Which of the following is the most significant source of blood flow resistance?
anatomy 2
| Question | Answer |
|---|---|
| what is the most significant source of blood flow resistance? | blood vessel diameter |
| the velocity of blood flow is? | slowest in the capillaries because of the total cross sectional area is the greatest |
What forces work to keep blood in the capillary?
The pressure that blood exerts in the capillaries is known as blood pressure. The force of hydrostatic pressure means that as blood moves along the capillary, fluid moves out through its pores and into the interstitial space.
Which two factors cause water to re enter the capillary at the venous end?
As blood passes from arteries to veins through the capillary bed, fluids are exchanged by diffusion, the movement of molecules from areas of high pressure to low pressure. This relies on two forces: hydrostatic pressure, or blood pressure, and osmotic pressure, the constant pressure needed to keep blood from diffusing.
What happens when capillary hydrostatic pressure increases?
Hydrostatic edema refers to accumulation of excess interstitial fluid which results from elevated capillary hydrostatic pressure while permeability edema results from disruption of the physical structure of the pores in the microvascular membrane such that the barrier is less able to restrict the movement of …
What happens when hydrostatic pressure decreases?
Glomerular filtration can be decreased by reducing capillary hydrostatic pressure with one of the following: (1) a decrease in glomerular blood flow as a result of low blood pressure or low cardiac output; (2) the constriction of the afferent arteriole as a result of increased sympathetic activity or drugs (e.g..
What factors affect hydrostatic pressure?
Hydrostatic pressure is determined by the weight of fluid directly above a point of reference; the latter depends on the distance between the top of the water and the reference point and the density of the fluid (Figure 1(a)).
What causes an increase in hydrostatic pressure?
Increased hydrostatic pressure leading to pulmonary edema may result from many causes, including excessive intravascular volume administration, pulmonary venous outflow obstruction (eg, mitral stenosis or left atrial [LA] myxoma), and LV failure secondary to systolic or diastolic dysfunction of the left ventricle.
Why is maintaining hydrostatic pressure important?
A great property of hydrostatic pressure is that it creates 3D pressure. Check out picture 2. It demonstrates how the force of hydrostatic pressure comes in all directions. This is important, particularly in hydrotherapy, because of the support it provides all surface areas of a submerged body part.
How do you maintain hydrostatic pressure?
Hydrostatic pressure is maintained by the arterioles, the smallest vessels on the arterial side of the vasculature. Arterioles respond to changes in pressure and/or flow via their myogenic response (Davis & Hill, 1999).
How does heart failure cause increased hydrostatic pressure?
As left ventricular failure becomes more severe, or during right ventricular failure, blood backs up into the systemic venous circulation. This elevates venous pressures and capillary hydrostatic pressures, which can lead to edema especially in the feet and legs.
How is hydrostatic pressure affected by low blood pressure?
Why would the osmotic pressure be low in someone who is starving?
In starvation, the formation of plasma proteins is reduced and therefore the protein osmotic pressure may not be sufficient to keep fluids inside the blood stream. The level of plasma proteins becomes low, and the fluid forces in the capillaries become unbalanced.
What is directly proportional to blood flow?
Vessel Length and Diameter The length of a vessel is directly proportional to its resistance: the longer the vessel, the greater the resistance and the lower the flow. As with blood volume, this makes intuitive sense, since the increased surface area of the vessel will impede the flow of blood.
What is the relationship between viscosity and blood flow?
Increased viscosity increases the resistance to blood flow and thereby increases the work of the heart and impairs organ perfusion. Some patients with anemia have low hematocrits, and therefore reduced blood viscosities. Another important factor that influences blood viscosity is temperature.
Does higher blood viscosity increase blood pressure?
Although it is commonly accepted that sustained hyperviscosity can decrease perfusion and increase blood pressure, it should be noted that increased blood viscosity has two effects in the cardiovascular system: it may act to increase shear stress on the endothelium and increase NO release, promoting vasodilation as …
What contributes most to the viscosity of blood?
The two most important determinants of blood viscosity are the hematocrit and fibrinogen levels.
What liquid has the same viscosity as blood?
The main ingredients of your final recipe probably consisted of corn syrup diluted with water and thickened with flour. This particular mixture resembles the flow of blood quite well because it has a similar viscosity, or resistance to flow.
What is the typical range for viscosity of the blood?
Laminar Flow Confined to Tubes—Poiseuille’s Law
| Fluid | Temperature (ºC) | Viscosity |
|---|---|---|
| Whole blood 1 | 37 | 2.084 |
| Blood plasma 2 | 20 | 1.810 |
| 37 | 1.257 | |
| Ethyl alcohol | 20 | 1.20 |
What is the average viscosity of blood?
Normal level In pascal-seconds (Pa·s), the viscosity of blood at 37 °C is normally 3 × 10−3 to 4 × 10−3, respectively 3 – 4 centipoise (cP) in the centimetre gram second system of units. Blood viscosity can be measured by viscometers capable of measurements at various shear rates, such as a rotational viscometer.
Is 0.41 blood viscosity normal?
The range of observed whole blood viscosity results in the ‘polycythaemic’ patients at the same haematocrit (0.46) was equivalent to the effect on whole blood viscosity of a rise in haematocrit from 0.41 to 0.51.
Can drinking lots of water thin your blood?
Water helps to thin the blood, which in turn makes it less likely to form clots, explains Jackie Chan, Dr. P.H., the lead study author. But don’t chug your extra H2O all at once. “You need to drink water throughout the day to keep your blood thin, starting with a glass or two in the morning,” adds Dr.
What does blood viscosity mean?
Blood viscosity is a measurement of the thickness and stickiness of an individual’s blood. It is a direct measure of the ability of blood to flow through the blood vessels.