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What is Nephron?

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  • Last Updated : 12 Sep, 2022
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Excretion is the main process to balance the pure & impure particle percentage in an animal body. Humans incur many things by the means of food, water, etc. Among them, many substances are such that may harm the body. All those substances will remove from the body. This method is called Excretion. If Excretion is not performed by any animal for a long time, then the death of the animal will be a matter of time. For humans, Excretion can take place with the help of skin, lungs, liver, etc. But the main component which helps to Excrete more is the Kidney. Sweat is the excretion material that comes out from the skin. Lungs help to excrete Carbon Dioxide. The Kidney helps to produce Urine as the excreted material. Nephron helps to excrete materials from the Kidney.

What Is Nephron?

The Nephron is the functional unit of the Kidney. The Nephron is the small functional structure that produces Urine in humans. The Urines which are being produced by the Nephrons are being excreted outside of the body. ‘Nephron’ word comes from the Greek word ‘Nephros’. This means ‘Kidney’ in Greek. In every Kidney, there are 1 million Nephrons present. There are two Kidneys in humans. So, there are nearly 2.5 million Nephrons present in the human body.

The human Kidney can be divided into two parts. One is the Cortex of the Kidney & another is the Medulla of the Kidney. The Cortex is the outermost part of the Kidney & Medulla is the innermost of the Kidney. Nephrons are usually located in between these two divisions. This means some parts of the Nephrons are fallen into the Cortex Region of the Kidney. And some parts have fallen into the Medulla Region of the Kidney.

Types 

Nephron

 

According to the location of the Nephrons, this can be divided into two subgroups. Depending upon the size, location & availability, the Nephrons are divided into two groups. They are:

  1. Cortical Nephrons: This is the main type of Nephrons that can be visible in the human body. This type has very small Nephrons. Mainly, this type of Nephrons has its maximum portion in the Cortex Region of the Kidney. A large percentage of the Nephron structure falls under the Cortex Region. That is why it is called the Cortical Nephrons. In the human body, 80% of Nephrons fall under this category.
  2. Juxtamedullary Nephrons: This is another type of Nephron. In this type, the portion which falls under the Medulla Region of the Kidney is quite larger than the Cortical Nephrons. So, in this type of Nephrons, it is quite difficult to answer which portion of the Nephron structure is larger. Nearly, both in the Cortex & Medulla Region, the length of the Nephron is nearly similar. In the human body, 20% of Nephrons fall under this category.

Structure

The structure of the Nephrons can be divided into two parts. One part is completely made with a tube-like structure. And another part is made with blood vessels & layers. Again those parts are divided into several other parts. First, we need to divide the Nephron into two main subparts:

  • Renal Corpuscles: This is the structure that is built with the blood vessels & the different layers. This is the front part of the Nephron. This portion will fall under the Cortex Region of the Kidney. The creation of Urine starts place in this area. This subpart can be further divided into two more subparts.
    • Glomerulus: This is the thread of the blood vessels. The term ‘Glomerulus’ defines as the ‘Thread of Ball’. Here, in this case, it is a thread of blood vessels. An Afferent Vessel comes into the space. Then it makes a ball of the blood vessels with very thin & small blood vessels. Then it comes out from space as the Efferent Vessel. The Afferent Vessel has a larger diameter than the Efferent Vessel.
    • Bowman’s Capsule: This is the cup-shaped layer present outside of the Glomerulus. This cup-shaped structure is completely made of layers. This acts as the bridge between the Glomerulus & the further tube-like structure of the Nephrons. The outer layer is made of Epithelial Cells. In between each cell, there are small pores. These small pores help to make urine. The middle layer is completely permeable. The inner layer is made with a special type of cell which helps to filter the impure blood into pure blood. These cells are known as Podocytes. It has finger-like projections called Podocel.
  • Renal Tubules: This is a complete tube-like structure. This is the remaining structure of the Nephrons. According to their position & location, the names are provided to it. This part can be divided into three subparts.
    • Proximal Convoluted Tubule (PCT): This is the front part of the Nephrons. After the Renal Capsule, this tube-like structure comes first. That is why it is known as the Proximal. The term ‘Convoluted’ means that this tube is highly folded to keep a high amount of tube in a small space. This portion will fall under the Cortex Region of the Kidney.
    • The Henle’s Loop: It is the middle part of the Nephrons. This is the bridge-like structure between the PCT & DCT. It has two limbs. One is the Descending Limb & another is the Ascending limb. This portion will fall under the Medulla Region of Kidney.
    • Distal Convoluted Tubule (DCT): This is the last part of the Nephron. After Henle’s Loop, this structure is present. As it is also highly collided, that is why it is also termed as the ‘Convoluted’. This structure joins the Henle’s Loop with the Collecting Duct. This portion will fall under the Cortex Region of the Kidney.
  • Collecting Duct: Though this is not part of the Nephron. But it has high significance. This is a wide tube where many Nephrons are joined. This is like a High Drain concept. Like the wastewater from every household meets in a big drain, Collecting Duct acts in the same way. This portion will fall under the Medulla Region of Kidney.

