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38 Cards in this Set
- Front
- Back
- 3rd side (hint)
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Types of Bones
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Flat (scapula, sternum)
Irregular (vertebrae, sphenoid) Short (capitate, talus) Long (radius, femur, ulna) |
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Epiphyseal lines vs Epiphyseal plate
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epiphyseal plate (growth plate) – area of hyaline cartilage that separates the marrow spaces of the epiphysis and diaphysis
enables growth in length epiphyseal line – in adults, a bony scar that marks where growth plate used to be |
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lamella
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osteon formed by a central canal and its concentric lamella connected to each other by canaliculi
a cylinder of tissue around a central canal |
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lacuna
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tiny cavities where osteocytes reside
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osteogenic cells
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stem cells found in endosteum, periosteum, and in central canals
arise from embryonic mesenchymal cells multiply continuously to produce new osteoblasts |
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osteoblasts
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– bone forming cells
line up as single layer of cells under endosteum and periosteum are nonmitotic synthesize soft organic matter of matrix which then hardens by mineral deposition stress and fractures stimulate osteogenic cells to multiply more rapidly and increase number of osteocytes to reinforce or rebuild bone secrete osteocalcin – thought to be the structural protein of bone stimulates insulin secretion of pancreas increases insulin sensitivity in adipocytes which limit the growth of adipose tissue |
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osteocytes
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former osteoblasts that have become trapped in the matrix they have deposited
lacunae – tiny cavities where osteocytes reside canaliculi – little channels that connect lacunae cytoplasmic processes reach into canaliculi some osteocytes reabsorb bone matrix while others deposit it contribute to homeostatic mechanism of bone density and calcium and phosphate ions when stressed, produce biochemical signals that regulate bone remodeling |
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osteoclasts
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bone-dissolving cells found on the bone surface
osteoclasts develop from same bone marrow stem cells that give rise to blood cells different origin from rest of bone cells unusually large cells formed from the fusion of several stem cells typically have 3 to 4 nuclei, may have up to 50 |
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intramembranous ossification vs
endochondral ossification |
intramembranous ossification – produce the flat bones of the skull and most of the clavicle (collar bone)
these bones develop within a fibrous sheet similar to epidermis of the skin (dermal bones) mesenchyme – embryonic connective tissue condenses into a layer of soft tissue with dense supply of blood capillaries mesenchymal cells differentiate into osteogenic cells endochondral ossification – process in which bone develops from pre-existing cartilage model beginning the 6th fetal week and ending in early 20’s most bones develop by this process mesenchyme develops into a body of hyaline cartilage in location of future bone covered with fibrous perichondrium perichondrium produces chondrocytes initially, and later produces osteoblasts osteoblasts form a bony collar around middle of cartilage model former perichondrium is now considered to be periosteum |
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bone growth
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interstitial growth - bones increase in length
bone elongation is really a result of cartilage growth within epiphyseal plate epiphyses close when cartilage is gone – epiphyseal line length-wise growth is finished occurs at different ages in different bones appositional growth - bones increase in width throughout life the deposition of new bone at the surface osteoblasts on deep side of periosteum deposit osteoid tissue Become trapped as tissue calcifies lay down matrix in layers parallel to surface forms circumferential lamellae over surface osteoclasts of endosteum enlarge marrow cavity |
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hypercalcemia vs hypocalcemia
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hypocalcemia - blood calcium deficiency
causes excess excitability of muscle, tremors, spasms or tetany (inability to relax) Na+ enters cells too easily and excites nerves and muscles hypercalcemia - blood calcium excess sodium channels less responsive and nerve and muscle less excitable than normal (sluggish reflexes, depression) |
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osteoporosis
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– the most common bone disease
severe loss of bone density bones lose mass and become brittle due to loss of organic matrix and minerals affects spongy bone the most since it is the most metabolically active subject to pathological fractures of hip, wrist and vertebral column kyphosis (widow’s hump) – deformity of spine due to vertebral bone loss complications of loss of mobility are pneumonia and thrombosis postmenopausal white women at greatest risk begin to lose bone mass as early as 35 yoa by age 70, average loss is 30% of bone mass |
