1. What does it mean to inhibit the transport of sodium ions in the loop of Henle? (ie how are they
normally transported? Where to/from?)
2. Explain how this inhibition of sodium ions in the loop of Henle could help increase urine
production.
3. How will increased urine production help treat hypertension (high blood pressure) and edema?
4. What symptoms might someone experience if they have dehydration due to these
medications?
Alcohol acts as a diuretic, although it is not used clinically for that purpose. It inhibits ADH
secretion from the posterior pituitary and results in increased urine volume.
5. How can and understanding of alcohols
effects on the nephron be used to explain
many of the symptoms of a hangover due to
over consumption of alcohol? (headache,
thirst, fatigue, rapid heartbeat, memory
loss…)
Xanthines, including caffeine, act as diuretics, partly because
they increase renal blood flow and the rate of glomerular
filtrate formation. They also influence the nephron by
decreasing sodium and chloride reabsorption. Caffeine also
inhibits the release of ADH.
6. How does increasing renal blood flow result in increased urine
formation?
7. Why would caffeine in the blood cause a decrease in ADH
release?
8. Why can it be said that caffeine affects the nephron twice in
terms of limiting water reabsorption from the nephron?
1. Normally, sodium ions are transported from the filtrate in the loop of Henle back into the bloodstream. Inhibiting this transport means that the sodium ions remain in the filtrate and are not reabsorbed.
2. Inhibiting the transport of sodium ions in the loop of Henle increases the concentration of sodium in the filtrate, which creates an osmotic gradient. This gradient promotes the movement of water from the collecting duct into the filtrate, increasing urine production.
3. Increased urine production helps treat hypertension and edema by reducing the volume of blood plasma and extracellular fluid in the body. This decrease in fluid volume leads to a decrease in blood pressure.
4. Symptoms of dehydration due to medications that inhibit sodium transport in the loop of Henle may include increased thirst, dry mouth, decreased urine output, dizziness, and fatigue.
5. Alcohol inhibits the secretion of ADH, which normally plays a role in water reabsorption in the kidneys. Without ADH, more water is excreted in the urine, leading to dehydration. Headache, thirst, fatigue, rapid heartbeat, and memory loss are common symptoms of dehydration.
6. Increasing renal blood flow results in increased urine formation because it increases the hydrostatic pressure within the glomerulus. This increased pressure enhances the filtration of fluid from the blood into the nephron.
7. Caffeine in the blood causes a decrease in ADH release because it acts as an adenosine receptor antagonist. Adenosine typically inhibits the release of ADH, so when caffeine blocks the adenosine receptors, it indirectly prevents the inhibition of ADH release.
8. Caffeine affects the nephron twice in terms of limiting water reabsorption. Firstly, it directly inhibits the release of ADH, which reduces water reabsorption in the collecting duct. Secondly, caffeine decreases sodium and chloride reabsorption by influencing the nephron, leading to an increase in water excretion in the urine.