Anonymous
Dec 10, 2023
Structure of Kidney and its functional unit:- mechanism of urine formation?
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Dec 10, 2023
The kidney is a bean-shaped organ located in the back of the abdominal cavity. It is composed of millions of functional units called nephrons. Each kidney contains around one million nephrons.
The structure of a nephron consists of several parts:
1. Renal corpuscle: This is the initial part of the nephron and consists of the glomerulus and Bowman's capsule. The glomerulus is a network of capillaries where blood is filtered, and Bowman's capsule surrounds the glomerulus and collects the filtrate.
2. Proximal convoluted tubule (PCT): This is a twisted tubular structure that arises from Bowman's capsule. It is responsible for reabsorbing most of the filtered water, ions, and nutrients back into the bloodstream.
3. Loop of Henle: This is a U-shaped tubular structure that descends into the medulla of the kidney and then ascends back towards the cortex. It plays a crucial role in concentrating the urine by creating a concentration gradient in the medulla.
4. Distal convoluted tubule (DCT): This is another twisted tubular structure that arises from the loop of Henle. It is responsible for fine-tuning the reabsorption and secretion of specific ions and substances.
5. Collecting duct: This is a tubular structure that receives urine from multiple nephrons. It further concentrates the urine by reabsorbing water and plays a role in maintaining the body's water and electrolyte balance.
The mechanism of urine formation involves three main processes:
1. Filtration: Blood enters the glomerulus under high pressure, and small molecules such as water, ions, glucose, and waste products are filtered out of the blood into Bowman's capsule. This filtrate is called the glomerular filtrate.
2. Reabsorption: As the glomerular filtrate passes through the PCT, most of the filtered water, ions, and nutrients are reabsorbed back into the bloodstream. This process helps maintain the body's fluid and electrolyte balance.
3. Secretion: In the DCT and collecting duct, certain substances such as hydrogen ions, potassium ions, and drugs are actively transported from the bloodstream into the tubules. This process helps eliminate waste products and maintain the body's acid-base balance.
The final product, urine, is formed as the remaining filtrate passes through the collecting ducts and is concentrated by reabsorbing water. The concentrated urine is then transported to the renal pelvis and eventually expelled from the body through the ureters, bladder, and urethra.
The structure of a nephron consists of several parts:
1. Renal corpuscle: This is the initial part of the nephron and consists of the glomerulus and Bowman's capsule. The glomerulus is a network of capillaries where blood is filtered, and Bowman's capsule surrounds the glomerulus and collects the filtrate.
2. Proximal convoluted tubule (PCT): This is a twisted tubular structure that arises from Bowman's capsule. It is responsible for reabsorbing most of the filtered water, ions, and nutrients back into the bloodstream.
3. Loop of Henle: This is a U-shaped tubular structure that descends into the medulla of the kidney and then ascends back towards the cortex. It plays a crucial role in concentrating the urine by creating a concentration gradient in the medulla.
4. Distal convoluted tubule (DCT): This is another twisted tubular structure that arises from the loop of Henle. It is responsible for fine-tuning the reabsorption and secretion of specific ions and substances.
5. Collecting duct: This is a tubular structure that receives urine from multiple nephrons. It further concentrates the urine by reabsorbing water and plays a role in maintaining the body's water and electrolyte balance.
The mechanism of urine formation involves three main processes:
1. Filtration: Blood enters the glomerulus under high pressure, and small molecules such as water, ions, glucose, and waste products are filtered out of the blood into Bowman's capsule. This filtrate is called the glomerular filtrate.
2. Reabsorption: As the glomerular filtrate passes through the PCT, most of the filtered water, ions, and nutrients are reabsorbed back into the bloodstream. This process helps maintain the body's fluid and electrolyte balance.
3. Secretion: In the DCT and collecting duct, certain substances such as hydrogen ions, potassium ions, and drugs are actively transported from the bloodstream into the tubules. This process helps eliminate waste products and maintain the body's acid-base balance.
The final product, urine, is formed as the remaining filtrate passes through the collecting ducts and is concentrated by reabsorbing water. The concentrated urine is then transported to the renal pelvis and eventually expelled from the body through the ureters, bladder, and urethra.
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