Control of growth in humans

1
Control of growth in humans
Syllabus 3.5.8 p. 40 Terminating development of
adult height.
2
Bone Growth
By the seventh week of embryonic life the
skeleton begins to turn from cartilage to bone.
3
Bone Growth
Cartilage at joint
At birth, all cartilage has been converted to
bone except at the joints and internally at the
end of the epiphysis along the epiphysis plate.
Epiphysis
Spongy bone
Epiphysis plate
Compact/hard bone
Diaphysis
Marrow
Periostium
Epiphysis plate
Epiphysis
Cartilage
4
Bone Growth
During growth, osteoblasts at the edge of the
growth plate convert the cartilage to bone and
new cartilage is formed by mitosis within the
growth plate. The growth plate is pushed further
into the epiphysis as the bone lengthens. Growth
continues until the growth plate is fully
calcified.
5
Bone Growth

• There are three periods of rapid growth in human
  development
• during the final trimester of pregnancy the
  foetus doubles in size.
• during the first two years after birth and
• 3. during puberty.

Growth spurt at puberty
Mass/kg
Growth spurt after birth
Growth slows after puberty and stops at age 24
approx. when the epiphysis plate is fully
calcified
Time/Years
Birth
Growth Curve in Humans
6
Adult height cannot be increased beyond that
which is genetically determined, even by
increasing nutrition.