N5315 Advanced Pathophysiology- Electrolyte Homeostasis and Fluid Balance/Imbalances

N5315 Advanced Pathophysiology- Electrolyte Homeostasis and Fluid Balance/Imbalances Fluid balance between the spaces is maintained by a number of dynamics. These include (5): osmolality (tonicity), osmosis, osmotic pressure, hydrostatic pressure, and oncotic pressure Osmolality the measure of solute concentration in a solution What is the osmolality in humans? it is basically the concentration of the plasma The _____ the number of solutes (particles) in a compartment (osmolality), the _____ the concentration is and therefore the _____ water is in that compartment higher; greater; less What is the osmolality of plasma? 280-295 mOsm/kg plasma osmolality may go as low as 275 _____ is largely responsible for maintaining the osmotic balance in the ECF Sodium _____ is responsible for maintaining the ICF osmolality potassium What is the effective osmolality? tonicity Effective osmolality the concentration of those solutes that do not readily cross the cell membranes and in effect contribute to the osmolality The effect of urea on osmolality Even though urea is a solute in the plasma, it freely diffuses through the cell membrane and has no effect on osmolality. The effect of sodium and glucose on osmolality sodium and glucose are limited to the extracellular space and greatly contribute to the effective osmolality _____ and osmolality may be used interchangeably tonicity Osmotic Pressure the amount of pressure or force that is exerted by solute molecules of a given compartment. The _____the osmolality, the _____ the osmotic pressure. higher; higher Osmotic pressure is a _____ force and will _____ water into a compartment. pulling; pull Osmotic pressure must be overcome by _____ _____ to oppose osmosis. hydrostatic pressure Osmosis the passive movement of water between compartments from an area of low concentration of solutes to one that has a high concentration of solutes. Osmosis is a passive force because it does not require energy. Hydrostatic Pressure is the force within a fluid compartment - the mechanical force of fluid against the walls of the compartment Example of hydrostatic pressure blood pressure Hydrostatic pressure is a _____ force and _____ fluid outside the compartment pushing; pushes Oncotic pressure (colloid osmotic pressure) is the force which helps to keep water/fluid within a compartment Oncotic pressure contributes to _____ _____ and is exerted by _____ _____. osmotic pressure; plasma proteins What is the main plasma protein? albumin Hydrostatic pressure is greater than oncotic pressure at the arterial end of the capillary bed What causes fluid to move out of the capillary bed into the interstitium? hydrostatic pressure being greater than oncotic pressure at the arterial end of the capillary bed. IV solutions often alter _____ and contribute to fluid _____. osmolality; shifts effective arterial blood volume (EABV) the amount of blood within the arterial space which effectively perfuses organs and tissues. True/ False: Volume changes in the extracellular fluid compartment will not cause changes in the EABV in the same direction false Correct answer: Volume changes in the extracellular fluid compartment will cause changes in the EABV in the same direction Decreased ECF volume will cause a _____ in EABV and vice versa decrease The main hormones that regulate fluid balance. Antidiuretic hormone, aldosterone, renin angiotensin aldosterone system (RAAS), and natriuretic hormones Antidiuretic Hormone is secreted by the pituitary gland in response to a water deficit, sodium excess or a low BP. Antidiuretic Hormone causes the kidneys to reabsorb water thus increasing plasma volume Aldosterone is a hormone secreted from the adrenal cortex Aldosterone is responsible for increased renal sodium resorption and potassium excretion. Where sodium goes water follows. This is the basis of osmosis. Renin angiotensin aldosterone system (RAAS) is activated by a low blood volume. Natriuretic Hormones are hormones that are released from the atria or ventricle of the heart Natriuretic Hormones work opposite of the RAAS to decrease blood volume Natriuretic Hormones promote urinary excretion of sodium and water thus decreasing blood volume Natriuretic Hormones examples atrial natriuretic peptides (ANP) and B-type natriuretic peptides (BNP). fluid is used to refer to the general water status and/or shifts in the distribution of water in the body One liter of water weighs ___lbs (___kg), so monitoring of weight is a very good way to monitor water balance 2.2lbs (1kg) Close weight monitoring is done frequently for heart failure, dialysis patients and liver failure patients Increased weight is often one of the first indicators that an individual is _____ fluid retaining Fluid Volume Deficit (dehydration) is a state in which the body's fluid intake is not sufficient t