Chapter 7 Flashcards
Flat bones
Thin, curved protect organs
Example: skull, scapula, hip
Long bones
Crucial for movement
Example: humerus, femur, tibia, fibula
Short bones
Irregular bones
Short-equal length and width
Irregular- vertebrae
Compact bone
Dense outer shell of bone
Spongy (cancellous) bone
Center of ends, and center of shafts of Long bones
Metaphysis
Growth zone
Load bearing from the epiphysis to the diaphysis
Diaphysis
Shaft that provides Leverage
Periosteum
Outer Fibrous layer of collagen
Endosteum
Thin layer of reticular connective tissue
Why are the inside of bones not solid?
To absorb impact and vibration, and helps faster healing
Osteogenic cells
-stem cells found in endosteum and inner layer of periosteum
-Give rise to osteoblast
Osteoblast
Bone forming cells
Osteocytes
Former osteoblast that have become trapped in the matrix they deposited
-Lacunae-Tiny cavities where osteocytes reside
-canaliculi-A little channels that connect lacunae
-Gap junctions, allow for passage of nutrients waste and signals
Osteoclasts
-Bone dissolving cells
-Preform osteolysis-the breakdown of bones
Rickets
-In children
-Is a disease caused by mineral deficiency and resulting in soft deformed bones
-Vitamin D deficiency
Osteogenesis imperfecta
-Brittle bone disease
-Results from a defect in collagen deposition
Osteons
Prevent spread of Microfractures
Spongy bone anatomy
-Space is filled with red bone marrow
-All osteocytes close to bone marrow
Red bone marrow (myeloid tissue)
-In nearly every bone in a child
-in adults, found in skull, vertebrae, ribs, sternum, part of the pelvic girdle, and proximal heads of humerus and femur
Yellow bone marrow
-Found in adults
-Transform back to red marrow in the event of chronic anemia
Intramembranous ossification
-Flat bones of the skull, most of the clavicle and part of the mandible
-important in Lifelong thickening and remodeling of long bones
Structure of metaphysis Corresponds to steps of cartilage replacement. What’s 1-5 order
1 Zone of reserve Cartilage
2 zone of cell proliferation
3 zone of cell hypertrophy
4 zone of calcification
5 zone of bone deposition
True or false
Carpal bones are not yet formed in children
True
Achondroplastic dwarfism
-Long bones stop growing in childhood -results in a normal torso, but short legs
-Failure of Cartlidge growth in metaphyisis
Pituitary dwarfism
-Lack of growth hormone
-Normal body proportions with short stature
Wolfs law of the bone
-Architecture of bone, determined by mechanical stress, is placed on it
-Tension and compression cycles create a small electrical potential that stimulates bone deposition and increases density at points of stress
-based off adaptation
Ectopic ossification
Abnormal calcification of tissues, such as a lung, brain, eye, muscle, tendon or artery
Mineral resorption
-Process of dissolving bone; releases minerals into blood
-performed by osteoclast
What is the normal calcium concentration in blood plasma
9.2 to 10.4 mg/dl
Hypocalcemia
Calcium deficiency; causes excessive excitability of nervous system and muscles
(O in hypo like 0, less, deficiency)
Hypercalcemia
-Rare
-Calcium excess; Causes nerve and muscle cells to be less excitable than normal
(Weird! Not hyper because less exciteable but more calcium)
Calcium homeostasis Is regulated by what three hormones
-calcitriol
-calcitonin
-parathyroid hormone
Calcitriol
-Form of vitamin D, produced by sequential actions of skin, liver, and kidneys
Liver adds…
Kidney adds…
…Hydroxyl group converting that to calcidiol
…hydroxyl group converting that to calcitriol
Calcitriol acts to raise blood calcium in three ways
-Increase calcium absorption by small intestine
-Increase calcium resorption from skeleton
-Weakly promotes Reabsorption of calcium from the kidneys
Osteomalacia
Vitamin D deficiency, soft bones
called rickets in children
-Deep bone pain
-Brakes would be in hip lower back and feet
Calcitonin
Produced by parafollicular(clear) cells of the thyroid gland; secreted when blood calcium levels are too high
-OsteoClasts inhibition
-OsteoBlasts stimulation
C-Thereby reducing bone reabsorption
B-To deposit calcium into balance
—-Important in children, but weak affect in adults
Parathyroid hormone PTH
Is secreted by parathyroid glands on posterior surface of thyroid
-!!!!!!In response to low calcium in blood
-!!!!!!!Promotes calcium reabsorption by kidneys so less is lost in urine.
Calcitriol Raises phosphate levels by promoting its absorption by what?
Small intestine
PTH Lowers blood phosphate levels by promoting its….
Urinary excretion
Bone remodeling
Osteoblasts or osteoclasts
Osteoclasts
Hard callus formation
Osteoclasts or osteoblasts
Osteoblasts
Order of fracture healing
Hematoma formation
Soft callus formation
Hard callus formation
Bone remodeling
Open reduction and internal fixation (ORIF)
Involves surgical exposure of the bone and the use of plates, screws or pens to realign the fragments
Osteoporosis
-Severe loss of bone density
-bones easily fracture
-DEXA scan
-Prevention methods are weight, bearing exercise, throughout life, even old age
