Bones grow through the process of bone cells forming in the growth plates located at the ends of bones. Growth plates allow bones to lengthen until late teens when they fuse shut. Several factors influence bone growth and height, including genes, diet, exercise, lifestyle and sleep. In adulthood, bones continue remodeling through the balanced actions of osteoblasts which build new bone and osteoclasts which break down old bone. Maintaining strong bones requires sufficient calcium, vitamin D, weight-bearing exercise and adequate sleep.

1. Secondary Two
Topic: Bones and Joints
Sub Topic: Bone Growth

2. • Students will understand the how bone
grow.
• Students will learn the concepts behind
growing tall.

3. • Growth plates
• Osteoblasts
• Osteoclasts

4. • One conversation
• No sleeping
• Putting of palm on whiteboard
• Class too noisy and need to quieten
down

5. In the previous lesson, you’d
learnt…

6. BONE GROWTH FROM
BIRTH

7. The Growing Bone
 When you first get
started in your mum’s
womb, your bone
looks like this at about
4 weeks.
 The “bone” is mainly a
“lump of cartilage”.
 Periosteum grows
around the cartilage
and controls the shape
and thickness of the
bone.
Periosteum

8. The Growing Bone
 At about 8 weeks,
bone cells will start
to form in the middle.
 The cartilage will
slowly be changed
into bone cells and
grows in length and
thickness.
Bone
Cells

9. The Growing Bone
 After birth, the
marrow cavity will
start to form.
 Growth plates
(epiphyseal plates),
which are bands of
cartilage, remains to
aid in the growth of
the bone.
Formationofthegrowth
plates

10. The Growing Bone
 The bone continues to grow after birth,
which gives rise to the growing height till
adulthood.

11. The Growing Bone
 In summary…

12. Feeling Lost?
 Not biology class
 Only required to have a rough idea
that:
◦ Bone started as one whole piece of
cartilage
◦ After birth, the bone continues to grow at
the Growth Plate (medical name known
as Epiphyseal Plate)
◦ One stops growing when the Growth Plate
is “fused”

13. GROWING TALLER…
What do you know about growing tall?

14. Question
 Which bone in your body determines a
large portion of your height?
◦ Femur (thigh bone) and tibia (shin bone)

15. Growth Plates
 Recall:
◦ The presence of the growth plates in the
bone aids the growing of the length of the
bones (eg. Femur and tibia)
 Growth plates will not be present in
your bones forever

16. Fusion of Growth Plates
 Femur (thigh bone)
◦ Upper end fuses around 18 yrs old
◦ Lower end fuses around 20 yrs old
 Tibia (shin bone)
◦ Upper end fuses around 16-18 yrs old
◦ Lower end fuses around 15-17 yrs old
http://www.medhelp.org/posts/Orthopedics/What-bone-age-do-the-growth-plates-completely-close/show/996787

17. You still can grow taller
How?

18. Factors Affecting Height
 Genes
◦ Determined by parents
 Diet
 Exercising
 Lifestyle
Determined by you

19. Factors: Genes
 Height is a polygenic trait
◦ Influenced by several different genes
 Estimated height
◦ Boys: (Sum of height of both parents + 13cm) /
2
◦ Girls: (Sum of height of both parents - 13cm) / 2
◦ +/- about 10cm
 Genes determines your maximum
possible height You can’t grow taller
than what your body
genes had decided for
you

20. Factors: Diet
 Calcium is required for bone growth
 Sources:
◦ Dairy products: eg. milk, yoghurt, cheese.
◦ Non dairy products: eg. Bok choy,
almond, orange, seaweed
Source: http://greatist.com/health/18-surprising-dairy-free-sources-
calcium

21. Factors: Diet
 𝐷𝑟𝑖𝑛𝑘 𝑚𝑖𝑙𝑘 𝑒𝑣𝑒𝑟𝑦𝑑𝑎𝑦 = 𝑆𝑡𝑟𝑜𝑛𝑔 𝑏𝑜𝑛𝑒𝑠?
 Have you ever wonder:
◦ Why I drank so much milk and I never grow
tall?
 Reasons are:
◦ Genetic reasons; or
◦ Lack of vitamin D
 Vitamin D
◦ Vital to promote the body absorption of the
calcium that we take in
◦ Best source: Sun
◦ Lead an active lifestyle, go under the sun!

22. Factors: Exercising
 Increases the rate of the process of
osteoclast and osteoblast (elaborated
later)
◦ In turn increases the speed of bone growth
 Weight bearing exercises
◦ Exercises that makes one goes against
gravity
◦ Eg. Running, jumping, climbing of stairs
 Helps not only in length growth of bone
◦ Also helps in maintaining strong bones in
adults
◦ Often prescribed for elderlies to maintain

23. Factors: Lifestyle
 One important factor that helps in
bone growth, but often neglected by
us.
 What is it?
Sleep

24. Factors: Lifestyle
 Why sleeping helps in growing taller?
 Body undergoes repair and building /
rebuilding when at rest
 Similar in bone growth
 Recommended at least 8 continuous
hours of sleep
 Not to disturb bio-clock to “confuse”
body
◦ i.e. you do not sleep the 8 hours during
daytime

25. BONE GROWTH IN
ADULTHOOD

26. Osteoblasts vs. Osteoclasts
 In adulthood, bones continue to
undergo process of building and re-
modelling
 Why?
◦ Strengthening of bones
◦ Damaging of bones via stress / impact
◦ Need to re-build bones
◦ Similar to maintenance of buildings:
 Need to replace older parts with newer parts

27. Osteoblasts vs. Osteoclasts
 Osteoblasts
◦ Cells that are responsible to make new
bone cells
 Osteoclasts
◦ Cells that are responsible to breakdown
bone cells
 Let’s watch a video for better
illustration

28. Repair of Bone
 What happens if we break our bone?

29. As we age…
 Our bones get
◦ Lighter (less dense)
◦ More brittle
◦ Grow shorter
 Common bone issues when old
◦ Osteoporosis
 Important to exercise and eat healthily
in order to keep bones healthy

30. Lets Recap!
 What is growth plate (epiphyseal
plates)?
Refers to the 2 bands of cartilage at the
end of the bone. It is responsible for the
length growth of long bones before 16-
20 years old.

31. Lets Recap!
 What is osteoblasts?
Cells that are responsible to make new
bone cells.

32. Lets Recap!
 What is osteoclasts?
Cells that are responsible to make
breakdown bone cells.

33. Lets Recap
 What is important in the diet for bone
growth?
Calcium + Vitamin D