Bone growth

1. A LESSON FOR PARENTS By Matt Cortale, Casey Dillon, Ian Doyle Bone growth

2. What is the Function of Bone? • Support, Movement & Protection! • gives shape to head, etc. • supports body’s weight • protects lungs, etc. • bones and muscles interact • when limbs or body parts move

3. Bone Growth In The Fetus

4. Intramembranous Bones In The Fetus • The flat bones of the skull are INTRAMEMBRANOUS BONES. • During their development, unspecialized connective tissue appears at the sites of future bones. • Dense blood vessels form and supply the connective tissue with blood. • Eventually, through a process called intramembranous ossification, this connective tissue forms flat bone.

5. Endochondral Bones In The Fetus • Most bones of the skeleton are ENDOCHONDRAL BONES. • They develop from masses of hyaline cartilage shaped like future bony structures. • These cartilaginous models grow rapidly for a time and then begin to change extensively. • Eventually, through a process called endochondral ossification, this hyaline cartilage forms endochondral bones.

6. Endochondral Bone Development Major Stages (a-d fetal), (e child), (f adult)

7. Fetal Stage • In the region known as the primary ossification center, bony tissue begins to replace hyaline cartilage. • The epiphyses remain cartilaginous and continue to grow into secondary ossification centers.

8. Child Stage • Here, in the child stage of long bone, we see the formation of the epiphyseal plates or disks. • These plates lie between the primary and secondary ossification centers of the long bone. • Long bone continues to lengthen while the epiphyseal plates are active. • However, once the epiphyseal plates ossify, lengthening is no longer possible at that end of the bone.

9. Adult Stage • A developing bone thickens as compact bone just beneath the periosteum or outer layer of bone. • The bone in the central regions of the epiphysis and diaphysis remains spongy, and hyaline cartilage on the end of epiphyses persists throughout life.

10. What Do Bones Need to Grow? • Vitamin A supports bone development • Vitamin C strengthens bone • Vitamin D supports bone structure • Bones, like muscles, need physical stress to break down and cause the bone to regenerate healthier cells

11. Vitamins • Vitamin A • Necessary for osteoblast and osteoclast • Deficiency may retard bone development • Vitamin C • Required for collagen synthesis • Deficiency results in slender, fragile bones • Vitamin D • Necessary for calcium absorption

12. Hormones • Growth Hormone • Stimulates division of cartilage cells • Pituitary dwarfism- bones fail to develop normally and child is very short. This is due to lack of growth hormone. • Pituitary gigantism- excess growth hormone is released, height may exceed 8 ft. • Acromegaly- In adults, excess growth hormone causes enlarged hands, feet, and jaw.

13. Hormones (cont’d) • Sex Hormones • In males testosterone, in females estrogen • Cause long bones to grow considerably. • Become abundant at puberty • Estrogen typically has a stronger effect on epiphyseal plates which is why females reach their maximum growth earlier than males.

14. Hormones (cont’d) • Thyroid Hormone • Stimulates replacement of cartilage with bone tissue • Increases cellular metabolism • Stimulates osteoblast activity

15. Male vs Female Growth • Females tend to hit puberty earlier than boys. This is why girls are usually taller than boys in elementary school. Girls usually stop growing at the age of 17. • Males develop longer and hit puberty at an older age. This is why men tend to be taller than women in adulthood. Men usually stop growing by the age of 18 but can grow up to the age of 25. • As our body ages, both sexes decrease in heighth after about age thirty.

16. Life-Span Bone Growth Puberty age 12 Puberty age 10 Age 30 Age 30 Male Skeletor Female Skeletor

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