CARDIO-Circulation Flashcards
What open and close the entrance to the capillary to perfuse them?
Precapillary spincters- via arterioles, these are a small msk ring that contrict and dialate
These structures have direct control of local blood flow via capillaries?
arterioles and metaartioles
Capillaries role is to do what?
- Exchange w/in ciruclatory system 2. Local control of blood flow at tissue of organ. 3. Total peripheral resistance
Which capillary have diff permeablity based on structure?
All are different depending on location.
Describe structure of a capillary?
10billion, single layered wall, Endothelilum + small basement memebran, no smooth msk, some have fenestrated/windows
Describe structure of a glomerulus capillary of kidney, brain, and liver?
Kidney-High pressure cap, fenstrated(window). Brain- tight junction via BBB. Liver- gap junctions
How are capillaries perfused or shunted?
Perfusion via artieroles, spincter dialate. Shunted spincters contricts, blood either bypasses capilliary bed to venous or continue in arteriole
What stucture allows blood to move past the capillary bed to dump/shunt in the venous?
Meteateriole
What is intermittent contraction of metarteriole?
Vasomotion- normal intermitency through capillaries
What occurs when local tissue is oxygen deprived?
Spincheters dialate to perfuse to capillary bed. If oxygen rich spinchters contrict
How is diffusion within capillary flow controlled passively?
Thermal controlled- Warmth quicker. Solubility-Lipid soluble O2, CO2 (faster), concentraction gradient- how much on both sides of membrane
Cl, Na, glucose diffuse through what w/in the membrane?
Intracellular pores.
What determines molecular permeablity through membranes?
Weight, size, charge, concentration. Ex. Protein, larger, neg. Repelled in cell membranes due membran neg.
What is gelatin like, small space, similar to plasma, where structures diffuse through?
Insterstial fluid- Proteins and plasma reside sometimes
The arteriole end of the capillary has high hydrostatic pressure, thus > than interstial fluid hydrostatic pressure, then this favors what?
Filtration. Sum of OUTWARD greater than INWARD
The venous end of the capillary has low hydrostatic pressure, then this favors what?
Absorbtion- hydrostatic pressure declines. Venous oncotic/collid pressure is low. Sum of INWARD greater than OUTWARD
IF the ICF/interstium has high colloid/oncotic pressure, what will occur?
Movement will be OUT from the capillary
What are the 4 starling forces?
- Hydrostaic Pressure/BP of the capillary- push OUT force 2. Instertiial hydrostatic fluid pressure- INWARD force 3. Plasma capillary colloid pressure-substance concentraion INWARD force to dilute blood 4. Instertial fluid colloid/oncotic pressure-substance concentration OUTWARD force
What make protein less difusable?
Donning Equilibrium-Sodium, Calcium, Potassim form halo around protein. Serum concentratin don’t always account for that
What occures as flow is moved through capillaries?
Hydrostatic pressure decrease due to Net filtration higer on one end of capillery. And low towards venous end
Why is venous net absorbtion different from arteriole net filtration accounts for the leak of fluid due to inc filtration across the capillaries?
Returned by the lymphatic system. Capillary don’t absorb everything. Must values stay constant b/c lypmh
What is only change amongst capillary bed?
Capillary hydtostatic pressure. To calculate, can simply =Venous Net= Change in BP- Net filtration of capillary
Is the circulatory system balanced?
Almost, most of the filtration is absorbed. The 0.3 difference is absorbed by lymphatics
Inc pressure= INC filtration= INC fluid accumlated by lymph. This leads to what?
Ascites edema. The lymph can only absorb so much
