UWorld Step 1 Qbank: Your world of learning. Subscribe now.
Welcome to sklawpirt's page.
Contributor score: 22

Comments ...

 +6  (nbme21#13)

I think the idea here is simply that one should think about where vesicles are coming from on their way to the golgi complex.

"Two steps forward and one step back." Specfically the question may be referring to a rare craniofacial disorder. an awarenesss of that disease is not necessary. What is necessary is understanding the origin from where vesicles are traficked to the Golgi apparatus.

COPI protein is needed to coat vescles from the RER to send to golgi. Thus, with a mutation in that protein, the packaged proteins that should bleb off and be sent to the golgi, instead accumulate in the RER and dilate it. Thus the answer.


hayayah  pg. 47 on FA got the good visuals!
notadoctor  COPII* proteins are needed to coat vesicles from the RER to Golgi. "Two(COPII) steps forward; one(COPI) step back." Anterograde goes RER -> Golgi -> Lysosomes/Secretory Vesicles -> Plasma membrane
titanesxvi  why not small lysosomes?
varunmehru  and I thought large lysosomes due to lack of enzymes to degrade
samsam3711  The size of the lysosome is not affected by the presence or absence of protein, but its function is compromised (eg. protein is getting stuck in the RER)
fattyacid  I hope this helps to whomever was lost like me Null mutation: A mutation (a change) in a gene that leads to its not being transcribed into RNA and/or translated into a functional protein product. For example, a null mutation in a gene that usually encodes a specific enzyme leads to the production of a nonfunctional enzyme or no enzyme at all.

Subcomments ...

submitted by _pusheen_(5),

I think this one is literally just asking what part of the kidney will be the most poorly perfused. That part would have the most renin. Also, the medulla doesn’t have JG cells so I guess that’s another reason why it couldn’t have the most renin.

sklawpirt  Exactly, it has to do with where in the kidney renin is released and requires a bit of knowledge of the artery branches that give rise to the afferent arteriole in the first place and where this branch point is located. http://anatomyforme.blogspot.com/2008/05/histology-of-kidney-lot-to-process.html Where renin production occurs in JGA cells, EPO production occurs in the renal peritubular interstitium (especially the proximal renal tubule, corext and some of the outer medulla.) Thus with the same questions stem it might ask where is concentration of EPO the highest? [And it would still be the cortex, with lower concentrations in the outer medulla, lowest concentration in the inner medulla, and none found in the papilla or renal pelvis. +8  
hayayah  Actually, the renal medulla receives significantly less blood flow than renal cortex. So the medulla is the one that's very sensitive to hypoxia and vulnerable to ischemic damage. I don't think this question is related to "what area is the most poorly perfused." It's just knowing that renal artery stenosis is going to decrease blood flow to the kidney. JG cells sense the decrease in perfusion pressure and secrete renin. Knowing that renin is produced by the JG cells and that JG cells are in the cortex should be enough to answer this question. +5  
cry2mucheveryday  I thought all the renin would collect in the pelvis where the arteries whould drain into a common vein and changed my answer to pelvis ._. +2  

why? like does my med school suck or am I just that dumb cuz we never learned anything like this

sklawpirt  I think its just that the patient is CONSCIOUSLY experiencing chest pain. Because he is consciously feeling the pain and would be able to directly point to it (and that it is not referred visceral pain) it has to be a somatic afferent nerve fiber. This narrows it down exclusively to the intercostal nerve exc;usively. https://en.wikipedia.org/wiki/Intercostal_nerves IMportant to the patients "right sided chest pain" is his history of MVA and x-ray confirming multiple rib fractures. I think this is correct? Does that make sense ? All of the other choices do not carry SA fibers in that area +8  

UWorld Step 1 Qbank: Your world of learning. Subscribe now.