ACTIVITY 3 Renal Response to Altered Blood Pressure 1. List the several mechanisms you have explored that change the glomerular filtration rate. How does each mechanism specifically alter the glomerular filtration rate?

The word glomerulus has Greek origin, which means ‘filter’. The glomerulus is present in the kidneys, this is a cluster of blood vessels that filter the blood. Approximately, 1 million glomeruli (singular; glomerulus) are present in one kidney. GFR (Glomerular filtration rate) is measured as filtrate produced per minute by the kidneys. The unit of GFR is mL/min (milliliter per minute).Three major mechanisms are involved in the regulation of GFR(Glomerular filtration rate):Sympathetic nervous activity: There is less stimulation of the sympathetic nervous system in normal conditions. This results in vasodilation leading to increased blood flow. This vasodilation is a result of decreased action potential. Increased blood flow leads to increased filtration.During stress, increased action potential leads to increased activity of the sympathetic nervous system. This causes stimulation of the adrenal medulla. The adrenal medulla releases epinephrine. The release of epinephrine causes constriction of the afferent arterioles leading to a reduction in the flow of blood to the glomerulus. This ensures that more blood is available to other body parts during an emergency.The sympathetic system stimulates the release of renin to the blood pressure falls. This increases the production of angiotensin which in turn stimulates the production of aldosterone. Aldosterone increases the reabsorption of sodium ions, thereby increasing the water reabsorption and blood volume.Arteriolar myogenic mechanism: Myogenic response also ensures that GFR remains constant over MAP (mean arterial pressures). This does so by contracting arteriolar smooth muscle when there is an increase in blood pressure. This confirms consistency in the reabsorption of the proximal tubule.Tubuloglomerular mechanisms: This involves paracrine signaling resulting in vasoconstriction or vasodilation to facilitate a steady flow of blood. Adenosine, NO (Nitrous oxide), and ATP (Adenosine triphosphate) stimulates the juxtaglomerular cells of the afferent arteriole. When there is an increase in blood pressure, the GFR rate is increased leading to decreased reabsorption by the proximal tubule. This increases the NaCl concentration in the distal tubule. Macula Densa detects increased concentration and releases local factors to stimulate constriction of the afferent arteriole. Constriction of afferent arteriole would decrease blood flow and GFR.There are three major mechanisms that alter GFR:Sympathetic nervous activityArteriolar myogenic mechanismTubuloglomerular mechanism

ACTIVITY 3 Renal Response to Altered Blood Pressure 1. List the several mechanisms you have explored that change the glomerular filtration rate. How does each mechanism specifically alter the glomerular filtration rate?

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