Download - 5.3 bone growth
Content Purpose• Students will understand the how bone grow.
• Students will learn the concepts behind growing tall.
Social Purpose• One conversation• No sleeping• Putting of palm on whiteboard• Class too noisy and need to
quieten down
The Growing BoneWhen 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
The Growing BoneAt 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
The Growing BoneAfter 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.
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The Growing BoneThe bone continues to grow after
birth, which gives rise to the growing height till adulthood.
The Growing BoneIn summary…
Feeling Lost?Not biology classOnly 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”
QuestionWhich bone in your body
determines a large portion of your height?◦Femur (thigh bone) and tibia (shin
bone)
Growth PlatesRecall:
◦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
Fusion of Growth PlatesFemur (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
oldWhat does
this mean
for you?
http://www.medhelp.org/posts/Orthopedics/What-bone-age-do-the-growth-plates-completely-close/show/996787
Factors: GenesHeight is a polygenic trait
◦Influenced by several different genesEstimated height
◦Boys: (Sum of height of both parents + 13cm) / 2
◦Girls: (Sum of height of both parents - 13cm) / 2
◦+/- about 10cmGenes determines your
maximum possible heightYou can’t grow taller than what your body genes had decided
for you
Factors: DietCalcium is required for bone
growthSources:
◦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
Factors: Diet
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!
Factors: ExercisingIncreases 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
healthy bones
Factors: LifestyleOne important factor that helps
in bone growth, but often neglected by us.
What is it?
Sleep
Factors: LifestyleWhy sleeping helps in growing taller?Body undergoes repair and building /
rebuilding when at restSimilar in bone growthRecommended at least 8 continuous
hours of sleepNot to disturb bio-clock to “confuse”
body◦ i.e. you do not sleep the 8 hours during
daytime
Osteoblasts vs. OsteoclastsIn 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
Osteoblasts vs. OsteoclastsOsteoblasts
◦Cells that are responsible to make new bone cells
Osteoclasts◦Cells that are responsible to
breakdown bone cellsLet’s watch a video for better
illustration
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
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.