B3.3.3 Maintaining Water Balance

Question 1

Why is it important to maintain water balance?

Answer 1

The body need to to balance water and salts in and water out (via sweating and excretion).
Ensure water and salt levels in blood plasma remain constant
Changes to water and salt levels in blood plasma can cause damage to cells.

Question 2

It is important that the water levels in your blood plasma remain constant. Why?

Answer 2

• If too much water is present it will move into your blood cells, causing them to swell and burst. This is known as lysis.
• If too little water is present, or if there is too much of a solute, water will diffuse out of your blood cells causing them to shrink. - crenation

Question 3

What is urine

Answer 3

A solution containing water urea and other waste substances

Question 4

Function of kidneys

Answer 4

Maintaining the balance of water and other substances in the body through urine production.
Filtering out the waste products, such as urea, water and ions from the body
Selectively reabsorbing useful substances such as glucose, ions and water into the blood.

Question 5

Function of renal artery

Answer 5

Brings blood containing urea and other substances in solution to the kidney

Question 6

Function of renal vein

Answer 6

Carries blood away from kidney after urea and other substances have been removed

Question 7

Function of urethra

Answer 7

Tube through which urine passes out of your body

Question 8

Function of ureter

Answer 8

Tube through which urine passes through kidney to bladder

Question 9

How does urine change

Answer 9

Your kidneys balance the amount of water you take in with the amount you lose through breathing and sweating, by altering the amount of urine you produce.
If you are short of water, your kidneys produce very little urine.
Water is saved for your body’s use.

Question 10

How does urine change p2

Answer 10

If you take in too much water the kidneys produce lots of urine.
Excess water is therefore lost from the body.
When you quickly consume several drinks you will produce a large amount of dilute urine.
This will appear almost colourless

Question 11

Why does selective reabsorption occur

Answer 11

It reabsorbs essential substances such as glucose, ions, and water from the filtrate back into the bloodstream.
This process prevents the loss of valuable substances from the body while allowing waste products to be excreted in urine.