[Traumatic Acid]

Hi there.
Recently In class I was given a molecule to name:

HOCH2CH(CH2CH3)CH(NH2)CH3


 I have attached an image of the drawing if it helps.
After the tutor said it was called "3-Amino-2-ethyl-1-butanol"
I'm confused as to why he didn't identify the longest carbon chain?
I'm probably wrong, but wouldn't this molecule be called something allong the lines of: 2-Amino-3-Hydroxymethyl Pentane?
I'm guessing there are some situations where you ignore the longest chain and treat part of it as a substituent?
Someone please explain 
Thanks

[kriggy]

Well, my nomenclature is rusty since I started using chemdraw to name my stuff but IIRC, you are looking for the longest chain with the highest priority group which in this case is butanol and then you add substituents

[Traumatic Acid]

Okay, kinda makes sense. Another thing I need to watch out for 

Cheers