Excretion in Living Organisms

Questions and Answers

What are the consequences of not discharging metabolic wastes from living organisms?

Accumulation of wastes can lead to toxicosis and obstruction of biological functions.

Describe the composition of feces in digestive excretion.

Feces are composed of undigested food materials, water, bacteria, and dead cells.

Which gases are primarily eliminated through pulmonary excretion?

Carbon dioxide and water vapor are primarily eliminated through the respiratory system.

Explain the role of kidneys in renal excretion.

Kidneys filter blood from excess water and harmful materials like urea and expel them through urine. Signup and view all the answers

What is the primary function of the skin in excretion?

The skin excretes excess amounts of water, salts, urea, and a small amount of carbon dioxide. Signup and view all the answers

Identify the two main layers of the kidney and their color characteristics.

The two main layers are the cortex, which is red, and the medulla, which is bright colored and striped. Signup and view all the answers

What are nephrons, and why are they important for kidney function?

Nephrons are the microscopic filtering units of the kidneys, crucial for urine formation. Signup and view all the answers

Describe the location of the kidneys in relation to the vertebral column.

Each kidney is located on the back wall of the abdominal cavity, on either side of the vertebral column. Signup and view all the answers

What is the significance of the pelvic cavity in the kidney?

The pelvic cavity is the center of the medulla and is the beginning of the ureter. Signup and view all the answers

What role does excretion play in the balance between cells and their environment?

Excretion helps maintain homeostasis by regulating the removal of metabolic wastes. Signup and view all the answers

Study Notes

Excretion in Organisms

Waste materials result from food metabolism in unicellular and multicellular organisms.
Accumulation of waste causes toxicosis and obstructs biological functions, necessitating excretion.
Excretion balances the cells and environment while regulating water and salt levels.

Types of Excretion in Humans

Digestive Excretion:
- Involves the expulsion of feces, comprising undigested food, water, bacteria, and dead cells from the digestive tract.
Pulmonary Excretion:
- Carbon dioxide and water vapor are expelled through the respiratory system.
Renal Excretion:
- Excess water and harmful substances, such as urea, are filtered from the blood by the urinary system.
Skin Excretion:
- The skin eliminates excess water, salts, urea, and small amounts of carbon dioxide.

Structure of the Urinary System

The urinary system carries out renal excretion, primarily involving the kidneys.
Kidneys:
- There are two bean-shaped kidneys located on either side of the vertebral column in the abdominal cavity.
- Each kidney is surrounded by a thin membrane called the capsule.
- Kidneys consist of two main layers:
  - Cortex:
    - The outer layer, red in color, containing microscopic filtering units known as nephrons.
  - Medulla:
    - The inner part, bright-colored and striped, housing many urinary tubules.
    - Contains the renal pelvis, which is the cavity at the center and the starting point of the ureter.
Circulation:
- Renal arteries supply blood to the kidneys, while renal veins remove waste products.

Description

This quiz covers the process of excretion in unicellular and multicellular organisms, focusing on how waste materials produced from food metabolism are removed. Understand the significance of excretion in maintaining homeostasis and preventing toxicosis within biological systems.