Lecture 4

Biomedical Engineering 355 with Drzewiecki at Rutgers University - New Brunswick/Piscataway

About this deck

By: Krina Doshi
Textbook: Vander's Human Physiology
Created: 2010-04-06
Size: 73 flashcards
Views: 11

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Organ and tissue blood flow and its local control

Organs and tissues receive blood flow according...
Tissue needs for blood flow are largely...
Metabolic, Myogenic, neurogenic, and hemodynamic...
Local blood flow phenomena include
Individual organ or blood flow to any tissue is...
Ratio supply of oxygen supply to oxygen demand
A lot of mechanisms responsible for how an...
Mostly about heart and coronary vasculature of...
Posterior and Anterior Picture of the heart

Organ and Tissue Blood flow and its local controls

Organs and tissues receive blood flow according to their needs
Tissue needs for blood flow

Local blood flow phenomena include

Reactive hyperemia
Pressure-flow auto regulation
Active (exercise, functional) hyperemia

Ratio supply of oxygen supply to oxygen demand

Quantify that ration and relate to blood flow in any organ or tissue

A lot of mechanisms responsible for how an individual organ regulates it blood supply

Metabolic
Myogenic ? the ability of a muscle cell to respond to stretch or de-stretch here the muscle cell interest is the...
Neurogenic ? ANS sympathetic division and the innervations of the sympathetic nerves on to those smooth muscle...
Hemodynamic

Posterior and Anterior Picture of the heart

Landmarks of the heart

Epicardium ? outermost, exterior layer of epithelial cells on the...
Subepicardium ? anything below the epicardium (initial layer of cells)
Midmyocardium ? Muscle layer btw the epicardium and the endocardium
Endocardium ? endothelial cells that line the ventricular and...
Two landmarks epithelial on outside of heart and endothelial...
Midmyocardium muscle that lie midway btw the epicardium and...
NOTE: Red vessels carry arterial blood that is well oxygenated...

Anterior/Posterior veins of the major coronary vasculature of the human (mammalian heart)

Root of aorta, left ventricle, right ventricle, origination of common coronary arteries how...
Of the total amount of blood flow going to the tissue of the heart about 80%? 85% goes thru...
This main left branch bifurcates into a semi branch called the left anterior descending
Circumflex branch carries blood flow from the left main coronary artery to the posterior...
Great cardiac vein ? it terminates inside the vena cava where it joins with the right atrium-...

Myogenic

? the ability of a muscle cell to respond to stretch or de-stretch here the muscle cell interest is the vascular smooth much cell in the wall of the blood vessel- ability of muscle to contract and relax

Neurogenic

? ANS sympathetic division and the innervations of the sympathetic nerves on to those smooth muscle vascular cells in a blood vessel ? ability of nerves to cause contraction relaxation in a blood vessel

Hemodynamic

- blood pressure consistency blood flow blood velocity

Physiologic concept of myocardial oxygen supply and demand

Scematic to show the general relationship of oxygen supply to oxygen demand (here myocardium...
Supply of oxygen on one side demand on other think of as a ratio
Supply and Demand in homeostasis and then sympathetic release bust of norepinephrine on to...
Innate design in mammalian heart is that once that ratio/homeostasis is interrupted myocytes...
This scheme in the heart is the adenosine hypothesis first made by Robert Berne

This main left branch bifurcates into a semi branch called the left anterior descending

LAD in coronary artery interest
In experiments isolate the Lad and study blood flow thru LAD

Epicardium

? outermost, exterior layer of epithelial cells on the surface the external surface of the ventricles, atria

Great cardiac vein ? it terminates inside the vena cava where it joins with the right atrium- the opening of it is called the coronary sinus

a orifice where most of the venous draining of the heart returning of the heart returns to the right atrium
KNOW

a orifice where most of the venous draining of the heart returning of the heart returns to the right atrium

If want to study oxygen supply to oxygen demand in the heart could instrument some of the vessels to collect information from them

Subepicardium

? anything below the epicardium (initial layer of cells)

Midmyocardium

? Muscle layer btw the epicardium and the endocardium

Endocardium

? endothelial cells that line the ventricular and atrial chambers

Influence of cardiac cycle on coronary blood flow (CBF, left) and influence of CBF in oxygen use (MVO2, right)

Coronary circulation
Figure data on oxygen supply to oxygen demand

Circumflex branch

carries blood flow from the left main coronary artery to the posterior surface of the left ventricle

Great cardiac vein

? it terminates inside the vena cava where it joins with the right atrium- the opening of it is called the coronary sinus - a orifice where most of the venous draining of the heart returning of the heart returns to the right atrium

Supply of oxygen on one side demand on other think of as a ratio

Supply of oxygen determined by
Main determinants of metabolic/oxygen demand

Supply of oxygen determined by

Content of oxygen in the arterial blood ? how much oxygen is bound to hemoglobin and how much oxygen is dissolved in solution -- the sum is the oxygen content
Coronary blood flow what volume of flow is passing thru lad and right coronary artery ?

