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Anatomy: Ch 6
| Question | Answer |
|---|---|
| What is skeletal cartilage? | Cartilage made of highly resilient, molded cartilage tissue that consists primarily of water. Contains no blood vessels or nerves. |
| What is the perichondrium? | Layer of dense connective tissue surrounding cartilage like a gridle. It helps cartilage resist outward expansion. Contains blood vessels for nutrient delivery to cartilage. |
| What is cartilage made up of? | Chondrocytes, cells encased in small cavities (lacunae) within jelly-like extracellular matrix. |
| What is the function of hylaine cartilage? | provides support, flex |
| What is the most abundant type of cartilage? | Hyaline cartilage |
| What types of fibers does hyaline cartilage contain? | ONLY collagen fibers |
| Where is hyaline cartilage located? | Articular (joints), costal (ribs), respiratory (larynx and respiratory passageways), nasal cartilage (external nose). |
| What fibers does elastic cartilage contain? | collagen and elastic fibers |
| Where is elastic cartilage located? | External ear and epiglottis |
| What fibers does fibrocartilage contain? | Thick collagen fibers that provide great tensile strength |
| Where is fibrocartilage located? | Menisci of knee, public symphysis, and inter-vertebral discs. |
| What does the term appositional growth mean? (Cartilage growth) | new matrix laid down on surface of cartilage. Cartilage forming cells in perichondrium secrete matrix against external face of existing cartilage. |
| What does the term interstitial growth mean? | new matrix made within cartilage. Chondrocytes within lacunae divide and secrete new matrix, expanding cartilage from within. |
| When does cartilage growth end? | During adolescence |
| What are the two types of cartilage growth? | appositional growth and interstitial growth |
| What is the axial skeleton? | Long axis of the body, which include skull, vertebral column, and rib cage. |
| What is the appendicular skeleton? | bones of upper and lower limbs and girdles attaching limbs to axial skeleton |
| What are long bones? | Bones that are longer than wide with a medullary cavity extending the length of the shaft. (Ex. most limb bones) |
| What are short bones? | Cube-shaped bones (Ex: wrist and ankle bones) |
| What are sesamoid bones? | short bones that form within tendons. Vary in size and number in different individuals. (Ex: patella of the knee) |
| What are flat bones? | Thin, flat, slightly curved bones. Ex: sternum, ribs, and most cranial bones. |
| What are irregular bones? | Complicated shaped bones. Ex: vertebrae and hip bones. |
| Bones contain several different types of tissues. Therefore, what would they be classified as? | Bones are organs. |
| What is compact bone? | Dense outer layer on every bone that appears smooth and solid |
| What is spongy bone? | Bone that is made up of a honeycomb of small, needle-like or flat pieces of bone called trabeculae. |
| What is the primary structure of all bone? | Thin plates of spongy bone covered by compact bone. Compact bone sandwiched between connective tissue membranes. |
| What does the term diploe refer to? | thin plates of spongy bone |
| What is the periosteum? | A connective tissue membrane that covers the outside of compact bone. White, double-layered membrane that covers external surfaces except joints. |
| What is the endosteum? | connective tissue membrane that covers the inside portion of compact bone |
| Where on bone does hyaline cartilage cover? | Areas of bone that is part of a movable joint |
| Where is bone marrow located in bone? | It is scattered throughout spongy bone in the free space between trabeculae. There is no defined marrow cavity. |
| What does the term diaphysis mean? | the tubular shaft that forms the long axis of a long bone |
| What does the term epiphyses mean? | the name for the two ends of a long bone |
| What does articular cartilage cover? | articular (joint) surfaces |
| Where is the epiphyseal line located? | located between the diaphysis and epiphysis. Remnant of the epiphyseal plate. |
| What is the epiphyseal plate? | Where bone growth occurs during childhood. Will become the epiphyseal plate during adulthood. |
| What is the fibrous layer of the periosteum? | outer layer consisting of dense irregular connective tissue consisting of Sharpey's fibers that secure to bone matrix. |
| What is the osteogenic layer of periosteum? | inner layer abutting bone |
| What does the osteogenic layer of the periosteum contain? | It contains primitive osteogenic stem cells that give rise to most all bone cells |
| What is the anchoring points for tendons and ligaments? | The periosteum |
| What is the endosteum? | delicate connective tissue membrane covering internal bone surfaces |
| What does the endosteum contain? | osteogenic cells |
| Where is the endosteum located? | Covers trabeculae of spongy bone and lines canals that pass through compact bone |
