Effects of Fluid Shifts on Cardiovascular Responses
Introduction
In the human body, the flow of blood through vessels is determined by pressure differentials and vascular resistance. There a number of feedback systems which are responsible for the regulation of arterial pressure, dependent on autonomic nerves and circulating hormones. Moreover, depending on the region of the body the vascular resistance is influenced by; level of sympathetic vasomotor nerves, levels of hormones and local factors including metabolites and endothelial factors. Additionally, resistance is dependent on the length of vessel and inversely with diameter; larger driving force equals faster flow, and increasing resistance hinders flow. The equation below conveys the relationship between pressure, resistance and flow.
Flow = Pressure ÷ Resistance
The main factors determining blood flow resistance are; 1) viscosity of blood; 2) length of conducting tube and; 3) radius vessel. The equation below represents Poiseuille’s law articulating the interaction between pressure gradient, resistance, and flow in a cylindrical vessel.
Flow = Pressure Gradient x Vessel Radius ÷ Vessel Length x Fluid Viscosity
The viscosity of blood along a vessel remains almost constant. Therefore, the radius of the vessel is the most important factor in relation to affecting the blood flow. If the radius of the vessel was to be halved, the flow would be decreased by 16-fold; and, doubling the radius increases the volume by a factor
In the blood flow equation (as seen to the right), blood flow is directly proportional to the fourth power of vessel radius. Dramatic changes happen in regards to blood flow because of small changes in blood vessel
(Marieb and Hoehn, 2010, p 703) defined Blood Pressure (BP) as ‘the force per unit area exerted on a vessel wall by the contained blood, and is expressed in millimetres of mercury (mm Hg)’. BP is still one of the essential and widely used assessment tools in healthcare settings. Nurses generally record the arterial BP which is the forced exerted blood that flows through the arteries, to establish a baseline and to determine any risk factors. BP
When the resistance of a fluid increases, the flow will decrease. One example of this is gravy and milk. Gravy has a greater resistance than milk and will take longer to flow out of a pitcher. The same can be said about respiratory therapy equipment. An increase in viscosity will decrease the flow. When
The cardiovascular system is a network of the heart, blood vessels and the blood. It circulates blood throughout the blood vessels in our body in order to provide individual cells with oxygen and nutrients, and help to dispose of metabolic waste. Capillaries, which are the smallest blood vessels, have extremely thin walls. This is so diffusion can happen more efficiently. Every cell has capillaries passing through very close so there is a shorter distance for diffusion to occur. During my experiment, it showed that the larger the agar cube, the more of remaining agar which was left to be diffused. It also showed that the smaller the agar cube, the less remaining agar was left to be diffused. The findings from my experiment prove that the smaller
Deacreased vascular resistance and increased arterial pressure causes an increase in blood flow. This is important to supply organs with oxygen. 4. Restate your predictions that were correct and give data from your experiment that support them. Restate your predictions that were not correct and correct them with supporting data from your experiment. MAP would increase due to increase in activity, SVR would decrease due to decrease in resistance, CO would increase due to more force of blood being expelled.
Some of the normal physiological reactions of the body to regulate blood pressure is to modulate the heartbeat of the person and/or adjust the expansion or constriction of the arterial walls and blood vessels to normalize the pressure.
29. If all the 280 million molecules of hemoglobin contained in RBCs were free in the plasma,
1. Blood pressure is the force of circulating blood against the walls of the arteries. The pressure of blood in the arteries correlates directly to the amount of blood pumped by the heart and the amount of resistance in the
I found the differences between arteries and veins are their functions they provide to the heart as well as their structure. Arteries transfers blood away from the heart into the periphery resulting in the pressure of the blood in the arteries being high. Where as, the veins transfer blood towards the heart. Arteries carry oxygenated blood distributing it in the periphery as the pulmonary artery moves deoxygenated blood into the lungs for purification. The wall of an artery consists of three layers machining it thicker than veins. The elasticity within the layers of the muscle allows arteries to handle great pressures of blood within it. The thickest layer is known as tunica media as the other two are recognized as tunica externa, and tunica interna. The vein obtains blood from the periphery and carries it towards the heart. Veins are known to carry deoxygenated blood and transfers it the heart for purification. The pulmonary vein is known to carry oxygenated blood. However, there are semilunar valves found within the vein that does not allow retrograde flow of blood in preventing blood to flow in the opposite direction. Veins are thinner when compared to arteries consisting of thin elastic muscle layers with one thick layer being the tunica adventitia. Arteries consist of: carrying oxygenated blood expect for the pulmonary artery; deeply found in the body; thick walled and
The main factor influencing cerebrovascular resistance is the diameter of the cerebral blood vessels. The vessels are innervated by postganglionic sympathetic fibers. They will respond to norepinephrine, but apparently, this does not play a major part in controlling the vascular resistance. The two most important controlling substances are oxygen and carbon dioxide. Carbon dioxide is the most powerful vasodilator for cerebral blood vessels. Oxygen has strong vasoconstrictor effects on these vessels.
Shearing forces acting on the vascular endothelium generated by blood flow causes a release of calcium and subsequent cNOS (cyclic nitric oxide synthase) activation. Therefore, increases in blood flow stimulate NO formation (flow-dependent NO formation). Nitric oxide then causes independent vasodilation by inhibiting vasoconstrictor influences of phenylephrine and alters its potency and contractile effect. (Richard E. Klabunde. 2010)
Basically, arterial blood pressure (BP) is directly proportional to the product of blood flow (cardiac output, CO) and the resistance to passage of blood through pre-capillary arterioles (peripheral vascular resistance, PVR) Hypertension can be caused by either an increase in Cardiac Output (CO) or by an increase in Peripheral Resistance (PR)
>>Increasing the afferent arteriole radius pushed the glomerular pressure, the glomerular filtration rate, and the volume of urine to be higher than the baseline data. Increasing the afferent arteriole radius increased the glomerular filtration rate.
reports the amount of force exerted by the blood into the arteries during ventricular contraction.
The purpose of the experiment is to see how different variables affect pulse rate and blood pressure.