bone tissues 2

Explain how mature bone continues to grow

Ossification happens through appositional growth

Explain how mature bone continues remodel itself

is the ongoing replacement of old bone tissue with new bone tissue
requires opposing collaborative processes between the osteoblasts and osteoclasts.
Deposition - osteoblasts build bone
Resorption - osteoclasts destroy bone

Resorption removes bone

Deposition deposits bone

Appositional Growth

growth in width/thickness

Describe the processes by which minerals are added to and removed from bone

Bone deposition (Mineral Addition) & Bone Resorption (Mineral Removal)

Mesoderm to Mesenchyme to

Osteoblast

bone deposition

is a crystallization process in which calcium, phosphate, and other ions are taken from the blood plasma and deposited in bone tissue, mainly as needlelike crystals of hydroxyapatite. begins in fetal ossification and continues throughout life

Bone Resorption

is the process of dissolving bone It releases minerals into the blood and makes them available for other uses is carried out by osteoclasts

Discuss the role of the bones in regulated blood phosphate levels

phosphorus levels in the body aren't as tightly controlled as calcium.
Changes in phosphorus levels don't cause immediate problems.
The same hormones that control calcium also help with phosphorus.
When PTH is released, it makes the body get rid of extra phosphorus in urine because phosphorus gets released when bone is broken down.
Calcitriol helps the body absorb more phosphorus from food since both calcium and phosphorus are needed to build strong bones.

Discuss the role of the bones in regulated blood calcium levels

Negative feedback allows body to control levels of Ca2+
Ca2+ levels are regulated by hormones
Parathyroid hormone (PTH) is secreted if Ca2+ levels falls
PTH gene is turned on & more PTH is secreted from gland Osteoclast activity increased while osteoblast activity decreased
Kidney retains Ca2+ and produces calcitriol, which increases Ca2+ uptake from diet
Calcitonin hormone is secreted if Ca2+ levels get too high Secreted from parafollicular cells in thyroid
Decreases osteoclast activity • Increases bone formation by osteoblasts