13.1 Excretion

This chapter of excretion explores the mechanisms by which living organisms rid themselves of waste products. In this chapter, we will delve into the intricate processes that maintain internal balance and ensure the efficient elimination of metabolic by-products.

Key concepts:

1. General Concepts of Excretion:

• Excretion is the process by which organisms eliminate toxic materials and waste products of metabolism to maintain internal balance.

2. Respiratory Excretion:

• Carbon dioxide is a waste product of respiration, and it is excreted through the lungs.

3. Urea Production in the Liver:

• Urea, a toxic waste product, is produced in the liver through the breakdown of excess amino acids.

4. Components of the Urinary System:

• Kidneys: Remove urea and excess salts and water from the blood, forming urine.
• Ureters: Transport urine from the kidneys to the bladder.
• Bladder: Stores urine until it is ready to be expelled from the body.
• Urethra: Conducts urine from the bladder to the exterior.

5. Need for Excretion:

• Excretion is necessary due to the toxicity of urea, emphasizing the importance of eliminating this waste product.

6. Nephron Structure:

• Bowman’s Capsule: Site of initial filtration in the nephron.
• Glomerulus: Capillary network within Bowman’s capsule involved in blood filtration.
• Tubules: Involved in reabsorption and secretion processes.
• Loop of Henle: Plays a role in water reabsorption.
• Collecting Duct: Concentrates urine and facilitates its transportation.

7. Nephron Function:

• a. Glomerulus Role: Filtration of water, glucose, urea, and ions from the blood.
• b. Reabsorption: Nephron reabsorbs glucose, some ions, and most water back into the blood.
• c. Formation of Urine: Involves the excretion of urea, excess water, and ions.

8. Liver’s Role in Amino Acid Assimilation:

• The liver plays a crucial role in assimilating amino acids by converting them into proteins.

9. Deamination Process in the Liver:

• Deamination in the liver involves the removal of the nitrogen-containing part of amino acids, leading to the formation of urea.