I/GCSE Biology - Kidneys (2)

Do you remember the previous post regarding kidney transplant and dialysis in I/GCSE Biology? In this post, we"ll continue talking about how kidneys work in human body! 😆

• Each kidney contains thousands of tiny, microscopic tubes called nephrons.

After knowing the structure of kidneys of I/GCSE Biology, you should also memorize the following process of how kidneys work!

• Blood flows in a network of capillaries called a Glomerulus which runs inside the Bowman’s capsule of the nephron.
• The high pressure of the blood squeezes small molecules through the tiny holes such as water, urea, ions and glucose. Big molecules cannot fit through the holes and stay in the blood. This process is called filtration.

• Some substances are reabsorbed if they are useful, like glucose.
• All the glucose is selectively reabsorbed – it is moved out of the nephron back into the blood against the concentration gradient.
• Sufficient water is reabsorbed, according to the level of ADH. The process of maintaining the right water content in the body is Osmoregulation.

• Urea and excess water are not reabsorbed.
• They continue out of the nephron, into the ureter and down to the bladder as urine.
• Urine is released through the urethra.

• The hormone responsible for controlling the water content of the blood is called Antidiuretic hormone – ADH.
• This is found in the pituitary gland and is secreted by it.
• The control of water content is a good example of negative feedback. This is where a change in a factor leads to the opposite change happening to keep things fairly constant, even if they keep changing.

Besides, it't crucial that you should remember what ADH is in I/GCSE Biology!!!!!

• Step 1: The brain senses there is not enough water in the blood.
• Step 2: The pituitary gland secrets more ADH.
• Step 3: The ADH causes the kidneys to reabsorb more water.
• Step 4: A small volume of concentrated urine is produced.

• Step 1: The brain senses there is too much water in the blood.
• Step 2: The pituitary gland secretes less ADH.
• Step 3: This makes the kidneys reabsorb less water.
• Step 4: A large volume of dilute urine is produced.

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

CLICK HERE TO LEARN MORE ABOUT OUR I/GCSE BIOLOGY COURSES

Drafted by Alyssa (Biology)

References:

1. "Anatomical structure of the kidney", https://www.researchgate.net/profile/Filippo-Massa/publication/281602804/figure/fig1/AS:664913114591234@1535539048491/Anatomical-structure-of-the-kidney-A-Macroscopical-representation-of-kidneys-and-their.png
2. "File:Blausen 0592 KidneyAnatomy", https://upload.wikimedia.org/wikipedia/commons/d/d6/Blausen_0592_KidneyAnatomy_01.png
3. "Ultrafiltration", https://ib.bioninja.com.au/_Media/glomerular-pressure_med.jpeg
4. "24.3D: Tubular Reabsorption", https://s3-us-west-2.amazonaws.com/courses-images/wp-content/uploads/sites/1940/2017/05/31172656/p1tm77srtkk3fhpq26yz.png
5. "Metabolic Waste Product", https://ars.els-cdn.com/content/image/3-s2.0-B9780123848604000058-f05-20-9780123848604.jpg
6. "Kidney ADH", http://2.bp.blogspot.com/-Xai5TlSVp4E/TcvErtJOZHI/AAAAAAAAAzs/gGwTtm0s9KQ/s1600/ADH.jpg