Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
140 Cards in this Set
- Front
- Back
|
Human skeleton
|
Initially consist of just cartilage, which is replaced by bone, except in areas requiring flexibility.
|
|
|
Skeletal Cartilage
|
-Made of highly resilient, molded cartilage tissue that consists primarily of water. -Contains no blood vessels or nerves |
|
|
Perichondrium
|
-A layer of dense irregular C.T surrounding cartilage like a girdle. -Helps resist outward expansion -Contains blood vessels for nutrient delivery to cartilage |
|
|
Bone tissue components (Cartilage) |
-All bones have the same basic components. -Cartilage is made up of chondrocytes, cells encased in small cavities lacunae, within jelly-like extracellular matrix. |
|
|
3 types of cartilage tissue
|
1. Hyaline 2. Elastic 3. Fibrocartilage |
|
|
Hyaline |
- Provides support with flexibility and resilience. - Most abundant type; contains collagen fibers only. -Articular (joints), Costal (ribs), Respiratory (larynx), Nasal Cartilage (nose tip) |
|
|
Elastic |
-Similar to hyaline cartilage, but contains elastic fibers. -External ear, Epiglottis |
|
|
Fibrocartilage |
-Highly compressible and have great tensile strength. -Intermediate between hyaline and elastic cartilage. -Consist of roughly parallel rows of chondrocytes alternating with thick collagen fiber. -Menisci of the knee and intervertebral disc. |
|
|
Growth of Catilage 1. Appositional Growth |
-Growth from outside. -Cartilage forming cells in perichondrium secrete matrix against external face of existing cartilage -New matrix laid down on surface of cartilage. |
|
|
2. Interstitial Growth |
-Growth from inside -Chondrocytes within lacunae divide and secrete new matrix, expanding cartilage from within. |
|
|
Calcification of cartilage |
-Occurs during normal bone growth in youth, but also occur in old age.
-Hardened cartilage is not the same as bone. |
|
|
Functions of Bones
|
-Support -Protection -Movement -Mineral storage -Blood cell formation -Triglyceride (fat) storage -Hormone production |
|
|
|
Long axis of the body. Skull, vertebral column and ribs. |
|
|
Appendicular Skeleton |
-Bones of the upper and lower limbs. -Girdles attaching limbs to axial skeleton |
|
|
Long Bones |
-Longer than they are wide, shaft and 2 ends -Limb bones |
|
|
Short Bones
|
-Cube shaped bones -Wrist and ankle |
|
|
Sesamoid Bones
|
-Form within tendons. -Vary in size and number in different individuals. -Patella (Largest sesamoid bone of body.) -Shape like sesame seed. |
|
|
Flat Bones |
-Thin, flattened, usually curved -Sternum, scapula, ribs, most skull bones) |
|
|
Irregular Bones
|
-Complicated shapes. -Don't fit in any other class -Vertebrae and hips. |
|
|
Bones are organs because they contain different types of tissue
|
Bone (osseous) tissue predominates, but a bone also has nervous tissue, cartilage, fibrous C.T, muscle cells and epithelial cells in its blood vessels.
|
|
|
Three Levels of Structure
|
-Gross -Microscopic -Chemical |
|
|
Gross Anatomy -Compact Bone (Lamellae) |
Looks solid and dense but riddled with passageways that serve as conduit for nerves, blood vessels and lymphatic vessels
|
|
|
-Spongy Bone (Trabecular bone)
|
Made up of a honeycomb of small, needle-like or flat pieces of bone called Trabeculae (open spaces between trabeculae are filled with red or yellow bone marrow)
|
|
|
Structure of short, irregular and flat bones |
-Consist of thin plates of spongy bone (diploe) covered by compact bone -Compact bone sandwiched between connective tissue membranes. -Bone marrow is scattered throughout spongy bone; no define marrow cavity. -Hyaline cartilage covers area of bone that is part of a movable joint. |
|
|
Periosteum |
Covers outside of compact bone
|
|
|
Endosteum |
Covers inside portion of compact bone
|
|
|
Structure of Typical Long Bone |
All long bones have a shaft (diaphysis), bone ends (epiphyses), and membranes.
|
|
|
Diaphysis |
Tubular shaft that forms long axis of bone. -Consist of compact bone surrounding central Medullary Cavity that is filled with yellow marrow in adults. |
|
|
Epiphyses |
End of long bones that consist of compact bone externally and spongy bone internally. -articular cartilage covers articular (joints) surface. |
|
|
Epiphyseal Line |
Between diaphysis and epiphyses -Remnat of childhood Epiphyseal Plate where bone growth occurs. |
|
|
Membranes -Periosteum |
White double-layered membrane that covers external surfaces except joints. -Contains many nerve fibers and blood vessels that continue on to the shaft through nutrients foramen openings. -Anchoring points for tendos and ligaments. |
|
|
a. Fibrous layer |
Outer layer consisting of dense irregular tissue consisting of Sharpey's fibers that secure to bone matrix.
