Tag: Excretion

Introduction 

All species, whether they have one cell or many, engage in diverse metabolic processes. The body produces harmful chemicals as a result of these processes. To prevent excessive accumulation of these waste products in the body, they must be excreted. The excretory system of the body performs the function of eliminating waste. Different species emit different wastes, and they are divided into 3 types- , Uricotelic, and Ammonotelic. The poisonous waste products produced by bodily metabolism must be eliminated from the body and this is done through the process of excretion. 

Excretion

Excretion is the process through which nitrogenous waste is expelled from the body. The excretory system in humans and the majority of chordates is responsible for the process of excretion. The human excretory system consists of two kidneys that filter the blood and remove the primary nitrogenous waste- Urea from the body. Nephrons, the kidney’s functional unit, filter blood and remove urea by the process of urine formation. Excretion is a very important step and it helps in maintaining the homeostasis of the body. Various organisms which stay in the abundance of water have their excretory products in the form of Ammonia and such are called ammonotelic organisms.

 Ammonotelism

• Ammonia is a waste product that some species, including amoeba, protozoa, echinoderms, Platyhelminthes, poriferans, cnidarians, and aquatic mammals, produce.
• These organisms are known as ammonotelic organisms and the process of excretion by such organisms is known as .
• To expel waste from their bodies, these organisms perform diffusion. The waste is excreted through their skin, gills, or kidneys.
• Ammonia has a small molecular size and it easily dissolves in water hence excretion is simple in aquatic animals.
• Elimination of ammonia from the body is very essential because when ammonia dissolves in water it generates ammonium hydroxide, which can result in necrosis of the tissues.
• Ammonotelism is the least energy-consuming and most water-intensive method of excretion. This is so because 1 gram of ammonia requires approx 500ml of water.

Physiological Aspect of Ammonotelic Excretion

• Fish and other aquatic species eat food that is high in protein and other nutrients.
• These organisms are unable to store amino acids for a long period, hence their intestines are designed for the deamination of amino acids.
• Uric acid is created during the process of deamination.
• Uric acid is oxidized which leads to the formation of  Allantoin and allantoic acid.
• Allantoin is hydrolyzed to form allantoate, and subsequent hydrolysis produces urea and glyoxylate.
• Urea is further broken down into ammonia and carbon dioxide in ammonotelic species.
• This ammonia then dissolves with the water and is expelled out of the body. 

Osmoregulation

Osmoregulation is the process of controlling the osmotic pressure of bodily fluids to maintain the water balance of the body. Since the cells of marine creatures are isotonic with saltwater, no regulatory mechanism is necessary. However, to keep the electrolyte balance in the body other organisms’ osmoregulation is a must. Osmoregulation helps maintain salts and water balance in the body. For instance, the antidiuretic hormone (ADH, also known as vasopressin) regulates the content of urine in humans. when the body’s water content is low More water is reabsorbed due to the presence of ADH. This leads to less urine production. More urine is produced when the body’s water content is high. Excretion and osmoregulation work in unison to make sure the steady state of the body is maintained.

Importance of Excretion

Excretion is a very important physiological process of the body. Its significance is given below.

• Excretion helps in the regulation of blood ionic composition.
• It helps in controlling blood pH.
• Regulation of blood volume and blood pressure is done through this process.
• It helps in maintaining blood osmolarity.
• The excretion of waste and foreign substances helps in cleaning the body of toxic and harmful wastes. 
• It assists in the maintenance of osmoregulation in the body.

Summary

Animals’ diets provide them with more amino acids. Ammonia, urea, and uric acid are excretory products that are created during the metabolism of proteins, amino acids, or nucleic acids. Organisms that are ammonotelic release ammonia as a waste product through their gills, skin, and kidneys. Removal of ammonia requires less energy. The regulation of water ion balance and homeostasis depends on the excretion of waste. By controlling the electrolyte balance, every organism keeps its internal environment in a steady state.

Frequently Asked Questions

1. Enlist excretory organs from different organisms.
Ans: Other excretory organs seen in various organisms are-

• Planaria – Flame cells
• Earthworm- Nephridia
• Cockroaches- malpighian tubules
• Prawns- green glands
• Molluscs- Renal glands

2. What are ureotelic and uricotellic organisms?
Ans: Ureotelic organisms – They release Urea as a waste product which is less toxic examples-Mammals and amphibians.

Uricotelic organism- They release Uric acid as a waste product which is the least toxic.  examples- Birds, reptiles, and insects.

3. Only aquatic animals are ammonotelic. Give reasons why?
Ans: Ammonia is highly toxic and hence cannot be stored in an organism’s body. Expulsion of ammonia from the body requires lots of water and hence aquatic animals such as fish only have the ability to form waste products in the form of ammonia.

Introduction

Every living thing engages in metabolic processes that produce compounds that, if allowed to build up in the body, could be poisonous. These materials are regarded as excretory wastes. Depending on several internal or external conditions, each organism uses a different technique to remove these wastes. We shall learn more about these excretory processes in this article, including the types of excretory products that each one eliminates.

Excretion and Excretory Wastes

The process of eliminating harmful or non-toxic wastes from the body is known as excretion. Each organism produces various excretory products. For instance, the primary excretory substance in fish is ammonia, whereas the primary excretory substance in humans is urea. These wastes are removed from the body via excretory organs.  Every living organism has a unique excretory system in its body.

For more help, you can refer to Science Class 7 Lesson No 11. Check out the video Lesson for a better understanding.

Methods of Excretion

Nitrogenous wastes produced during protein metabolism are the main excretory products produced by an organism. The conversion of the main nitrogenous waste ammonia results in the final excretory products of an organism. The final excretory products that are eliminated using a particular procedure are used to categorize the various excretion processes.

