bone mineral density

Examples of bone mineral density in the following topics:

• Aging and the Skeleton

  • In osteoporosis, bone mineral density (BMD) is reduced and the integrity of bone proteins is altered, increasing the risk of fracture.
  • Osteoporosis is a bone disease that leads to an increased risk of fracture.
  • In osteoporosis, the bone mineral density (BMD) is reduced, bone microarchitecture deteriorates, and the amount and variety of proteins in bone is altered.
  • The underlying mechanism in all cases of osteoporosis is an imbalance between bone resorption and bone formation.
  • Physical deformation can occur secondary to compromised bone densities.

• Osteoporosis

  • Osteoporosis, the result of reduced bone mineral density, can lead to an increased risk for fractures.
  • Weight-bearing exercise such as walking helps maintain bone strength.
  • In osteoporosis, the bone mineral density (BMD) is reduced, bone microarchitecture deteriorates, and the amount and variety of proteins in bone is altered.
  • The three main mechanisms by which osteoporosis develop are an inadequate peak bone mass (the skeleton develops insufficient mass and strength during growth), excessive bone resorption, and inadequate formation of new bone during remodeling.
  • Its main consequence is the increased risk of bone fractures.

• Female Athlete Triad: Disordered Eating, Amenorrhea, and Premature Osteoporosis

  • Female athlete triad is a combination of eating disorders, disrupted menstruation, and low bone density.
  • Female Athlete Triad is a syndrome in which eating disorders (or low energy availability), amenorrhoea/oligomenorrhoea, and decreased bone mineral density (osteoporosis and osteopenia) are present.
  • As osteoclasts break down bone, patients see a loss of bone mineral density.
  • Low bone mineral density renders bones more brittle and hence susceptible to fracture.
  • Additionally, because those suffering with female athlete triad are also restricting their diet, they may also not be consuming sufficient amounts vitamins and minerals which contribute to bone density; not getting enough calcium or vitamin D further exacerbates the problem of weak bones.

• Bone and Calcium Homeostasis

  • Calcitonin stimulates incorporation of calcium in bone.
  • Supplementation with vitamin D and calcium slightly improves bone mineral density.
  • As bone formation actively fixes circulating calcium in its mineral form by removing it from the bloodstream, resorption actively unfixes it, thereby increasing circulating calcium levels.
  • The resulting high levels of calcitonin in the blood stimulate the bone to remove calcium from the blood plasma and deposit it as bone.
  • Removal of calcium from the bone is also inhibited.

• Bone

  • Osteocytes, the living cells of bone tissue, form the mineral matrix of bones.
  • Compact bone (or cortical bone), forming the hard external layer of all bones, surrounds the medullary cavity (innermost part or bone marrow).
  • Osteons are cylindrical structures that contain a mineral matrix and living osteocytes connected by canaliculi which transport blood.
  • Compact bone tissue forms the outer layer of all bones while spongy or cancellous bone forms the inner layer of all bones.
  • Spongy bone reduces the density of bone, allowing the ends of long bones to compress as the result of stresses applied to the bone.

• Exercise and Bone Tissue

  • If loading on a particular bone increases, the bone will remodel itself to provide the strength needed for resistance.
  • If the load on a bone decreases, the bone will become weaker due to turnover.
  • In summary, gender differences in acquisition and age-related loss in bone and muscle tissues may be important for developing gender-specific strategies for ways to reduce bone loss with exercise.
  • Simple aerobic exercises like walking, jogging, and running could provide an important role in maintaining and/or increasing bone density in women.
  • Their bodies have reabsorbed much of the mineral that was previously in their bones.

• Gross Anatomy

  • All the bones in the body can be described as long bones or flat bones.
  • They also produce various blood cells, store minerals, and provide support for mobility in conjunction with muscle.
  • Cortical bone is compact bone, while cancellous bone is trabecular and spongy bone.
  • The mineralized matrix of bone tissue has an organic component—mainly made of collagen—and an inorganic component of bone mineral made up of various salts.
  • These are flat bone, sutural bone, short bone, irregular, sesamoid bone, and long bone.

• Postnatal Bone Growth

  • It forms the epiphyses of long bones and the extremities of irregular and flat bones.
  • Osteoblasts are also responsible for the mineralization of this matrix.
  • Minerals required for mineralization and related processes include zinc, copper, and sodium.
  • Osteoblasts produce bone matrix and mineral, and osteoclasts break down the tissue.
  • Minerals are deposited in the matrix between the columns of lacunae, but are not the permanent bone mineral deposits.

• Bone Repair

  • Substitution of the woven bone with lamellar bone precedes the substitution of the hyaline cartilage with lamellar bone.
  • The lamellar bone begins forming soon after the collagen matrix of either tissue becomes mineralized.
  • At this point, the mineralized matrix is penetrated by channels, each containing a microvessel and numerous osteoblasts.
  • The osteoblasts form new lamellar bone upon the recently exposed surface of the mineralized matrix.
  • This new lamellar bone is in the form of trabecular bone.

• Bone Remodeling and Repair

  • Bone remodeling is the replacement of old bone tissue by new bone tissue.
  • It involves the processes of bone deposition or bone production done by osteoblasts and bone resorption done by osteoclasts, which break down old bone.
  • Normal bone growth requires vitamins D, C, and A, plus minerals such as calcium, phosphorous, and magnesium.
  • Bone turnover rates, the rates at which old bone is replaced by new bone, are quite high, with five to seven percent of bone mass being recycled every week.
  • Compact bone is added to create bone tissue that is similar to the original, unbroken bone.