ADA 2009 Quick Questions

[MedHopeful234]

Just a few questions form the ADA 2009 Bio:

- Intracellular Buffer is PHOSPHATE No? I remember seeing this in Destroyer

- Doesn't the placenta develop partly from the allantois? This question has come up in so many different practice tests but every time I see the answer I swear it's different!

- Doesn't longitudinal bone growth occur at the metaphysis? I googled this and I see it stated in multiple sources.

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[customx]

Intracellular is phosphate, extracellular is sulfate I believe

I think the allantois is only involved with forming the umbilical cord

 

[MedHopeful234]

Thanks customx,

Can someone please confirm where growth of long bones occurs? I swear it's the metaphysis, but apparently someone asked this question a few years before and others mentioned it was the epiphyseal plate in the metaphysis... but that still makes it the METAPHYSIS NOT EPIPHYSIS

The answer options were:
A. Diaphysis
B. Metaphysis
C. Epiphysis (not the same as epiphyseal plate last time I checked)
D. Periosteum
E. Medullary cavity

 

[mbvc28]

Thanks customx,

Can someone please confirm where growth of long bones occurs? I swear it's the metaphysis, but apparently someone asked this question a few years before and others mentioned it was the epiphyseal plate in the metaphysis... but that still makes it the METAPHYSIS NOT EPIPHYSIS

The answer options were:
A. Diaphysis
B. Metaphysis
C. Epiphysis (not the same as epiphyseal plate last time I checked)
D. Periosteum
E. Medullary cavity

The physis, which separates the epiphysis and metaphysis, is the growth plate where bone grows and endochondrial ossification occurs. It's also known as the epiphyseal plate.
Since it's nicknamed the epiphyseal plate, I would have gone with C. epiphysis.

I also remember from histology class that the epiphysis was the site of bone growth since the newer chondrocytes are formed on the surface of the epiphysis and the older chondrocytes are pushed towards the diaphysis. So technically, the only site that is "growing" (adding new cells) is the epiphysis. The metaphysis would just be the site where the chondrocytes ossify.

 

[mbvc28]

Just a few questions form the ADA 2009 Bio:
- Intracellular Buffer is PHOSPHATE No? I remember seeing this in Destroyer
- Doesn't the placenta develop partly from the allantois? This question has come up in so many different practice tests but every time I see the answer I swear it's different!

From all the questions I've seen on "buffers" in the body, all the answers were bicarbonate.

Placenta develops from the chorion, umbilical cord from the allantois.

 

[datthirty]

You can refer the following picture, there are two places where a long bone grows. One is below the cartilage and one is the above the epiphyseal plate.

Metaphysis is the region where the diaphysis and epiphysis meet. If there is no epiphysis choice, metaphsis is a answer. If there is epiphysis, it is the correct answer. The reason is epiphysis including all the two places that grow the long bone.