 In this video, I will describe how each of the following functions in the extrinsic control of GFR. Sympathetic nervous system, Renon angiotensin mechanism, and natural erratic peptides. Extrinsic control of glomerular filtration rate by the sympathetic nervous system involves the sympathetic efferent fibers of the renal nerve releasing norepinephrine and norepinephrine binds to receptors on the vascular smooth muscle of the efferent arteriole stimulating contraction and this constriction of the efferent arteriole increases resistance to blood flow into the glomerulus leading to a decrease in the glomerular blood hydrostatic pressure leading to decreased net filtration pressure and decreased glomerular filtration rate so in response to a stressful situation part of the fight-or-flight stress response coordinated by the sympathetic nervous system is to Decrease the amount of blood being filtered in the kidneys This will make sense if you had a stressful situation that led to bleeding you would want to maintain as much blood volume in the circulation as possible and it's not really necessary to Send a large amount of blood to the kidneys when you're dealing with this acutely stressful situation the Renon angiotensin mechanism provides another extrinsic control of glomerular filtration rate this is initiated as Cells of the maculadenza within the distal convoluted tubule Detect a low sodium concentration of the filtrate This stimulates the maculadenza to secrete a paracrine signal called prostaglandin e2 Prostaglandin e2 then binds to receptors in the juxtaglomerular cells surrounding the afferent arteriole and stimulates the juxtaglomerular cells to secrete renin renin is an enzyme that Catalyzes the conversion of angiotensinogen to angiotensin 1 Angiotensinogen is a precursor of a hormone that is secreted by the liver and is circulating in the blood so Angiotensinogen is converted to angiotensin 1 by the enzyme renin then angiotensin 1 Still requires further activation to become a fully functional hormone the angiotensin converting enzyme is Found in the endothelium of blood vessels in the lungs So as the blood containing angiotensin 1 flows through the pulmonary circuit Angiotensin 1 is activated to form angiotensin 2 by the action of the angiotensin converting enzyme Then angiotensin 2 is the active hormone that can bind to receptors on the surface of vascular smooth muscle cells stimulating vasoconstriction of the afferent arteriole Will lead to a decrease in glomerular filtration rate so angiotensin 2 will cause widespread vasoconstriction as a mechanism to increase blood pressure but will also cause vasoconstriction of the afferent arteriole leading to a decrease in glomerular blood hydrostatic pressure a decrease in the net filtration pressure and a resulting decrease in the glomerular filtration rate As we move on to discuss more the regulation of Reabsorption we'll see that angiotensin 2 can also have a function to stimulate the cells in the adrenal cortex to secrete another hormone known as aldosterone And aldosterone will have an effect in the kidney to stimulate the reabsorption of sodium another extrinsic control mechanism regulating glomerular filtration rate is the natural reddit peptides atrial natural reddit peptide is secreted by the heart muscle cells the cardiomyocytes or myocardial cells in response to stretching an increase in plasma volume Can lead to stretching of the atria in the heart stimulating an increased secretion of atrial natural reddit peptide that binds to receptors on the vascular smooth muscle leading to dilation of the afferent arteriole and At the same time constriction of the efferent arteriole Together these effects will increase glomerular blood hydrostatic pressure Leading to increase net filtration pressure and increase glomerular filtration rate another effective Atrial natural reddit peptide is to inhibit the secretion of renin leading to decreased Activity of the renin angiotensin mechanism which would also lead to this increase in glomerular filtration rate So atrial natural reddit peptide is only one of several natural reddit peptides. There's also a brain natural reddit peptide that's produced in the brain But has similar functions to atrial natural reddit peptide To stimulate an increase in the glomerular filtration rate