Nephron

Nephron
The basic structural and functional unit of kidney are called Nephron.
OR
Kidney consist of million of microtubules are called Nephron.
Structure of Nephron
Each nephron is sub-divided into
1. Renal Corpuscle
2. Renal Tubule
1. Renal Corpuscle
Each renal corpuscle is divides into two
i. Bowman’s Capsule
ii. Glomerulus
i. Bowman’s Capsule
In each nephron inner end forms a cup-shaped swelling called Bowman’s capsule.
ii. Glomerulus
Each bowman’s capsule have a ball of capillaries called glomerulus. Glumerulus circulates blood through capsule as it arrives through Aferent Arteriole. Blood carried away from the capsule by a small vessel called Efferent Arteriole. The blood vessel sub divide again into another network of capillaries called Peritubular Capillaries.
2. Renal Tubule
Bowman capsule continuous as extensively tubular system.
i. Proximal Convoluted tubule
ii. Loop of Henle
iii. Distal convoluted tubule
iv. Common collecting duct
i. Proximal Convoluted Tubule
Bowman capsule gives out a coiled tubule called Proximal Convoluted Tubule.
ii. Loop of Henle
The proximal convoluted opens into a U-Shaped structure called loop of Henle. Loop of Henle consist of descending and ascending limbs.
iii. Distal Convoluted Tubule
The ascending limb of loop of Henle opens into another convoluted tubule called Distal Convoluted Tubule.
iv. Collecting Tubules
Distal tubule empties into collecting tubules which open into pelvis.
Functions of Kidney
Urine formation take place in these following steps:
1. Ultra Filtration
2. Selective Reabsorption
3. Tubular Secretion
4. Counter Current Exchange
2. Selective Reabsorption
All the important constituent of the glomerular filtrate are reabsorbed when filtrate pass in tubular system.

• Prominal convoluted tubule reabsorb salt amino acid, glucose and water.
• Descending limb of loop of Henle reabsorb Na and Cl inter in the interstial fluid. Na and Cl reabsorbed by active transport. Water is not reabsorb.
• Distal convoluted tubule have hypotonic solution due to high concentration of water. In this part by the action of hormones concentration of various salt is adjust.

3. Tubular Secretion
Tubular section is also very important process of excretion. The tubular epithelium also secrete substances into teh lumen this secretion is very selective and mainly of hydrogen into balance pH value of the filtrate passing through the tubule.
4. Counter Current Exchange
The exchange of solute and water in the medulla of kidney is called counter current exchange. There are two counter exchanges:
i. Counter Current Multiplier
ii. Counter Current of Vasa Recta
i. Counter Current Multiplier
When the filtrate passes through the descending limb of loop of Henle water is reabsorbe due to this process the filtrate became hypertonic.
ii. Counter Current of Vasa Recta
The blood vessels which run parallel to the loop of Henle are called Vasa recta. Through these blood vessels only about 10% of blood of kidney passes very slowly. This blood supplies oxygen and nourishment to the cell of medulla and carries away the reabsorb water from the filtrate. The system is regulate and maintained properly.
Reabsorption in the Nephron
Types of Nephron
There are two type of nephron
1. Cortical Nephron
2. Juxtamedullary Nephron
1. Cortical Nephron
The nephron which have small length of loop of Henle and only present in cortex region of kidney are called Cortical Nephron.
2. Juxtamedullary Nephron
These nephron have long loop medullar of kidney reabsorb more water are called juxtamedullary nephron.
Effect of Hormones on the Working of kidney
Certain hormones control the working of kidney.
1. Andiurelic Hormones (ADH)
2. Aldosteron Hormones (AH)
3. Parathormon Hormone (PTH)
1. Antidiurelic Hormones
Pituitary gland secrete ADH. It is also called vasopressin.
Functions
Hormones helps in reabsorption of water. Hormone is produce at the time of dehydration. It causes shortage of water in the body due to rapid loss of water. The osmotic pressure of blob increases. This hormone helps to balance the amount of water.
2. Aldosteron Hormones
Outer part of adrenal cortex secreted aldosteron harmine.
Functions
It control the concentration of Na+ in the bosy fluid. It increase the reabsorption of sodium ion in nephrone.
3. Parathormon Hormones
Parathyroid gland secrete parathormone.
Kidney Problem
Kidney is not perform properly due to different reason are called Kidney problem or Kidney disease.
There are many problems of kidney
1. Kidney Stone
2. Renal Failure
1. Kidney Stone
Stone solid materials are found in the kidney called Kidney Stone.
Causes
Kidney stones are caused by metabolic disease.
70% of kidney stone are formed due to calcium oxalate and phosphate oxalate. Oxalate are produced in the metabolic process and added in the urine and deposit in kidney change into stones. Oxalates are present in green vegetables and tomatoes therefore may be the source of oxalate stone.
Infective Stone
20% stone are called as infective stone. Infective stone consist of combination of calcium, magnesium and ammonium phosphate.
Uric Acid Stone
5% stone are formed in uric acid.
Cure
Lithotripsy
The lithotripsy is used for non surgical removal of kidney stone. It is a technique used to break up stones that form in the kidney, ureter or gall bladder.
Method
There are several way to do it although the most common is shock wave lithotripsy or ultrasonic lithotripsy. High concentration X-Ray or ultrasound are directed from a machine outside the body to the stone inside. The shock waves break the stone in tiny pieces or into sand which are passed out of the body in urine.
2. Renal Failure
Sometimes the working of kidney is badly damaged due to certain reason or infection. They are not able to filter the harmful nitrogenous substance it is called renal failure. In such condition the harmful substance remain in blood.
Symptoms

• Nausea
• Vomiting
• Loss of appetite
• Weakness
• Difficulty in breathing

In severe condition patient may suffer by pneumonia high blood pressure coma and ultimately death.