Microcirculation Flashcards
Give an equation relation flow rate, pressure gradient and resistance
Give the overall purpose of the CV system and the def of blood flow rate
Adequate blood flow through the capillaries
Volume of blood passing through a vessel per unit of time
How is blood pressure determined in a capillary and how will increased pressure gradient influence blood flow?
Increased ΔP will increase blood flow rate
What is the def of resistance in a blood vessel?
‘Hindrance to blood flow due to friction between moving fluid and stationary vascular walls’
How can you relate flow rate, vessel length,pressure, vessel radius and blood viscosity
How does raised blood pressure / arteriolar vasoconstriction influence ‘deltaP, resistance and flow rate’
How can you mathematically relate blood flow rate, pressure gradient and resistance in an organ?
Why is vascular tone important?
Vascular tone-Natural partial contraction of arteriolar muscle
-It allows the artery to undergo vasodilation or vasoconstriction at any time
How does vasoconstriction/vasodilation affect flow rate, resistance and vessel radius?
What 2 functions do arteries regulate their radii independently for and through what means are they regulated?
Function 1: Match blood flow to the metabolic needs of specific tissues (depending on body’s momentary needs)
Regulated by local (intrinsic) controls and independent of nervous or endocrine stimulation
Function 2: Help regulate systemic arterial blood pressure
Regulated by extrinsic controls which travel via nerves or blood and are usually centrally coordinated
What is arteriolar vasodilation normally driven by and what is another term for it?
Chemically driven
-Metabolites(ATP metabolites are powerful vasodilators)
-O2 usage
Active hyperaemia
What is arteriolar vasoconstriction normally driven by and what is another term for it?
Physically driven
-Drop in blood temp
-Vessel distension due to increased BP
Myogenic autoregulation
Explain these graphs
Pressure gradient across the arteriole is higher(higher perfusion pressure)
Vessel senses increased pressure, in turn constricts the vessel, increasing resistance and reducing blood pressure back to normal
How can you mathematically relate cardiac output, total peripheral resistance and blood pressure?
How is arterial blood pressure regulated neurally and hormonally?
Neural:
CV control center in the medulla sends signals through the sympathetic trunk
Hormonal:
Vasopressin/ADH from pituitary
Angiotensin II from lungs
Adrenaline/Noradrenaline from adrenal glands
How does capillary network density vary?
More dense capillary networks in more metabolically active tissue
What are the 3 capillary types and how are they different?
Continuous-Has regular H20 gap junctions between endothelial cells
Fenestrated-Has ~80nm wide fenestrae
Discontinuous-Has open gaps between endothelial cells
Outline hydrostatic and oncotic force in capillaries and what causes them
Outline the structure of a lymphatic vessel
Give the general structure+main ducts+drainage capacity of the lymphatic system
