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79 Cards in this Set
- Front
- Back
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What does the skeletal system include?
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Cartilages, ligaments, and connective tissues |
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What are the five primary functions of the skeletal system?
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Storage of minerals (calcium) & lipids (yellow marrow) Blood cell production (red marrow) Protection Leverage (force of motion) |
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How are bones classified?
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By their shape, internal tissue organization, and bone markings (surface features; marks) |
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What are the six bone shapes?
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2. Irregular 3. Short 4. Flat 5. Long 6. Sesamoid |
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What are Sutural bones?
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Found between the flat bones of the skull |
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What are irregular bones? Give an example
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Ex; spinal vertebrae, pelvic bones |
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What are short bones? Give an example
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Ex; ankle and wrist bones |
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What are flat bones? Give an example
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Ex; Found in the skull, ribs, and scapulae |
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What are long bones? Give an example
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Found in arms, legs, hands, feet, fingers, and toes |
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What are sesamoid bones? Give an eample |
Small and flat Develop inside tendons near joints of knees, hands, and feet |
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What are the types of bone markings?
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- Along bone surface Elevations or projections - Where tendons and ligaments attach - At articulations with other bones Tunnels - Where blood and nerves enter bone |
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What is the structure of a long bone?
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Diaphysis Epiphysis Metaphysis |
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What is the Diaphysis of a long bone?
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-The shaft -A heavy wall of compact/dense bone -A central space called medullary (marrow) cavity |
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What is the Epiphysis of a long bone? |
-Wide part at each end -Articulation with other bones -Mostly spongy (cancellous) bone -Covered with compact bone (cortex) |
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What is the Metaphysis of a long bone?
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-Where diaphysis & epiphysis meet
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What are the structures of a flat bone
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Resembles a sandwich of spongy bone Between two layers of compact bone Within the cranium, the layer of spongy bone between the compact bone is called diploe |
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What is bone (Osseous) tissue?
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Contains specialized cells Produces solid matrix of calcium salt deposits Around collagen fibers |
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What are the characteristics of bone tissue?
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-Deposits of calcium salts -Osteocytes (bone cells) with lacunae organized around blood vessels -Canaliculi -Periosteum |
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What are the functions of Canaluculi in bone tissue?
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Exchange nutrients and waste |
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What are the functions of Periosteum in bone tissue?
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Consists of outer fibrous and inner cellular layers |
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What are the characteristics of the bone matrix in bone tissue?
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-2/3 of the bone matrix is calcium phosphate *Reacts with calcium hydroxide to form crsytals of hydroxyapatite which incorporates other calcium and salt ions -1/3 of the bone matrix is protein fibers (collagen) |
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What are the types of bone cells?
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2. Osteoblasts 3. Osteoprogenitor cells 4. Osteoclasts Makes up only 2% of bone mass |
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What are osteocytes?
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Live lacunae Between layers (lamellae) of matrix Connect by cytoplasmic extensions through Canaliculi in lamellae They do not divide |
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What are the two major functions of osteocytes?
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To help repair damaged bone |
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What are osteoblasts?
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Osteoblasts surrounded by bone become osteoclasts |
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What is osteoid?
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A matrix produced by osteoblasts, but not yet calcified to form bone
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What are osteoprogenitor cells?
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Mesenchymal stem cells that divide to produce osteoblasts Located in endosteum, the inner cellular layer of periosteum Assist in fracture repair |
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What are osteoclasts?
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Giant, multinucleate cells Dissolve bone matrix and release stored minerals (osteolysis) Derived from stem cells that produce macrophages |
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What is homeostasis in bone tissue?
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-More breakdown than building, bones become weak -Exercise, particularly weight-bearing exercise, causes osteoblasts to build bone |
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What is the structure of compact bone?
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Osteon is the basic unit -Osteocytes are arranged in concentric lamellae -Around a central canal containing blood vessels -Perforating canals |
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What are the functions of perforating canals in compact bone?
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Carry blood vessels into bone marrow |
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What are the functions of circumferential lamellae in compact bone?
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Bind osteons together |
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What are the structures of spongy bone?
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The matrix forms an open network of trabeculae Trabeculae have no blood vessels The space between trabeculae is filled with red bone marrow and yellow bone marrow |
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Functions of red bone marrow in spongy bone
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Forms red blood cells Supplies nutrients to osteocytes |
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Functions of yellow bone marrow in spongy bone |
Is yellow because it stores fat |
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What are weight-bearing bone?
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-Causing tension on the lateral side of the shaft and compression on the medial side |
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Characteristics of compact bone covered with membrane
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-Covers all bones except parts enclosed in joint capsules -Made up of an outer, fibrous layer and an inner cellular layer -Perforating fibers: collagen fibers of the periosteum |
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Characteristics of perforating fibers in compact bone
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What are the functions of periosteum?
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Provides a route for circulatory and nervous supply Participates in bone growth and repair |
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What are the characteristics of endosteum in compact bone?
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On the inside An incomplete cellular layer -Lines the medullary (marrow) cavity -Covers trabeculae of spongy bone -Lines central canals -Contains osteoblasts, osteoprogenitor cells, and osteoclasts -Is active in bone growth and repair |
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Human bones grow until about what age?
