Alcohol and Urine

For the last couple of weeks, I’ve talked to you about pee… a lot. But now that we’ve got all of that good stuff down pat, it’s time to get to the point of this whole thing: the effects of alcohol on urine!

Whenever you drink alcohol, you eventually feel the need to urinate frequently. But why?!

Well, last week we learned about the two hormones that are involved in regulating the production of urine: the antidiuretic hormone and aldosterone.

Interestingly enough, alcohol has an inhibitory effect on the antidiuretic hormone. This hormone is responsible for helping the body retain water by preventing the loss of water through excretory pathways, like the urine system.

The inhibition of the antidiuretic hormone results in the loss of regulating how much water is reabsorbed in the kidneys, which means that there is an uncontrollable loss of water in your urine, which is why you feel the need to urinate a lot. Your bladder is always filled because there is no reabsorption of water in the nephron of your kidneys.

So basically, alcohol reduces the amount of water reabsorbed in the kidneys, which leads to the water ending up in your bladder and putting pressure on your urinary sphincters. And then you feel the need to urinate, even if you already went to the bathroom 10 minutes ago.

One of many life’s mysteries have been solved. The inhibition of the antidiuretic hormone by alcohol is another reason why rehydration is so important for post-drinking. You lost all of the water your body would have reabsorbed when you peed, so you need to drink even more water to save your body from being in a state of dehydration.

And that’s how alcohol affects your body’s urinary system! Next week, we’ll look into hangovers.

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The Urinary System – Concentration and Dilution

Last time, we talked about how the urinary system allows for our bodies to selectively reabsorbs things that were filtered out of our circulatory system. One of the molecules that can be reabsorbed is water, which is an important molecule for several reasons. In terms of the urinary system, water is important for the concentration and dilution of our urine.

The concentration and the dilution of urine is regulated by 2 hormones: Anti-diuretic hormone and Aldosterone.

The anti-diuretic hormone is released if you’re dehydrated, and literally translates to “against the passing of urine”. In situations where you are dehydrated, your blood volume will be low due to the lack of a sufficient amount of water, resulting in a lower blood pressure. To counteract this, the anti-diuretic acts to reduce the amount of water lost by the body and minimizes how much urine you make and release. This will result in a more concentrated urine that has a less water than usual and is a deeper yellow due to the higher concentration of urea.

Aldosterone is also released when you’re dehydrated. This hormone is responsible for the increase in thirst while also helping your body retain water by increasing the amount of sodium in your body. The more solute there is in your body, the more likely water is to stay with the solute (rules of osmosis, hurray!).

These hormones exert their effects primarily on the distal tubule of the nephron (after the loop of Henle), so that is where the water is reabsorbed!

So when these hormones are released, your urine will be more concentrated because water is retained by your body! Amazing, right?

Next week: We will finally get to talking about the effect of Alcohol on Urine!

Is there something you’d like to learn about? Tell me about it here and I may just do a post about it 🙂

The Urinary System – Selective Reabsorption

Last week, we learned about the general filtration process that occurs in our kidneys. This week, we’ll learn just how our kidneys modify the filtrate to produce urine.

The filtrate that is in the renal tubule consists of water as well as other small molecules, like sugars and urea. Some of these molecules, like sugars, can return to the bloodstream in a ‘process’ known as selective reabsorption. It’s called ‘selective’ reabsorption because the bloodstream is picky as to what it absorbs from the tubule. The molecules that leave the tubule enter tiny blood vessels next to the tubule, which are called peritubular capillaries. The molecules can then be carried through the rest of the circulatory system, to provide our body cells with nutrients (if they’re sugars).

Parts of the Kidney

Selective reabsorption mainly occurs in the proximal tubule, which is the beginning of the tubule. The proximal tubule is just after the Bowman’s capsule. Whenever a molecule leaves, it is accompanies by water, which means a lot of water is reabsorbed by the bloodstream in this process.

By returning the molecules to the bloodstream, the remaining filtrate’s composition changes. As water leaves, the concentration of particles in the tubule increases.

Hormones can affect what is reabsorbed in the distal tubule. These hormones are the anitidiuretic hormone (ADH), which is also known as vasopressin, and aldosterone. They’ll be discussed next week when we talk about Concentration and Dilution!