Microcirculation Flashcards
What is the main function of microcirculation?
to transport and exchange nutrients to the tissues and remove cell excreta
The walls of capillaries are thing, ___-layer and highly permeable _____ cells
single; endothelial
An artery branches 6-8x into an _____, which then branches 2-5x into the ______
arteriole; capillaries
The capillary wall is comprised of a unicellular layer consisting of endothelial cells, and has a thin _____ membrane and contains small passageways or ____
basement; pores
The intercellular cleft is a ___ between adjacent endothelial cells which allows ____ to freely move
junction; fluids
Plasmalemmal vesicles, also known as Caveolae, contain caveolin, cholesterol and lipids and play a major role in ____cytosis and ___cytosis
endocytosis; transcytosis
Brain contains ____ junctions, whereas the liver is wide open due to extremely large ____
tight; clefts
The glomerular capillaries of the kidney include ____ which penetrate through the middle so small molecular and ionic substances can pass through, but not larger ____ proteins
fenestrae; plasms
Is Vasomotion continuous or intermittent?
intermittent
Vasomotion depends on the tissue _____
needs
Vasomotion is primarily caused by the opening/closing of ______
pre-capillary sphincters
The most important factor involved in blood flow regulation is the concentration of ____, __ nutrients and ____ products in the tissues
oxygen, b-nutrients, waste products
In the exchange of water and nutrients, there is first a ___ of substances b/w the plasma and interstitial fluid via ____
transfer; diffusion
In the exchange of water and nutrients, the diffusion that occurs results from ___ motion of the water molecules and dissolved substances in the fluid, with random movements in which directions?
thermal; all directions
The rate of diffusion is ____ to the concentration difference of the substance b/w the ___ sides of the membrane
proportional; 2
Particles will diffuse from ___ to ___ concentration
high; low
If a membrane is lipid soluble, the gap is 20x ____ than water soluble so that diffusion can occur directly through the cell membranes without having to go through the ____
larger; pores
If a membrane is water soluble, things cannot pass through the ____ membranes of the endothelial
lipid
Collagen fiber bundles are ___ and provide most of the ____ strength of the tissues
strong; tensional
In the interstitial fluid, proteoglycan filaments are 98% ______ and 2% ____
hyaluronic acid; protein
Gel is a fluid derived by ____ and _____ from the capillaries and fluid entrapped in _____ filaments
filtration; diffusion; proteoglycan
Diffusion through gel is _____
rapid
Free fluid is free of _____ filaments and composes less than 1% of the interstitium and interstitial fluid
proteoglycan
____ occurs when small pockets and rivulets of free fluid expand tremendously
edema
What are the main components of the interstitium and interstitial fluid? (4)
- Collagen fiber bundles
- Proteoglycan filaments
- Gel
- Free fluid
Hydrostatic pressure is the ___ of fluid and its dissolved substances through the capillary pores into the _____
force; interstitial spaces
Osmotic pressure is caused by the ____ proteins causing fluid movements by osmosis from the interstitial spaces into the ____
plasma; blood
Starling forces include capillary ____ (Pc), interstitial fluid ____ (Pif), capillary ____ colloid ____ pressure (np) and the interstitial ___ colloid osmotic ___ (nif)
pressure
pressure
plasma; osmotic
fluid; pressure
Net filtration pressure = ___ + Net fluid filtration - Net fluid _____
NFP; absorption
Capillary filtration coefficient (Kf) is the ____ and ____ of pores in each capillary and the number of capillaries in which the blood is ____
number; size
flowing
Filtration = ___ x NFP
Kf
Mean Capillary Pressure in some tissues such as skeletal muscle and the gut tends to be ____ (direct measures) and ____ (indirect measures)
25 mmHg; 17 mmHg
Pressures in large capillary loops include the arterial ends of capillaries (__-__), venous ends of capillaries (__-__) with the average tending to be ___-___ mm Hg
30-40
10-15
17-25
Capillary Hydrostatic Pressure is ____ variable depending on the particular ____ and physiological condition
highly; tissue
In loose subcutaneous tissues, pressures are slightly ____
negative
Pumping by which system is the basic cause of negative interstitial fluid pressure?
lymphatic
What are the only dissolved constituents in the plasma and interstitial fluids that do not readily pass through the capillary pores?
proetins
Proteins of the plasma and interstitial fluids that are responsible for the ____ pressures on the 2 sides of the ___ membrane
osmotic; capillary
Colloid osmotic pressure averages about ___ mm Hg
28
19 mm Hg of colloid osmotic pressure is caused by what?
molecular effects of dissolved proteins
The remaining 9 mm Hg osmotic pressure is caused by what?
the Donnan effect
What is the Donnan effect?
Extra osmotic pressure caused by sodium, potassium and other cations held in the plasma by the proteins
Capillary pressure at the arterial ends of the capillaries is ___ to ___ mm Hg greater than at the ____ ends
15-25; venous
Fluid “filters” out of capillaries at their ____ ends but at their ____ ends, fluid is reabsorbed back into the capillaries
arterial; venous
____ amount of fluid actually “flows” through the tissues from the arterial ends of the capillaries to the venous ends
small
NFP = (___ - ___) - (___ -___)
(Pc - Pif) - (np-nif)
What is starling equilibrium?
Under normal conditions, there is a state of near-equilibrium existing in most capillaries
The amount of fluid filtering ___ from the arterial ends of the capillaries equals almost exactly the fluid returned to circulation by ____
outward; absorption
The slight disequilibrium that does occur accounts for the fluid that is eventually returned to the circulation by the way of ______
lymphatics
Net ___ filtration pressure is largely caused by the ____ system
0.3; lymphatic
Filtered fluid in the interstitium occurs via lymphatic system-accessory route through which fluid can flow from where to where?
interstitial spaces into the blood
The function and structure of the microcirculation is to transport and exchange _____ and to remove cell ____
nutrients; excreta
____ pressure moves fluid from the capillary into the interstitial space
Hydrostatic
____ pressure moves fluid from the interstitial space into the blood
Osmotic
Colloid osmotic pressure is driven by proteins, ____ being the driving protein
albumin
The starling equilibrium would indicate that under normal conditions, the amount of fluid filtering ____ from the ___ ends of the capillaries equals almost exactly the fluid returned to the circulation by ______
outward; arterial; absorption
Any fluid that is filtered outward is returned to the circulation via the _____
lymphatics
