Section 1 Flashcards
What is the equation that describes the flow of blood through a vessel?
F = Δ P / R
Flow = Change in Pressure / Resistance
Flow is ____________ to the pressure gradient
a) inversely proportional
b) proportional
flow is proportional to the pressure gradient (ΔP)*
Flow is ____________ to resistance
a) inversely proportional
b) proportional
Flow is inversely proportional to resistance
What is Pressure gradient (ΔP)
the difference in pressure from the beginning of the vessel to its ends
What generates pressure within the cardiovascular system?
The pressure within the cardiovascular system is generated by the heart, which acts as a pressure-generating pump.
What is the main function of the heart in terms of pressure generation?
The heart functions as a pressure-generating pump, responsible for creating the pressure needed to propel blood through the cardiovascular system.
What happens when the ventricles of the heart contract?
When the ventricles contract, they generate pressure within themselves until the pressure is sufficient to eject the blood.
What is the relationship between heart contraction and blood ejection in terms of pressure?
The ventricles of the heart contract, generating pressure within themselves, and this pressure builds up until it is great enough to eject the blood into the circulatory system.
where is blood pressure the highest
within the circulatory system?
When blood is in the left ventricle, cardiac muscle contraction will cause an increase in pressure that
will open the aortic valve.
Blood will then be transferred into the aorta. This is the highest pressure within the circulatory system and serves as the driving force for blood flow throughout the body
As blood travels through the vessels of the circulatory system, the ______ pressure measured in the aorta _____ the further the blood travels from the heart. Why?
As blood travels through the vessels of the circulatory system, the HIGH pressure measured in the aorta DECREASES the further the blood travels from the heart. Why?
This is because as blood flows through vessels, the friction between the blood and the vessel walls causes a decrease in pressure. This results in a pressure gradient
What is the relationship between resistance and the pressure gradient required to maintain blood flow?
When resistance increases, a greater pressure gradient is needed to keep blood flowing
How does increased resistance affect the workload of the heart?
When resistance increases, the heart has to work harder to maintain blood flow.
Name the three factors contributing to the resistance of blood flow.
The three factors contributing to resistance are viscosity of the blood, vessel length, and vessel radius.
Define viscosity in the context of blood and resistance.
Viscosity refers to the state of being thick or semifluid in consistency due to internal friction. In the context of blood, thicker blood results in higher frictional forces and, consequently, higher resistance.
Why is vessel radius considered the most important factor in determining resistance?
A small change in vessel radius has a significant impact on resistance to flow. Vessel radius is the most crucial factor influencing resistance to blood flow.
Explain the relationship between vessel length and resistance.
At a constant radius, a longer vessel has higher resistance. This can be compared to blowing through a garden hose: a short hose is easier to push air (or water) through, while a longer hose requires more effort. Fortunately, vessel length in the body is constant, making it less influential in determining blood flow.
Define resistance in the context of blood flow.
Resistance is the force that opposes blood flow, primarily caused by the frictional forces of flowing blood and the static vessel walls.
What are the two main contributors to resistance in blood flow?
The two main contributors to resistance in blood flow are the frictional forces of flowing blood and the static vessel walls.
How is resistance related to the force of blood flow?
: Resistance acts as a force that opposes blood flow, requiring additional pressure to overcome the frictional forces within the bloodstream and against the walls of blood vessels.
What is the significance of understanding resistance in the context of cardiovascular function?
Understanding resistance is crucial in cardiovascular physiology as it helps explain the factors influencing blood flow and the workload placed on the heart.
Describe the relationship between vessel radius and resistance.
The relationship between vessel radius and resistance is described by the equation: Resistance = 1/ radius to the 4th power. This implies that even a small change in vessel radius can have a substantial impact on blood flow.
Explain the significance of the equation Resistance = 1/ radius to the 4th power.
The equation highlights that changes in vessel radius have a disproportionate effect on resistance. A small alteration in radius can lead to a significant change in blood flow.
What happens to blood flow if the radius is decreased by half, according to the equation?
If the radius is decreased by half, there is a 16-fold reduction in blood flow, as indicated by the equation Resistance = 1/ radius to the 4th power.
What factors are involved in determining blood flow rate according to Poiseuille’s Law?
Blood flow rate (Q) is determined by the pressure gradient (Δ pressure), vessel radius to the fourth power, blood viscosity, and vessel length, as per Poiseuille’s Law.
Provide the equation for Poiseuille’s Law.
Poiseuille’s Law is expressed as: Flow rate (Q) = (pi * Δ pressure * radius^4) / (8 * viscosity * length).
what is emphasized as the prime determinant of blood flow rate?
Vessel radius is emphasized as the prime determinant of blood flow rate in the context of Poiseuille’s Law.
Describe the path of blood flow in the systemic circulation starting from the left ventricle.
Blood leaves the left ventricle and enters the aorta, which then divides into major arteries. These major arteries further branch into smaller vessels until reaching small arteries that enter specific organs.
What is the role of arterioles in the circulatory system?
Arterioles branch from arteries within organs and further divide into the smallest blood vessels, the capillaries.
What is the primary function of capillaries in the circulatory system?
Capillaries are crucial for nutrient and waste exchange, representing the most important function of the circulatory system.
After the capillaries, what structures do blood vessels form during the return journey to the heart?
Capillaries rejoin to form small venules, which then come together to form veins leaving the organs.
Describe the path of blood flow in the systemic veins.
Systemic veins from individual organs come together to form larger and larger veins until they eventually return to the heart, completing the systemic circulation.
Describe the path of blood flow in the systemic circulation, including key vessels and their functions.
The blood leaves the left ventricle, enters the aorta, and divides into major arteries, which further branch into smaller vessels until reaching small arteries entering specific organs. Arterioles branch from these arteries, leading to the smallest blood vessels, the capillaries, where nutrient and waste exchange occurs. Capillaries then rejoin to form small venules, which further combine to form veins leaving the organs. Systemic veins from individual organs continue to merge into larger veins until they ultimately return to the heart, completing the systemic circulation.
Is the distribution of blood to each organ equal?
No, the distribution of cardiac output amongst all of the tissues of the body is not equal, and the relative amount of blood flowing to each organ can be adjusted if necessary.
How many layers are in a blood vessel? Generally
3
Inner, middle and outer layer
Describe the composition of the inner layer of a blood vessel.
The inner layer consists of a single layer of endothelial cells surrounded by a basement membrane of connective tissue.
What is the main makeup of the middle layer in a blood vessel?
The middle layer is composed of circular arrangements of smooth muscle cells and some connective tissues.
Explain the composition of the outer layer of a blood vessel.
The outer layer is made up of collagen-rich connective tissues.
In some blood vessels, what additional layers of connective tissue can be found between the outer and middle layers, and between the middle and inner layers?
In some vessels, elastic fiber-rich layers of connective tissue can be found between the outer and middle layers, as well as between the middle and inner layers. These layers play a role in maintaining the shape and size of the vessel.
which type of vessel do you think would have the highest proportion of elastic fibres? Why would this be the case?
