Chapter 13: Excretion in humans

Question 1

What do the kidneys excrete?

Answer 1

Urea, excess water and ions

Question 2

What is waste’s journey from the kidney 💀?

Answer 2

Kidney, ureter, bladder, urethra

Question 3

What is the structure of the kidneys?

Answer 3

Cortex on the outside, medulla on the inside

Question 4

What is the structure and function of a nephron and its associated blood vessels?

Answer 4

Glomerulus: filters water, glucose, urea, and ions from the blood, as they are small enough to pass through the filter, but large molecules and blood cannot
Nephron: reabsorbs all of the glucose, some of the ions and most of the water back into the blood

Question 5

How is urine formed?

Answer 5

As blood passes through the glomerulus, small molecules, water, glucose, urea, and ions are filtered into the nephron. Toxic substances such as urea, and water and ions in excess requirement, called urine, continue through the nephron. However, substances needed by the body, such as glucose, some of the ions, and most of the water, are reabsorbed in the nephron

Question 6

What happens to proteins when digested?

Answer 6

Protein in food is taken into the alimentary canal, and the protein molecules are broken down to amino acids during digestion. The amino acids are absorbed into the blood and taken to the liver in the hepatic portal vein, where amino acids that are needed are made into proteins in the liver, or released into the blood to be assimilated by body cells. Excess amino acids are deaminated and form urea.

Question 7

Define ‘deamination’

Answer 7

The removal of the nitrogen-containing part of amino acids to form urea

Question 8

What is the importance of excretion?

Answer 8

Prevents urea from reaching toxic levels in the body