Excretion and Osmoregulation

Introduction

The human body should excrete eight to ten glasses of water per day to maintain a healthy equilibrium. Urination, faeces, perspiration, and, to a lesser extent, respiration all contribute to this. The human body’s organs and tissues are submerged in fluids that are kept at a consistent pH, temperature, and solute content, all of which are essential parts of homeostasis.

Mineral salts and sugars make up most of the solutes in physiological fluids, and osmotic control is how mineral salts and water are kept in balance. Despite the influence of extrinsic factors like nutrients, temperature, and meteorological conditions, osmotic homeostasis is maintained.

Table of Contents

• Osmotic Balance and Osmoregulation
• Function of Osmoregulation
• Excretion and Its Significance
• Osmoregulation and Urine Formation
• Frequently Asked Questions – FAQs

Osmotic Balance and Osmoregulation

The diffusion of water over a membrane in response to osmotic pressure, created by an imbalance of molecules along either side of the membrane, is called osmosis. The act of maintaining salt and water balance (osmotic equilibrium) across membranes in the body’s fluids, which are made up of water, electrolytes, and non-electrolytes, is known as osmoregulation.

The passage of solutes and/or water over a semi-permeable membrane tends to equalise the solutes’ concentration on two sides of the membrane. As shown in the figure, a cell placed in water swells due to water gain from the hypotonic or “low salt” environment. In contrast, a cell immersed in a solution with a higher salt concentration causes the membrane to shrink up due to water loss into the hypertonic or “high salt” environment. Isotonic cells have the same concentration of solutes in and around the cell, balancing the osmotic pressure on both sides of the semi-permeable cell membrane.

The human body does not function in isolation. The system receives a steady supply of water and electrolytes. Excessive electrolytes and wastes are delivered to the kidneys and eliminated, preserving osmotic equilibrium, while osmoregulation is performed throughout membranes within the body.

Osmoregulation can be divided into two categories:

• Osmoconformers: Osmoconformers are organisms attempting to adapt their body’s osmolarity to that of their surroundings. These organisms have the same osmotic pressure both outside water and inside the body. They conform in two ways, actively or passively. Osmoconformers are marine creatures like starfish, jellyfish, and lobsters.
• Osmoregulators: Osmoregulators are organisms proactively controlling their osmotic pressure without depending on their surroundings. Humans, like any other vertebrate, are osmoregulatory. The majority of freshwater fish are osmoregulatory.

Function of Osmoregulation

Our metabolic functions as organisms rely on osmoregulation and the regulation of body fluid levels. As previously stated, this is the outcome of good organ circulation, thermoregulation, toxic waste excretion, and electrolyte balance.

The osmolarity of the extracellular fluid has an effect on the movement of water in and out of a cell on a cellular level. Osmotic stress is caused by large levels of solute changes, which are harmful to cells. Osmoregulation is aided by a number of processes including hormonal regulation, autoregulation, and sympathetic regulation.

Excretion and Its Significance

Excretion is the process of removing undesired metabolic waste products from the body. CO₂, H₂O, bile pigments, nitrogenous wastes, excess inorganic salts, hormones, and vitamins are among the waste products produced.

Secondary excretory organs include the skin, lungs, and liver. However, the kidney serves as a key excretory organ in all vertebrates. The excretory system is established in the animal body to remove these nitrogenous wastes.

The following are the different excretory products and organs of various organisms:

Methods of Excretion

In mammals, there are five methods of excretion depending on the excretory product. They are as follows:

• Ammonotelism (Type of excretion- ammonia)
• Aminotelism (Type of excretion – amino acids)
• Uricotelism (Type of excretion – uric acid)
• Ureotelism (Type of excretion – urea)
• Guanotelism (Type of excretion – guanine)

Significance of Excretion

Green plants producing water as respiratory products, excrete as well. Green plants need carbon dioxide generated by people during exhalation in the photosynthesis process. Plants use transpiration and guttation to get rid of surplus water.

When wastes build up in the body, the excretory system in humans expels them, which are usually harmful. Sweating is a sort of excretion that people exhibit. Sweat also aids in lowering the body’s temperature, as high temperatures can be lethal or result in life-threatening injuries.

Also Read:

Excretion And Its Importance

Osmoregulation and Urine Formation

The excretion process is used by everyone, including plants and animals, to remove various waste products from our bodies. Both kidneys perform a crucial function in filtering blood cells throughout the excretion process.

• The three main phases in the formation of urine are glomerular filtration, reabsorption, and secretion.
• Urine is 95% water and 5% wastes like salt, potassium, and calcium ions, as well as nitrogenous wastes like creatinine, urea, and ammonia.
• The process of sustaining bodily homeostasis is known as osmoregulation.
• It maintains osmotic balance by allowing solutes and water to diffuse over a semi-permeable membrane.
• Osmoregulation is a mechanism in which the kidney adjusts the osmotic pressure of blood by filtration and purification.

Further Reading:

• Osmosis
• Urine Formation and Osmoregulation
• Human Excretory System
• Excretory Products and Their Elimination