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categories/types of joints
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bony joints
fibrous joints cartilaginous joints |
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types of levers
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First-Class Lever
has fulcrum in the middle between effort and resistance (RFE) Second-Class Lever resistance between fulcrum and effort (FRE) Third-Class Lever effort between the resistance and the fulcrum (REF) most joints of the body |
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structure of long bones
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epiphyses and diaphysis
compact and spongy bone marrow cavity articular cartilage periosteum |
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compact vs spongy bone
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Compact
osteon (haversian system) – the basic structural unit of compact bone formed by a central canal and its concentric lamella connected to each other by canaliculi a cylinder of tissue around a central canal perforating (Volkmann) canals are transverse or diagonal passages along the length of the osteon collagen fibers “corkscrew” down the matrix of the lamella giving it a helical arrangement helices coil in one direction in one lamella and in the opposite direction in the next lamella for added strength blood flow - skeleton receives about half a liter of blood per minute nutrient foramina – on the surface of bone tissue that allow blood vessels and nerves to enter the bone open into the perforating canals that cross the matrix and feed into the central canals innermost osteocytes near central canal receive nutrients and pass them along through their gap junction to neighboring osteocytes they also receive wastes from their neighbors and transfer them to the central canal maintaining a two-way flow of nutrients and waste not all of the matrix is organized into osteons circumferential lamellae - inner and outer boundaries of dense bone – run parallel to bone surface interstitial lamellae – remains of old osteons that broke down as bone grew and remodeled itself |
Spongy
sponge-like appearance spongy bone consists of: slivers of bone called spicules thin plates of bone called trabeculae spaces filled with red bone marrow few osteons and no central canals all osteocytes close to bone marrow provides strength with minimal weight trabeculae develop along bone’s lines of stress |
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cartilage zones
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zone of reserve cartilage
typical hyaline cartilage farthest from marrow cavity shows no sign of transforming into bone zone of proliferation chondrocytes multiply forming columns of flat lacunae zone of hypertrophy chondrocyte enlargement matrix between lacunae become very thin zone of calcification mineral deposited in the matrix between columns of lacunae temporary support for cartilage zone of bone deposition chondrocytes die, longitudinal columns fill with osteoblasts and blood vessels, osteoclasts dissolve the calcified cartilage osteons and spongy bone are created by osteoblasts |
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achondroplastic dwarfism
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long bones stop growing in childhood
normal torso, short limbs failure of cartilage growth in metaphysis spontaneous mutation produces mutant dominant allele |
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Wolff’s law
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Wolff’s law of bone - architecture of bone determined by mechanical stresses placed on it and bones adapt to withstand those stresses
remodeling is a collaborative and precise action of osteoblasts and osteoclasts bony processes grow larger in response to mechanical stress |
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PTP Parathyroid hormone
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(PTH) – secreted by the parathyroid glands which adhere to the posterior surface of thyroid gland
PTH released with low calcium blood levels PTH raises calcium blood level by four mechanisms binds to receptors on osteoblasts stimulating them to secrete RANKL which raises the osteoclast population promotes calcium reabsorption by the kidneys, less lost in urine promotes the final step of calcitriol synthesis in the kidneys, enhancing calcium raising effect of calcitriol inhibits collagen synthesis by osteoblasts, inhibiting bone deposition intermittent injections or secretion of low levels of PTH causes bone deposition, and can increase bone mass |
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Calcitriol
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calcitriol – a form of vitamin D produced by the sequential action of the skin, liver, and kidneys
produced by the following process: epidermal keratinocytes use UV radiation to convert a steroid, 7-dehydrocholesterol to vitamin D3 liver adds a hydroxyl group converting it to calcidiol kidneys adds another hydroxyl group, converting that to calcitriol (most active form of vitamin D) – also from fortified milk calcitriol behaves as a hormone that raises blood calcium concentration increases calcium absorption by small intestine increases calcium resorption from the skeleton increases stem cell differentiation into osteoclasts which liberates calcium and phosphate from bone promotes kidney reabsorption of calcium ions, so less lost in urine necessary for bone deposition – need adequate calcium and phosphate abnormal softness of bones (rickets) in children and (osteomalacia) in adults without adequate vitamin D |
