1 Control of growth in humans Syllabus p. 40 Terminating development of adult height.

2 By the seventh week of embryonic life the skeleton begins to turn from cartilage to bone. Bone Growth

3 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 plate Cartilage at joint Compact/hard bone Marrow Spongy bone Periostium Epiphysis plate Cartilage Epiphysis Diaphysis Bone Growth

4 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. Bone Growth

5 There are three periods of rapid growth in human development: 1.during the final trimester of pregnancy the foetus doubles in size. 2.during the first two years after birth and 3. during puberty. Growth Curve in Humans Growth slows after puberty and stops at age 24 approx. when the epiphysis plate is fully calcified Time/Years Mass/kg Growth spurt at puberty Growth spurt after birth Birth Bone Growth

6 Adult height cannot be increased beyond that which is genetically determined, even by increasing nutrition.