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As in previous chapters, we will not discuss here the pathophysiology of the urinary system caused by diseases such as cancer, infections etc.
We will discuss the following topics:
Kidney stones can develop and accumulate in the kidney pelvis when the urine becomes more concentrated (‘darker’). This is called nephrolithiasis or urolithiasis. (link)
Then the solutes such as uric acid may ‘precipitate’ (= this is when a compound is deposited as a solid form in a fluid).
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.
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.
If these stones are stuck, they can be removed by surgery, either by an incision or through a catheter or a scope.
Link: Lithiasis = formation of stones (=calculi) in the body, such as in the kidneys.
Ever had a hangover? (Of course, you have!). Did you then notice that, the next day, your mouth felt very dry?
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)
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.
The solution? Stop drinking alcohol and start drinking a lot of water!
Obstruction in a ‘tubular’ system such as the urinary system is of course always dangerous (and painful).
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).
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.
If the prostate hypertrophies, this may squeeze the urethra, making it more difficult to urinate.
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).
Urinary incontinence occurs when you ‘accidently’ lose urine. This can occur in woman and in males.
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.
In both genders, an overactive bladder can also cause incontinence, possibly due to an infection, cancer, or whatever.
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.
Fortunately, there is an increasing number of therapeutic options to treat such incontinence, ranging from physiotherapy (developing your pelvic muscles) to the implantation of an artificial sphincter!
As you have seen from the previous pages, your two kidneys play a crucial role in the continuous filtering of the blood and removal of all toxic material. Without them, you would quickly accumulate toxins in your body and ultimately die!
Unfortunately, there are conditions in which the kidneys will no longer work properly. These can be infections, trauma or, most often, cancer.
If you are lucky (as happened to me), only one kidney may have to be removed. Then, the other kidney will continue to filter your blood without any problem. This is a nice example in which some of our organs are able to compensate for the loss of their counterpart.
However, in some patients, both kidneys may become damaged, perfuse less, and this may lead to irreversible damage. What can be done? Three things:
Kidney transplantation is only possible if a suitable donor is available. This is often the case in your own family but must be tested before the transplantation is performed. As stated in 3, the donor can easily live with a single kidney.
Quite often, a donor is not available and another method must be used to filter and ‘clean’ your blood; this is called dialysis.
(‘dia’= through, and “lysis=” loosening or splitting).
There are currently two types of dialysis; haemodialysis and peritoneal dialysis.
In haemodialysis, blood (=’haemo’) is pumped through a ‘kidney’ machine to filter out all the accumulated toxins in the blood.
This kidney machine was first developed in 1943 (during WW2!), is quite large and needs proper attention and cleaning. Therefore, this machine can only be used in hospitals or specialized centres.
Therefore, patients who don’t have functioning kidneys have to go regularly to such a dialysis centre. There, two tubes are inserted in their circulation, usually in the lower arm, one to the venous system and one to the arterial system.
4.
The blood from the arteries is pumped into a ‘filter’ where the toxins are removed through a semi-permeable membrane, very much like what happens at the capillary level (link).
In peritoneal dialysis, use is made of your own peritoneum. What is the peritoneum?
The peritoneum is the lining of all the organs in your abdomen. This thin membrane covers the inside of the abdominal cavity and all its organs (stomach, intestines, liver etc).
This thin peritoneum is filled with blood vessels, arteries, veins and capillaries, which makes it an excellent (semipermeable) membrane.
How do we use this membrane for dialysis? Well, a permanent catheter is inserted and placed inside the peritoneal cavity.
During this time, the solution will interact, through the semipermeable membrane, with the blood streaming through the peritoneal capillaries, thereby absorbing waste products such as urea and creatinine from the blood.
So, gradually, all the toxins in the blood diffuse into the solution in your peritoneum. After several hours, the fluid is pumped out of the peritoneal cavity and replaced with a fresh solution, and the whole process starts again.
This can be done at home (after proper training), some 3-4 times a day.
Nowadays, the system can even be automated and then can be used during your sleep!
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