Ammoniotelic: Ammonia is released as a waste product during ammoniotelic. Because ammonia removal needs a significant amount of water, aquatic creatures like fish, poriferans, protozoans, etc. exhibit ammoniotelic. These creatures are referred to as ammoniotelic organisms.

Ureotelism: Ureotelism is the process of discharging urea as the final excretory waste. In terrestrial species like humans, it is common. A moderate amount of water is necessary for the body to remove urea from it. Ammonia is changed into urea in the livers of ureotelic organisms.

Uricotelism: Uricotelism is the elimination of uric acid, which is the ultimate excretory product. Because uric acid does not dissolve in water, the waste produced by uricotelic organisms is expelled as paste or pellets. Animals, including birds, reptiles, and some insects, exhibit uricotelism.

Guanotelism: Guanine is released as the body’s ultimate excretory product during Guanotelism. Guanine cannot be removed with water since it is an insoluble substance. Guanotelism has been observed in various spider species, as well as some types of earthworms and reptiles.

Aminotelism: The elimination of final waste products in the form of amino acids is known as aminonotelism. Mollusks and echinoderms both use this technique of excretion.

Excretion in Humans

The human body produces urea, uric acid, ammonia, and carbon dioxide as excretory products. Three of these are nitrogenous metabolic wastes that are eliminated in the urine or sweat, but carbon dioxide is a non-nitrogenous metabolic waste that is eliminated in the expired air. Let’s talk in detail about these excretory processes in humans.

Urination: The kidneys and other related organs perform several procedures to remove nitrogenous waste from the body. Urine, the last byproduct of this process, is excreted from the body by micturition. Urine formation happens in three stages. The nephron, which is the kidneys’ functional unit, performs each of these processes.

Glomerular filtration: The renal capsule, a nephron-like structure containing a cluster of blood capillaries, is where the first stage of urine production takes place. In this step, the blood is ultrafiltered, and the majority of the plasma as well as a few other molecules, including wastes, are taken out of it in the form of glomerular filtrate. This glomerular filtrate travels into the nephron’s long renal tubule, where it is absorbable.

Tubular reabsorption: The nephron is a structure that filters blood into a fluid called filtrate, much of which is then reabsorbed into the body. Resorption is a carefully regulated process that is modified to keep blood volume, pressure, plasma osmolarity, and pH in a stable state. Through the peritubular capillaries, reabsorbed liquids, ions, and molecules are restored to the bloodstream instead of being eliminated as urine.

Secretion: In this stage, chemicals like creatinine, hydrogen ions, and drugs are released from the renal tubule walls and transferred to the urine. Each nephron produces urine, which the collecting duct gathers and then excretes through the ureters into the urinary bladder. The urethra is the passageway through which urine exits the body once the urinary bladder has become bloated.

Expiration: Humans expel carbon dioxide through breathing, which is the metabolic waste product created during respiration. During this phase of breathing, the air is expelled through the nostrils.

Sweating: Sweating eliminates extra water, salt, and some urea from the body. This is brought on by the sweat glands in the skin producing sweat.

Examples of Excretion

The human body’s different organs that are responsible for excretion include the kidneys, lungs, large intestine, liver, and skin. A few examples of excretion include the release of bile by the liver, which travels to the small intestine before exiting the body via the large intestine. The large intestine is one organ in the body that excretes solid wastes.

Importance of Excretion in Living Organisms

• The removal of wastes from the body is crucial because if they are left there for an extended period, they can seriously harm the organ systems. 
• For instance, if urea builds up in the body, it can be extremely poisonous and cause uremia. 
• Too much carbon dioxide in the blood will cause carboxyhemoglobin to form and cause the blood to become acidic, which will reduce its ability to carry oxygen. 
• If faecal matter forms in the alimentary canal after the conclusion of absorption is not cleared, it could lead to the accumulation of hazardous bacteria and fermentation products, which could injure or impair the gut’s normal function.

Summary

The process of eliminating harmful or non-toxic wastes from the body is known as excretion. The final excretory products that are eliminated using a particular procedure are used to categorize the various excretion processes. The body produces urea, uric acid, ammonia, and carbon dioxide as excretory products. The human body’s different organs that are responsible for excretion include the kidneys, lungs, large intestine, liver, and skin. The removal of wastes from the body is crucial because if they are left there for an extended period, they can seriously harm the organ systems. 

Frequently Asked Questions  

1. What is Renal Ultrafiltration? When does it Occur?
Ans. One of the kidney processes that dialysis treatment substitutes are the process of ultrafiltration, which involves draining fluid from a patient. When a driving pressure causes fluid to cross a semipermeable barrier, ultrafiltration occurs.

2. Nephrons are made up of different Parts, what are They?
Ans. Each nephron is made up of a proximal tubule, which is a convoluted and straight component, a renal corpuscle (glomerulus inside Bowman’s capsule), an intermediate tubule, a connecting tubule, a distal convoluted tubule, an outer, cortical, and inner medullary collecting ducts, among other structures.

3. Give an example of a Disease that can Develop as a Result of the Buildup of Nitrogenous Waste in the Body.
Ans. A medical disease known as uremia is brought on by the harmful consequences of unusually high levels of nitrogenous chemicals in the blood as a result of the kidneys’ inability to eliminate waste products through the urine.

4. What Happens if Excess Carbon Dioxide Accumulates in the Blood?
Ans. Too much carbon dioxide in the blood will cause carboxyhemoglobin to form and cause the blood to become acidic, which will reduce its ability to carry oxygen.