|
|
|
b. Osteogenic layer
|
-Inner layer abutting bone and contais primitive osteogenic stem cells that gives rise to most all bone cells. |
|
|
- Endosteum |
-Delicated C.T membrane covering internal bone surface. -Covers trabeculae of spongy bone. -Line canals that pass through compact bone. -Contains osteogenic cells that can differentiate into other bone cells. |
|
|
Hematopoietic Tissue in Bones -Red Marrow -Yellow Marrow |
Found within trabecular cavities of spongy bone and Diploe of flat bones, such as sternum. -In newborns, medullary cavities and all spongy bone contain red marrow. -In adults, is located in heads of femur and humerus, but most active areas are flat bone diploe and some irregular bones such as Hip Bone. -Yellow marrow can convert to red, if person is anemic. Yellow marrow is found in middle of long bones. It is made up of fat cells that have an important function in the body. It serves as the body’s natural energy and blood reserve. |
|
|
Bone Making |
-Site of muscle, ligament, and tendon attachement on external surfaces. -Areas involved on joint formation or conduits for blood vessels and nerves. |
|
|
Bone marking: Projection |
Outward bulge of bone
-May be due to increased stress from muscle pull or is a modification for joints. |
|
|
Bone marking: Depression
|
Bowl or groove-like cut out that can serve as passageway for vessels and nerves, or plays a role in joints. |
|
|
Bone marking: Opening
|
Hole or canal in bone that serves as passageways for blood vessels and nerves. |
|
|
Microscopic Anatomy of Bone -Cell of bone tissue |
Five majors cell types, each which is a specialized from of the same gasic cell type 1. Osteogenic cells 2. Osteoblasts 3. Osteocytes 4. Bone-lining cells 5. Osteoclasts |
|
|
1. Osteogenic Cells
|
-Also called Osteoprogenitor cells -Mitotically active stem cells in periosteum and endosteum. -When stimulated, they differentiate into osteoblast or bone-lining cells. -Some remain as osteogenic stem cells. |
|
|
2. Osteoblasts
|
-Bone forming (making) cells that secrete unmineralized bone matrix called Osteoid. -Osteoid is made up of collagen and calcium-binding proteins -Collagen makes up 90% of bone protein. -Osteoblasts are actively mitotic. |
|
|
3. Ostecytes
|
-Mature bone cells in lacunae that no longer divide. -Maintain bone matrix and act as stress or strain sensor. |
|
|
4. Bone-Lining Cell |
-Flat cells on bone surfaces believed to also help maintain matrix (along with osteocytes) -On external bone surface, lining cells are called periosteal cells. -On internal surfaces, they are called endosteal cells. |
|
|
5. Osteoclast
|
-Large cells -Breaking down of bone and replacement |
|
|
Compact Bone (lamellar bone)
|
Consist of: -Osteon (Haversian system) -Canals and canaliculi. -Interstitial and circumferential lamellae. |
|
|
-Osteon (Harversian System)
|
-Structural unit of bone. -Is an elongated cylinder oriented parallel to the axis of the bone. -Tiny weight-bearing pillars. -An osteon cylinder consists of several rings of bone matrix called Lamellae (like ring of a tree) |
|
|
-Lamellae
|
-Contain collagen fibers that run in different directions in adjacent rings. -Withstands stress and resists twisting. -Bone salts are found between collagen fibers |
|
|
-Interstitial Lamellae
|
-Lamellae that are not part of osteon. -Some fills gaps between forming osteons or all remnants of osteons cut by bone remodeling |
|
|
-Circunferential Lamellar |
-Located just deep to periosteum, butsuperficial to the endosteum. -These layer of lamellae extended around entire surface of diaphysis. -Help long bone to resist twisting. |
|
|
Canal and Canaliculi -Cental (Harvasian) Canal |
-Runs through the core of each osteon. -Contains small blood vessels and nerve fibers. |
|
|
-Perforating (Volkmann's) Canals |
-Canals lined with endosteum that occur at right angle to cental canal. -Connects blood vessels and nerves of periosteum, medullary cavity, and cental canal |
|
|
Lacunae (Osteocytes) |
Small cavities that contain Osteocytes
|
|
|
Canaliculi |
Hairlike canals that connect the lacunae to each other and to the central canal
|
|
|
Spongy Bone |
-Appears poorly organized but is actually organized along lines of stress to help bone resist any stress
|
|
|
Trabeculae |
Like cables on a suspension bridge, confer strength to boneNo osteons are presents, but trabeculae do contain irregularly arranged lamellae and osteocytes interconnected by canaliculi.Capillaries in endosteum supply nutrients
|
|
|
Chemical Composition of Bone |
Bone is made of: -Organic and -Inorganic Components |
|
|
Organic Components |
-Includes (cell of bone tissue) and Osteoid. -Resilience of bone is due to sacrificial that stretch and break to dissipate energy and prevent fractures. -Is no additional trauma, bonds re-form. |
|
|
Osteoid |
-Makes up 1/3 of organic bone matrix, is secreted by osteoblasts. -Consist of ground substances and collagen fibers which contribute to high tensile strength and flexibility of bone 1. Proteoglycans 2. Glycoproteins |
|
|
Osteogenic Cell |
Stem cell
|
|
|
Osteoblasts
|
Matrix-synthesizing cell responsible for bone growth.
