Human Excretory System

Human Excretory System is one of the types of life processes. Excretion helps to excrete out all the metabolic waste produced due to any reaction in the body. The excretion system is of two types i.e., the internal and external, human excretory system is an internal excretion system.

Excretion in Humans

Human Excretory System is a complete set of organs & tubes. All of them together make a complete mechanism to throw out the waste materials outside of the body. Though human body can able to excrete waste material in some other forms also. Like the means of the sweet, some waste materials can remove from the body. But the amount of waste removed from the body by the sweet is very less. Whereas by the largest excretory system, a huge amount of waste can be removed at a time.

It is very normal to create a waste product in the human body. Whatever we intake as food or drink, create waste product inside the body. They store in the cells. Also, there are some other important processes executed inside the body. These create waste products also. All the waste product needs to be removed. So, they have to store in the cell & at last, they are removed from the body.

Excretory System Organs

The human excretory system is a complete set of organs. There are many organs present that make the process easy. These organs together make the system a complicated one. There are the below-mentioned organs:

• Two sets of Kidneys
• Two sets of Ureters
• One Urinary Bladder
• One Urethra

Kidneys

Kidneys are the most important organ in the excretory system. It is a red bean shape structure present on both sides of the backbone. The normal size of a kidney is 10-12 cm, the width of 5-7 cm, and the weight is approx 120-170g. There are excreted materials produced. Kidneys have a hard outer layer. This is known as the Capsule. The Capsule can further be divided into two major parts.

• Cortex: This is the outermost layer of the kidney. This is completely made with connective tissues. There is a salt concentration than in the other areas of the kidney. Nephrons are the functional unit of the kidney. The part of the nephron lies in the cortex area. The Renal Capsule, Proximal Convoluted Tubule & Distal Convoluted Tubules are present in this part.
• Medulla: This is the inner part of the kidneys. Their pyramid-like structures are present. This place is a high-concentration area inside the kidney. Only the Henle’s Loop of the nephron is present there. As Henle’s Loop can able to reabsorb the salt. That is why this part has a high salt concentration. Also, the collecting ducts of the Nephron are present there. All the collecting ducts merge there & make a large collecting tube there.

Capsule

The outermost layer of the kidney is known as the capsule. It is hard in nature made up of stromal cells surrounded by connective tissue. It plays an important role in the development of kidneys.

Nephron

The functional unit of the Kidney has some anatomical structure there. This can be divided into some parts. This is responsible to reabsorb, secrete, and filtration of the waste product inside the kidneys. These units all together perform the production of the waste product.

• Glomerulus: It is the ball of tiny blood vessels. The small blood vessels come together & make a network of blood vessels there. The Afferent blood vessels & Efferent blood vessels make this network. In this way, the polluted blood comes to the nephron inside the kidney. It filters the blood & makes fresh blood. Then it comes out from the nephron.
• Bowman’s Capsule: This is the free space in the nephron. The Glomerulus is surrounded by the Bowman’s Capsule. There are three layers. All of them are made with epithelium layers. In those layers, there are small pores. This help to move forward those waste substances inside of the nephrons for further process.
• Proximal Convoluted Tubules: This is the first tube-like structure in the nephron. This tube is not linear. This means there are some loops present. These loops happen as there is a large length of the tube is convoluted there. In this part, the reabsorb of the important substances occurs.
• Henle’s Loop: This is also a tube-like structure. There are two arms in this loop. One is ascending arm & another is descending arm. This area is also performed re-absorption. Water & salt are being reabsorbed here.
• Distal Convoluted Tubules: This is another part of the Nephron. This is also convoluted like the proximal convoluted tubules. Here, the secretion of some hormones & other substances is performed.

Types of Nephrons

Nephrons can be divided into two categories as per their size & location. As the Nephrons are situated in the Kidney, so there are two locations in the Kidney where the Nephrons can be located. The types are:

• Cortical Nephron: This is the main type of Nephron present in the human body. Nearly 80% of Nephrons fall under this category. This type of Nephron is mainly located in the Cortex of the Kidney. The maximum parts of the Nephron belong to the Cortex area of the Kidney. From the location of the Nephron, it is called the Cortical Nephron.
• Juxtamedullary Nephron: This is another type of Nephron. This type of Nephrons can be found small in amount. Nearly 20% of Nephrons fall under this category. Here, the Nephrons are mainly located inside the Medulla area of the kidney. So, as per the location of the Nephron, the name is allocated. They are small in size also.

