Natriuresis is the process of sodium excretion in the urine via the kidneys. These changes directly act to increase blood pressure and so perfusion of the juxtaglomerularĪpparatus increases and renin production is ceased. Aldosterone and angiotensin II act in the kidneys to increase the reabsorption of sodium andĬhloride ions, and the excretion of potassium ions, as well as the retention of water. Angiotensin II results in aldosterone production in the adrenal gland cortex, vasoconstriction of Renin cleaves inactive angiotensinogen into active angiotensin I, which is then converted toĪngiotensin II by angiotensin-converting-enzyme (ACE). Decreased perfusion of the juxtaglomerular apparatus in the kidneys results in release of renin by System is activated when there is a drop in blood pressure/volume The principal cells’ water permeability therefore decreases When the principal cells are not stimulated by ADH, aquaporin-2 molecules are removed from within minutesĪDH production shuts down, and soon its blood level is zero. By contrast, intake of water decreases osmolarity of blood and interstitial fluid. This results in production of a small volume of concentrated urine. Water molecule move by osmosis from the renal tubular fluid into the cells, and then from theĬell into the bloodstream. Of principal cells in the collecting ducts of the kidneys, resulting in increased water permeability. This promotes the insertion of water-channel proteins (aquaporin-2) into the apical membranes Neurosecretory cells that extend from the hypothalamus to the posterior pituitary gland. An increase in the osmolarity of plasma and interstitial fluid stimulates release of ADH by ![]() How these mechanisms may become deranged in a variety of pathological conditions. The renin-angiotensin-aldosterone system, natriuretic peptides vasopressin, thirst sensation and explain Discuss the mechanisms controlling the absorption and excretion of sodium and water – renal mechanisms, ![]() Solutes in body fluids are electrolytes, and fluid balance depends on electrolyte balance the two Because osmosis is the primary means of water movement between ICF and IF, theĬoncentration of solutes in these fluids determines the direction of water movement. Despite continual exchange of water and solutesīetween fluid compartments, by filtration, reabsorption, diffusion and osmosis, the volume ofįluid is each compartment remains fairly stable. Fluid balance means the required amounts of water and solutes are present and are correctly Plasma membranes of individual cells separate ICF and interstitial fluids, and blood vessel walls The GI tract, synovial fluid at joints, aqueous humor and vitreous body in the eyes, endolymphĪnd perilymph in the ears, pleural, pericardial and peritoneal fluids between membranes, and ECF also includes lymph in lymphatic vessels, cerebrospinal fluid in the nervous system, fluids in Interstitial fluid – occupies microscopic spaces between tissue cells Extracellular = fluid outside of cells, including all other body fluids. Body fluids are partitioned into two main compartments – the intracellular compartment and the Discuss the concept of body fluids in a number of compartments that are in equilibrium with each other,Īnd explain the mechanisms governing movements of fluids between these compartments.
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