Human Body Excretion Processes Quiz

Study Notes

Excretion: The Process of Removing Wastes from the Human Body

Excretion is the process of removing wastes and excess water from the body. It is an essential process in all living things, and it is one of the major ways the human body maintains homeostasis and prevents damage to the body. Wastes include by-products of metabolism, some of which are toxic, and other non-useful materials, such as used up and broken down components.

Organs of Excretion

The main organs of excretion include the skin, liver, large intestine, lungs, and kidneys. These organs all excrete wastes, but they don't work together in the same way that organs do in most other body systems. Each of the excretory organs "does its own thing" more-or-less independently of the others, but all are necessary to successfully excrete the full range of wastes from the human body.

The skin removes excess water and salt via sweat.
The lungs exhale carbon dioxide, a gaseous waste product from cellular respiration.
The liver breaks down toxic substances in the blood and converts nitrogenous waste into urea.
The kidneys filter blood and regulate water balance in the body, producing urine as a waste product.
The large intestine eliminates solid waste that remains after food is digested and collects and excretes wastes from throughout the body, including bilirubin in bile.

Excretory Functions of the Liver

The liver plays a crucial role in excretion by breaking down toxic substances in the blood and converting nitrogenous waste into urea. This process is called detoxification. The liver also creates bile for fat digestion, which is stored in the gallbladder and released into the small intestine to aid in the digestion of fats.

Main Excretory Functions of the Large Intestine

The main excretory function of the large intestine is to eliminate solid waste that remains after food is digested. It also collects and excretes wastes from throughout the body, including bilirubin in bile. The large intestine also absorbs water and electrolytes from the remaining food and excretes it as feces, which is passed into the rectum and eliminated from the body through the anus.

Physical States of Waste Excretion

Wastes from the human body are excreted in various physical states. Carbon dioxide is excreted as a gas through the lungs, while water and solids are excreted through the kidneys in the form of urine. The large intestine eliminates solid waste in the form of feces, while the skin excretes excess water and salt via sweat.

Example of Excretion in the Human Body

Ridding the body of excess water is important because it helps to maintain the proper balance of fluids in the body, which is essential for maintaining proper blood pressure, regulating body temperature, and lubricating joints.

Brown Color of Feces

Feces are brown due to a substance called urobilinogen, which is a byproduct of the breakdown of bilirubin in the liver. Urobilinogen is then excreted in the bile and urine, giving feces their characteristic brown color.

Regrowing the Liver

The liver is the only organ in the human body that can regrow if a portion of it is removed. This ability is due to the liver's unique structure, which consists of small functional units called hepatocytes that can regenerate and replace damaged or lost cells. However, the liver cannot regrow a limb, as this is not a natural function of the liver or any other organ in the human body.

Excretion in Plants

Excretion in plants occurs mainly through transpiration, where gaseous wastes and water are excreted through stomata, lenticels of the stem, and the outer surface of stems, fruits, etc. Some organic wastes are also stored in plant parts such as barks and leaves. Aquatic plants excrete metabolic wastes through diffusion, while terrestrial plants excrete into the soil.

Excretion in Aquatic and Terrestrial Plants

Aquatic plants excrete metabolic wastes through diffusion, while terrestrial plants excrete into the soil. Excretion in plants can be summarized as follows: transpiration, storing, and diffusion.

Excretion and Osmoregulation

Excretion is closely related to osmoregulation, the process of maintaining proper fluid balance in the body. The kidneys play a crucial role in osmoregulation by filtering blood and regulating water balance in the body. The unit of osmoles is used to express the number of particles, which is the number of active solute particles in a solution. One osmole refers to one mole of osmotically active solute particles.

Description

Test your knowledge on the excretory system in the human body, including the organs involved in waste removal, functions of the liver and large intestine, physical states of waste excretion, and the importance of excretion for maintaining homeostasis. Learn about the process of detoxification in the liver, the formation of urine by the kidneys, and the significance of transpiration in plants for excretion.