How Does the Filtration Barrier at the Kidney Work?

[sameeralord]

Red-capillary Purple- Basement membrane Blue-podocyte

Hello everyone, Now my question is after something if filtered from the capillary how does it go to the podocyte. The basement membrane looks too thick with no pores to me, it seems to be blocking the passage of molecules. Thanks

 

[bobze]

What do you mean, "go to the podocyte"?

 

[Andy Resnick]

The podocyte processes are separated in space, these are called "slit diaphragms" The size of these are about (IIRC) 10 nm wide, allowing transport of the blood plasma into the glomerular tuft. Again, AFAIK the slit diaphragms are too small to allow passage of viruses/bacteria/cells.

Podocytes are interesting cells- they don't divide (you are born with a full complement), and have a very high amount of cholesterol in the cell membrane, increasing the rigidity. The slit diaphragms are subject to enormous fluid stress- which you can very for yourself, given the size of the pore and the amount of fluid that passes (each kidney deals with about 150 L of fluid per day)

 

[mtc1973]

Basement membrane - think coffee filter - not barrier. It is a mesh of connective tissue fibres (collagen/elastin). PS nice diagram - where is it from?

 

[LudusRex]

I am happy to provide an explanation for the filtration barrier at the kidney. The filtration barrier is made up of three layers: the red-capillary, the purple-basement membrane, and the blue-podocyte. The red-capillary is responsible for filtering small molecules and waste products from the blood, while the purple-basement membrane acts as a physical barrier to prevent larger molecules and cells from passing through. The blue-podocyte, with its unique structure of interlocking foot processes, serves as a final barrier to ensure that only the necessary molecules and fluids are able to pass through and enter the urine.

To address your question, after filtration occurs at the red-capillary, the small molecules and waste products pass through the pores of the purple-basement membrane and reach the blue-podocyte. While the basement membrane may appear thick and impermeable, it actually contains small pores that allow for selective passage of molecules based on their size and charge.

The podocytes also play a crucial role in this process. As the molecules pass through the basement membrane, the podocytes use their foot processes to actively regulate and control the passage of molecules. This ensures that only the necessary substances are able to pass through and enter the urine, while larger molecules and cells are retained in the blood.

In summary, the filtration barrier at the kidney is a complex and highly regulated process that involves the coordinated function of the red-capillary, purple-basement membrane, and blue-podocyte. Each layer serves a specific purpose in filtering and regulating the passage of molecules, ultimately maintaining the body's fluid and electrolyte balance. I hope this explanation helps to clarify the role of each component in the filtration barrier. Thank you.