1. Calcitonin  Gland?  Stimulus?  Cell Activated?  Result?  1.  2. Parathyroid Hormone  Gland?  Stimulus?  Cell Activated?  Result?  1.  2.  3. HORMONE REVIEW

2. Calcitonin  THYROID GLAND  High blood Calcium  OsteoBLAST  Result?  1. Release Calcium in Urine  2. Store Calcium in Bones Parathyroid Hormone  PARATHYROID GLAND  Low Blood Calcium  OsteoCLAST  Result?  1. Retain calcium in Kidneys, do not release in urine  2. Absorb calcium from food in Digestive System  3. Digest bony matrix to release stored calcium in bone HORMONE REVIEW

3. Ms.Giraldo BONE FORMATION, GROWTH, AND REMODELING

4.  The skeleton is formed from two of the strongest connective tissues in the body – Cartilage and Bone.  Bone formation, also known as ossification, happens in two stages: 1.Bone matrix completely covers hyaline cartilage skeleton by bone forming cells called osteoblasts. 2.Hyaline cartilage is then digested away, opening up a medullary cavity within the newly formed bone. BONE FORMATION

6.  By the time of birth most baby’s hyaline cartilage models have been converted to bone with the exception of two places-articular cartilages (cover bone ends) and epiphyseal plates.  Can anyone assume why these sites stay as cartilage?  Bone growth is an ongoing active process. Bones cells are constantly being rebuilt and destroyed by 2 bone cell types:  Osteoclasts break down bone.  Osteoblasts form new bone cells in these areas. BONE GROWTH

7. BONE GROWTH AND REMODELING

8. Long Bone Growth  Bone lengthening  Controlled by  Growth hormones  Sex hormones during puberty  Ends during adolescence. Appositional Growth  Bone widening  Controlled by  Activity levels  Nutrition  Changes in Exercise  Continues throughout life BONE GROWTH

10. BONE GROWTH AND REMODELING

11.  Bones are CONSTANTLY remodeling themselves. Bone is a very active tissue. Osteoclasts and osteoblasts are always at work.  Bones must remodel themselves in order to retain normal proportions as the body grows increasing in size and weight.  Bones remodel and change their appearance in response to changes in 2 factors: 1.Calcium levels in blood 2.The pull of gravity and muscles on the skeleton BONE REMODELING