Spirometry Problem

[darknebula]

This is from a past AAMC. I dont know how to do it.. ..

 

Assuming that breathing rate is 10 breaths/min and the tidal volume is 800mL/breath, and the dead space is 150mL, what is the net volume of fresh air that enters the alveoli each minute?

 

A) 650mL 785 mL c) 6500 mL d) 7850 mL

 

I got C but the answer key says its A. I would really appreciate some help with this.

 

Thanks!

[sparkles3288]

This is how I would think about it:

 

Tidal volume is 800mL/breath

 

Dead space is 150mL/breath.

 

800-150=650mL/breath in which air can come in.

 

650mL/breath *10breaths/min = 6500mL/min.

[darknebula]

This is how I would think about it:

 

Tidal volume is 800mL/breath

 

Dead space is 150mL/breath.

 

800-150=650mL/breath in which air can come in.

 

650mL/breath *10breaths/min = 6500mL/min.

 

yeah thats what i thought too! but the answer for some reason is A. I am using the old AAMC PT5 key so i am going to assume that the answer key is wrong on this one.

[nosuperman]

At first I thought maybe there's some trickery that has to do with the *net* amount i.e. exhalation comes into play... but it says "fresh" so I've got nothing.

[sparkles3288]

Im pretty sure the answer is NOT A, as I have access online and it's definitely C.

[placenta]

Yeap the answer is C

[premed89]

Just to confirm, the answer is C (6500mL)