When it is cold, the body, through the skin, reacts by contracting arrector pili muscles. Contraction of arrector pili muscles moves hair follicles upward through the formation of goosebumps on the skin's surface. More air is trapped under the lifted hair follicles and acts as an insulator for the body (Barclay, 2019. When the body temperature rises due to heavy yardwork, the skin reacts by reducing temperature through sweating. Sudoriferous glands produce sweat, which is delivered on the surface of the body as water where it evaporates. When the water evaporates, it absorbs heat and in turn, cooling the surface of the body (Barclay, 2019.
During the repair of a fracture, periosteal cells are the most significant cells and play an essential role. This is because the periosteum is made up of many precursor cells that are transformed into chondroblasts and osteoblasts, which form chondrocytes and osteocytes. The chondrocytes and osteocytes aid in the remodeling and healing of the bone.
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When blood Ca+ levels are low, the most active cells are the osteoclasts. Parathyroid hormone is released when blood Ca+ levels drop breaking down osteoclasts, releasing Ca. In the process, other minerals are also released, thereby balancing the deficiency of Ca.
The most active cells when there is a localized response to increased mechanical load are born reforming and resorbing osteoclasts in the BMU (Basic Multicellular Unit). During physical activities, ground reaction forces exert mechanical forces on the bones. Osteoclasts and osteoblasts play a significant function in depreciating and provision of mechanical stress on the body.
When one consumes a diet that is deficient in calcium for a long time, then the result is a reduction in calcium levels in the blood. Parathyroid glands are therefore triggered to break down osteoclasts, which releases calcium from the bone. This action balances the deficiency of calcium in the blood.
Chondrocytes are most active during the adolescent stage. The chondrocytes are contained in the epiphyseal bone plates. Through endochondral development, chondrocytes undergo continuous mitosis. The cells, therefore, rearrange themselves into newer (osteocytes ossify) and older (chondrocyte degenerates) rows.
Reference
Barclay, T. (2019, 16). Integumentary System. Retrieved from https://www.innerbody.com/anatomy/integumentary#continued
