In the human is nephron has a glomerulus which functions as a microscopic filter that constantly filters blood. Blood which is to be filtered and touched the glomerulus which consists of fenestrated capillaries as they have openings or pores. These fenestrations are hundred times more permeable than the continuous capillaries capillaries without funny stations that are found in other parts of the body.
The physical characteristic of the glomerular capillary bol determine what is filtered and how much is filtered into the bowman’s capsule. Working from the inside towards outside the capillary walls are made up of the three layers. The three layers of the capillary was make the filtration membrane.
The three members are as follows:-
Endothelium layer
- It is the most innermost layer.
- It has a relatively large pores 70–100 NM in diameter.
- Solutes and fluid can pass through the endothelium but not plasma proteins and blood cells.
- The proteins associated with the ports of the endothelium are negatively charged so they tend to repel negativity charged substances and allow only positively charged substance to pass more readily.
Glomerular basement membrane
- It is the middle layer.
- It is made up of a complex Nache of intracellular proteins and is fused to the endothelial Layer.
- It’s job is to prevent plasma proteins from being filtered out of the bloodstream.
Epithelium layer
- It is the most outermost layer.
- It consists of specialised cells called podocytes with extending finger like arms to cover the glomerular capillaries.
- They wrapped around the capillaries but leaves gaps let’s between the particles known as filtration slits.
Attend diaphragm between the plates act as a final filtration barrier before the fluid containing inorganic ions and small organic molecules such as glucose urea and amino acid fast from the blood plasma into the lumen or the bowmens capsule. The force required for filtration is supplied by blood pressure. The glomerulus consists of two agrios efferent arterioles which deliver blood to the glomerulus and different attributes which carry it away. Constrictions of efferent arterioles as blood exist the glomerulus provide resistance to blood flow in the capillary preventing a pressure drop. The two arterial change in size to increase or decrease the blood pressure in the glomerulus. Afferent arteriole are smaller in diameter than afferent arteriole.
As a result the pressurized blood enters the glomerulus through a relatively wide tube but is forced to exit through a narrow tube.
Together these unique features plus the fact that the heart supplies the kidney with over a litre of blood per minute around 20% of its output helps maintain a high glomerular capillary pressure so that the filtration function of the kidney continuous regardless of fluctuations in blood flow. It is interesting to note that during the formation of this filtrate up to 25% of water and solutes are removed from the blood. The renal corpuscle of the human kidney are capable of producing 180 litre of urine a day but we produce only about 1 to 2 litre urine per day which means that about 98% of the fluid volume of the urine is reabsorbed And re turned to the bloodstream.
