Fluid Shift Across Capillary Wall: Pulmonary And Systemic Oedema Flashcards
How much body water is extracellular
1/3rd
How much extracellular fluid is interstitial
75%
What does the interstitial fluid do
Act as a go between blood and body cells
What are capillaries
Single layer of endothelial cells
Allow rapid changes of gases, water and solutes with interstitial fluid
Delivery of nutrients and oxygen to the cells
Removal of metabolites from cells
Blood flow in caps dep oh the contractile state of arterioles
What do terminal arterioles regulate
Regional blood flow to capillary bed in most tissues
What regulates the the flow in tissues
Precapillary sphincters
What is the blood flow like in the cap bed
Very slow for adequate time for exchange
What is the transport across the capillary wall
Fluid move follows pressure gradient
Movement of gases and Solutes follow Ficks law of diffusion
Lipid sol substances go through the endothelial cells
Water sol subs go though water filled pores
Large mols can’t pass
What is trans capillary fluid flow
Trans cap fluid flow passively driven by pressure gradients across cap wall
Is ultra filtration - exchange of protein free plasma
What is net filtration pressure proportional to
Forces favouring filtration - forces opposing filtration
What also affects filtration
Filtration coeff
What are forces favouring filtration.
Cap hydrostatic pressure
Interstitial fluid osmotic pressure
What are forces opposing filtration
Capillary osmotic pressure
Interstitial fluid hydrostatic pressure
Where does the starling forces favour filtration and reabs
Filtration - arteriolar
Reabs - venular
Pulmonary resistance is only
10% of systemic circulation
What is cap osmotic pressure
25 mmHg
What is oedema
Accumulation of fluid in interstitial space
Diffusion distance increases - gas exchange compromised in pulmonary oedema
What does raised cap pressure do to oedema
Arteriolar dilatation - more blood to cap in case hydrostatic pressure increase filtration
Raise pd venous pressure - left vent failure, right vent fail, prolonged standing giving swollen ankles
What does reduced plasma osmotic pressure do to oedema
Oedema is
What does lymphatic insufficiency do to oedema
Lymph node damage
Filariasis - elephantiasis
What does changes in cap perm do to oedema
Inflammation
Histamine increases leakage of protein -
What is left vent failure pulmonary oedema
Pulmonary oedema is accumulation of fluid in the interstitial and intralveolar lung spaces
Manifested clinically by varying degrees of shortness of breath
Chest x Rays shows
Where can pitting oedema be Sen
Ankles and sacrum
What promotion in the total body water in terms of weight
Approx 60% of body weight