Main determinants of metabolic/oxygen demand

heart rate
ventricular contractility
wall tension -how much tension in midmyocardium how much force (mechanic)

This scheme in the heart is the adenosine hypothesis first made by Robert Berne

at university of Virginia ? adenosine is an important coronary vasculature vasodilator

Used by many companies to help patients

An experiment revealing the influences of extravascular compression of pussatile CBF

How blood supply to the left side of the heart is regulated

Figure data on oxygen supply to oxygen demand

Blood flow a function oxygen consumption(which is on the ordinate)
If we did a aggression analysis when blood flow the independent variable myocardial oxygen...
If coronary blood flow and oxygen consumption switched get the same exact results?have an...
Single cardiac cycle aortic blood pressure, blood flow measure thru main left and right...
Depicts the importance of tension in the wall of the myocardium on extra vascular compression

If coronary blood flow and oxygen consumption switched get the same exact results?have an identical relationship

Don?t know which is true
He thinks oxygen consumption is the independent variable and coronary blood flow is the dependant variable

Depicts the importance of tension in the wall of the myocardium on extra vascular compression

Systole period of time between the two vertical broken lines (systolic pressure)
Diastole
Compare what?s happening to CBF in the left side of the heart during systole when myocardial generating its greatest force blood flow in the left main coronary artery is at its lowest point
NOTE That in the left ventricle red conc most CBF occurs during diastole

Compare what?s happening to CBF in the left side of the heart during systole when myocardial generating its greatest force blood flow in the left main coronary artery is at its lowest point

Means that our left ventricles the majority of blood flow occurs during the diastolic phase of the cardiac cycle
Systole is time when vessels compressed by walls generating force

Systole is time when vessels compressed by walls generating force

when walls compressed blood flow reduced
but myocardium still metabolically active still desire and require oxygen but are not...
Production and release of adenosine up during systole even when vessels compressed...
Coronary blood flow is regulated on a beat to beat basis
Opposite in the right coronary artery most of flow occurs during systole and the...

Opposite in the right coronary artery most of flow occurs during systole and the lower amount during diastole

Because myocardium of left ventricle is four to six times thicker than in the right ventricle so left has more contractile force, or tension generating capacity
Right ventricle is an appendage of the left ventricle, like atrial chambers

How blood supply to the left side of the heart is regulated

3 variables

Coronary perfusion pressure
The hydrostatic pressure or driving force that pushing...
Coronary oxygen sinus content or partial pressure of oxygen
When induce ventricular fibrillation it causes the...
When retain coronary perfusion pressure constant so...
The oxygen demand now is reduced when heart no longer...
Illustrates the importance of extra vascular...
Related experiment look at effect of sympathetic...

Coronary oxygen sinus content or partial pressure of oxygen

Veins less oxygen in arteries

Related experiment look at effect of sympathetic nerves stimulation on those relationships

When stimulate left illac ganglion

Coronary blood flow drops
The sympathetic nerves release norepinephrine on adrenergic receptors and constrict the arterioles
Same norepinephrine is activating the myocardium causing a more vigorous contraction and an accelerated heart...
Bc of increase of oxygen demand the coronary sinus partial pressure of oxygen decrease more oxygen is being...

Same norepinephrine is activating the myocardium causing a more vigorous contraction and an accelerated heart rate driving up oxygen demand and blood flow increase and increase two to three fold above the base line level despite the fact that sympathetic nerves are constantly stimulated

*If you have two situations a neurogenic mediated coronary vasoconstriction and a simultaneous positive intropic ,positive conotropic demand driving up oxygen consumption lead to vasodilatation. Vasodilatation always predominate over vasoconstriction. hence net effect of increase in flow despite the presence of nerve stimulation

Class Questions

Inotropy ? increased strength or vigor of contraction
Chronotropy ? increase of rate (either heart rate or rate of...
Hyperemia ? excess flow (in coronary circulation ) caused by...
Independent variable x axis
Dependant variable y axis on ordinate
When adenosine released overrides sympathetic nerve...
If the blood flow not maintained experimentally as soon as heart...

Local Blood Flow

Reactive hyperemia ? excessive blood flow reactive blood supply?means that the blood supply or blood flow to an organ...
Pressure flow auto regulation ? relationship between blood pressure and blood flow in an organ that displays this...
Active hyperemia (functional exercise) - at times blood supply can decrease because of the function of the organ (why...
Hyperemia means excessive blood flow

Dependant variable y axis on ordinate

Ratio of Oxygen supply to oxygen demand ration of about 1 with homeostasis, tissue is demanding same amount of oxygen that blood flow is delivering to it

Reactive hyperemia in perfused skeletal muscle preparation

Reactive hyperemia is time dependant
Picture is of skeletal muscle and the femoral artery
The longer the period of exclusion the greater the duration of...
The peak flow increases with increase period of exclusion
Direct correlation between period of lack/disruption of flow and...
No flow thru the artery but still pressure in the vessel...
Why high altitude dwellers above 1400 or 1500 feet don?t die of...

