Changes

'''Angiotensin II''' acts on '''AT1 receptors''' to stimulate the release of '''[[Aldosterone|aldosterone]]''' from the [[Adrenal Glands - Anatomy & Physiology#Adrenal Glands|zona glomerulosa]] of the adrenal glands.  This mineralocorticoid increases the reabsorption of sodium and therefore water and chloride from the distal tubule of the kidney, thus helping to increase blood pressure and volume. It also stimulates the thirst center and increases the secretion of [[Pituitary Gland - Anatomy & Physiology #Posterior Pituitary Gland |anti-diuretic hormone (ADH)]] to help increase blood volume. The RAAS allows pressure to return to 50% of baseline within 15 minutes of a significant haemorrhage occuring.

'''Angiotensin II''' acts on '''AT1 receptors''' to stimulate the release of '''[[Aldosterone|aldosterone]]''' from the [[Adrenal Glands - Anatomy & Physiology#Adrenal Glands|zona glomerulosa]] of the adrenal glands.  This mineralocorticoid increases the reabsorption of sodium and therefore water and chloride from the distal tubule of the kidney, thus helping to increase blood pressure and volume. It also stimulates the thirst center and increases the secretion of [[Pituitary Gland - Anatomy & Physiology #Posterior Pituitary Gland |anti-diuretic hormone (ADH)]] to help increase blood volume. The RAAS allows pressure to return to 50% of baseline within 15 minutes of a significant haemorrhage occuring.

==Effects of Angiotensin 2 on GFR==

==Effects of Angiotensin II on GFR==

If blood pressure drops then [[The Formation of the Filtrate by the Glomerular Apparatus- Anatomy & Physiology#Glomerular Filtration Rate|glomerular filtration rate (GFR)]] also drops due to a reduced blood flow through the kidneys.  Therefore it is important to prevent this.  If contraction of the efferent arteriole occurs then the pressure difference between the afferent and efferent arterioles increases creating a greater filtration pressure.  This effect is mediated by Angiotensin II and means that when blood pressure falls there is minimum alteration of GFR.  Blood flow which is already reduced due to the reduced pressure will then be further reduced by the increase in resistance.  This increased renal resistance to blood flow and the maintained GFR has many advantageous effects.   

If blood pressure drops then [[The Formation of the Filtrate by the Glomerular Apparatus- Anatomy & Physiology#Glomerular Filtration Rate|glomerular filtration rate (GFR)]] also drops due to a reduced blood flow through the kidneys.  Therefore it is important to prevent this.  If contraction of the efferent arteriole occurs then the pressure difference between the afferent and efferent arterioles increases creating a greater filtration pressure.  This effect is mediated by Angiotensin II and means that when blood pressure falls there is minimum alteration of GFR.  Blood flow which is already reduced due to the reduced pressure will then be further reduced by the increase in resistance.  This increased renal resistance to blood flow and the maintained GFR has many advantageous effects.