| Where is red bone marrow found? | Within trabecular cavities of spongy bone and diploe of flat bone. |
| Where is red bone marrow found in children? | In the medullary cavity and spongy bone |
| Where is red bone marrow located in adults? | In heads of femur and humerus, flat bone diploe, and some irregular bones (such as the hip bone). |
| What is the most active areas of hematopoiesis in adults? | flat bone diploe and some irregular bones (such as the hip bone) |
| What are the three categories for bone markings? | Projections, surfaces and , depressions and openings |
| What are projections | sites of muscle and ligament attachment |
| What are surfaces? | form joints |
| What are depressions and openings? | for blood vessels and nerves |
| What is a tuberosity? | large rounded projection; may be roughened |
| what is a crest? | narrow ridge of bone; usually prominent |
| What is a line? | narrow ridge of bone; less prominent then a crest |
| What is a trochanter | very large, blunt, irregular shaped process (the only examples on femur) |
| What is a tubercle? | Small rounded projection or process |
| What is a epicondyle? | raised area on or above a condyle |
| What is a spine marking? | sharp, slender, often pointed projection |
| What is a process? | Any bone prominence |
| What is a head surface? | bony expansion carried on a narrow neck |
| What is a facet surface? | Smooth, nearly flat articular (joint) surface |
| What is a condyle surface? | Rounded articular projection; often articulates with a corresponding fossa. |
| What is a groove (depression or opening)? | Furrow |
| What is a fissure opening? | narrow, slit-like opening |
| What is a foramen opening? | Round or oval opening through a bone |
| What is a notch? | indentation at the edge of a structure |
| What is a meatus? | cavity within a bone, filled with air and lined with mucous membrane |
| What is a fossa? | shallow, basin-like depression in a bone, often serving as an articular surface |
| What are osteoprogenitor cells? | mitoically active stem cells in periosteum and endosteum |
| What are osteoblasts? | Bone forming cells that secrete unmineralized bone matrix called osteoid. |
| What does osteoid mean? | Unmineralized bone matrix |
| What percentage of collagen makes up bone protein? | 90% |
| What are osteoblasts in reference to mitosis? | They are actively mitotic |
| What are osteocytes? | Mature bone cells in lacunae that no longer divide. And, they maintain bone matrix and act as stress and strain sensors. They also communicate information to osteoblasts and osteoclasts |
| What do osteocytes respond to? | respond to mechanical stimuli |
| What are osteoclasts? | cells that destroy bone for bone remodeling. Function in bone resorption. |
| What are bone lining cells? | flat cells on bone surfaces believed to also help maintain matrix. |
| What are periosteal cells? | bone-lining cells on external bone surface |
| What are endosteal cells? | Bone-lining cells on internal surfaces |
| Where are osteoclasts located when activated? | Bone depressions called resorption bays |
| What is lamellar bone? | Another name for compact bone. |
| What are the three components of compact bone? | Osteon, canals and canaliculi, and interstitial and circumferential lamellae |
| What is a osteon (Haversian system)? | An osteon is the structural unit of compact bone |
| What are lamellae? | Rings of bone matrix in the osteon cylinder |
| What do lamellae contain? | Collagen fibers that run in different directions in adjacent rings. |
| Where are bone salts found within lamellae? | Between the collagen fibers |
| What is one of the functions of lamellae? | They can withstand stress and resists twisting |
| What is the central (haversian) canal? | runs through core of osteon |
| What is the perforating (volkmann's) canal? | canals lined with endosteum that occur at right angles to central canals |
| What are lacunae? | small cavities that contain osteocytes |
| What are canaliculi? | hairlike canals that connect lacunae to each other and to central canal |
| What does canaliculi enable? | communication between all osteocytes and permit nutrients and waste to be relayed from one cell to another |
| What are interstitial lamellae? | Lamellae that are not part of the osteon. Some fill gaps between forming osteons; others are remnants of osteons cut by bone remodeling. |
| What are circumferential lamellae? | Just deep to periosteum, but superficial to endosteum, these layers of lamallae extend around entire surface of diaphysis. Help long bone resist twist. |
| How is spongy bone organized? | organized along lines of stress to help bone resist any stress. |
| What do trabeculae contribute to spongy bone? | confer strength to bone |
| Does spongy bone have osteons? | NO!!! |
| How does spongy bone get nutrients? | Capillaries in endosteum supply nutrients |
