In our kidneys, it is various functional renal cells that play the function.
And their main function is to eliminate the toxins in the blood out of the body,
and this filtration is mainly acted out by the glomerulus. Therefore, we attach
much importance to the glomerulus.
Then why the glomerulus filtration rate (GFR) will decrease? To answer this
question, we need to analyse how glomerulus work. According to the research, the
filtration function is achieved by two functions of the glomerulus. One is the
mechanical barrier function and the other is the charge barrier function. The
mechanical barrier function means the glomerulus can filter out some
micromolecular substances while it can keep some macromolecular substances in at
the same time, which keeps some macromolecular substance stay in the blood and
send the micromolecular substance to the urine. And most the micromolecular
substance belongs to the toxins, so that means the mechanical barrier function
can send a part of the harmful substance into the urine. Then the charge barrier
function means that the glomerulus can let the substance with positive charge
pass while they can block the substance with negative charge.
By the above two function, glomerulus can eliminate the harmful substance
into the urine during the filtration process. when the urine pass through the
kidney tubules, the kidney tubules can play their resorption function to absorb
a part of useful substance for the body.
Afterwards, with the development of the medical science, we have discovered
the secret of the filtration of the glomerulus and the resorption of the kidney
tubules. We realized that the barrier function of the glomerulus stem from the
functional cells in the capillary endothelium, which includes the capillary
endothelial cells and capillary mesangial cells. And there are epithelium cells
on the cortex of the capillary. The function of epithelium cells: the epithelium
cells are a part of filtration barrier and they are the smallest filtration
pores. Epithelium cells contain a large amount of sulfuric acid heparin, which
lie in the two flanks of the basilar membrane and maintain the electric charge
barrier; epithelium cells also possess the function of secreting and helping
regulate the haemodynamics. Epithelium can generate collagens (basilar membrane
collagens) and glycosaminoglycan, and join in the repair of basilar membrane.
And there is a type of renal tubules endothelial cells. On the basis of the
theory of cells, we can know the reason of the decrease of the filtration
function is the damage to the four types of functional cells.
While once our human body is attacked by various diseases, this will cause
the change of the elements in the blood, which will further cause the extra
workload to the glomerulus and kidney tubules. And all of these may impair or
damage the original filtration balance. The essence of this damage is the damage
to the above mentioned four types of functional cells. The damage process of
kidney function is just the process of necrosis and decrease of renal inherent
cells, the process of the development caused by hyperplasis of extracellular
matrix, and the process of the whole kidney turn into the accretion of
extracellular matrix. The damage degree of kidney function can be from impair to
damage, from damage to failure, from failure to junked, this process is also a
process of renal inflammation turn into organism combining then into fibrosis.
Therefore, we reach a conclusion that the process of kidney function being
damaged is the process of renal fibrosis.
