Physiology of Bone Growth
Understanding Bone Growth
Ossification is a process of cartilage gradually changing into bone tissue. •
Fetus’s bones are made of cartilage.
During childhood, the cartilage is replaced by bony tissue. •
New bone is formed along the epiphysical growth plates.
The epiphysical growth plates are found at the end of long bones as the body grows taller.
Osteocytes are bone cells. There are two types of osteoclasts and osteoblasts. •
Osteoclasts break down areas of old or damaged bone.
10% of entire skeleton is broken down and rebuilt each year (Turley, 2007). •
Generally occurring in areas that are damaged or subjected to mechanical stress. •
Osteoblasts are deposits of new tissue in those areas; forming, and rebuilding bones. •
Begins as immature cells, but later becomes a mature cell that produces bone, cartilage, or collagen fibers.
Through all stages of life, formation of new bone is dependent on having enough calcium and phosphorous in the diet. •
Calcium in the body is stored in the bone throughout the body. •
Calcium is an extremely important mineral for proper functioning of skeletal muscles and heart, keeping them contracting regularly and forcefully. •
After the osteoclasts process, calcium is continuously released to the rest of the body.
Slide 2 Speaker Notes
ossification is the process of converting the cartilage in embryonic skeletons into bone. Cartilage is deposited early in development into shapes resembling the bones-to-be. Cells inside this cartilage grow and begin depositing minerals. The spongy bone forms, and osteoblasts attach and lay down the mineral portions of spongy bone. Osteoclasts remove material from the center of the bone, forming the central cavity of the long bones. The perichondrium, a connective tissue, forms around the cartilage and begins forming compact bone while the above changes are occurring. Blood vessels form and grow into the perichondrium, transporting stem cells into the interior. Two bands of cartilage remain as the bone develops, one at each end of the bone. During childhood, this cartilage allows for growth and changes in the shape of bones. Eventually the elongation of the bones stops and the cartilage is all converted into bone. Mature bone is a hard substance that is also a living tissue that undergoes change. Slide 3
Physiology of Muscular Movement
Fascicle is a bundle of individual muscle fibers. These muscle fibers run parallel to each other, so when they contract they pull in the same direction (Turley, 2007). •
Each muscle is composed of several muscle fascicles.
Fascicles are composed of many muscle fibers surrounded by fascia. •
The muscle is wrapped in fascia and connects to the tendon. •
Fascia is a thin tissue sheet that connects each muscle or group of muscles. •
The fascia merges into and becomes part of the tendon.
Multinucleated is a muscle fiber having hundreds of nuclei scattered along the length of the muscle (Turley, 2007). •
The nuclei help speed up the chemical process that must occur along the length of the muscle fiber before it can contract and move (Turley, 2007). •
Each muscle fiber is composed of myofibrils.
Myofibril is composed of thin strands of protein actin and thick strands of protein myosin. •
Myofibril gives the skeletal muscle its characteristic striated (striped) appearance (Turley, 2007). •
Actin and myosin is the source of a muscle contraction at a microscopic level (Turley, 2007).
A muscle is composed of many parts. The body of the muscle is composed of muscle fascicles. Around each of the fascicles are arteries, veins, and nerves. Each fascicle contains bundles of muscle fibers (muscle cells) that contain thin strands of actin and thick strands of...
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