|Prep for USMLE|
|         Forum      |     Resources||New Posts   |   Register   |   Login||»  |
In which segment of the systemic circulation does the greatest decrease in blood pressure occur?
A. Aorta and large arteries
D. Small arteries
E. Vena cavae and large veins
F. Venules and small veins
yes its arterioles
yeah arterioles seems right
The correct answer is B.
As blood flows through the systemic circulation the mean pressure of the blood decreases from about 100 mm Hg in the aorta to about 0 mm Hg in the right atrium.
The mean blood pressure is about the same in all portions of the aorta (choice A) and it only falls by a few mm Hg in the large arteries (choice A). The blood pressure decreases by 10 to 20 mm Hg in the small arteries (choice D) so that blood entering the arterioles has a pressure averaging about 80 to 90 mm Hg. By the time the blood has reached the ends of the arterioles (choice B) the pressure has fallen to about 35 mm Hg.
The pressure falls another 25 mm Hg as it flows through the capillary network (choice C), so that blood entering the venules has a pressure of about 10 mm Hg. The blood pressure falls by about 10 mm Hg as it flows along the venous system (choices E and F) to the right atrium.
The fall in blood pressure (from 100 to 0 mm Hg) along the various types of blood vessels in the circulation is summarized in the table.
The table also shows the relative resistance (expressed as % of total peripheral resistance) to blood flow in the various segments of the circulation.
Type of blood vessel Fall in BP (mm Hg) (% of TPR)
Aorta and large arteries <1
Small arteries 10-20
Venules and small veins 9
Vena cavae <1
well as I understood, the greatest fall in blood pressure occurs in the arterioles, in a graphic you will see that after the arterioles occurs another drop in blood pressure (capillaries), but it doesnt mean that capillaries has the gratest resistance because the pressure was diminished by the arterioles.
This thread is closed, so you cannot post a reply.
| Similar forum topics|
CARDIO......A pt. of acute MI
CARDIO......A pt. of atrial fib....
| Related resources|
Advertise | Support | Premium | Contact