UNit 4 Flashcards
Blood flow
quantity of blood that passes in a given point in circulation at a given period of time - aka Cardiac Output - which is the vol of blood pumped into aorta/ per min
Laminar flow
non-turbulent steady continous flow smooth vessel, flow in streamlines,
high velocity in center of vessel
Turbulent flow
high veolicty
pulsatile nature
sudden change in diameter and turns
large vessel diameter caused
Reynolds number
measure of turbulence - use mean velocity - diameter and density all divided by viscocity
Blood pressure
Pressure exerted per unit area on the vessel wall
Conductance
proportional to diameter ^4 - is the measure of blood flow thru vessel in a given pressure difference , aka reciprocal to resistance
Compliance
total quantity of blood can be stored in a portion of circulation for each mmHg pressure rise
Venous return
rate of blood flow into heart / ea min
affected by inc blood vol, inc large vessel tone, and dilation of arterioles
Blood reservoirs
ex are spleen , liver , abd veins, lungs and heart
Vasomotion
Intermittent contraction of meta-arterioles and pre-capil sphincters
Caveolae
plasma vesicles, made from caveolin associated with cholesterols and sphingolipides play roles in transcytosis of macromolecules
Tissue gel
combo of plasma (with lower m.w prot) become entrapped in brush pile made from fine filaments of proteoglycants, - make fluids diffuse with eases
Starling forces:
1) Capil Hydrostatic P - outward of capil force
2) Interstitial Oncotic colloid osmotic P - Outward force of the intersittial fluid to the inside of capil
3) Capil plasma colloid oncotic P- inward force of fluid entering in the capil system
4) Interstitial fluid P - inward fluid of capil into interstiial spaces
Acute control of local blood flow
Achieved by rapid changes in vasodilation or vasoconstriction of arterioles - metaarterioles - precapil sphinceters - up to 8x
Vasodilator theory - theory that the greater the metab rate of o2 the more forming vasodilating substances which inc adenosine for ex and that vasodilates
Oxygen lack theory- in absence of o2 the blood vessels simply relax and dilate, causing vasomotion and speed propotional to need for oxygen
Blood flow autoregulation
Returning blood flow to normal levels- even after sustained peak of A.P
Metabolic theory - when P becomes to high it provides to much o2 and excess nutrients and that washes out the vasodilating subsantsace causing the vessels to constrict to normal
Myogenic Theory - When high pressure it stretches the vessel to much, so then the vessel constriction occurs to bring back to normal
Venous return
quantity of blood returned to the hear right atrium per minute, sum of all local blood flows , same as CO
Bainbridge reflex
Its a reflex in inc heart rate due to inc CNS P, preventing blood damming of blood in veins and atrium and pulm circulation
FrankStarling law
States that whne inc quantities of blood flow inot heart - it inc volume and that stretches the wall and that causes muscle to contract with increased force
Barro-R
Stimulated when stretched recepeter on walls of arteries
Vasomotor center
responsible to transmit parasymp (vagus nerve to heart) and Sym (symp fibbers to arteries/a’ioles and veins)
using : vasonctrictor areas , vasodialtor areas and sensory area
Ionic influence to circulation
vasoconstricts= ca , NE , Epi , ADH and AngII Vasodilator = K+ , Mg2+ , H+ bradykinin, histamines , Adenosine
Humoral control
is the control of circulation by substances secreted or absorbed into body fluids - ex:hormones and locally made factors
What is the M.A.P of aorta?
100mmHg
What are the principles of circulation
1-Rate of blood flow to each tissue is precisely controlled
2-C.O = sum of local tissue flows
3-Artery Regulation Pressureis independant of local flow or cardiac output (nervous reflexes )
What are the factors taht determins blood flow
Pressure difference
and
Vascular resistance
C.O
is the quantity of blood that flows thru aorta per given time usually 5000mL/Min
Conductance
Measure of blood flow trhu a vessel for a given pressure difference
Conductance = 1/R = diameter ^4
Vascular distensability
inc volume / inc pressure x ori vol
What affects Pulse pressure
Stroke Vol output
Ejection of blood from systol
Compliance of arterial tree
What is the most important to regulating circulation ?
The autonomic nervous system. as it is the fastest.