| What are the organic components of bone? | osteogenic cells, osteoblasts, osteocytes, bone-lining cells, osteoclasts, and osteioids. |
| What are osteoids? | make up 1/3 of organic bone matrix. Consists of ground substance and collagen fibers. |
| What creates resilience in bone? | sacrificial bonds in or between collagen molecules that stretch or break to dissipate energy and prevent fractures. |
| What is the inorganic components of bone? | Hydroxyapatites ( mineral salts) |
| What does hydroxyapatities consist of? | mainly tiny calcium phosphate crystals in and around collagen fibers |
| What is hydroxyapatites function? | responsible for hardness and resistance to compression |
| What is ossification (osteogenesis)? | the process of bone tissue formation. |
| What is endochondral ossification? | Bone forms by replacing hyaline cartilage. Bones are called cartilage (endochondral) bones. |
| What process forms most of the skeleton? | endochondral ossification |
| What is intramembranous ossification? | Bone develops from fibrous membrane. Bone are called membrane bones. |
| What happens during the first step of endochondral ossification? | Bone collar forms around diaphysis of cartilage model. |
| What happens during the second step of endochondral ossification? | Central cartilage in diaphysis calcifies, then develops cavities. |
| What happens during the third step of endochondral ossification? | Periosteal bud (made of blood vessels, nerves, red bone marrow, osteogenic cells, and osteoclasts) invades cavities, leading to formation of spongy bone. |
| What happens during the fourth step of endochondral ossification? | Secondary ossification centers appear in epiphyses. Secondary ossification centers appear in epiphyses. |
| What happens during the fifth stage of endochondral ossification? | Epiphyses ossifies. Hyaline cartilage remains only in epiphyseal plates and articular cartilages. |
| What is intramembranous ossification? | Begin within fibrous connective tissue membranes formed by mesenchymal cells. Forms frontal, pariental, occipital, temperal, and clavicle bones. |
| What happens during the first step of intramembranous ossification? | Ossification centers are formed when mesenchymal cells cluster and become osteoblasts. |
| What happens during the second stage of intramembranous ossification? | Osteoid is secreted, then calcified |
| What happens during the third stage of intramembranous ossification? | Woven bone is formed when osteoid is laid down around blood vessels, resulting in trabeculae. Outer later of woven bone forms periosteum. |
| What happens during the fourth step of intramembranous ossification? | Lamellar bone replaces woven bone, and red bone marrow appears. |
| During postnatal bone growth, how do long bones grow? | Long bones grow lengthwise by interstitial (longitudinal) growth of epipyseal plate. |
| During postnatal bone growth, what causes bones to increase in thickness? | appositional growth |
| What is the resting zone of the epiphyseal plate? | Area of cartilage on epiphyseal side of epiphyseal plate that is relatively inactive. |
| What is the proliferation (growth) zone? | Area of cartilage on diaphysis side of epiphyseal plate that is rapidly dividing. |
| What is the hypertrophic zone? | area with older chondrocytes closer to diaphysis. Cartilage lacunae enlarge and erode, forming interconnecting spaces. |
| What is the calcification zone? | Surrounding cartilage matrix calcifies; chondrocytes die and deteriorate. |
| What happens in the ossification zone? | Chondrocytes deterioration leaves long spincules of calcified cartilage at epiphysis-diaphsis junction. Spicules are then eroded by osteoclasts and are covered with new bone by osteoblasts. Ultimately replaced with spongy bone. Medullary cavity enlarges. |
| When does epiphyseal plate closure occur? | When epiphysis and diaphysis fuse. |
| When does bone lengthening cease in males and females? | Females: around; Males: around 21 |
| When do bones thicken? | In response to increased stress from muscle activity or added weight |
| What do osteoblasts and osteoclasts do when bone thickens? | Osteoblasts beneath periosteum secreate bone matrix on external bone. Osteoclasts remove bone on endosteal surface. |
| What is a growth hormone? | Most important hormone in stimulating epiphyseal plate activity in infancy and childhood. |
| What hormone modulates activity of growth hormone and ensures proper proportions? | thyroid hormone |
| What are the two different processes bone remodeling consists of? | bone reposit and bone resporption |
| What is the function of osteoclasts? | Resorption |
| What processes do osteoclasts undergo when resorption is complete? | apoptosis |
| What hormone does osteoclast activation involve? | parathyroid hormone (PTH) and immune T cell proteins |
| What is a osteoid seam? | band of unmineralized bone matrix that marks areas of new bone matrix |
| What is the calcification front? | abrupt transition zone between osteoid steam and older mineralized bone. |
