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Osmoregulation is a function of our body that controls the fluid’s osmotic pressure and the balance of electrolytes in our body. Osmoreceptors that detect the changes in osmotic pressure are used for this process in animals. These Osmoreceptors can be found in most warm-blooded organisms including humans, in their hypothalamus. These osmoregulators are not only found not only in the brain but in the kidneys as well. There are two major kinds of Osmoregulators. These are osmoconformers and osmoregulators namely. The difference is while the former regulates the osmotic pressure of the body according to its surroundings, the latter is independent of its surroundings. Different animals show osmoregulation in their body differently, like fishes, Bacteria, Plants, Animals and Humans, all have different systems of Osmoregulation.
Key Terms: Osmoregulation, Pressure, Animals, Plants, Kidneys, Osmoconformers, Osmoregulators, Fluids, Kidneys
What is Osmoregulation?
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Osmoregulation is the process of actively controlling an organism’s body fluids’ osmotic pressure, which is detected with the help of osmoreceptors, and this helps for maintaining the organism’s water content’s homeostasis, which means the maintenance of the balance of fluids and the electrolytes’ concentration, which stops the body fluids from becoming either too concentrated or diluted. Osmotic pressure is a measure of the tendency of water to move into one solution from another by osmosis. The higher osmotic pressure of the solution will mean that the amount of water intake is more. Water’s diffusion due to osmosis from pure water’s side can be stopped by applying pressure to the hypertonic side of the semi-permeable membrane.
Although osmotic balance has a lot of variations, an animal can be found in a steady osmotic state over the long term. Organisms in terrestrial and aquatic environments need to have the correct amount of water and concentration of solutes in the fluids of their body. This includes excretion, that is, to get rid of metabolic nitrogen wastes and toxic hormones through the kidneys and skin.
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Osmoregulation Detailed Video Explanation:
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Types of Osmoregulation
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Osmoregulation can be classified into two major kinds:
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Osmoconformers
Osmoconformers are the kind of organisms that match their body’s osmolarity according to their surroundings. They tend to keep the osmotic pressure consistent throughout the body as the same as the outside water. They conform through passive or active means. Most of the invertebrates that are marines, such as jellyfish, lobsters and starfish are osmoconformers.
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Osmoregulators
Osmoregulators are the type of organisms that are actively maintaining their osmotic pressure, regardless of the environment surrounding them, as they are independent. Many vertebrates, such as humans, are osmoregulatory, the same as most freshwater fishes, whose gills keep up taking salt from the surroundings by using mitochondria-rich cells. Water diffuses into the fishes, excreting dilute urine that expels all extra water.
Osmoregulation in Plants
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Stomata that is present under the leaves is used to control water loss. Plants that grow in well-hydrated soils use transpiration to compensate for water loss as they keep absorbing extra water from the soil. Plants that are grown in semi-arid areas use their vacuoles to store water. They also tend to have fleshy and thick cuticles which helps to prevent water loss. A hormone called Abscisic Acid helps to close the stomata and to increase the intake of water from the roots, so it is vital for conserving water for plants.
Osmoregulation in Fish
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Marine fish and Freshwater fish use different ways to osmoregulate. The environment surrounding them has different salinity levels and so does the process of osmoregulation.
Osmoregulation in Fish
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Osmoregulation in Freshwater Fish
The fishes in Freshwater are hypertonic to their surroundings, so the salt concentration is higher in their blood than in their surroundings. They tend to take in a controlled amount of water with the help of their mouth and the gills. This large intake of water causes them to produce lots of urine, which helps in losing excess salt. The salt gets removed by using the mitochondria in the rich cells of the gills. These cells are used to take the salt into the blood from its surroundings.
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Osmoregulation in Marine Fish
Marine fishes go through the opposite of what freshwater fishes go through. The concentration of water in their blood is higher than their surroundings. This results in it losing water and absorbing salt. But to counter this difficulty, the marine fishes drink large amounts of water and limit urination. They also continuously expel salt from the body using the gills, and this costs them a lot of their energy.
Osmoregulation in Animals
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Animals use their developed excretory system to regulate the loss of water from the body. This helps them to maintain the osmotic pressure.
Osmoregulation in Humans
Kidneys are the organs responsible for the handling of osmoregulation in human beings. Amino acids, glucose and Water are reabsorbed by the kidneys. The body releases a vast amount of urine that is hypotonic when the water level in the body is high. However, it keeps water and makes less amount of hypertonic urine when the water level is low. This helps the kidneys to maintain an electrolytic balance.
Angiotensin II, Antidiuretic hormones and Aldosterone are the ones responsible for controlling the absorption process in our body. Perspiration causes the loss of some water and electrolytes.
Osmoreceptors present in the hypothalamus region of the brain are responsible for controlling our thirst and the production of ADH. ADH is responsible for opening the water channels of aquaporins that allows the water to flow. Thus, As long as the pituitary gland keeps releasing ADH, the kidneys will keep absorbing water.