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25 |
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What is osteogenesis?
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Bone formation
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What is ossification? |
The process of replacing other tissues with bone |
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What is calcification?
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Occurs during bone ossification and in other tissues |
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What are the two main forms of ossification?
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Intramembranous ossification |
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What is Endochondral ossification?
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Ossifies bones that originate as hyaline cartilage Most bones originate as hyaline cartilage There are 7 main steps in endochondral ossification |
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What is Appositional growth?
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Compact bone thickens and strengthens long bone with layers of circumferential lamallae
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What are epiphyseal lines?
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-Epiphyseal cartilage disappears -Is visible on x-rays as an epiphyseal line |
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What is a mature long bone?
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Osteons form around blood vessels in compact bone |
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What is intramembranous ossification?
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-Occurs in the dermis Produces dermal bones such as mandible and clavicle There are 5 main steps in intramembranous ossification |
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Characteristics of blood supply of mature bones
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2. Metaphyseal vessels 3. Periosteal vessels |
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What are the characteristics of nutrient artery and veins in mature bones?
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Enter the diaphysis through the nutrient foramen Femur has more than one pair |
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What are the characteristics of Metaphyseal vessels in mature bones?
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Supply the epiphyseal cartilage Where bone growth occurs |
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What are the characteristics of Periosteal vessels in mature bones?
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Send blood to superficial osteons Secondary ossification centers |
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The periosteum also contains?
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Networks of lymphatic vessels & sensory nerves |
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Characteristics of the adult skeleton
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Replaces mineral reserves Recycles and renews bone matrix Involves osteocytes, osteoblasts, and osteclasts |
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Characteristics of adult skeleton remodeling itself
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Turnover rate varies: -If deposition is greater than removal, bones get stronger -If removal is faster than replacement, bones get weaker |
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What are the effects of exercise on bone?
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Heavily stressed bones become thicker and stronger |
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At what rate to bones degenerate? |
They degenerate quickly, up to 1/3 of bone mass can be lost in a few weeks of inactivity |
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Normal bone growth and maintenance depends on what?
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-A dietary source of calcium and phosphate salts plus small amounts of magnesium, fluoride, iron, and magnese |
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What hormones affects normal bone growth?
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Growth hormone & thyroxine stimulates bone growth Estrogen and androgens stimulates osteoblasts Calcitonin & parathyroid hormone regulate calcium & phosphate levels Calcitriol -Made in the kidneys -Helps absorb calcium and phosphorus from digestive tract -Synthesis requires vitamin D3 (cholecalciferol) |
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What vitamins are required for normal bone growth?
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-Collagen synthesis and stimulation of osteoblasts differentiation Vitamin A -Stimulates osteoblast activity Vitamins K & B12 -Helps synthesize bone proteins |
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How is the skeleton like a calcium reserve?
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Calcium is the most abundant mineral in the body |
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Calcium ions are vital to what?
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Membranes, neurons, muscle cells, especially heart cells |
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What is calcium homeostasis?
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-Must be closely regulated Homeostasis is maintained -By calcitonin and parathyroid hormone (PTH) -Which controls storage, absorption, and excretion |
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Calcitonin and Parathyroid Hormone affects what?
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-Where calcium is stored Digestive Tract -Where calcium is absorbed Kidneys -Where calcium is excreted |
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Characteristics of Parathyroid Hormone (PTH)?
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Produced by parathyroid glands in neck Increases calcium ion levels by -Stimulating osteoclasts -Increasing intestinal absorption of calcium -Decreasing calcium excretion at kidneys |
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Characteristics of Calcitonin?
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Decreases calcium ion levels by -Inhibiting osteoclast activity -Increasing calcium excretion at kidneys |
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What are fractures?
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Caused by physical stress |
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How are fractures repaired?
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2. Cells of the endosteum & periosteum 3. Osteoblasts 4. Osteoblasts and osteocytes remodel the fracture for up to a year |
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What does bleeding do for a fracture?
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Establishes a fibrous network Bone cells in the area die |
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What do cells of the endosteum & periosteum do for a fracture?
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Calluses stabilize the break -External callus of cartilage & bone surrounds break -Internal callus develops in medullary cavity |
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What do osteoblasts do for a fracture?
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Replace central cartilage of external callus with spongy bone |
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What does osteoblasts and osteocytes remodeling the fracture for up to a year do for the fracture?
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Reduces bone calluses |
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What are the major types of fractures?
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Displaced Compression Spiral Epiphyseal Comminuted Greenstick Colles Pott's |
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What are age-related changes that happen to bones?
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Bones become thinner & weaker with age -Osteopenia begins between ages 30 & 40 -Women lose 8% of bone mass/decade, men lose 3% The epiphyses, vertebrae, and jaws are most affected resulting in fragile limbs, reduction in height and tooth loss |
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What is osteoporosis?
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Severe bone loss Affects normal function Over age 45, occurs in 29% of women 18% of men |
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How do hormones affect bone loss?
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Bone loss in women accelerates after menopause |
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How does cancer affect bone loss?
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-Stimulates osteoclasts and produces severe osteoporosis |
