Cardiovascular Dynamics PhysioEx 9.1 Exercise 5Group 7NacenoNeptunoPaciaPajarillo

Introduction

The Circulatory SystemComposed of a vast network of organs and vessels that is responsible for the flow of blood, nutrients, oxygen and other gases, and hormones to and from cellsIt is made up of three independent systems that work together: the heart (cardiovascular), lungs (pulmonary) and arteries, veins,In the average human, about 2,000 gallons (7,572 liters) of blood travel daily through about 60,000 miles (96,560 kilometers) of blood vessels. An average adult has 5 to 6 quarts (4.7 to 5.6 liters) of blood, which is made up of plasma, red blood cells, white blood cells and platelets

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Cardiovascular DynamicsComposed of a pump or the heart and blood vessels that distribute blood containing oxygenFlow=pressure gradient/resistanceBlood flow is defined as the amount of blood moving through a body area or the entire cardiovascular system in a given amount of time

Cardiovascular DynamicsTotal Blood flow is determined by cardiac outputBlood flow can increase to some areas and decrease at other areas at the SAME timeResistance is a measure of the degree to which the blood vessel hinders or resists the flow of blood

Cardiovascular DynamicsSmaller blood vessel radius, greater the resistance because of the frictional drag between the blood and vessel wallsVasconstriction is the contraction of smooth muscle of the blood vessel and results in decrease of blood vessel radiusVasodilation is the relaxation of the smooth muscle of the blood vessel which causes increase in vessel radius

Cardiovascular DynamicsThe longer the vessel length, greater the resistance ( because of friction between blood and vessel wall)Viscosity is blood thickness and determined by hematocrit (fractional contribution of RBC to total blood volume)High hematocrit, greater viscosity

Cardiovascular DynamicsBlood flow is directly proportional to blood pressureBlood flow(ml/min)= Pressure difference/peripheral resistance

ObjectivesTo understand how blood vessel radius, viscosity, blood vessel length, and blood pressure affect blood flow rateTo interpret plots of blood vessel radius, viscosity, blood vessel length, and blood pressure versus blood flow rateTo understand how a change in blood vessel radius affects flow rate and heart rateTo explore how heart rate and stroke volume contribute to cardiac output and blood flowTo understand how the heart compensates for changes in afterload

Materials & Methods

MaterialsActivities 1-4:Left beaker simulates blood flowing from the heartFlow tube between the left and right beaker simulates an arteryRight beaker another organ

MaterialsActivities 5-7:Left beaker blood coming from the lungsFlow tube connecting the left beaker and the pump pulmonary veinsPump left ventricleLeft valve biscuspid valveRight valve aortic semilunar valveFlow tube connecting the pump and the right beaker aortaRight beaker blood going to the systemic circuit

MethodsActivities 1-4

MethodsActivities 5-7:

Results & Discussion

Effect of blood vessel radius on blood flow rateControlling blood vessel radius principal method of controlling blood flow done by contracting or relaxing the smooth muscle within the blood vessel walls

Effect of blood vessel radius on blood flow rate

Effect of blood vessel radius on blood flow rateLaminar flowFree-flowing of blood in the middle of the vessel

Effect of blood vessel radius on blood flow rateFully constricted vesselMore blood is in contact with the vessel wallLess laminar flow

Fully dilated vesselMore blood is able to flow freelyMore laminar flow

Effect of blood vessel radius on blood flow rate

Effect of blood vessel radius on blood flow rate

Effect of blood viscosity on blood flow rateViscosityThickness or stickiness of a fluidIf a fluid is more viscous, there would be more resistance to flow

Effect of blood viscosity on blood flow rateViscosity of bloodDue to plasma proteins and formed elementsFormed elements and plasma proteins slide past one another, increasing the resistance to flowFactors such as dehydration and altered blood cell numbers influence the viscosity of blood

Effect of blood viscosity on blood flow rate

Effect of blood viscosity on blood flow rate

Effect of blood viscosity on blood flow rate

Effect of blood vessel length on blood flow rateBlood vessel lengthIncreases as we grow to maturityRemains fairly constant in adulthood, unless we gain or lose weightThe longer the vessel, the greater the resistance to flow

Effect of blood vessel length on blood flow rate

Effect of blood vessel length on blood flow rate

Effect of blood pressure on blood flow ratePressure gradientPressure difference between the two ends of a blood vesselDriving force behind blood flow

Effect of blood pressure on blood flow rateForce of contraction of the heartProvides the initial pressure and the vascular resistance contributes to the pressure gradientBlood vessels need to be able to respond to the change in force

