity.
Water consists of only water molecules with no added solutes, thus making it hypo-osmotic relative to plasma. Coke consists of a high amount of glucose (sugar), water, small amount of sodium and caffeine making it hyperosmotic relative to plasma. Gatorade consists of water, glucose and electrolytes such as NaCl and K+ which makes it isoosmotic relative to plasma in active state.
In active state, body would be losing water snd solutes and Gatorade would replenish these items. When there is increase in osmolarity the osmoreceptors will detect it and will cause the hypothalamus to secrete of antidiuretic hormone(ADH) to begin to reabsorb water. The blood pressure and blood volume will be low which will cause low urine flow rate .
Gatorade consists of solutes and after consumption it increases blood pressure and volume. Gatorade function is to hydrate those when more solutes will excrete. Due to increase in blood volume the volume receptors in atrial muscle stimulate to release Atrial Naturetic Peptide(ANP) which inhibits sodium reabsorption in distal convulated tubule and increase of sodium followed by water. Increase in ANP will increase glomerular filtration rate which inturn will increase urine flow rate and decrease specific gravity. Only water consumption makes the body more dehydrated but Gatorade function to make the body hydrated. Soo water is having low specific gravity than gatorade.
Coke contains little more sugar and caffeine than gatorade.Caffeine had an effect on sodium excretion and associated water flow which causes low urine flow rate and higher urine specific gravity ( urine flow rate is inversely proportional to urine specific gravity).