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Phys2 Microcirculat

QuestionAnswer
What is microcirculation? The systemic and pulmonary circulations that are adapted for exchange of: 1.Gas. 2.Nutrients. 3.waste.
What structures make up microcirculation? 1.Arterioles. 2.Capillaries. 3.AV shunts. 4.Venules.
what makes up a capillary? 1.simple squamous endothelium. 2.Basement membrane.
3 different Types of Transcapillary Exchange 1.Continuous: Low (muscle, nerve, adipose) and high (lymph, thymus). 2.Fenestrated: Open (glomeruli) and closed (endocrine, GI Villi). 3.Discontinuous: liver, bone marrow, spleen (areas of major BL cell release)
What controls vasomotion? 1.ANS: Sympathetics (alpha1 & Beta2). 2.Local control: autoregulation of precapillary sphincters via metabolites.
How is microvascular resistance regulated myogenicly? If there is a large Inc in pressure, there is an active relaxation. If there is a Dec in pressure: active contraction. **Autoregulation that prevents EDEMA with sudden increase in BP!!
How does active hyperemia regulation microvascular resistance? BL flow increases with Inc metabolism. Causes of smooth muscle RELAXATION: 1.Adenosine. 2.Inc CO2. 3.Dec O2. 4.Inc H+.
Where is Adenosine a particularlly important regulator of microvascular resistance? 1.Brain. 2.Heart.
Why are capillaries not resistance vessels? 1.there is always a % of capillaries allowing BL flow. 2.Extensive AV shunt system keeping pressure from building in capillary vessels.
What can move out of continuous capillaries? Since they have tight junctions, only: 1.gas. 2.nutrients.
What key components are involved in endothelial induced vasodilation? ACh or Bradykinin cause the release of NO from cell in the presence of ARGININE. NO activates GC in the smooth muscle, activating cGMP, activating PKG, activating MLCP which will dephosphorylate the myosin.
Nutrient transfer by Fick's Law of diffusion Diffusion (J) = PS/concen difference. *Things affecting P & S: 1.Temperature. 2.molecuar radius. 3.viscosity. 4.% of capillaries open. 5.type of capillary. **O2 has Inc driving force OUT of BL, CO2 has Inc driving force INTO BL
2 ways of LIMITING transport from/into the capillaries? 1.Flow Limited: Fast diffusion, limiting factor is the rate of BL flow to that tissue. 2.Rate Limited: (slow diffusing/larger molecules) have difficulty moving through pores so the limiting factor is their rate of diffusion.
Pneumonia's effect of diffusion rates Inc fluid Inc the distance & viscosity through which O2 must move from the alveoli to the RBC. **This changes diffusion from Flow to RATE limited diffusion b/c the rate of diffusion goes down due to Inc fluid.
Water movement depends on 1.Pressure difference (across membranes). 2.Hydraulic conductivity. 3.Area of diffusion.
Capillary Filtration Coefficient (K) Compares how leaky different tissues are for water. **changes with permeability of each capillary & cross sectional area perfused.
Is K ever constant? Yes, in healthy tissue.
How do burns affect K? Inc permeability which greatly increases leakiness. **BL proteins can also escape (albumin)
What are the 4 pressures influencing the movement of water? 1.Capillary hydrostatic CHP (water pres w/in the capillary). 2.Tissue Hydrostatic THP (water press in the interstium 1-2mm). 3.Tissue Oncotic TOP (colloid/protein in the interstitial fluid). 4.Capillary oncotic COP (colloid/protein in the plasma).
Which direction would water move if high TOP? OUT OF LUMEN Into the interstium b/c of its high colloid/protein, the water will want to move dilute the interstial fluid. **pulling force
Which direction would water move if high COP? IN TO LUMEN into the plasma due to its high colloid/protein, water will want to dilute it. **pulling force
Which direction would water move if high CHP? OUT OF LUMEN into the interstium due to high pressure. **PUSHING force
which direction would water move if high THP? IN TO LUMEN into the plasma due to high interstial pressure. **PUSHING force
What would be the net movement if Pt experienced tissue dehydration? COP>CHP, the water would be pulled INTO the plasma from the interstium.
What would be the net movement if Pt experienced tissue edema? CHP>COP, the water would be pushed OUT of the plasma into the interstitium.
Why dont we consider THP and TOP? because they are both ~0mmHg
What is the california gangster rule? CHP=COP. if they are not equal, water movement will occur.
What would you see in a Pt with Right HF or DVT? Edema due to INCREASED CHP. CHP>COP **Also will see small amount of edema with vein removal
What would you see in a Pt with low plasma proteins? what all could cause this? Edema due to COP 1.Quashiorkor (low plasma prtotein). 2.Burn victoms. 3.nephrosis (protein escaping through kidney)
What would you see in a Pt with a bad sinus infection? why? Edema. Sinuses are clogged, so lymph immune proteins and dead cells can't be drained, therefore Inc TOP. **CHP+TOP>COP
How are perfusion pressure and vascular resistance related? The Inc and Dec together (directly related)
Created by: WeeG