Notes
I. Describe the role of the following hormones in the formation of urine, specifically explain the stimulus for their release, actions (decrease/increase GFR) and whether or not dilute/concentrated urine results):
ADH (Vasopressin) – ADH has an antidiuretic action that prevents the production of dilute urine.
Formation of urine = in the DCT and collecting ducts, water movement out of the body is regulated by ADH.
Stimulus for their release = lowered blood pressure or low salt or water concentration in the blood will stimulate the release of ADH from the posterior pituitary.
Actions (decrease/increase GFR) = increased ADH would decreases the GFR and a decrease in ADH would increase GFR.
Dilute/Concentrated Urine Results = if there is a high amount of ADH, water moves out and will produce concentrated urine and if ADH is absent water will not be reabsorbed and will produce dilute urine.
Renin-Angiotesin-Aldosterone System
Stimulus for their release = if blood pressure drops dramatically this will trigger renin secretion from the JG cells, renin acts on angiotensinogen to form angiotensin I, angiotensin I is converted to angiotensin II therefore angiotensin II causes mean arterial pressure to rise and stimulates the adrenal cortex to release aldosterone. As a result, both systemic and glomerular hydrostatic pressure rises.
Actions (decrease/increase GFR) = the efferent arteriole constricts, forcing blood to build up in the glomerulus, which maintains the GFR. The activation of the RAAS causes a decrease in GFR.
Dilute/Concentrated Urine Results = activation of the Renin-Angiotensin-Aldosterone System will result in concentrated urine results.
Atrial Naturetic Pepetide (ANP) Hormone
Stimulus for their release = large increase in blood volume promotes release of ANP.
Actions = result is more urinary output, less blood volume and decreased blood pressure. GFR will increase with the release of ANP.
Dilute/Concentrated Urine Results = urine will be
ADH (Vasopressin) – ADH has an antidiuretic action that prevents the production of dilute urine.
Formation of urine = in the DCT and collecting ducts, water movement out of the body is regulated by ADH.
Stimulus for their release = lowered blood pressure or low salt or water concentration in the blood will stimulate the release of ADH from the posterior pituitary.
Actions (decrease/increase GFR) = increased ADH would decreases the GFR and a decrease in ADH would increase GFR.
Dilute/Concentrated Urine Results = if there is a high amount of ADH, water moves out and will produce concentrated urine and if ADH is absent water will not be reabsorbed and will produce dilute urine.
Renin-Angiotesin-Aldosterone System
Stimulus for their release = if blood pressure drops dramatically this will trigger renin secretion from the JG cells, renin acts on angiotensinogen to form angiotensin I, angiotensin I is converted to angiotensin II therefore angiotensin II causes mean arterial pressure to rise and stimulates the adrenal cortex to release aldosterone. As a result, both systemic and glomerular hydrostatic pressure rises.
Actions (decrease/increase GFR) = the efferent arteriole constricts, forcing blood to build up in the glomerulus, which maintains the GFR. The activation of the RAAS causes a decrease in GFR.
Dilute/Concentrated Urine Results = activation of the Renin-Angiotensin-Aldosterone System will result in concentrated urine results.
Atrial Naturetic Pepetide (ANP) Hormone
Stimulus for their release = large increase in blood volume promotes release of ANP.
Actions = result is more urinary output, less blood volume and decreased blood pressure. GFR will increase with the release of ANP.
Dilute/Concentrated Urine Results = urine will be