Homeostasis is an important of life. Keeping your temperature, water, nutrients, oxygen and carbon dioxide is what keeps you healthy.
Homeostasis is the maintenance of a constant internal environment.
The kidney’s main function is to filter the blood and assist in regulating the water balance in the body.
Blood enters through the Renal Artery and into the kidney. At this stage the blood contains waste (such as urea).
The blood is filtered. The clean blood exits through the Renal Vein and the toxins exit through the Ureter as Urine.
Click on the animation to the right
So what actually happens in the kidney?
Watch the video bellow
Blood enter the glomerolous and all the urea, water, glucose and ions are filtered out. Proteins however are too larger to diffuse across.
The main source of filtration occurs in the Nephrons. There are over 1.3 million Nephrons in one kidney!
To the right is an image of a Nephron. Scroll over to enlarge it.
There are 3 parts of the Nephron you need too know.
Scroll over each word:
Glomerolous
Loop of henle
Collection duct
The blood continues to the loop of Henle.
Here, water and important ions are reabsorbed back to the blood. This happens via diffusion
The amount of water reabsorbed is controlled by a hormone called ADH.
ADH is released from the pituitary gland. ADH is released when water levels in the blood are low. This means that more water will be absorbed from the food and drinks passing through the kidney.
Finally, all waste and excess water is sent to the collecting ducts where it travels to the bladder.
When it comes to keeping water, we have to make sure that everything we put out, is returned to our bodies.
Exhaled air, sweat, urine and faeces all contains water that we excrete.
Food and drinks are our main source of water.
Questions
1. List three ways in which your body gains water and three in which it loses water.
2. Define Homeostasis
3. Suggest two different things that could cause you to make a small amount of concentrated urine
4. What are 2 differences which could cause you to make a lot of dilute urine
5. Define the term hormone.
6. Draw a flow Diagram illustrating how homeostasis works with ADH
7. Which molecules do your kidney filter out of the blood in the glomerolous and which are filtered back in, in the loop of Henle.
8. If someone drank the same amount of water over 2 days, explain why their urine may be darker on a hot day than on a cold day?
9. Explain why blood cells or protein in a person’s urine is a sign of kidney damage.
