epinepherine and alpha blockade---why bp go down - got2study2pass

[ArchivalUser]

ok so if we give large does of Epi---syst and diast bp go up

now if we give nonselective alpha blocker eg, phenotalamine with it

now bp is going down....why

B1 effect shud increase the bp----it acts on heart

b2 shud decrease bp---so why net effect is that the bp is going down.

[ArchivalUser]

anyone

[ArchivalUser]

someone

[ArchivalUser]

somoene.

[ArchivalUser]

still waiting.

[ArchivalUser]

because at high doses epi acts on alpha receptors while on low doses b recptr action predominates ..............so at high doses when u gv a blockage a1 gets blocked n b2 takes over .........n b1 stimulation increases systolic pressure only n hence pulse pressure is increases .........so if u have both b1 n b2 stimulation b2 will cause decrease in bp due 2 dec tpr ........n this will b overall effect

[ArchivalUser]

n this action is relative not absolute

[ArchivalUser]

got2study2pass
u should know the main action of the receptors and the relative functions
such
b1>>>>(ino+chronotropic )mainlyyyyyyyyy but share in increase bp(relative)
b2>>vasodilatation of blood vesels of the muscles>.dec tpr>>.dec bp
a 1>>>>>vasoconstriction of blood vesels directly>>>>>>inc bp mainlyyy

soooooooooooooo

if u block a1 (not working so no inc in tpr)+( then b1+b2 working )>>lead to b2 (decr bp)+b1(inc heart rate ) this is the net effect

[ArchivalUser]

so b2 pred over b1.. and b1 wud just inc heart rate,

not the bp right. ok

cool

thanks a lot.

[ArchivalUser]

B2 are in il lung , A1 receptor are in perferal arterial, you have dilatation and decrese in BP ???????????????