Volume changes in the extracellular fluid compartment will cause changes in the EABV in the same direction. Decreased ECF volume will cause a
decrease in EABV and vice versa. Antidiuretic HormoneAntidiuretic Hormone is secreted by the pituitary gland in responseto a water deficit, sodium excess or a low BP. It causes the kidneysto reabsorb water thus increasing plasma volume. Renin Angiotensin Aldosterone Systemactivated by a low blood volume. A low blood volume triggers the release of renin. Renin converts angiotensinogen (a plasma protein) to angiotensin I. ACE converts angiotensin I to angiotensin II. Angiotensin II causes arterial vasoconstriction and stimulates release of aldosterone. Aldosterone then stimulates renal Na reabsorption and potassium excretion. Where sodium goes water follows via osmosis, and water is retained. The person produces less urine and the blood volume increases. Regulates BPAngiotensis 2 causes Vasoconstriction of arterioles in kideneys increases BPPt produces less urine and the blood volume increases Release of aldosterone decreases potassium bc leaves through urine Natriuretic Hormones released from the atria or ventricle of the heart. They work opposite of the RAAS to decreaseblood volume. They promote urinary excretion of sodium and water thus decreasing blood volume. Examples of these hormones are Atrial natriuretic peptides (ANP) and B-type natriuretic peptides (BNP). c.Differentiate between the etiology, clinical manifestations, and pathophysiology of fluid volume deficit, fluid volume excess and edema. Alteration in Water MovementEtiologyClinical Manifestations Pathophysiology
Fluid Volume DeficitThe most common cause of water loss is increased renal clearance of free water as a result of impaired tubular function or inability to concentrate the urine, as with diabetes insipiduspoor skin turgor, dry mucous membranes, sunken eyes, sunken fontanels (in babies), less urinary output, fatiguebody’s fluid intake is not sufficient to meetthe body’s fluid needs.Fluid Volume ExcessAcute renal failure, severe congestive heart failure, and cirrhosis are clinical conditionsthat can precipitate water excess. Decreased urine formation from renal disease or decreased renal blood flow contributes to water excess.Edema, tightness of the skin, puffiness of the eyes, rales, cerebral edema with confusion and convulsions. Weakness, nausea, muscle twitching, headache, and weight gain The overall effect is dilution of the ECFwith the movement of water to the intracellular space byosmosis. The syndrome of inappropriate secretion of ADH (SIADH), also known as vasopressin dysregulation, enhances water retention because ADH levels are elevated. Water excess is usually accompanied by hyponatremia.Edema 1. Thrombophlebitis, hepatic obstruction, tight clothing and prolonged standing common causes of venous obstruction. 2.
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