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Excretory System

Excretory System is one of the most important systems in the human body, which performs excretion via waste discharge and elimination of toxins from the body. The human excretory system consists of some organs.

What is excretion? Excretion is a very important process for the human body. Everything that we consume in our body is removed with the help of excretion. After the intake of food, all the useful substances and nutrients are absorbed by the body, and the rest of the waste, which might be harmful to the body, is removed with the help of excretory organs present in the body. The human excretory system consists of a urinary bladder, pair of kidneys, pair of ureters, and a urethra. All these organs work together to remove the metabolic wastes from the body.

Organs of the Excretory system

  • A pair of kidneys

It is the main organ of the excretory system and is located on either side of the spine. They are kidney-shaped bean structures that have an inner concave side. It is made up of very small functional units called nephrons.

The blood goes into the kidneys with the help of renal arteries and leaves through renal veins. Kidneys are divided into three regions, namely renal cortex, renal medulla, and renal pelvis.

The renal cortex is the outer layer, the renal medulla is the inner layer, and the renal pelvis is the one carrying the urine from the kidneys to the ureter. The kidneys produce urine, which is a liquid solution of the waste material and toxins of the body.  It also has uric acid and urea. When purines are broken down in the body, uric acid is produced. Purines are present in the body and are natural substances. Urea is produced by the amino acid breakdown in the liver.

The kidney components are:

  • Capsule

The outer layer of the kidney is called a capsule. The kidney contains two zones-outer zones, which are called the cortex, and the inner zone, which is called the medulla. 

  • Nephrons 

They are the functional and basic units of the kidney. It is the primary unit of homeostasis in the body. Every nephron consists of two parts- the glomerulus and the renal tubule. The nephron is along a tubule consisting of many blood vessels. The upper end of the tubule is Bowman’s Capsule. Glomerular filtration occurs in the bowman’s capsule. Besides the Bowman’s capsule, the highly coiled thing in the tubule is the proximal convoluted tubule, which is followed by a loop of Henle.

  • Loop of Henle

The loop of Henle consists of three parts- the ascending limb, The descending limb, and the u-shaped bend. In this area, water from urine is absorbed, and the urine becomes concentrated. There are two types of nephrons- juxtamedullary and cortical. The loop of Henle is very short in the case of cortical, whereas it is very long and deep into the medulla in the case of juxtamedullary. 

  • Ureters

These tube-like structures exist in pairs and come out of the kidneys. They help carry urine from the kidney to the urinary bladder. 

  • Urinary Bladder

This sac-like structure is the place where all the urine is stored. It gets emptied when all the urine is excreted from the urinary bladder. It has muscular walls and is elastic in nature. It receives urine from the kidneys via ureters.

  • Urethra

It is a tube-like structure that arises from the urinary bladder. The urine comes out of the body finally through this. In males, it is the common path for sperms and urine. 

Secondary Excretory Organs

Apart from those organs, there are other organs that help in the removal of wastes from the body.

  • Liver

It is a very important organ in the process of excretion. It is useful for the detoxification of nitrogenous wastes. The liver cells play a major role in the biochemical processes that create ammonia from amino acids. It helps in the removal of excess fat and cholesterol. Many drugs first undergo the process of metabolism in the liver.

  • Skin

Wastes are excreted through the skin in the form of sweat. All the salts and excess water are removed through the body. Since it is the largest organ of the body, it helps a lot in the excretion process. 

  • Lungs 

The carbon dioxide produced in the lungs is removed when oxygen is taken in. The waste product is removed from the cells and sent to the bloodstream. As the blood reaches the lungs, it is exchanged for oxygen and liberated into the atmosphere.

The excretory system also maintains the osmotic level of blood and plasma and the balance of electrolytes in the body. 

Conclusion

The excretory system is very vital for the existence of an organism. The food that we take needs to be removed as well, and it would be possible only with the help of the excretory system. Not only does it help remove metabolic wastes from the body, regulate blood pressure, and maintain the electrolyte balance in the body. Organs like skin also help in the removal of wastes from the body in the form of sweat. In this process, the salts and urea are excreted from the body. Lungs and liver are also included in the secondary excretory system organs list.

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