Study MaterialsNCERT Exemplar SolutionsClass 11BiologyImportant Topic of Biology: Osmoregulation

Important Topic of Biology: Osmoregulation

The kidneys are responsible for maintaining the secretion process and osmoregulation in humans. Next to the kidneys, there is a whole excretory system responsible for maintaining body osmoregulation. The kidneys, ureter, bladder, and urethra are part of the digestive system.

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    Osmoregulation which means the maintenance of the concentration of salt and water in the body is known as osmoregulation. In biodiversity, different organs are responsible for this process. The definition of Osmoregulation in biology or chemistry is the same as mentioned above. We will learn more about what osmoregulation is and the roles of the various organs that help us carry out this process.


    Understanding the kidneys will help us to understand what osmoregulation is. They are reddish in colour and two in number per person. They are in the form of beans and are found in the abdominal cavity. The right kidney is slightly lower than the left kidney due to the liver taking up more space. Inside the kidneys, we have nephrons that are responsible for the formation of urine and maintaining the balance of osmotic or osmoregulation of the body. The kidneys are covered with three layers:

    • Renal Capsule: It is a very inner layer and is strong protection. It is made up of white fibrous connective tissue. Other stretch muscles and muscles are also present.
    • Adipose Capsule: A medium-sized cover as the name suggests the presence of adipose tissue. It acts as a shock absorber.
    • Renal Fascia: It is the outer layer and helps to connect the abdominal wall.

    The nephron

    Here we will understand more about the occurrence of what is osmoregulation. It is known as the unit of structure and function of the kidneys. Glomerulus and renal tubule are two parts of the nephron. The glomerulus is formed by the afferent arteriole. Active arterioles are formed by glomerular capillaries. The renal tube contains the bowman’s capsule and distal convoluted tubule and proximal convoluted tubule. The concentration of salt and water is caused by nephrons in their long ends. This is the true meaning of osmoregulation. It also helps with the formation of urine.

    Types of Osmoregulation

    There are two main types of osmoregulation:


    Osmoconformers are organisms that try to match the osmolarity of their body with their environment. In other words, these organisms maintain the same osmotic pressure inside the body as outside water. They go hand in hand with effective or inactive methods. Most invertebrates such as starfish, jellyfish, and lobsters are osmoconformers.


    Osmoregulators are organisms that actively control their osmotic pressures, independent of their environment. Many vertebrates, including humans, are osmoregulatory. Much freshwater fish are considered osmoregulatory as well.

    Osmoregulation Biodiversity

    Different organisms show different types of osmoregulation. The following are some of the biological processes of bioregulation:

    Osmoregulation in Fish

    Freshwater fish and marine fish are osmoregulated in different ways. Areas with different levels of salt, which is why the process of osmoregulation is different.

    Osmoregulation in Freshwater Fish

    Freshwater fish are hypertonic in their environment, which means that salt levels are higher in their blood than the surrounding water. They absorb a controlled amount of water through the mouth and gill membranes. As a result of this water absorption, they produce a lot of urine that loses a lot of salt. Salt is converted with the help of rich mitochondria cells in gills. These cells absorb salts of blood from the surrounding water.

    Osmoregulation in Marine Fish

    Compared to marine fish, marine fish face the opposite problem. They have a higher level of water in their blood than their surroundings. As a result, it causes a tendency to lose water and absorb the salt. To solve this problem, marine fish drink a lot of water and stop urinating. Another additional energy cost also comes as these insects actively require the removal of salt from the body (through gills).

    Osmoregulation in Bacteria

    Bacteria use a transport mechanism to absorb electrolytes as the surrounding osmolarity grows. Osmotic pressure activates certain genes in bacteria that include osmoprotectants.

    Osmoregulation in Plants

    Plants use the stomata on the lower side of the leaves to control water loss. Plants that grow in moist soil compensate for water loss by changing the air by absorbing more water from the soil. Plants that grow in desert areas store water in vacuoles and have thick and fleshy pieces to prevent water loss.

    Osmoregulation in Animals

    Animals have an improved excretory system that helps keep water lost in the body, thus maintaining osmotic pressure.

    Osmoregulation in People

    The kidneys are the main organ responsible for osmoregulation in humans. Water, amino acids and glucose are also absorbed by the kidneys. When the water level in the body is high, it releases a large amount of hypotonic urine. When the water level is low, it retains water and produces a low amount of hypertonic urine. Thus, the kidneys maintain the electrolytic balance of the body.

    Tubules functions:

    After understanding the kidneys, we will understand what osmoregulation is in biology and the structures responsible for its preservation.

    Proximal Convoluted Tubule:

    Cuboidal brush cells that line the epithelium line this tubule. This helps to expand their surface area so that they can absorb more salt and water. About 70-80% of the electrolytes are absorbed into this tuber. More than 80% of the water is absorbed in this sector. A proximal convoluted tubule is very helpful in maintaining the ionic balance of body fluids and the body’s pH balance. This is done by the selective release of hydrogen ions and ammonia and the absorption of hydrogen carbonate ions in it.

    Loop of Henle:

    A small absorption occurs in this area. But it plays a major role in maintaining the high osmolarity of the medullary interstitial fluid. The descending loop is able to penetrate water and is impervious to electrolytes. The rising loop is absorbed into the electrolytes and does not penetrate into the water.

    Distal Convoluted Tubule:

    Selected absorption of sodium and water ions occurs here. Also, it is selective in selecting hydrogen and potassium ions and ammonia to maintain pH and osmotic balance in the body.

    Collection Canal:

    As the name suggests, this channel helps to collect all the water and concentrations that have been filtered through tubes so far. It plays an important role in maintaining pH and mineral concentration in the blood.

    Also read: Important Topic of Biology: Renin


    Describe Osmoregulation?

    The process by which the body maintains osmotic balance throughout the membrane is known as osmoregulation. It is an important biological function.

    What Organisms Are Organised by Osmoregulation?

    Osmoregulation is caused by all living things. Both vertebrates and invertebrates rely on osmoregulation to maintain the full functioning of their body.

    Why Is Osmoregulation Needed in Aquatic Animals?

    Osmoregulation is necessary for all living things, including aquatic creatures, to maintain the balance of body fluids in order to perform vital bodily functions.

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