Starling's law of capillaries - Capillary exchange

Starling’s Law of Capillaries – Summary Starling’s Law describes how fluid moves in and out of capillaries based on the balance of hydrostatic and oncotic (osmotic) pressures. Key Starling Forces: Capillary Hydrostatic Pressure | Pc | Pushes fluid out of the capillary into tissues Interstitial Hydrostatic Pressure | Pi | Pushes fluid into the capillary (usually negligible) Capillary Oncotic Pressure | πc | Pulls fluid into the capillary (due to plasma proteins like albumin) Interstitial Oncotic Pressure | πi | Pulls fluid out of the capillary (usually low) Net Filtration Pressure (NFP): {NFP} = (P_c - P_i) - (\pi_c - \pi_i) Positive NFP (arterial end) → Filtration (fluid leaves capillary) Negative NFP (venous end) → Reabsorption (fluid enters capillary) ApproximateTypical Values Table (mmHg): | Pc (Capillary Hydrostatic) |Arterial End ~35 |Venous End ~15 | | Pi (Interstitial Hydrostatic) |Arterial End ~0 |Venous End ~0 | | πc (Capillary Oncotic) |Arterial End ~25 |Venous End ~25 | | πi (Interstitial Oncotic) |Arterial End ~1 |Venous End ~1 | NFP Arterial: (35-0) - (25-1) = 11 mmHg (Filtration) NFP Venous: (15-0) - (25-1) = -9 mmHg (Reabsorption)