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Thin, roughly parallel surfaces, for muscle attachment and protection (roof of skull, sternum, rips, scapula)
For muscle attachment, complex shapes and notched or ridged surfaces (vertebrae, pelvic bones)
Sutural or wormian bones
small, flat irregularly shaped bones between flat bones of the skull. Individual variations on size, position and number of bones
Anatomy of a long bone
Epiphysis, Metaphysis, Diaphysis (shaft), Spongy bone, compact bone, marrow cavity
The ends of long bones, consist largely of spongy bone covered by a thin layer (cortex) of compact bone
Forms an open network of struts and plates called trabeculae, makes up the interior of the bone (stress from many directions), red marrow found here
Relatively solid bone always located on the surface of the bone where it forms a sturdy protective layer (stress in one direction)
loose connective tissue, yellow bone marrow is full of fat cells, red bone marrow mixture of mature and immature red and white blood cells and the stem cells that produce them. Yellow is energy reserve, red important site of blood cell formation
Form osteoblasts, undifferentiated, inner layer of periosteum (the endosteum) spongy bone
Form bone through osteogenesis, make and release proteins and other organic components of the matrix
Mature cells, develop from osteoblasts, control day-to-day activities (each occupies a lacuna, a pocket sandwiched between layers of matrix
Begins when osteoblasts differentiate within connective tissue, produces dermal bones (cranial, facial, sesamoid bones)
Embryo about the 4th week, hyaline cartilage skeleton is replaced by bone, most of skeleton is formed this way. Increases bone length
Narrow cartilaginous region separates epiphysis and diaphysis in a growing bone, in adults you can see where the plate used to be in "epiphyseal lines"
Hormonal Regulation of Bone Growth
Before puberty, hGH (human growth hormone), insulin-like growth factors (IGFs), thyroid hormone, insulin. At puberty, increase in testosterone, estrogens
Organic and mineral components of bone are continuously recycled and renewed, especially in response to weight-bearing stress/exercise
Loss of mass in bone
Caused by no stress, lack of Ca2+, lack of osteoblast activity, increase in osteoclast activity (age, exercise, hormones, Calcium and phosphate ion absorption and excretion, genetic and environmental factors
Calcium is required for homeostatis
Muscle cells contraction, neurons, hormone secretion from glands, tight junctions, blood clotting
Effects of Diet on Bone
Vitamin A & K stimulates osteoblasts, C synthesis of collagen, osteoblast differentiation, Vitamin K and B12, protein synthesis
Immediate control of free Ca2+ levels
Blood calcium drops, parathyroid senses, secretes PTH to increase plasma calcium
parathyroid hormone. Stimulates osteoclasts to resorb bone, kidneys decrease calcium secretion, phospate still excreted. Stimulates osteocytes
Regulation of calcium levels over time
intestinal absorption and renal excretion or reabsoption. Promotes formation and action of calcitriol (intestinal absorption of calcium and phosphate, stimulates osteoclast activity, stimulates kidneys to reabsorb more calcium)
Vitamin D Deficiency
Impairs calcium absorption, PTH maintains levels at expense of bone, Rickets causes bones to become soft and deformed (bow legged), osteomalacia in adults
Only one side of the shaft is broken, and the other is bent (children whose bones aren't fully developed)
break in the distal portion of the radium, typically the result of reaching out to cushion a fall
occur where bone matrix is undergoing calcification and chondrocytes are dying. Can cause stopping of growth
occur where vertebrae subjected to extreme stresses, such as landing on your seat when you fall
Aging and the Skeletal system
Physical activity decreases, bones lose mass, decrease protein synthesis (bones brittle, more likely to break), decreasing size and reiliency of intervertebral discs causes some height loss, Osteoporosis
Post-menopausal females decrease in estrogen, decrease osteoblast activity (osteoclasts more active?), inadequate exercise and diet, 10x more common in women
Expanded articular end of an epiphysis, separated from the shaft by the neck (formed for articulation with adjacent bones)
Narrow connection between the epiphysis and the diaphysis (formed for articulation with adjacent bones)
Smooth grooved articular process shaped like a pulley (formed for articulation with adjacent bones)
Chronic, joint inflammation, swelling stiffness and pain, cartilage changes can result in crippling deformity
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