Ureters

It is a thin tube-like structure. This comes out from the kidney by a special location, called Renal Pelvis. This helps to move the urine to the urinary bladder. This is made with small tissues. There are two ureters in the human body.

Urinary Bladder

This is the sac-like organ present in the human body. This helps to store the urine inside of it for a while. The capacity of the bladder is 500ml of urine. The bladder can be divided into two parts, they are the upper part & lower part. In the lower part, there is the neck. From the neck, the Urethra is attached to this area. The bladder is situated in the pelvic cavity of the human body.

Urethra

This is the muscular tube present after the urinary bladder. It helps to remove both the urine & the sperm. It is a long tube that opens nearly the prostate gland. Then it helps to remove the urine produced in the kidney. There is a Sphincter muscle in the urethra. This helps to guard the opening of the urethra. It helps to regulate the removal of urine.

Diagram of Human Excretory System

Urine Formation

The kidney is the major organ that performs the main function of urine formation. Inside the Glomerulus, due to the large pressure of the blood, waste products come inside the nephron. It then stores in the Bowman’s Capsule for a while. Then the fresh blood comes out from the nephron or the kidney. 

Inside the Glomerulus, the filtration process is completed. After that, the waste product is stored inside the Bowman’s Capsule. After that, it comes to the proximal convoluted tubules. There the reabsorption process takes place. This means from there some substances like Glucose, Water, etc are get reabsorbed. These will again move to the blood. There is a blood capillary close to the Proximal Convoluted Tubules. This will help to make the substances available there.

Then insides of Henle’s Loop more reabsorption takes place. There are two different types of reabsorption takes place. In the ascending limb of Henle’s Loop, the water is reabsorbed. But in the descending limb, water doesn’t reabsorb. At last, in the Distal Convoluted Tubules, the secretion process takes place. With the help of the secretion process, some more waste products like Uria, Uric Acid, and Ammonia removes from the body.

Then the produced urine will come out from the renal pelvis of the kidney. Then it moves forward with the help of the Ureters & comes to the Urinary Bladder. Inside the bladder, the urine is stored for a certain amount of time. When the stored urine goes beyond the capacity of the bladder, it removes from the body. The removal of urine can take place with the help of the Urethra.

Functions of Human Excretory System

The main function of the excretory system is to produce urine or waste material. The process of the production of the water material is mainly inside the kidney. Also, some more functions are being served by the urinary bladder.

Kidney

The Nephrons are the functional unit of the kidney. The polluted blood comes to the nephron by the Afferent blood vessel in the Glomerulus. Thereby the help of the filtration process those waste materials come inside the nephrons. The fresh blood then returns to the body by the efferent blood vessels. The filtration process is completed by the high blood pressure inside the Glomerulus. Then those waste products are stored for some time inside the Bowman’s capsule.

Then the waste product comes inside the proximal convoluted tubules. There the reabsorption takes place. Some important substances are present in those waste products. As the filtration can’t able to efficiently pick only the waste product. So, reabsorption takes place. Here, NaCl, Glucose, Water, etc. gets reabsorbed.

In Henle’s Loop reabsorption also occur. There in the ascending limb of Henle’s Loop, Sodium, Potassium, and Magnesium ions are gets reabsorbed. In the descending loop, only the water & salt can be reabsorbed.

At last, inside the Distal Convoluted Tubule, the secretion takes place. These harmful substances like Uria, Uric acid are secreted. Hence the urine is produced finally. Then they come together to the collecting duct. There they all mixed up & come out from the kidney by the renal pelvis.

Ureter

Here, the urine which is produced by the kidney moves to the urinary bladder. The only function of the Ureter is to carry the urine to the bladder.