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Calcitonin
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calcitonin - secreted by C cells (clear cells) of the thyroid gland when calcium concentration rises too high
lowers blood calcium concentration in two ways: osteoclast inhibition reduces osteoclast activity as much as 70% less calcium liberated from bones osteoblast stimulation increases the number and activity of osteoblasts deposits calcium into the skeleton important in children, weak effect in adults osteoclasts more active in children due to faster remodeling deficiency does not cause disease in adults reduces bone loss in women during pregnancy & lactation |
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ectopic ossification
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abnormal calcification (ectopic ossification)
may occur in lungs, brain, eyes, muscles, tendons or arteries (arteriosclerosis) calculus – calcified mass in an otherwise soft organ such as the lung |
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healing of a fracture
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Hematoma formation
The hematoma is converted to granulation tissue by invasion of cells and blood capillaries. Soft callus formation Deposition of collagen and fibrocartilage converts granulation tissue to a soft callus |
Hard callus formation
Osteoblasts deposit a temporary bony collar around the fracture to unite the broken pieces while ossification occurs Bone remodeling Small bone fragments are removed by osteoclasts, while osteoblasts deposit spongy bone and then convert it to compact bone |
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osteomalacia
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abnormal softness of bones (rickets) in children and (osteomalacia) in adults without adequate vitamin D
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scoliosis
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– abnormal lateral curvature
most common usually in thoracic region particularly of adolescent girls developmental abnormality in which the body and arch fail to develop on one side of the vertebrae |
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fracture types
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stress fracture – break caused by abnormal trauma to a bone
falls, athletics, and military combat pathological fracture – break in a bone weakened by some other disease bone cancer or osteoporosis usually caused by stress that would not break a healthy bone fractures classified by structural characteristics direction of fracture line break in the skin multiple pieces |
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appendicular skeleton
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includes the bones of the upper limb and pectoral girdle, and the bones of the lower limb and pelvic girdle
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axial skeleton
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forms the central supporting axis of the body
skull, auditory ossicles, hyoid bone, vertebral column, and thoracic cage (ribs and sternum) |
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sesamoid bone
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bones that form within some tendons in response to stress; the patella is the largest of these
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sutures
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bony joints in the head separating the other cranial bones
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facial bones
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2 maxillae
2 nasal bones 2 palatine bones 2 inferior nasal conchae 2 zygomatic bones 1 vomer 2 lacrimal bones 1 mandible |
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cervical, thoracic, lumbar, sacral, coccygeal vertebrae
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C1-7
T1-12 L1-5 |
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herniated disc elements
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herniated disc (‘ruptured’ or ‘slipped’ disc) puts painful pressure on spinal nerve or spinal cord
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ACL Anterior Cruciate Ligament
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anterior cruciate ligament (ACL)
prevents hyperextension of knee when ACL is pulled tight one of the most common sites of knee injury |
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flexion vs extension
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flexion – movement that decreases the a joint angle
common in hinge joints extension – movement that straightens a joint and generally returns a body part to the zero position |
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abduction
vs adduction |
abduction - movement of a body part in the frontal plane away from the midline of the body
hyperabduction – raise arm over back or front of head adduction - movement in the frontal plane back toward the midline |
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pronation
vs supination |
supination – forearm movement that turns the palm to face anteriorly or upward
forearm supinated in anatomical position radius is parallel to the ulna pronation – forearm movement that turns the palm to face posteriorly or downward radius spins on the capitulum of the humerus disc spins in the radial notch of ulna radius crosses stationary ulna like an X |
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