New News Biology #31

Kidneys - Part 1/3

Main Usages of the Kidneys:

Filter our blood

Remove the waste products

Regulate the levels of useful stuff:

Ions; too much or too little is bad

Water; we lose it through sweating, breathing, and urinating

Question: why is water regulation so important for us?

Answer: If too much ... cells could swell or burst!

If too little ... cells could shrink

How Does the Kidney Do Its Job?

In the kidneys, there are nephrons, and are mainly made up with something known as the tubule.

The tubule:

It’s entangled with the blood vessels

It can absorb small things like water, glucose, amino acids, and urea

This process of the tubule absorbing all these things is known as ‘filtration’, and it is important to also know that this process ONLY involves the small things, because the tubule doesn’t have the ability to absorb large things like cells. It’s quite fortunate that it can’t, or all of our blood cells would be sucked away in the process.

Fun Fact: after absorbing all the small things, there’s another process called selective re-absorption, which is the process of re-absorbing the useful stuff like glucose

How Does the Kidneys Control the Water Concentration?

At the start, there’s a part of the brain called the hypothalamus that is responsible for detecting water concentration.

If ... the water concentration is too low, then the hypothalamus will tell the pituitary gland to release a hormone called ADH (‘Anti-diuretic hormone’) which tells the kidney to reabsorb more water, bringing the water concentration back to normal (hopefully)

If ... the water concentration is too high, then the hypothalamus just stops sending signals to the pituitary gland and it releases less ADH and the kidney reabsorbs less water. Congrats, the water concentration is back to normal (again).