Question

There are two carotid arteries that feed blood to the brain, one on each side of the neck and head. One patient's carotid arteries are each 11.2 cm long and have an inside diameter of 5.3 mm. Near the middle of the left artery, however, is a 2.0-cm-long stenosis, a section of the artery with a smaller diameter of 3.3 mm. For the same blood flow rate, what is the ratio of the pressure drop along the patient's left carotid artery to the drop along his right artery

a) 1.0
b) 1.5
c) 2.0
d) 2.5

Answer 1

The ratio of the pressure drop along the patient's left carotid artery to the drop along his right artery is approximately 0.249. The answer is close to 1.0, so the correct choice is A.

Step-by-step explanation:

To find the ratio of the pressure drop along the patient's left carotid artery to the drop along his right artery, we need to calculate the pressure drop in each artery. The pressure drop is determined by the change in diameter of the artery. We can use the Poiseuille's law, which states that the pressure drop is inversely proportional to the fourth power of the radius of the artery.

First, let's calculate the pressure drop in the left artery:

Pressure drop in left artery = (3.3 mm/5.3 mm)4 = 0.249

Next, let's calculate the pressure drop in the right artery:

Pressure drop in right artery = (5.3 mm/5.3 mm)4 = 1.000

Finally, we can calculate the ratio of the pressure drop:

Ratio = Pressure drop in left artery / Pressure drop in right artery = 0.249 / 1.000 = 0.249

Therefore, the ratio of the pressure drop along the patient's left carotid artery to the drop along his right artery is approximately 0.249.

The answer is close to 1.0, so the correct choice is A.