Urinary Bladder

The main function of the Urinary Bladder is to store urine there. The receptors which are present on the walls of the Bladder send the signal to the Central Nervous System. It is then stretched & stores the urine inside it. Again, it receives the signal from the central nervous system & charges out the urine. This process is known as Micturition.

Urethra

This helps to finally throw out the urine outside of the body. Not only urine but is also used to eject sperm outside of the body. This is used as the common route. The sphincter muscle regulates the amount of urine that needs to be thrown out of the body. It is also controlled by the central nervous system.

Disorder of Human Excretory System

Following are the disorders which are related to the human excretory system are:

• Renal Failure: In this disease, the filtration process of the Glomerulus is affected mostly. As the kidney can’t able to filter the blood, the production of urine hampers. In severe conditions, both kidneys may get failed.
• Renal Caliculi: This is the disorder commonly known as Kidney Stone. There create some stones inside the kidney with the help of insoluble salts. And they get stuck inside the kidney walls. This creates a large size kidney. When that pass, patients feel immense pain.
• Nephritis: This is also known as the Bright Diseases. In this case, there is inflammation of the kidney. Due to a disorder of the nephron. Some parts of the nephron start malfunctioning. This creates a problem. The inflammation of the Glomerulus can also cause this. In some cases, artificial kidneys are the only way to survive.

Dialysis Process

As the kidney is not responding, the excretory of the body will stop. This causes a poisoning state of the body. Many substances like Uria, Uric Acid, and Ammonia need to remove from the body within a proper interval. If this doesn’t happen repeatedly those substances are stored in the cells of the body. This creates a lot of trouble in the body.

Dialysis is needed when the kidney is severely damaged. Due to any disorder of the kidney, when it can’t able to execute the tasks then Dialysis is highly needed. After a kidney stone, if the disease is not sorted out immediately. It can lead to kidney failure in the future. So, without any delay, patients need to take care of their kidneys.

Regulation of Human Excretory System

If a kidney is damaged & can only able to work 15% or less than that, then dialysis is needed for that patient. There are mainly two types of dialysis present. one is for the routine patient. Another is for the scheduled patients. Routine patients need to come to the hospital or a specific location for dialysis purposes. But the scheduled patients need to do the dialysis at their own homes. As the dialysis process for them is quite easier than that of routine patients.

Here, a machine is attached to the body. It is the same as the kidney in our body. There are two transporters in the machine. One helps to deliver the polluted blood of the body to the machine. Inside the machine, the blood gets purified. All the waste products are gets filtered in the machine. Then the purified blood comes into the body of the patient again. This process is being done at some intervals. After every particular second, the blood needs to be again purified. In a single day, a human body can produce 32 ounces of waste product & water from its blood.

Importance of Human Excretory System

• Time by time, the body gets infected with waste which is removed by the human excretion system.
• Some poisons may arise inside the body if the waste product is stored for a long time. The removal of waste products is very important. 
• If the waste can not be thrown out outside of the body, then it will directly affect health.
• Human urine is the way, by which a large amount of waste can be thrown out.

FAQs on Human Excretion System

Q1. What is Dialysis?

Answer:

Dialysis is the process by which the function of the kidney can be performed artificially. The kidney purifies the blood by draining out the waste products. In the dialysis machine, the blood goes to the machine & gets purified artificially. This is done when there is a disorder with the kidney.

Q2. In a single day how many times, does the blood get filtered by the kidney?

Answer:

The kidney can purify the blood. In a single day, nearly 400 times the kidney can purify the blood. It is a very necessary process. In a single second, a good amount of waste is being created inside the body.

Q3. Urinary Bladder can store what amount of urine at a time?

Answer:

At a single time, Urinary Bladder can store up to 500ml of urine there. After storing that amount of urine there, it sends the signal to the central nervous system. This helps to empty the bladder from time to time. This helps to make the circle better.

Q4. Why does the medulla of the kidney have a high salt concentration?

Answer:

The Henle’s Loop of the nephron is located inside the medulla portion. Only the Henle’s Loop is responsible for reabsorbing the salt from the mixture. After reabsorbing the salt, it stores them inside the medulla pyramid. Hence, there is a large salt concentration other than any other part of the kidney.