Importance

There is no need to define the importance of Nephron. As it is the functional unit of the Kidney, hence it is highly important to our life. Excretion takes part with the help of Nephrons. Though there are also many other ways to excrete impure substances. But the excretion process of Nephron can’t be balanced with any other method. Skin, Lungs, and Liver can excrete impure things. But Kidney can excrete nearly all types of impurities of the body. That is why unfunctional Kidney may arise many diseases. If we can’t throw out the impurities outside of the body, it will cause severe damage to the body. Not excretion of the impurities of the body, since a long time can lead to the death of certain human individuals.

Mechanism of the Excretion

Excretion is a multistage process. Every part of the Nephrons contributes to the mechanism. The Excretion process is a combination of three sub-processes. These subprocesses are Filtration, Re-Absorption & Secretion. These sub-processes are performed by the different parts of the Nephrons.

  • Processes Performed By The Renal Corpuscles

Here, first, the blood comes to the Glomerulus by the Afferent Vessels. Then the blood enters the Glomerulus for further process. The walls of the Glomerulus blood vessels are very thin. As the difference in the diameter of the Afferent & Efferent Blood Vessels, high blood pressure will occur in the Glomerulus. Due to the high blood pressure, the impure blood which comes to the Nephrons is being filtered by the Filtration process. In this process, the impure blood is filtered by the high blood pressure & enters the impurities into the Bowmen’s Capsule. Then the pure blood will come out by the Efferent Vessels.

Then the impurities along with the water will store in the Bowmen’s Capsule for a while. Then the impurities will be further transported through the walls of the Capsule. Hence, it will enter into the Renal Tubule.

  • Processes Performed By The Proximal Convoluted Tubule (PCT)

Through the Filtration process, the impurities will come inside the Nephrons. But still, there are some necessary items present. These items can’t be prevented while the Filtration process is going on. For this purpose, Re-Absorption takes place. As these items are very necessary for the body, they will be Re-Absorbed. And these items will be returned to the blood.

In the PCT, some items are being Re-Absorbed. These items like NaCl, Glucose, Water, Amino Acid, etc. Here, in the PCT, nearly 70% NaCl, 98% Glucose, 70% Water & 97% Amino Acids are being Re-Absorbed.

  • Processes Performed By The Henle’s Loop

The function of the Henle’s Loop is different in its different limbs. Through the ascending limb of the Henle’s Loop, water can’t be moved out. From this limb, only some particular substances like 25% Sodium, 25% Calcium, 20% Potassium, and 55% Magnesium can be removed. Means here also, a little percentage of Re-Absorption takes place. Whereas in the descending limb, water can only be removed. In this part of Nephron, the concentration of Urine is performed.

  • Processes Performed By Distal Convoluted Tubule (DCT)

In this part of Nephron, the final step of excretion is performed. Here also, some little amount of Re-Absorption can visualize. Like some little amount of Sodium, Calcium is being Re-Absorbed here. Besides it, the Secretion step is performed here. Some important impure substances or harmful ions are Secreted from the DCT. Thus, these substances will mix up with the Urine. The ions are Hydrogen, Potassium & Ammonium ions. Also, sometimes Uria & Uric Acid mixed up with the excretion in a small amount. 

