[Gulara]

Hi, everyone.

I have a relatively old edition of Kaplan Anatomy and there's a test after the Histology chapter:

A patient has a smaller than normal number of Clara cells. What will be seen in this patient?

A Respiratory infections
B Hyaline membrane disease
C Reduced ability to trap airborne toxins
D Reduced ability to produce surfactant
E Reduced ability to generate new Type I pneumocytes

The given right answer is C. Although in the lecture it is said that Clara cells also secrete surfactant in addition to Type II pneumocytes, as well as take part in chloride transport. Could it be that the information changed in a couple of years?

 

[step1an]

Well i have 2009 edition kaplan.... and the information given is the same as mentioned by you. By the way what edition you are using?

When i saw this question, i was more in the favor of options D or E. But the answer given in C. Doesn't make any sense to me either. May be its one of those things you just have to cram and move on.....:notsure:

Or may be some body else can shed more light......

 

[rasheed]

Two similar options are wrong

Options B and D are essentially the same therefore they must both be wrong, read here http://www.usmle-forums.com/usmle-articles/1928-two-similar-options-wrong.html

Function of Clara Cells (Reference Wikipedia)
One of the main functions of Clara cells is to protect the bronchiolar epithelium. They do this by secreting a small variety of products, including Clara cell secretory protein (CCSP) and a solution similar to the component of the lung surfactant. They are also responsible for detoxifying harmful substances inhaled into the lungs. Clara cells accomplish this with cytochrome P450 enzymes found in their smooth endoplasmic reticulum. Clara cells also multiply and differentiate into ciliated cells (most notably the type II pneumocytes) to regenerate the bronchiolar epithelium.

However, I have to say that this is a poorly written question. You will stumble upon many questions like these in your prep and you don't need to bother yourself about them too much. The real exam won't give you a question unless at least three professors agree on the answer.

 

[Gulara]

Thank you for the help. Inconsistencies like that could be real demotivators. Besides there was no information on the function of the cells in the text. Since the book is in PDF format i don't have the year of the edition, probably 2006.
So, if I come across questions that are not covered in the book, should I just go ahead and do some research on the web or does it mean there's a need for a different source of reading?

 

[lee-usmle]

Thank you for the help. Inconsistencies like that could be real demotivators. Besides there was no information on the function of the cells in the text. Since the book is in PDF format i don't have the year of the edition, probably 2006.
So, if I come across questions that are not covered in the book, should I just go ahead and do some research on the web or does it mean there's a need for a different source of reading?

You can always expand your knowledge from reliable online resources such as Wikipedia and Emedicine.
However, if you short of time then I suggest you don't kill yourself with too much details. Just read the specific factoid quickly and add a small note to your book and move on.
The need for another resource to read can be decided when you do question banks and see your performance if you find that you are not doing well then only you should decide to add extra resources.

 

[Haisook]

Main function of Clara cells is detoxification.
So if you see the word 'toxin", it's the right answer.

Surfactant production by Clara cells is only a possiblility. The main producer of surfactant are pneumocytes type 2.

 

[ashishkabir]

What exactly does CSSP do - does anyone know? Also - the p450 system here is it similar to the liver p450 system?

 

[vikash]

clara cells aid in detoxification

yes clara cells has p450 similar as liver do, while it is written that clara cells aid in detoxofication (probably it is not the major function).