Storyboard

The effective circulating volume (ECV) is the volume of blood that effectively fills the vascular tree and determines cardiac preload. The Starling equation for capillaries governs fluid exchange between the plasma and the interstitium: filtration (P_c - P_if) drives the fluid outward; the oncotic pressure (_c - _if) retains it. The net balance determines whether there is edema (filtration > reabsorption + lymphatic drainage).

The Starling equation explains cardiogenic pulmonary edema: in left HF, pulmonary P_c rises > 25 mmHg (· 25 mmHg) J_cap becomes positive and massive edema. It also explains edema due to hypoalbuminemia: if _c falls (malnutrition, nephrotic syndrome) less oncotic retention generalized edema (anasarca).

Oncotic pressure () depends on the concentration of plasma proteins, mainly albumin (~55% of the total oncotic pressure). The cubic Landis-Pappenheimer formula reflects non-ideal effects (Donnan effect, protein-protein interactions) that cause oncotic pressure to grow more than linearly with C_prot.

Blood viscosity (Chien's law) depends critically on the hematocrit Hct: at low shear, blood is non-Newtonian (erythrocytes aggregate and increase ). In severe anemia (Hct < 0.25), although decreases (favoring flow), O transport (DO = CO × CaO) falls because CaO Hb. The heart compensates with tachycardia and increased CO.

Plasma osmolality (Osm_p 275295 mOsm/kg) is the main regulator of intracellular volume through ADH (vasopressin): Osm_p ADH reabsorption of free water in the collecting duct correction. Hyponatremia (Na < 135 mEq/L) is the most common electrolyte alteration in hospitalized patients and hyperosmolality (Na > 145 + elevated glucose) causes brain cell dehydration.

>Model

ID:('ky', 37)

Description

ID:(0, 37)