Haversian Canal System |
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An easy way to remember the work of osteoblasts, osteoclasts, and osteocytes is
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Osteoblasts giveth. Osteoclasts taketh away. Osteocytes maintaineth. |
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Osteoblasts |
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Osteoblasts are the builders and make collagen and hydroxyapatite. Some of the
osteoblasts become buried in their matrix and then they are referred to
as osteocytes. The rest of the osteoblasts cover the new bone's surface. Waves of osteoblasts that move into the area form new layers of bone. |
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Osteoclasts |
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Osteoclasts are larger cells whose function is to dissolve bone by acting on the mineral matrix. They make enzymes such as collagenase, which breaks down collagen. Osteoclasts also secrete various acids that can dissolve the hydroxyapatite structure. |
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Osteocyte |
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After
the osteoblasts are buried in bone, they're referred to as osteocytes.
Osteocytes account for 90 percent of all cells in the skeleton |
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Calaliculi |
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Osteoblasts change their shape and become buried in their matrix, connected to each other only by thin processes called canaliculi |
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Parathyroid |
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regulation of calcium metabolism |
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Calcitonin |
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inhibits bone removal by osteoclasts, and promotes bone formation by osteoblasts |
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Compact Bone |
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Compact bone is the hard material that makes up the shaft of long bones and the outside surfaces of other bones
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Spongy Bone |
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Spongy bone consists of thin, irregularly shaped plates called trabeculae, arranged in a latticework network.
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Diaphysis |
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The diaphysis, or shaft, is the long tubular portion of long bones. It is composed of compact bone tissue.
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Epiphysis |
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The epiphysis (plural, epiphyses) is the expanded end of a long bone.
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Metaphysis |
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The
metaphysis is the area where the diaphysis meets the epiphysis. It
includes the epiphyseal line, a remnant of cartilage from growing bones.
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Medullary Cavity |
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The
medullary cavity, or marrow cavity, is the open area within the
diaphysis. The adipose tissue inside the cavity stores lipids and forms
the yellow marrow.
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Articular Cartilage |
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Articular cartilage covers the epiphysis where joints occur.
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Endosteum |
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The endosteum is the membrane that lines the marrow cavity.
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Periosteum |
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The
periosteum is the membrane covering the outside of the diaphysis (and
epiphyses where articular cartilage is absent). It contains osteoblasts
(bone-forming cells), osteoclasts (bone-destroying cells), nerve
fibers, and blood and lymphatic vessels. Ligaments and tendons attach
to the periosteum. |
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Long Bones |
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Long bones are some of the longest bones in the body, such as the
Femur, Humerus and Tibia but are also some of the smallest including
the Metacarpals, Metatarsals and Phalanges. The classification of a
long bone includes having a body which is longer than it is wide, with
growth plates (epiphysis) at either end, having a hard outer surface of
compact bone and a spongy inner known an cancellous bone containing
bone marrow. Both ends of the bone are covered in hyaline cartilage to
help protect the bone and aid shock absorbtion |
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Short Bones |
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Short bones are defined as being approximately as wide as they are long
and have a primary function of providing support and stability with
little movement. They consist of only a thin layer of compact, hard bone with cancellous
bone on the inside along with relatively large amounts of bone marrow. |
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Flat Bones |
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strong, flat plates of bone with the main function of providing
protection to the bodies vital organs and being a base for muscular
attachment. |
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Irregular Bones |
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These are bones which do not fall into any other category, due to their
non-uniform shape. Good examples of these are the Vertebrae, Sacrum and
Mandible (lower jaw). |
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Zoomed In Bone |
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Image: |
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Tendons |
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Connect muscle to bone |
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Ligaments |
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Connect bone to bone |
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Stress Fracture |
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small crack in bone |
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Compound Fracture |
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the bone exits and is visible through the skin, or a deep wound that exposes the bone through the skin. |
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Greenstick fracture |
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incomplete fracture. The broken bone is not completely separated.
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Spiral Frcture |
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the break spirals around the bone; common in a twisting injury.
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Bone is composed of... |
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Collagen and Calcium Salts |
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Lack of Vitamin D results in ... |
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Rickets ( Bones bow out due to weight) |
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Long Bone Structure |
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Image: |
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Lamellar Bone |
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Lamellar bone has a regular parallel alignment of collagen into sheets (lamellae) and is mechanically strong. Formation is slower than woven. |
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Woven Bone |
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Woven bone characterised by haphazard organisation of collagen fibers and is mechanically weak Woven bone is produced when osteoblasts produce osteoid rapidly which occurs initially in all fetal bones Forms quickly |
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Periosteum |
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Membrance that covers bones |
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Perichondrium |
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Membrance that covers cartilage |
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