Alpha Agonist and A-V pO2 difference - USMLE Forums
USMLE Forums Logo
USMLE Forums         Your Reliable USMLE Online Community     Members     Posts
Home
USMLE Articles
USMLE News
USMLE Polls
USMLE Books
USMLE Apps
Go Back   USMLE Forums > USMLE Step 1 Forum

USMLE Step 1 Forum USMLE Step 1 Discussion Forum: Let's talk about anything related to USMLE Step 1 exam


Reply
 
Thread Tools Search this Thread Display Modes
  #1  
Old 06-19-2011
INCOGNITO's Avatar
USMLE Forums Guru
 
Steps History: Step 1 Only
Posts: 343
Threads: 127
Thanked 525 Times in 192 Posts
Reputation: 535
Question Alpha Agonist and A-V pO2 difference

in an experimental lab what would u expect the effect of alpha-agonist on
A-V PO2 difference

a)increase
b)decrease
c)no change
Reply With Quote Quick reply to this message
The above post was thanked by:
bebix (06-28-2011), Claus_CU (06-28-2011)



  #2  
Old 06-28-2011
INCOGNITO's Avatar
USMLE Forums Guru
 
Steps History: Step 1 Only
Posts: 343
Threads: 127
Thanked 525 Times in 192 Posts
Reputation: 535
Default

i myself forgot the answer..lol
Reply With Quote Quick reply to this message
The above post was thanked by:
Claus_CU (06-28-2011)
  #3  
Old 06-28-2011
Claus_CU's Avatar
USMLE Forums Addict
 
Steps History: 1 + CS
Posts: 113
Threads: 8
Thanked 89 Times in 61 Posts
Reputation: 99
Default

Quote:
Originally Posted by IKR123 View Post
i myself forgot the answer..lol
please...try to remember...:sorry:
Reply With Quote Quick reply to this message
 
  #4  
Old 06-28-2011
USMLE Forums Master
 
Steps History: 1+CK+CS+3
Posts: 1,175
Threads: 38
Thanked 854 Times in 478 Posts
Reputation: 864
Default

I think it would be No Change.

An agonist would cause bronchoconstriction, as well as arteriolar constiction. If you have less air coming into the bronchioles, then less air will get transferred to the artery. Thus making it no change.

AV Po2 Changes only in conditions when there is problems with diffusion, transfer and hemoglobin..
Reply With Quote Quick reply to this message
The above post was thanked by:
bebix (06-28-2011)
  #5  
Old 06-28-2011
bebix's Avatar
USMLE Forums Master
 
Steps History: 1+CK+CS+3
Posts: 1,357
Threads: 194
Thanked 3,268 Times in 881 Posts
Reputation: 3278
Default

Quote:
Originally Posted by patelMD View Post
I think it would be No Change.

An agonist would cause bronchoconstriction, as well as arteriolar constiction. If you have less air coming into the bronchioles, then less air will get transferred to the artery. Thus making it no change.

AV Po2 Changes only in conditions when there is problems with diffusion, transfer and hemoglobin..
but this is an alpha agonists...why bronchoconstriction?
Reply With Quote Quick reply to this message
  #6  
Old 06-28-2011
USMLE Forums Master
 
Steps History: 1+CK+CS+3
Posts: 1,175
Threads: 38
Thanked 854 Times in 478 Posts
Reputation: 864
Default

Quote:
Originally Posted by bebix View Post
but this is an alpha agonists...why bronchoconstriction?
Alpha agonist would cause constriction of smooth muscles of bronchioles
Reply With Quote Quick reply to this message
The above post was thanked by:
bebix (06-28-2011)
  #7  
Old 06-28-2011
bebix's Avatar
USMLE Forums Master
 
Steps History: 1+CK+CS+3
Posts: 1,357
Threads: 194
Thanked 3,268 Times in 881 Posts
Reputation: 3278
Default

Quote:
Originally Posted by patelMD View Post
Alpha agonist would cause constriction of smooth muscles of bronchioles
really?...I didnt know that...thanks!
Reply With Quote Quick reply to this message
  #8  
Old 06-28-2011
dr.Irina's Avatar
USMLE Forums Veteran
 
Steps History: 1 + CK
Posts: 229
Threads: 6
Thanked 73 Times in 62 Posts
Reputation: 83
Default

a1 receptors -atrerioles and veins contraction
b2 receptors-bronchiolar smoot muscle relax
m3 receptors-bronchiolar smoot muscle contract
i know it
Reply With Quote Quick reply to this message
The above post was thanked by:
bebix (06-29-2011)
  #9  
Old 06-28-2011
USMLE Forums Guru
 
