Chapter 7 Flashcards by Courtney Freeman

Flat bones

Thin, curved protect organs
Example: skull, scapula, hip

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Long bones

Crucial for movement
Example: humerus, femur, tibia, fibula

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Short bones
Irregular bones

Short-equal length and width
Irregular- vertebrae

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Compact bone

Dense outer shell of bone

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Spongy (cancellous) bone

Center of ends, and center of shafts of Long bones

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Metaphysis

Growth zone
Load bearing from the epiphysis to the diaphysis

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Diaphysis

Shaft that provides Leverage

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Periosteum

Outer Fibrous layer of collagen

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Endosteum

Thin layer of reticular connective tissue

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Why are the inside of bones not solid?

To absorb impact and vibration, and helps faster healing

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Osteogenic cells

-stem cells found in endosteum and inner layer of periosteum
-Give rise to osteoblast

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Osteoblast

Bone forming cells

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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

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Osteoclasts

-Bone dissolving cells
-Preform osteolysis-the breakdown of bones

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Rickets

-In children
-Is a disease caused by mineral deficiency and resulting in soft deformed bones
-Vitamin D deficiency

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Osteogenesis imperfecta

-Brittle bone disease
-Results from a defect in collagen deposition

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Osteons

Prevent spread of Microfractures

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Spongy bone anatomy

-Space is filled with red bone marrow
-All osteocytes close to bone marrow

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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