F.5. Urinary Pathophysiology


Introduction:
1.
As in previous chapters, we will not discuss here the pathophysiology of the urinary system caused by diseases such as cancer, infections etc.
2.
Instead, we will concentrate on pathophysiological issues that are related to normal and abnormal physiology of the urinary tract.
3.
We will discuss the following topics:
a. kidney stones
b. hangover (yes!!)
c. urethra obstruction
d. incontinence

A. Kidney Stones: top?
1.
Kidney stones can develop and accumulate in the kidney pelvis when the urine becomes more concentrated (‘darker’). This is called nephrolithiasis or urolithiasis.
(What is lithiasis?) Link: Lithiasis = formation of stones (=calculi) in the body, such as in the kidneys.
2.
This can be caused for example by dehydration, when less water is available to the body and the kidneys.
3.
Then the solutes such as uric acid may ‘precipitate’ (= this is when a compound is deposited as a solid form in a fluid).
4.
Once a small pebble is formed, it can act as a depository for more solutes to precipitate, making the stone larger.
5.
If the stones remain small, below 0.5 mm, then they will be easily discharged through the ureters and the bladder to the outside world.
6.
But if they become bigger, then they can get stuck in the system, either in the kidney pelvis, or along the ureters or in the urethra.
7.
If they are stuck, the muscle layers will make every effort to expel these stones and this is extremely painful. In addition, these stones may damage the muscle layer, thereby causing bleeding (hematuria = ‘blood in the urine’).
8.
In fact, these patients often have bouts of sudden and violent pain, called (renal) colic, in which they move restlessly, possibly with vomiting, nausea, sweating etc.
9.
If these stones are stuck, they can be removed by surgery, either by an incision or through a catheter or a scope.
10.
A new treatment is the application of shock waves (= lithotripsy), which will disintegrate the stones into fragments that can then be removed through micturition.

B. Alcohol Hangover: top?
1.
Ever had a hangover? (Of course you have!). Did you then notice that, the next day, your mouth felt very dry?
2.
Why is that? Well, drinking to much alcohol inhibits the production of ADH by the pituitary gland (in the brain).
3.
Remember that ADH =(anti-diuretic hormone) keeps the water ‘inside’ the body. When there is not enough ADH, then more water will be excreted and removed in the urine. (link)
4.
This will cause a decrease in the amount of water in your blood, decreased blood pressure, which then causes dizziness, headache, dry mouth etc. In other words, a perfect hangover! But in fact, you are actually, and seriously, dehydrated.
5.
The solution? Stop drinking alcohol and start drinking a lot of water!

C. Urethra obstruction: top?
1.
Obstruction in a ‘tubular’ system such as the urinary system is of course always dangerous (and painful).
2.
We already discussed above the problems with an obstruction such as by a kidney stone in the kidney pelvis (= nephrolithiasis) or in the ureters (= urolithiasis).
3.
Another problem could be an obstruction in the urethra. This is often the case in older males. But not by a (kidney) stone!
4.
In these (older) males, the prostate has become too big. Remember that the prostate is located below the bladder and that the urethra ‘runs’ through the gland.

Effects of an enlarged prostate on the male urethra: obstruction
5.
If the prostate hypertrophies, this may squeeze the urethra making it more difficult to urinate.
6.
This can cause pain (=dysuria), increase the frequency to urinate, maybe causing swelling of the bladder etc.
7.
In those cases, the (surgical) therapy is to ‘scrape the prostate tissue with a catheter knife running through the urethra; a TURP (= Trans Urethral Resection Prostate).

D. Incontinence: top?
1.
Urinary incontinence occurs when you ‘accidently’ lose urine. This can occur in woman and in males.
2.
In woman, accidental loss of (little) urine may occur after giving birth (vagally). During that procedure (birth!), the muscles in the pelvis and the sphincter may have been overstretched.

Symbol of male and female urinary urgency!
3.
In both genders, an overactive bladder can also cause incontinence, possibly due to an infection, cancer, or whatever.
4.
In older males, if they develop prostate cancer, then their prostate may have to be removed. This also removes the external and/or the internal urinary sphincter.
5.
Fortunately, there is an increasing amount of therapeutic options to treat such incontinence, ranging from physiotherapy (developing your pelvic muscles) to the implantation of an artificial sphincter!
Artificial sphincter in a male urethra

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F.5. Urinary Pathophysiology
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