The rate at which blood is filtered by the kidney is called GFR or Glomerular filtration rate. The primary driving force or outward pressure for the filtering process is due to the blood pressure as it enters the glomerulus. It is normal for our blood pressures to fluctuate during the day but surprisingly the blood pressure has no effect on GFR. The intrinsic mechanisms of regulating GFR is:Renal Autoregulation - The kidney is capable of self-regulation by constriction or dilation of different arterioles that can counteract blood pressure changes. Renal autoregulation can work over a large range of blood pressures. But if you have kidney disease then this intrinsic process can malfunction.There are a couple of extrinsic mechanisms of GFR regulation as explained below:Hormonal and Nervous System Control - These extrinsic processes can impact renal autoregulation and diminish the GFR when needed. For instance, if someone loses a lot of blood, their blood pressure would drop in a big way. The nervous system would then stimulate afferent arteriole constriction which will reduce urine production. If the system requires further measures then the nervous system could also activate a hormone system called the renin-angiotensin-aldosterone system that does the job of balancing fluid and regulating blood pressure.Hormonal Control - The GFR can be increased by a hormone called the atrial natriuretic peptide. This hormone is produced inside the heart and gets secreted there is an increase in plasma volume which increases urine production.