I/GCSE Biology - Osmoregulation (2)

Have you read the previous post regarding the topic of osmoregulation in I/GCSE Biology? In this post, we'll keep on talking about it!

1. The KIDNEYS play a vital role in balancing levels of water, waste and other chemicals in the blood.
2. The brain monitors water content constantly and causes the kidney to adjust the concentration and volume of urine produced-

• When the water level of our BLOOD PLASMA is LOW, more water is reabsorbed back into the blood and the urine becomes more CONCENTRATED
• When the water level of our BLOOD PLASMA is HIGH, less  water is reabsorbed back into the blood and the urine becomes more DILUTE

In I/GCSE Biology, it's important to study the following factors!

The amount of water that needs to be reabsorbed depends on a number of factors:

• External temperature
  • High → Concentrated urine
  • Low → Dilute urine
• Level of exercise
  • High → Concentrated urine
  • Low → Dilute urine
• Fluid intake
  • High → Dilute urine
  • Low → Concentrated urine
• Salt intake
  • High → Dilute urine
  • Low → Concentrated urine

In I/GCSE Biology, ADH is commonly asked in the exam!

The concentration of urine is controlled by a hormone called ADH, which is released into the bloodstream by the PITUITARY GLAND.

1. When the level of water in the blood is too low, 
2. ADH is released and this causes concentrated urine to be produced.
3. This is because the hormone causes the kidney to make MORE PERMEABLE, allowing water to be reabsorbed.

1. When the level of water in the blood is too high,
2. ADH is NOT released.
3. The kidney becomes LESS PERMEABLE and this causes dilute, watery urine to be produced.

In I/GCSE Biology, you should know that the osmoregulation is a kind of negative feedback responses!

• Alcohol causes the kidneys to produce a greater volume of more dilute urine. This can lead to DEHYDRATION
• This is because alcohol suppresses (restrains) ADH production

• Ecstasy causes the kidneys to produce smaller volume of less dilute urine. This can result in the body having TOO MUCH water
• Ecstasy increases ADH production which means the kidneys reabsorb water

And we're done with this topic! Well Done!

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Drafted by Alyssa (Biology)

References:

1. "What Is Osmoregulation?", https://cdn1.byjus.com/wp-content/uploads/2016/07/47.png
2. "Kidney 1". Photo from the internet.

3. "Kidney 2". Photo from the internet.

4. "Water Balance", https://swh-826d.kxcdn.com/wp-content/uploads/2011/01/Renin-angiotensin-aldosterone_system.png
5. "Ecstasy", https://ichef.bbci.co.uk/news/466/mcs/media/images/54134000/jpg/_54134329_008148651-1.jpg