Osmoregulation in Humans
Osmoregulation in Bacteria
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Bacteria absorb electrolytes by using a transport mechanism when the osmolarity increases around it. The osmotic stress causes the activation of genes in bacteria that are used to synthesise osmoprotectants.
Things to Remember
- Osmoregulation is a process that controls the fluids’ osmotic pressure and the balance of electrolytes in our body.
- Its receptors detect the changes in osmotic pressure in animals.
- Osmoreceptors are found in most warm-blooded organisms including humans.
- These osmoregulators are not only found not only in the brain but in the kidneys as well.
- There are two major kinds of Osmoregulators.
- These are osmoconformers and osmoregulators namely.
- Osmoconformers match their body’s osmolarity according to their surroundings.
- They keep the osmotic pressure consistent throughout the body as the same as the outside water.
- Osmoregulators actively maintain their osmotic pressure, regardless of the surroundings they are in, as they are independent.
Sample Questions
Ques. What organisms have osmoregulation? (3 Marks)
Ans. Most of the animals that are marines as well as invertebrates such as jellyfish, lobsters and starfish are osmoconformers. Many vertebrates, such as humans, and other animals are osmoregulatory.
Bacterias are Osmoregulatory too, along with various kinds of Freshwater Fishes and Marine Fishes.
Ques. What are the processes involved in achieving Osmoregulation in Humans? (5 Marks)
Ans. There are four processes involved in Osmoregulation in humans:
- Filtration – The fluid portion of the blood is filtered from the nephron into Bowman's capsule and it flows to the proximal convoluted tubule to the Loop of Henle in the kidney’s medulla portion.
- Reabsorption – Viscous glomerular filtrate goes back to the blood vessels surrounding the convoluted tubules.
- Secretion – the rest of the fluid becomes urine, and goes to the kidney’s medullary region.
- Excretion – the urine is kept in the urinary bladder and it leaves from the urethra; however, in other vertebrates, the urine gets mixed with other wastes leaving the body.
Ques. What is the osmoregulation of an amoeba? (3 Marks)
Ans. Amoeba lives in both freshwater and marine. The amoeba in Freshwater has a contractile vacuole for osmoregulation. So the difference of the concentration of solute inside the amoeba and the concentration of the solvent in the surrounding waters causes the water to move towards the inside of the Hypertonic body and thus the contractile vacuole removes the excess water inside the body.
However, the marine amoebas lack the contractile vacuole because a hypertonic environment is already present in their surrounding waters, so that’s why they have to work on the loss of water.
Ques. Which hormone is responsible for osmoregulation? (3 Marks)
Ans. The hormone called the Antidiuretic hormone (ADH) is the main contributor to osmoregulation as it controls the amount of the formation of urine. The body helps to maintain the concentration of electrolytes and water at a constant level by the function of osmoregulation.
Ques. What is the significance of Osmoregulation? (5 Marks)
Ans. The Mammalian body has evolved so that it can control osmotic pressure. It does so by balancing the concentration of electrolytes in three basic fluids: extracellular fluid, intracellular fluid and blood plasma. The osmotic pressure can cause Water migration across membranes and this can affect the volume of the fluid compartments. Osmotic pressure can affect blood pressure directly as blood plasma is one of the main fluid components.
Consuming water and food and sweating, excreting faeces and urinating, these ways are used by complex multicellular animals to exchange the nutrients and water with the environment. However, When a body gets a disease or an injury. The body’s system gets disrupted and toxic waste that is accumulated can pose a health risk because of the lost control of Osmotic Pressure.
Ques. What is the role of osmoregulation? (3 Marks)
Ans. Osmoregulation is the physiological process that regulates a fixed concentration of ions and of cell membrane-impermeable molecules that are found in the surrounding environment of the cell. Osmoregulation is important to the health and well-being of animals and plants as water is important for life.
Ques. Describe the process of Osmoregulation in Euryhaline. (5 Marks)
Ans. There are a few species called euryhaline creatures. They are known to spend part of their life in freshwater and the rest of their life in seawater. Salmon, for example, can tolerate a variety of levels of salt. They developed osmoregulation in their body to survive in a range of aquatic habitats. Their skin absorbs the hypotonic water in freshwater.
The fish do not drink a lot of water and tend to keep the balance of electrolytes by avoiding dilute urination and they vigorously absorb salts with the help of their gills. These salmon fishes, however, lose water once they are relocated to a hypertonic saltwater body, and thus they excrete the excess salts through their urine and gills.
Ques. What are the two kinds of Osmoregulation? (5 Marks)
Ans. The two kinds of Osmoregulation are as follows:
- Osmoconformers: Osmoconformers are the kind of organisms that match their body’s osmolarity according to their surroundings. They tend to keep the osmotic pressure consistent throughout the body as the same as the outside water. Most of the invertebrates that are marines, such as jellyfish, lobsters and starfish are osmoconformers.
- Osmoregulators: Osmoregulators are the type of organisms that are actively maintaining their osmotic pressure, regardless of the environment surrounding them, as they are independent. Many vertebrates, such as humans, are osmoregulatory.
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