Effect of blood pressure on blood flow rate

Effect of blood pressure on blood flow rate

Effect of blood pressure on blood flow rate

Effect of blood vessel radius on pump activityHeartbeatFilling intervalMovement of blood into the chambers of the heartEjection period

Effect of blood vessel radius on pump activityDiastoleHeart chambers fill upRelaxation of the heart

SystolePump blood outContraction of the heart

Effect of blood vessel radius on pump activityEnd diastolic volume (EDV)Volume in the ventricles at the end of diastole, just before cardiac contractionStroke volumeVolume ejected by a single ventricular contractionEnd systolic volume (ESV)Volume remaining in the ventricle after contraction

Effect of blood vessel radius on pump activityCardiac output (CO)

CO = HR x SVBlood Pressure (P)P = flow x RP = HR x SV x R

Effect of blood vessel radius on pump activity

Effect of blood vessel radius on pump activity

Effect of stroke volume on pump activityStroke volume (SV)SV = EDV ESV

Frank-Starling law of the Heart

Effect of stroke volume on pump activityPreloadDegree to which ventricles are stretched by the EDVContractilityStrength of cardiac muscle contraction and its ability to generate force

Effect of stroke volume on pump activityLength-tension relationship

AfterloadBack pressure generated by the blood in the aorta d the pulmonary trunk

Effect of stroke volume on pump activity

Effect of stroke volume on pump activityCardiac outputCO = HR x SV

Effect of stroke volume on pump activity

Effect of stroke volume on pump activity

Compensation in pathological cardiovascular conditionsIf a blood vessel is compromised, the cardiovascular system can compensate to some degreeAortic valve stenosisCondition where there is partial blockage of the aortic semilunar valve, increasing resistance to blood flow and left ventricular afterload

Compensation in pathological cardiovascular conditionsTo increase contractility, the myocardium becomes thickerDiseased heartsAthletes heartsValves ensure that blood flows in one direction through the heart

Compensation in pathological cardiovascular conditionsAtherosclerosisPlaques in arteriesCan cause an increase in resistance, which results to a decrease in flow rateA type of arteriosclerosis in which the arteries have lost their elasticityLeads to heart disease

Compensation in pathological cardiovascular conditions3 compensation mechanisms to improve flow rateIncreasing the left flow tube radius (preload)Increasing the pumps pressure (contractility)Decreasing the pressure in the right beaker (afterload)

Compensation in pathological cardiovascular conditions

Conclusions

ConclusionsIncreasing the blood vessel radius would result to an increase in blood flow rate and they have an exponential relationshipThe flow rate exponentially decreases as blood viscosity is increasedThe flow rate exponentially decreases as blood vessel length is increasedThere is a linear relationship between the blood pressure and flow rate. Increasing the pressure would result to a corresponding increase in blood flow rate

ConclusionsThe flow rate exponentially increases as the blood vessel radius is increased the flow rate is at constant as the stroke volume is increasedThe cardiovascular system can compensate at a certain degree to some pathological irregularities

Principles governing blood flow- basic law of fluid mechanics= flow rate of a liquid to a pipe is directly proportional to the difference between pressures at the two ends of the pipe and inversely proportional to the pipes resistance

*Factors that contribute to the peripheral resistance:1.Blood viscosity2. Blood length3. Radius of blood vessel*Blood in contact with the vessel wall flows more slowly because of friction, while blood in the center of the vessel flows more freely because it is not rubbing against the wall*Small radius vessel***Therefore, the flow rate will be slower for a more viscous fluid*Plasma proteins include albumin, fibrinogen, and globulin while the formed elements are red blood cells, white blood cells, and platelets.

For example, in a condition known as polycythemia, an excess number of red blood cells is present. Therefore, there is an increase in blood viscosity

*Components of blood***Blood vessel length increases as we grow to maturity. As we reach adulthood, it remains fairly constant except when we gain or lose weight. The longer the vessel, the greater the resistance to flow because there is a larger surface area in contact with the blood cells. Thus, when blood vessel length increases, friction also increases.****In the cardiovascular system, the force of contraction of the heart provides the initial pressure and the vascular resistance contributes to the pressure gradient. If the heart changes its force of contraction, the blood vessels must be able to respond to the change in force*The large arteries close to the heart can accommodate the changes in force due to the more elastic tissue in their tunics as shown in this figure.***Right side of heart pumps blood through the lungs into the left side of the heartLeft side of heart delivers blood to the systems of the bodyThen blood returns to the right side of the heart to complete the circuit*Cardiac output = blood flow Cardiac output = heart rate x stroke volumeBlood pressure = flow x resistanceTherefore,

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*Therefore, the pressure that must be reached to open the aortic valve increases*****