Hence, in this way the excretion process completes. This mix-up will then comes to the Collecting Duct. All the excreted liquid comes to the common Collecting Duct & ready to be ejaculated outside of the body.

Types of Transporters in Nephron

The Transporter is the substance by which different elements get exchanged through the membrane. Here, in the case of Nephrons, the processes of Filtration, Re-Absorption & Secretion are also completed with the help of these transporters present in the membrane of the Renal Tubules.

  1. Uniporter: This is a type of transporter. In this type, an element can move in the opposite direction through the membrane. There is no need to exchange any element while transferring. In such cases, it will use an active transport mechanism & diffusion to complete such purposes. The Filtration process is completed by such transporters.
  2. Symporter: This is another type of transporter. This type of transporter uses a secondary active transport mechanism. In such cases, two or more two elements can go through the membrane at a time. But the movement of such elements should be in the same direction. Also, in these cases, there is no need to exchange any element. The Re-Absorption process is completed by such transporters.
  3. Antiporter: This is another type of transporter. Here, two elements move in the opposite direction of each other. This means for transporting, will take the help of an exchange mechanism. One element will move outside of the cell. Instead, it will collect an element from outside of the cell. The Secretion process is completed by such transporters.

Function Of The Nephrons

  1. Waste Excretion: The main function of the Nephrons is to excrete the waste products outside of the body. It generally produces Urine for all upper-level animals. All types of impurities in the blood are being thrown out of the body. Nephrons produce Urine in the Kidney & hence it is ejaculated outside of the body.
  2. The pH Maintenance: Nephrons are reliable for the pH maintenance of the body. It returns the NaCl salt to the blood. Hence, it controls the salt balance in the body. Salt is the balancer of the pH in the body. Due to the condition of the body, Nephrons regulate the salt absorption in the Renal Tubules.
  3. Blood Pressure Regulator: Though Nephrons are not completely influencers for a blood pressure regulator. But still, with the help of the ADH hormone, Nephrons can regulate blood pressure. If necessary, the Nephrons can regulate the blood pressure in the Glomerulus. Hence, it also helps to regulate the blood pressure in the body.

FAQs on Nephron

Question 1: What is the length of each nephron?

Answer:

Every nephron is 35 to 40 cm long in a folded way. The coiled tube can’t measure how much can be the length of the tube in unfolded manner. So, scientists measure the total length of Nephrons as nearly 40 cm.

Question 2: Why the Medulla of the Kidney is more salted?

Answer:

The Medulla of the Kidney is more salted than the Cortex of the Kidney. As the Henle’s Loop is situated inside of the Medulla of the Kidney. The Loop helps to remove the salt from the Nephrons to the Medulla of the Kidney. But in Cortex, this type of conversation can’t be present there. That is why the Medulla part is more salted.

Question 3: What is Bowman’s Space?

Answer:

In the cup-shaped Bowman’s Capsule, there is a thin space available. In between the Inner & Outer layer of the Bowman’s Capsule this space is present. This space is known as Bowman’s Space. In this space, after filtration, the excreted item is stored for a while.

Question 4: What is the Renal Pelvis?

Answer:

The Renal Pelvis is the common space in the Kidney. There are all the Collecting Ducts combined. This is the last space where the excreted item is stored before leaving the Kidney.

Question 5: Write down the parts of the Nephrons with their region inside of the Kidney

Answer:

The parts of the Nephrons along with the region of the Kidney is:

  • Glomerulus: Cortex Region of Kidney
  • Bowman’s Capsule: Cortex Region of Kidney
  • Proximal Convoluted Tubules (PCT): Cortex Region of Kidney
  • Henle’s Loop: Medulla Region of Kidney
  • Distal Convoluted Tubules (DCT): Cortex Region of Kidney
  • Collecting Duct: Medulla Region of Kidney

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