The Structures of the Bone and Muscle
The bone microstructure comprises the bone cells, which amount to a small volume of the bone. These cells include:
Osteoblasts (endosteum and periosteum); found in the growing portion of the bone, and it is responsible for the synthesis and secretion of collagen and calcium salts.
Osteocytes; located in the lacuna. They secret the enzymes that maintain the mineral concentration of the matrix.
Osteogenic cells; the only one cells that divide. They differentiate into osteoblasts.
Osteoclasts; they are responsible for bone resorption (BC Campus, n.d.).
The macrostructure is made up of the compact (outer part) and spongy (inner part) bone tissues. The compact part is referred to as the cortical tissue. The inner (cancellous) tissue comprises plate-like and rod-like structures that accommodates the blood vessels and the bone marrow.
The muscles are a group of tissues that contract to bring about movement. It is segmented into the skeletal, cardiac, and smooth muscles.
The skeletal muscle: it consists of various integrated tissues which include the blood vessels, skeletal muscle fibers, nerve fibers, and the connective tissue. Each skeletal muscle is wrapped in the epimysium, which allows the muscle to contract and move without altering its structural integrity. The skeletal muscle fibers are organized into the perimysium connective tissue, which allows the nervous system to trigger certain movements. Endomysium surrounds the extracellular group of cells, and it transmits the force generated from the muscle fibers to the tendons.
The cardiac muscle: this muscle contains striations, and it pumps blood into the circulatory blood vessels. It is made up of the cardiac muscle fibers, which are interconnected by intercalated discs (Burgoyne, et al. 2015). The intercalated discs contain the gap junctions and desmosomes. The gap junctions transmit depolarizing current from cations to the cardiac muscle cells. Desmosomes anchor the ends of the cardiac muscle fires (Prakash, 2016).
The smooth muscle: it lacks striations. The smooth muscle consists of myofilaments, and the nucleus at its centroid. The cell membrane is located in the cytoplasm of this tissue. The basal lamina anchors the smooth muscle cells to the surrounding connective tissue. The actin and myosin filaments lie between the denser parts of the cytoplasm. Moreover, it has intermediate filaments termed as vimentin and desmin, which support the cell structure (Prakash, 2016).
BC Campus (n.d.). Anatomy and Physiology: Bone Structure. Retrieved from https://opentextbc.ca/anatomyandphysiology/chapter/6-3-bone-structure/
Prakash, Y. S. (2016). Emerging concepts in smooth muscle contributions to airway structure and function: implications for health and disease. American Journal of Physiology-Lung Cellular and Molecular Physiology, 311(6), L1113-L1140.
Burgoyne, T., Morris, E. P., & Luther, P. K. (2015). Three-dimensional structure of vertebrate muscle Z-band: the small-square lattice Z-band in rat cardiac muscle. Journal of molecular biology, 427(22), 3527-3537.