The Kidneys (GCSE)

Hiya! Today we're looking at the kidneys as part of the endocrine system topic! Enjoy!

         Urine production relies on a hormone called ADH (antidiuretic hormone) which controls how much water should be reabsorbed by the kidneys. If there is low water levels in the blood, the pituitary gland will release more ADH which will cause the kidneys to retain more water and the urine concentration will be higher.

The production of urine goes as follows;

1.       Excess proteins are digested by enzymes into amino acids

2.       The liver removes these amino acids (deamination) and produces ammonia (toxic!)

3.       In the kidney, the toxic ammonia is converted into less toxic Urea

4.       This urea is diluted with water (different concentration based on ADH)

5.       The urine is passed out of the body

          In the kidneys, small molecules can leave through millions of tubules. Larger molecules like RBC (red blood cells) and large proteins remain in the blood whereas smaller molecules like glucose and water can diffuse through and be reabsorbed. This is called selective reabsorption. 

        If a person has blood in their urine, it can be a sign of kidney failure as the linings are allows larger particles through which shouldn’t be there. Kidneys are hard-working organs which help to filter through toxins and allows waste products to be removed from the body; but if something goes wrong you can have kidney failure. Kidney failure can be caused by infections, injuries and an accumulation of waste and salts. Kidney failure is dangerous;

-          Toxins like urea may not be passed out of the body

-          Levels of glucose and water can be affected due to failed selective reabsorption

-          The Kidney’s tubules can gain holes so selective reabsorption can fail and blood can enter the urine.

Kidney failure can be treated using dialysis which is removing waste and excess fluid from the blood using an artificial kidney machine (dialysis machine). Patients attach themselves to a machine for 4+ hours at a time to remove built up matter from when they’re not connected to the machine. The dialysis fluid in the machine has the same concentration of glucose and ions as in the body so as not to disturb concentration levels. However the dialysis solution contains a lower concentration of the waste and salts so that they can diffuse out of the body.

Update! Just came across a question about dialysis and treatment so had to do some quick research into it. Patients can have dialysis (as above) or have a kidney transplant. The advantages and disadvantages are as below;
Dialysis Disadvantages

• DISADVANTAGE- Dialysis is a very time consuming process and requires patients to be attached to machines for several hours a week 
• DISADVANTAGE- The machines and fluid are expensive
• DISADVANTAGE- Only works for a limited time for a patient 

Advantages

• ADVANTAGE- Greatly reduced levels of urea 
• ADVANTAGE- No overall change to blood glucose levels
• ADVANTAGE- Correct water and ion levels returned