Steps History: Not yet
Posts: 339
Threads: 94
Thanked 331 Times in 150 Posts
Reputation: 291
Default

so what will be the answer?
Reply With Quote Quick reply to this message
  #10  
Old 06-28-2011
pass7's Avatar
USMLE Forums Guru
 
Steps History: 1+CK+CS+3
Posts: 406
Threads: 30
Thanked 141 Times in 109 Posts
Reputation: 151
Default

yeah so wats the answer??
Reply With Quote Quick reply to this message
  #11  
Old 06-28-2011
dr.Irina's Avatar
USMLE Forums Veteran
 
Steps History: 1 + CK
Posts: 229
Threads: 6
Thanked 73 Times in 62 Posts
Reputation: 83
Default

may be B
Reply With Quote Quick reply to this message
  #12  
Old 06-28-2011
adorisz's Avatar
USMLE Forums Scout
 
Steps History: 1 + CK
Posts: 54
Threads: 15
Thanked 46 Times in 21 Posts
Reputation: 56
Default

I would say increase.
The reason is that since there is vasoconstriction the blood flow will decrease (Resistance is inversely related to flow). Since blood flows slower through the tissues there is more time for oxygen uptake by the tissues and therefore an increase in A-V difference.

I just remember hearing this somewhere, not sure though. Plus is u think about it, its the exact opposite with sepsis (since its high output failure it basically causes the blood to flow so fast through tissues that there isnt enough time for gas exchange)
Reply With Quote Quick reply to this message
The above post was thanked by:
bebix (06-29-2011)
  #13  
Old 06-29-2011
USMLE Forums Addict
 
Steps History: Not yet
Posts: 140
Threads: 5
Thanked 118 Times in 66 Posts
Reputation: 128
Default

yeah i think itl increase too. but i usually think of physiology trying to compensate, so id think that since there would be vaso constriction, less blood would reach the tissue, in which case it would try and extract more oxygen from the blood that does, hence leaving very little o2 in its venous end...AVO2 is the difference between the o2 concentration in the arterioles and veins right?

I think someone was mentioning the alveolar gradient (A-a difference) while referring to the diffusion component above.

hey adorisz, I havent done cardio for a while but i thought flow was directly proportional to the radius power 4 (or inversely to the resistance), so in that case vasoconstrict would decrease the flow...oh wait, i think you mean the same thing i was saying, that the amount of blood going through the vessels would decrease? (as compared to before)

gah! now im confused ...
Reply With Quote Quick reply to this message
  #14  
Old 06-29-2011
USMLE Forums Master
 
Steps History: 1+CK+CS+3
Posts: 1,175
Threads: 38
Thanked 854 Times in 478 Posts
Reputation: 864
Default

Quote:
Originally Posted by bandar View Post
I think someone was mentioning the alveolar gradient (A-a difference) while referring to the diffusion component above.
Holy crap, I misread the question as A-a PO2 difference

Adorisz is right!
__________________
PGY-3
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
Reply With Quote Quick reply to this message



Reply

Tags
Pharmacology-, Physiology-, Respiratory-

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the USMLE Forums forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:
Medical School
Choose "---" if you don't want to tell. AMG for US & Canadian medical schools. IMG for all other medical schools.
USMLE Steps History
What steps finished! Example: 1+CK+CS+3 = Passed Step 1, Step 2 CK, Step 2 CS, and Step 3.

Choose "---" if you don't want to tell.

Favorite USMLE Books
What USMLE books you really think are useful. Leave blank if you don't want to tell.
Location
Where you live. Leave blank if you don't want to tell.

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes


Similar Threads
Thread Thread Starter Forum Replies Last Post
Alpha blocker for Glaucoma Mahir USMLE Step 1 Forum 6 01-06-2013 02:54 AM
Differentiating Alpha from Beta Thalassemias bebix USMLE Step 1 Bits & Pieces 0 05-31-2011 06:16 AM
Alpha 1 Antitrypsin Secretion in the lung! geof1 USMLE Step 1 Forum 5 02-09-2011 01:52 AM
Alpha-Fetoprotein in hepatitis C? doctorF USMLE Step 1 Forum 1 07-28-2010 06:30 AM

RSS Feed
Find Us on Facebook
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.

USMLE® & other trade marks belong to their respective owners, read full disclaimer
USMLE Forums created under Creative Commons 3.0 License. (2009-2014)