After the calcium phosphate is deposited, those cells are referred to as osteocytes. Bone is constructed in lamellae (thin, concentric layers), which are laid down around narrow channels called Haversian canals that run parallel to the length of the bone. Haversian canals are interconnected and contain nerve fibers and blood vessels the latter allow to osteocytes to remain alive even though they are embedded in a calcified matrix. .
Bone formation happens in two ways. In flat bones, like the skull, osteoblasts in a web of dense connective tissue make bone within that tissue. In long bones, the bone is first "modeled" in cartilage. Calcification then occurs, and bone is formed as the cartilage degenerates. The ends and interiors of long bones are composed of an open lattice of bone called spongy bone tissue, the spaces of which contain marrow, where most blood cells are formed. Surrounding the spongy bone tissue of concentric layers of compact bone tissue, where the bone is much denser. Compact bone tissue gives bone the strength to withstand mechanical stress. .
The mechanical movements of the body occur at the joints, or articulations, where one bone meets another. There are three kinds of joints: immovable joints, slightly movable joints, and freely movable joints. Immovable joints include the sutures that join the bones of the skull. In a fetus, the skull bones are not fully formed, and there are open areas of dense connective tissue ("soft spots", or fontanels) between the bones that allow the bones to flex slightly as the fetus moves through the birth canal during childbirth. Later bone replaces most of this connective tissue. Slightly movable joints are the bones bridged by cartilage. Pads of cartilage called intervertebral discs separate the vertebral bones of the spine. These cartilaginous joints allow some movement while acting as efficient shock absorbers. Freely movable joints are also called synovial joints since the articulating ends of the bones are within a synovial capsule filled with a lubricating fluid.
Utopia is completely attainable. Utopia, derived from the Greek words meaning no place, was always thought to be a model to strive for. Unfortunately human pessimism has never allowed Utopia to become a tangible place. Strangely enough it is this human aspect that is the barrier to a perfect existe...
Both lack an external tail and both are capable of reaching an upright posture as well as bipedal locomotion, walking on two legs. Humans and apes both have an appendix, which is an appendage that it believed to be used for the digestion of rocks, sticks, and tree bark. ...
Class Metamonada consists of unicellular organisms in which the nuclei are attached to the undulipodia (a cilium or flagellum whose purpose is locomotion or feeding) by rhizoplasts (also known as nuclear connectors. ... They digest cellulose from the wood that these insects eat, and at some stages of digestion, small particles of wood are visible in their cytoplasm. ... Members of this phylum lack flagella and instead used pseudopods for locomotion; they extend their protoplasm and re-form their bodies in the direction in which they wish to move (Anonymous 1998). ...