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If the radius of an arteriole increases from 2 to 3 mm how does this affect resistance and blood flow?
Intuitively, it's easy to think of blood flow through the arteries in the same way that you think of the flow of water through pipes. Change the radius of the pipe, and you change how fast water flows to them. Likewise, if you change the radius of an arteriole, you change the rate that blood flows through it.
The underlying reason behind these observations is the same. Flow (Q) is determined by a pressure gradient (ΔP) and the resistance to flow (R):
Q = ΔP / R
If you increase resistance, you decrease flow; likewise, decrease resistance and you increase flow. But what determines resistance? Poiseuille's law tells us that resistance (R) is inversely proportional to the fourth power of radius (r).
So let's say we take a normal blood vessel and measure the resistance; let's call that resistance R1. Now if we double the vessel radius, what happens to the resistance? Poiseuille's law (see link to left) tells us that if we double the radius, our resistance goes down by a factor of 16. So R2 is one-sixteenth of R1.
How does this affect blood flow? For that we go to our original equation that related flow, pressure gradient, and resistance. From that you can see that flow is inversely proportional to resistance. So if you halve resistance, then you double flow; likewise, if you take our example and reduce resistance to a factor of one-sixteenth, then flow increases by a factor of 16.
The same principles and steps can be used to figure out what happens when you change the radius of an arteriole from 2 mm to 3 mm. Only this time you're not increasing radius by a factor of 2; you're increasing it by a factor of 3 / 2, or 1.5.
What else can I help you with?
What is the effect of reducing afferent arteriole radius on filtration?
reducing afferent arteriole radius decreases filtration rate
What is the effect of reducing afferent arteriole radius on filtration rate?
As the afferent arteriole dilates it exposes the glomerulus to an increased blood pressure, closer and closer to that of the full systemic blood pressure. This increases GFR and Glomerular pressure. -6th Year Medical Student
When the afferent arteriole radius is 0.35 mm and the efferent arteriole radius is 0.40 mm what is the glomerular filtration rate?
26.74!
What are the factors that determine vascular resistance?
The factors that determine vascular resistance include the radius of the blood vessels (smaller radius increases resistance), the length of the blood vessels (longer length increases resistance), the viscosity of the blood (higher viscosity increases resistance), and the presence of any obstructions or blockages in the blood vessels.
What happens to blood pressure when the smooth muscle of an arteriole contracts?
When the radius of the smooth muscle decreases the pressure increases. So the blood pressure becomes higher
Airway resistance is affected primarily by the?
airway length - a large surface area means more friction airway radius - halving the radius increases resistance 16-fold flow rate
If you double the radius of cylinder how does this affect the volume of the cylinder?
The volume increases by a factor of four.
How does atomic radius increases in the periodic table?
atomic radius increases down a group as the number of shells increases
A piece of wire is stretched such that its length increases and its radius decreases the resistance of the wire will tend to?
A piece of wire stretched such that its length increases and its radius decreases will tend to have its resistance increase. The formula for this is: R = ρL/A where ρ = resistivity of the material composing the wire, L = length of the wire, and A = area of the conducting cross section of the wire. It can easily be seen that as area decreases resistance gets higher. In the case proposed the wire length is not reduced as it is stretched to reduce the area, this increases the resistivity as well.
What happened to the fluid flow rate as the radius of the flow tube increased?
As the radius of the flow tube increases, the fluid flow rate increases proportionally. This is described by the Hagen–Poiseuille equation, which states that flow rate is directly proportional to the fourth power of the tube radius. Increasing the radius reduces the resistance to flow, allowing more fluid to pass through per unit of time.
How does radius affect arc length?
The arc length of a circle is directly proportional to its radius. Specifically, the formula for arc length (L) is given by (L = r \theta), where (r) is the radius and (\theta) is the central angle in radians. This means that as the radius increases, the arc length also increases for a given angle. Conversely, for a fixed radius, a larger angle will result in a longer arc length.
What is the effect on resistance if the radius of a vessel is halved?
If the radius of a vessel is halved, the resistance will increase by a factor of 16. This is because resistance is inversely proportional to the fourth power of the radius (R ∝ 1/r^4). Therefore, a decrease in radius leads to a significant increase in resistance.