Inotropy

? increased strength or vigor of contraction

Chronotropy

? increase of rate (either heart rate or rate of contraction)

Hyperemia

? excess flow (in coronary circulation ) caused by increase in demand of oxygen

Pressure flow auto regulation in the skeletal muscle vasculature

Pressure flow autoregulation means? Ability of...
Three types of blood flow
Most complex form don?t know everything yet
NOTE: The relative constant flow over the range...
Normalization ? the physiologic concept that the...
Elevate pressure increase elevation of blood...
If patient for a few seconds after change in...
Biphasic response (2 steps)
Our organs display pressure flow auto...

Reactive hyperemia

? excessive blood flow reactive blood supply?means that the blood supply or blood flow to an organ or tissue responds to some intervention suddenly and precipitously?happens in heart

Why high altitude dwellers above 1400 or 1500 feet don?t die of heart attack, myocardial infarction

The people live in a hypoxic environment that stimulates angiogenesis which is the growth of collateral blood vessels in the heart
Left ventricle benefits from collateralization
Lung and right ventricle get pulmonary hyper tension and die around 50

Pressure flow auto regulation

? relationship between blood pressure and blood flow in an organ that displays this phenomenon ? ability of an organ regulate its own blood supply independent of external influences including nerves, ability to maintain good oxygen demand ratio despite external innervations

Active hyperemia

(functional exercise) - at times blood supply can decrease because of the function of the organ (why aka functional or exercise) responds but in a more controlled fashion the way oxygen supply to demand is unbalanced after you eat, blood supply lower before lunch because gut needs more oxygen after you eat?not as precipitously in a more controlled fashion

Summary

Reactive hyperemia a metabolic/Myogenic response
Duration of hyperemia corresponds to duration of the occlusion
Pressure flow auto regulation 2 phases passive then active
Occurs in several organs multiple organs involved

Three types of blood flow

Active hyperemia, reactive hyperemia, autoregulation on blood flow

Volume repayment

(b-a)/ (a) *100

Biphasic response (2 steps)

Blood flow changes as change in pressure initially in the first step

Passive flow responsive?elevate the pressure the head of hydrostatic pressure opens vasculature, distended the vasculature, while pressure still elevated the vasculature contracts in response to the increase of pressure as it contraction diameter decreases resistance increases and blood flow back to steady state balance
Near constant flow despite wide range of perfusion pressures

Questions

What causes change in flow during passive and active phase
Active phase begins 120-140 not a rapid response gradual(few minutes)
Myogenic means the ability of vasculature smooth muscle cells or...
All blood vessels display receptors for a wide rage of agonists...
By definition little or no difference between hyperemia in heart...
Signal transduction = stimulus response
Main difference between active and reactive is the reactive...

Duration of hyperemia corresponds to duration of the occlusion

Time dependant

NOTE

The relative constant flow over the range of 20—120 mmHg

What causes change in flow during passive and active phase

Metabolites, vasodilators, Myogenic response

Active Hyperemia in skeletal muscle

Picture
Limb instrumented so measure
Phasic and mean blood flow increase during activity
No occlusion of blood flow before increase in activity

Myogenic means the ability of vasculature smooth muscle cells or the cells of any blood vessel to respond to trans mural pressure, the intravascular pressure increases and muscle cells will s to that stretch

Trans mural?mural mean wall?the difference in pressure inside the vessel minus the pressure outside the vessel
It?s that difference that distends the vessel

By definition little or no difference between hyperemia in heart and skeletal muscle

All three phases

_______,Oxygen debt, oxygen restoration
The difference in which of the players mediate the predominate response

Alveolar oxygen uptake as a function of oxygen delivery (demand) by the peripheral tissues

Relationship between tissue utilization of oxygen (abscissa) and pulmonary delivery of oxygen to the body
If you?re an elite athlete have greater oxygen delivery and oxygen uptake
Sedentary vs. elite athlete

Signal transduction

stimulus response

No occlusion of blood flow before increase in activity

On treadmill skeletal muscle active and demands more oxygen gets by wither blood vessels dilate and blood flow to...
Skeletal muscles extract more oxygen
If you run a lot that stimulates angiogenesis in heart and other tissues
By design the heart cardinogenesis the vascular angiogenesis and the blood erythropoisis occur simultaneously,...

On treadmill skeletal muscle active and demands more oxygen gets by wither blood vessels dilate and blood flow to all those muscles increase or the body has to adjust blood flow somewhere else in body

Blood flow to kidneys heart gut and brain decrease, kidney and gut become relatively unimportant in resting they take 50% of output, during active they don?t get that blood flow renal and _________ blood flow go down

About this deck

By: Krina Doshi
Textbook: Vander's Human Physiology
Created: 2010-04-06
Size: 73 flashcards
Views: 11

About StudyBlue

“Simply amazing. The flash cards are smooth, there are many different types of studying tools, and there is a great search engine. I praise you on the awesomeness.”
Dennis