| What two control loops is remodeling maintained by? | Maintaining Ca2+ homeostasis and keeping bone strong. |
| What is critical for maintaining the resting membrane potential in cells? | maintaining extracellular fluid calcium levels within homeostatic levels. |
| What is required for nerves to fire and muscles to contract? | Ca2+ |
| When is parathyroid hormone produced in regards to bone remodeling? | produced by parathyroid glands in response to low blood calcium levels. PTH stimulates osteoclasts. |
| When is calcitonin produced in regards to bone remodeling? | produced by parafollicular cells of thyroid in response to high levels of blood calcium levels |
| What is hypocalcemia? | a neuromuscular problem in which low levels of calcium cause hyerexcitability |
| What is hypercalcemia? | A neuromuscular problem in which high levels of calcium cause non responsiveness. |
| What does the Wolf's law state? | Bones grow or remodel in response to demands placed on them. |
| What happens to bones if stress is off centered? | They tend to bend. The diaphysis is thicker where bending stresses are greater. |
| What does handedness result in regarding Wolf's law? | thicker and stronger bone of the corresponding upper limb |
| What does curve bones buckling in relation to Wolf's law mean? | Curved bones are thicker where most likely to buckle. |
| Where do large, bony projections occur in relation to Wolf's law? | Large, bony projections occur where heavy, active muscles attach. |
| What does hormonal controls determine in relation to remodeling? | Hormonal control determines whether and when remodeling occurs in response to changing blood calcium levels, but mechanical stress determine where it occurs. |
| What is a fracture? | A break in the bone. |
| What is a nondisplaced and displaced fracture? | Nondisplaced: ends retain normal position Displaced: ends are out of normal alignment |
| What is a complete fracture and a incomplete fracture? | Complete: broken all the way through Incomplete: not broken all the way through |
| What is a open (compound) fracture and a closed (simple) fracture? | Open (compound): skin is penetrated Closed (simple): skin is not penetrated |
| What is a comminuted fracture? | bone fragments into three or more pieces |
| What is a compression fracture? | bone is crushed |
| What is a spiral fracture? | ragged break occurs when excessive twisting forces are applied to bone |
| What is a epiphyseal fracture? | Epiphyseal separates from the diaphysis along the epiphseal plate. |
| What is a depressed fracture? | Broken bone portion is pressed inward |
| What is a greenstick fracture? | bone breaks incompletely, much in the way a green twig breaks. Only one side of the shaft breaks; the other side bends. |
| What are the four stages of repair for a fracture? | 1. Hematoma forms; 2. fibrocartilaginous callus forms, 3. bony callus forms, 4. bone remodeling occurs. |
| Hematoma forms (bone fracture repair) | Torn blood vessels hemorrhage, forming mass of clotted blood called hematoma. |
| Fibrocartilaginous callus forms | Phagocytic cells clear debris. Fibroblasts secrete collagen fibers that connect two ends. Osteoblasts form spongy bone within matrix. |
| What is the fibrocartilaginous callus | the mass of repair tissue made of cartilage |
| Bony callus forms | New trabeculae appear in fibrocartilaginous callus. Then converted to hard callus of spongy bone. |
| Bone remodeling occurs | compact bone is layed down to reconstruct shaft walls |
| What is osteomalacia? | Bones poorly mineralized. Not enough calcium salts. Results in soft, weak bone. |
| Rickets | Osteomalacia in children. Caused by vitamin D deficiency or insufficient dietary calcium |
| What is osteoporosis? | When bone resorption exceeds deposit. Results in weak bones. Bone mass declines. |
| What is a high risk factor of osteoporosis in women? | postmenopausal females due to decrease production of estrogen. |
| What are risk factors for osteoporosis? | insufficient exercise to stress bones, diet poor in calcium and protein, smoking, genetics, hormone related conditions: hyperthyroidism and diabetes mellitus, and consumption of alcohol or certain medications. |
| What does the drug bisphosphonates do in relation to osteoporosis? | decrease osteoclast activity and number |
| What does the drug denosumab do in relation to osteoporosis? | monoclonal antibody shown to reduce fractures in males with prostate cancer. Improve bone density in elders. |
| What is Paget's disease? | Excessive and haphazard bone deposit and resorption cause bone to grow fast and develop poorly. Called pagetic bone. |
| When is bone ossification completed? | age 25 |
| What is a large factor in density of bone change over a lifetime? | Genetics |
| What happens to bone mass, mineralization, and healing ability of bone with age? | Everything decreases |
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