HP - Lecture 6 on Physiology Essentials: Oedema PDF

PHYSIOLOGY ESSENTIALS: OEDEMA Thursday, Sept. 21 st 10:00-11:00 – sign up individual Zoom office hours Friday, Sept. 22nd 2:00- 2:30 – drop-in group Zoom office hours Starling Forces 2 Hydrostatic...

PHYSIOLOGY ESSENTIALS: OEDEMA Thursday, Sept. 21 st 10:00-11:00 – sign up individual Zoom office hours Friday, Sept. 22nd 2:00- 2:30 – drop-in group Zoom office hours Starling Forces 2 Hydrostatic Interstitial Pressures (P) fluid Filtration PIF πIF 2 Colloid plasma Pc Reabsorption πP Osmotic Pressures (π) Balance of Starling Forces The Starling-Landis Equation Net Fluid Movement (NFM): NFM = Kf [(PC - PIF) – (πP – πIF)] bl it has would be VERY permeable Dowmans capsule of Kidney Kf = filtration coefficient - fenestrations represents the permeability of the capillary and surface area of the endothelium Varies in different tissue: very high in kidney compared to muscle But constant in any single capillary bed (under normal conditions) Assume it equals 1 unless otherwise stated Starling Forces NFM = (PC - PIF) – (πP – πIF) Favours Filtration Favours Reabsorption NFM = (PC + πIF) – (PIF + πP) PIF πIF Pc πP Potential Problems with Arteriole versus Venus Net Filtration use Pa on venule end Arteriole NFM &Venous NFM NFM = 1 [(25 + 5) – (28 + -6] ~ NFM = 1 [(10 + 5) – (28 + -6)] ↑ g = = 7 - on use Pc - - ve # means reabsorption ar te riole end + re # means filtration Pc = 25 mmHg Pc = 10 mmHg Learning Objectives: 1. Describe the conditions that can lead to oedema. ↑ accumulation of fluid extracellularly  takes interstitial fluid and re t u r n s through - blood system The Lymphatic System W A series of small channels leading to larger and larger vessels Found in skin, GI, genitourinary and respiratory systems, part of the immune system Drains the tissue of excess interstitial fluid, which accumulates daily ~20 L of fluid filters out of the blood into the interstitial space (this excludes what happens in the kidneys) -Kidneys filters 1801 fluid ~17 L returns by reabsorption, remaining 3 L is taken up by the lymphatic system  extracellular oedema ↳ Oedema Abnormal increase of interstitial fluid volume Can result from excess filtration OR inadequate reabsorption Some Types of Oedema but not Peripheral oedema -Harmful dedy Dependent oedema Cerebral oedema Every Dad Myocardial oedema Every dangerous  Oedema: The swelling of tissue due to an increase in interstitial fluid Pc πIF PIF volume ↳ filtration , I reabsorption πP arteriole end · ↑ hydrostatic p re s s u re in in plasma · ↓ proteins to " · proteins in interstitial spacei ss u e injury leak proteins) endothelial cells · adjust permeability of ar2 clsseability Kf lowclose Favours Filtration Favours Reabsorption NFM = Kf [(PC + πIF) – (PIF + πP)]  Increasing Pc Higher than normal blood blood pressure ↳ long high pressure (chronic) Decreased venous return ↳ restric t diameter ↳ Fell that blocks flow of plague Pc πIF PIF πP Kf Favours Filtration Favours Reabsorption NFM = Kf [(PC + πIF) – (PIF + πP)]  Increasing πIF More proteins entering interstitial fluid Increased permeability of capillaries (Increasing Kf) inflammation /histamine L reactions (cytokines) for allergy , Damage that is chemical, PIF ↑mechanical, thermal need Pc πIF πP damage to increase gap Kf Favours Filtration Favours Reabsorption NFM = Kf [(PC + πIF) – (PIF + πP)]  Decreasing πP Liver m a ke s a lot of protein , so liver diseases would protein production I ↓ Less plasma proteins being produced or ingested Kwashiorkor malnutrition is seen in severely malnourished children Pc πIF PIF Very low protein diet πP Kf Favours Filtration Favours Reabsorption NFM = Kf [(PC + πIF) – (PIF + πP)]  Increasing the Volume of Interstitial Fluid Decreased removal of IF by the lymphatic blockage - of lymphatic system vessels PIF of limbs Enlargement Elphantiasis Pc πIF ↓ πP Caused by a parasite that damages the lymphatic vessels ↳ block modes w h e re vessels can't lymph Kf cancer can drain modes a re removed , properly , if c a n c e ro u s lymph nodes will it causes temporary ocdema , but lymph back eventually grow Favours Filtration Favours Reabsorption NFM = Kf [(PC + πIF) – (PIF + πP)]