renal qn1

Prep for USMLE Forum

» Log in | Register

Forum

Step 1

Match

Prep4USMLE Forum » USMLE Step 1 Forum » Physiology Forum

renal qn1

Author

10 Posts

doc179
Forum Guru

Topics: 67
Posts: 1,217

04/16/07 - 03:30 PM

file attached.

Attached Files:
22renal.jpg (84 KB, 77 downloads)

indidoc1
Forum Guru
avatar

Topics: 50
Posts: 978

04/16/07 - 11:13 PM

Is it c? 49 mmol/day

veryyyyyyyyyy conceptual question..

in fact, all ur qs are fantastic doc149 nod

.. may i know the source plz. (by pm if there r copyright issues)

___________________
"Whether you think you can or whether you think you can't, you're right!" ~ Henry Ford

indidoc1
Forum Guru
avatar

Topics: 50
Posts: 978

04/16/07 - 11:18 PM

How i came up wth C?

Well.. net HCO3 added= net H+ secreted= ammonium + titrable acid

here, as titration shows us a change by -1 pH unit, the H ion conc must be 10 mmol/L (pH= - log [H+] )
as urine output= 1 L/day, H ion conc=10mmol/day

out of these, 1 mmol/day is present to neutralise the bicarb being passed out..

So net secreted H+ = 10-1 = 9 mmol/day

net H+ secretion= 40 + 9 =49

Busted my brains over this n thats what i came up wth shaking head

hope i didn't mess up big time.. though i hv a sneaky feeling i did sticking out tongue

___________________
"Whether you think you can or whether you think you can't, you're right!" ~ Henry Ford

new_n_lost
Politically InCorrect
avatar

Topics: 650
Posts: 6,058

04/17/07 - 08:30 AM

TOO MANY CALCULATIONS not good at it ini mini mieni mo D wink

___________________
FORUM RULES-- Those who believe in telekinesis, raise my hand. I get enough exercise just by pushing my luck --P4U World.." The pure and simple truth is rarely pure and never simple."

doc179
Forum Guru

Topics: 67
Posts: 1,217

04/17/07 - 02:34 PM

guys...you are wonderful... indidoc dont worry you did not mess up. Infact your explanation is better than their's. Niiiiiiiiiiiiice...thanx for the detailed correct answer smiling face

. Do you guys still want me to attach what they say? Indidoc check your PM grin

NNL if you say ini mini mieni mo you will always get D grin

indidoc1
Forum Guru
avatar

Topics: 50
Posts: 978

04/17/07 - 04:51 PM

I GOT IT RIGHT!!! shocked

Thanks fr the encouraging words doc179 nod

I feel like a brand new bicarbonate just secreted into the circulation sticking out tongue

(Basically that means i m pretty happy)

___________________
"Whether you think you can or whether you think you can't, you're right!" ~ Henry Ford

wyb
Forum Junior

Topics: 8
Posts: 43

04/18/07 - 10:55 AM

My ans. D.

Hi indidoc1, how wonderful you did the calculation! The brand new HCO3 added = nontitrable acid + titrable acid; but 'net secreted H+ = 10-1 = 9 mmol/day', could you explain it alittle bit more? Thanx!

indidoc1
Forum Guru
avatar

Topics: 50
Posts: 978

04/18/07 - 06:32 PM

wyb wrote:
My ans. D.

The brand new HCO3 added = nontitrable acid + titrable acid; but 'net secreted H+ = 10-1 = 9 mmol/day', could you explain it alittle bit more? Thanx!

So i did mess it up.. only in terms of writing it down.. grin

i meant what ws correct n calculated so too..
Lemme give a breakdown of the hydrogen ion concentration in this person's urine..

Net H+ excreted= net H filtered - H reabsorbed + H secreted

Here..

bicarb passing out = 1mmol/day

so, H fitered-H reabsorbed = 1 mmol/day

H secreted= H in ammonium + Free H in urine - (H filtered - H reabsorbed)

= 40 + 10 - 1

= 49 mmol/day

Ans = C

___________________
"Whether you think you can or whether you think you can't, you're right!" ~ Henry Ford

wyb
Forum Junior

Topics: 8
Posts: 43

04/19/07 - 07:11 PM

Thanks alot for helping me out! Now is real crystal clear.

wyb
Forum Junior

Topics: 8
Posts: 43

04/19/07 - 07:22 PM

#10

You don't have permission to post.