Embryology 4 - a sense of proportion

Question 1

what would happen if humans were not in proportion internally

Answer 1

body would be ‘in big trouble’ if one organ were too small to serve the needs of the others that depend on it

Question 2

how is growth control achieved?

Answer 2

growth hormone is released by the pituitary gland and delivered to local tissues

Question 3

what are pituitary tumours associated with

Answer 3

gigantism

Question 4

what does growth factor affect post-natally

Answer 4

muscle growth directly, other tissues indirectly

Question 5

how does the growth plate maintain itself

Answer 5

using internal and external signals

Question 6

a possible explanation for rate of growth falling away with size

Answer 6

when the bone is small, the growth plate is near the edge
when the bone is large, the growth plate is much further away

Question 7

what is a peculiar vulnerability of limb growth

Answer 7

it takes place very rapidly and makes high demand for oxygen
needs vascular system to grow very quickly into the elongating limbs
uniquely vulnerable to anything impairing vascular growth

Question 8

what is achondroplasia

Answer 8

activating mutation in FGFR3 gene
FGF signalling via FGFR3 usually inhibits both proliferation and differentiation of chondrocytes
activating mutations cause growth plates full of chondrocytes, and premature closure of growth plates