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85 terms

Anatomy Chapter 6

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Skeletal System Functions
Support, protection, leverage, movement, hemopoiesis, storage
Classification of bones by shape
Long, short, flat, irregular, sesamoid, and sutural bones
Long bones
Slightly curved for strength, levers (femur, arm and forearm, for example)
Short bones
Weight transfer - small and boxy (carpal and tarsal bones)
Flat bones
Thin, roughly parallel surfaces, for muscle attachment and protection (roof of skull, sternum, rips, scapula)
Irregular bones
For muscle attachment, complex shapes and notched or ridged surfaces (vertebrae, pelvic bones)
Sesamoid bones
Stress, develops within tendons (patella)
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
Epiphysis
The ends of long bones, consist largely of spongy bone covered by a thin layer (cortex) of compact bone
Metaphysis
Narrow zone where diaphysis and epiphysis are connected
Diaphysis
tubular shaft in middle of bone
Spongy 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
Compact bone
Relatively solid bone always located on the surface of the bone where it forms a sturdy protective layer (stress in one direction)
Marrow (medullar) cavity
central space within the diaphysis
Bone marrow
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
4 cells within bone
Osteoprogenitor, osteoblasts, osteocytes, osteoclasts
Osteoprogenitor
Form osteoblasts, undifferentiated, inner layer of periosteum (the endosteum) spongy bone
Osteoblasts
Form bone through osteogenesis, make and release proteins and other organic components of the matrix
Osteocytes
Mature cells, develop from osteoblasts, control day-to-day activities (each occupies a lacuna, a pocket sandwiched between layers of matrix
Osteoclasts
Resorb bone, release Ca2+ and PO42- into blood (this erosion is called osteolysis)
Periosteum
Covers bone, not at articulations
Endosteum
Lines marrow cavity, central canals, surrounds trabeculae
Ossification
process of converting other tissues to bone
Calcification
process of depositing calcium salts into tissues
Intramembranous Calcification
Begins when osteoblasts differentiate within connective tissue, produces dermal bones (cranial, facial, sesamoid bones)
Endochondral Ossification
Embryo about the 4th week, hyaline cartilage skeleton is replaced by bone, most of skeleton is formed this way. Increases bone length
Epiphyseal plate
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"
Appositional growth
bone diameter increases
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
Remodeling
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
Calcitriol
Comes from kidneys, promotes calcium and phosphate absoption along digestive tract
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
PTH
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)
Calcitonin function
decreases the calcium concentration
Complete absence of PTH for a few days
results in death, usually asphyxiation
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
Simple or closed fractures
doesn't break through skin
Open or compound fractures
ends pierce through skin
Impacted fractures
one end of break driven into other end
Comminuted fractures
shatter the affected area into a multitude of bony fragments
Greenstick fractures
Only one side of the shaft is broken, and the other is bent (children whose bones aren't fully developed)
Pott's fractures
occurs at the ankle and affects both bones of the leg
Colle's fractures
break in the distal portion of the radium, typically the result of reaching out to cushion a fall
Displaced fractures
produce new and abnormal bone arrangements
Spiral fractures
produced by twisting stresses that spread along the length of the bone
Pathologic fractures
From weakening caused by disease, e.g. bone cancer
Stress fractures
Tiny fractures caused by repeated stress, e.g. running
Transverse fractures
breaks a shaft bone across its long axis
Epiphyseal fractures
occur where bone matrix is undergoing calcification and chondrocytes are dying. Can cause stopping of growth
Compression fractures
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
Osteoporosis
Post-menopausal females decrease in estrogen, decrease osteoblast activity (osteoclasts more active?), inadequate exercise and diet, 10x more common in women
Process
Any projection or bump
Ramus
An extension of a bone making an angle with the rest of the structure
Trochanter
Large rough projection where tendons and ligaments attach
Tuberosity
Smaller rough projection where tendons and ligaments attach
Tubercle
small rounded projection where tendons and ligaments attach
Crest
Prominent ridge where tendons and ligaments attach
Line
A low ridge where tendons and ligaments attach
Spine
A pointed process where tendons and ligaments attach
Head
Expanded articular end of an epiphysis, separated from the shaft by the neck (formed for articulation with adjacent bones)
Neck
Narrow connection between the epiphysis and the diaphysis (formed for articulation with adjacent bones)
Condyle
smooth rounded articular process (formed for articulation with adjacent bones)
Trochlea
Smooth grooved articular process shaped like a pulley (formed for articulation with adjacent bones)
Facet
Small flat articular surface (formed for articulation with adjacent bones)
Fossa
A shallow depression
Sulcus
A narrow groove
Foramen
Rounded passageway for blood vessels or nerves
Canal
Passageway through the substance of a bone
Fissure
Elongate cleft
Sinus or antrum
Chamber within a bone, normally filled with air
Osteomyelitis
Inflammation of bone marrow, bacterial
Supernumerary bone
Extra bone, often a finger or toe
Rheumatoid arthritis
Chronic, joint inflammation, swelling stiffness and pain, cartilage changes can result in crippling deformity
Cleft palate
Palate, portion of lower face doesn't form properly
Osteoarthritis
noninflammatory, degeneration of bones and joints
Osteogenic sarcoma
worst bone cancer, can metastasize to lungs, usually starts in long bones
Gigantism
Too much hGH
Dwarfism
Too little hGH
Acromegaly
Over secretion of hGH in adult, growth especially in face and hands