Bone Development & Growth Bone Growth Video Segment.
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Transcript of Bone Development & Growth Bone Growth Video Segment.
![Page 1: Bone Development & Growth Bone Growth Video Segment.](https://reader035.fdocuments.in/reader035/viewer/2022062321/56649e575503460f94b50490/html5/thumbnails/1.jpg)
![Page 2: Bone Development & Growth Bone Growth Video Segment.](https://reader035.fdocuments.in/reader035/viewer/2022062321/56649e575503460f94b50490/html5/thumbnails/2.jpg)
Bone Development & Growth
Bone Growth Video Segment
![Page 3: Bone Development & Growth Bone Growth Video Segment.](https://reader035.fdocuments.in/reader035/viewer/2022062321/56649e575503460f94b50490/html5/thumbnails/3.jpg)
Hyaline Cartilage – the most common cartilage
Chondrocytes = cartilage cells
Lacunae = pockets that house chondrocytes
Cartilage is avascular (without a blood supply)
![Page 4: Bone Development & Growth Bone Growth Video Segment.](https://reader035.fdocuments.in/reader035/viewer/2022062321/56649e575503460f94b50490/html5/thumbnails/4.jpg)
The Early Embryonic Skeleton
• First skeleton composed of cartilage• Replaced with bone (ossification); starting 6 weeks
after fertilization• More than 300 bones at birth → fuse to 206
Bonedevelopslater →
![Page 5: Bone Development & Growth Bone Growth Video Segment.](https://reader035.fdocuments.in/reader035/viewer/2022062321/56649e575503460f94b50490/html5/thumbnails/5.jpg)
Bone Growth2 types:
• Interstitial – in length
at epiphyseal plate; when growth ceases, bone shows epiphyseal lines
• Appositional – in width;
new bone is added to the outer surface by osteoblasts from periosteum
![Page 6: Bone Development & Growth Bone Growth Video Segment.](https://reader035.fdocuments.in/reader035/viewer/2022062321/56649e575503460f94b50490/html5/thumbnails/6.jpg)
Bone Remodeling = replacement of old bone by new• bone is very metabolically (chemically) active • bone is remodeled along the lines of mechanical stress
(remember to exercise; exercise increases bone mass)
• different rates in different regions • distal head of the femur is replaced ~ every 4
months
![Page 7: Bone Development & Growth Bone Growth Video Segment.](https://reader035.fdocuments.in/reader035/viewer/2022062321/56649e575503460f94b50490/html5/thumbnails/7.jpg)
Bone Nutrition
• Minerals – Calcium (dairy, leafy vegetables, tofu; the most
abundant mineral in the human body)– Phosphorus (dairy, lean meat, fish)
• Vitamins – A – stimulates osteoblasts– C – needed for collagen synthesis– D – needed to make calcitriol (hormone that increases
intestinal absorption of Ca++)
– B12 & K – needed for synthesis of bone proteins
![Page 8: Bone Development & Growth Bone Growth Video Segment.](https://reader035.fdocuments.in/reader035/viewer/2022062321/56649e575503460f94b50490/html5/thumbnails/8.jpg)
Homeostatic Imbalances
Rickets
Homeostatic Imbalance: Rickets
• Disease of children due to lack of vitamin D
• Calcium is not deposited in bones
• Bones become soft & deformed
![Page 9: Bone Development & Growth Bone Growth Video Segment.](https://reader035.fdocuments.in/reader035/viewer/2022062321/56649e575503460f94b50490/html5/thumbnails/9.jpg)
Hormonal Regulation
• Growth hormone• responsible for general growth of all body tissues
• Sex hormones (testosterone and estrogen) stimulate osteoblasts
• Calcitonin & parathyroid hormone regulate Ca++ level
(calcitonin ↓ [Ca++ ] while parathyroid hormone ↑ [Ca++ ] in the blood)
• Calcitriol ↑ Ca++ level
![Page 10: Bone Development & Growth Bone Growth Video Segment.](https://reader035.fdocuments.in/reader035/viewer/2022062321/56649e575503460f94b50490/html5/thumbnails/10.jpg)
Calcium Homeostasis
• Bone serves as a “buffer” to prevent sudden changes in blood Ca++ levels
• too much blood Ca++ (hypercalcemia) or too little (hypocalcemia) can cause the heart to stop working
![Page 11: Bone Development & Growth Bone Growth Video Segment.](https://reader035.fdocuments.in/reader035/viewer/2022062321/56649e575503460f94b50490/html5/thumbnails/11.jpg)
Homeostatic ImbalancesAnother Example of Homeostatic Imbalance:
Osteoporosis
• Decline in bone density• Increased risk of fracture
Possible causes:– Lack of estrogen in women– Lack of exercise to stress the bones– Inadequate intake of calcium and phosphorus– Abnormalities of vitamin D metabolism– Loss of muscle mass
![Page 12: Bone Development & Growth Bone Growth Video Segment.](https://reader035.fdocuments.in/reader035/viewer/2022062321/56649e575503460f94b50490/html5/thumbnails/12.jpg)
Osteoporosis
![Page 13: Bone Development & Growth Bone Growth Video Segment.](https://reader035.fdocuments.in/reader035/viewer/2022062321/56649e575503460f94b50490/html5/thumbnails/13.jpg)
Bone Fractures
• Fracture = break of the bone
• Repair of bone:– Spongy bone forms in first few days– Blood vessels regrow and spongy bone hardens – Full healing takes 1-2 months
![Page 14: Bone Development & Growth Bone Growth Video Segment.](https://reader035.fdocuments.in/reader035/viewer/2022062321/56649e575503460f94b50490/html5/thumbnails/14.jpg)
Steps in the Repair of a
Fracture
Fig. 6.9