A 50-year-old man, Mr. Johnson, is experiencing frequent urination, especially at night, along with fatigue and swelling in his ankles. Upon examination, his doctor suspects a possible issue with his excretory system. Mr. Johnson is concerned about his condition and seeks clarification on how the excretory system fiunctions and its role in maintaining overall health.
(i) What are the organs involved in excretion in human body and the substances excreted by the excretory system?
(ii) How does the excretory system regulate the balance of water and electrolytes in the body?
(iii) Discuss the role of the kidneys in excretion.