Chapter 9 - The Excretory System

Question 1

What is excretion?

Answer 1

The removal of wastes that are made in the body cells

Question 2

What are the excretory organs and what are the waste products they excrete?

Answer 2

Lungs –> Co2 + water (Wastes of respiration)
Kidneys –> Urea, water + salts (Urine)
Skin –> Water + salts (sweating)

Question 3

What is urea?

Answer 3

If we eat more protein than is needed (to build + repair our cells) we can’t store it, so it’s broken down in the liver to form urea

Question 4

What parts make up the urinary system, and what are their functions?

Answer 4

• the kidneys (remove urea and other waste from the blood and form urine)
• the renal arteries + renal veins (carry blood rich in wastes to the kidneys + blood with wastes removed away from the kidneys)
• the ureters (carry urine from the kidneys to the bladder)
• the bladder (stores urine before it’s released from the body)
• the urethra (carries urine out of the body)

Question 5

What is the function of the excretory system?

Answer 5

To get rid of urea, excess water + salts

Question 6

What is urine made up of?

Answer 6

Urea, water and salts

Question 7

How is urine formed?

Answer 7

1. Blood enters kidneys through the renal arteries
2. Contains many useful substances like glucose, body wants to get rid of wastes but keep useful substances
3. Therefore main function of kidneys is to filter the blood
4. Urea, excess water + salts are converted into urine, glucose + other useful substances are taken back into bloodstream + kept in body
5. Urine then travels from kidneys through ureters to bladder, stores then released from body through urethra

Question 8

Where does filtration occur in the kidneys?

Answer 8

The outer parts