usmletopper1
Forum Junior
Topics: 13
Posts: 73
|
D
|
| glycogen
Forum Senior
Topics: 5
Posts: 135
|
why d?
|
| hope4dabest
Forum Elite
Topics: 16
Posts: 433
|
|
| hope4dabest
Forum Elite
Topics: 16
Posts: 433
|
Answer is B
Explaination---there r 2 factors that affect wall tension: the radius of the vessel and pressure as T is directly prop to P and r. The wall tension of an aneurysym is greater than the surrounding vessel because it has greater radius. The larger the aneurysym, the greater the wall tension. Vessel pressure also raises wall tension directly and possibly indirectly by causing an increase in radius. Of the choices given only maintaining a supine position would reduce wall tension. In an upright position the effect of gravity increases pressure in vessels below heart level. A supine posture elimitaes this gravity effect. None of the other choices would reduce pressure in abd aorta, rather they would likely incrrease pressure and wall tension.......
now i have a confusin that y r they stressing on pressure...alpha agonist can constrict the vessel and can decrease the wall tension....y not this way??
|
| black_horse
Forum Newbie
Topics: 1
Posts: 24
|
Well, you expect an alpha agonist to constrict the aorta!! This can't be, stimulation of alpha receptors can't constrict the aorta or any of the large arteries because of two reasons:
1.Functionally, constricting them will lead to a very high increase in work load on the heart eventually leading to heart failure, so they normally act as low resistance expandable vessels that convert bl.flow to pulsatile.
2.Anatomically, the walls of these vessels consist almost from elastic fibers with very few smooth muscle fibers so they can't constrict, conversely the elastic fibers enable them to serve the aforementioned function.
So administrating an alpha agonist will only lead to arteriolar constriction with increase in TPR which will elevate Bl.pressure (especially diastolic in aorta) and lead to an increase in wall tension.
Hope I explained it right.
GL
|
| hope4dabest
Forum Elite
Topics: 16
Posts: 433
|
Well thanks a lot...i had no idea of this..
|
|
| |
| | | | | | |