|
|
|
Osteocyte |
Mature bone cell that monitors and maintains the mineralized bone matrix. |
|
|
Bone lining cells |
Flat cell found on bone surface where bone remodeling is not going on. Help maintain the matrix.
|
|
|
Osteoclasts |
Bone-reforming cell.
|
|
|
Inorganic Components -Hydroxyapatities(Minerals salts) |
- Makeup 65% of bone tissue by mass. -Consist mainly of tiny calcium phosphate crystals in and around collagen fibers. -Responsible for hardness and resistance to compression. -Last long after desth because of mineral composition -Bone is half as strong as steel in resisting compression and as strong in resi |
|
|
Ossification (osteogenesis) |
-Is the process of bone tissue formation. -Formation of bony skeleton begins in month 2 of development. -Postnatal bone growth occurs until early adulhood. -Bone remodelind and repair are lifelong. |
|
|
Formation of the Bony Skeleton
|
Up to about week 8, fibrous membranes and hyaline cartilage of fetal skeleton are replaced with bone tissue. |
|
|
Endochondral Ossification |
-Forms essentially all bones inferior to base od skull, except clavicles. -Bone develops by replacing hyaline cartilage.-Process begins in month 2 of development |
|
|
Primary Ossification Center |
-Region in the center of a hyaline cartilage shaft where endochondral ossification occurs. -Blood vessels infiltrate perichondrium, converting it to perosteum. -Mesenchymal cells specialized into osteoblasts. |
|
|
Endochondral Ossification Stage 1: |
Bone collar forms around the diaphysis of the hyaline cartilage model.
|
|
|
Endochondral Ossification Stage 2: |
Central cartilage in diaphysis calcifies, then develops cavities.
|
|
|
Endochondral Ossification Stage 3:
|
Periosteal bud invades cavities, leading to formation of spongy bone. -Bud is made up of blood vessels, nerves, red marrow, osteogenic cells, and osteoblast. |
|
|
Endochondral Ossification Stage 4:
|
Diaphysis elongates, and medullary cavity forms.-Secondary ossification canters appear in epiphyses
|
|
|
Endochondral Ossification Stage 5: |
Epiphesis ossify-Hyaline cartilage remains only in epiphyseal plates and articular cartilages.
|
|
|
Intramembranous Ossification |
-Begins within fibronus connective tissue membrane formed by messechymal cells.-Forms cranial bones of the skull ( frontal, parietal, occipital, temporal) & clavicles.
|
|
|
Intramembranous Ossification Step 1: |
Ossification center appears in the fibrous connective tissue. |
|
|
Intramembranous Ossification Step 2:
|
Bone matrix (osteoid) is secreted within the fibrous membrane and calcifies
|
|
|
Intramembranous Ossification Step 3: |
Woven bone and periosteum form.
|
|
|
Intramembranous Ossification Step 4: |
Lamellar bone replaces woven bone, just deep to the preiosteum. Red marrow apprears.
|
|
|
Postnatal Bone Growth |
-Long bones grow lenthwise by interstitial (longitudinal) growth of epiphyseal plate -Bones increase thickness through appositional growth. -Bones stop growing during adolescence -Some facial bones continues to grow slowly through life |
|
|
Growth in Length of Long Bones
|
-Interstitial growth requires presence of epiphyseal cartilage in the epiphyseal plate -Epypheseal plate maintains constant thickness-Rate of cartillage growth on one side balanced by bone replacement on other
|
|
|
Epiphyseal Plate Consist of Five Zones
|
1. Resting (quiescent) zone 2. Proliferation (growth) zone 3. Hypertrophic zone 4. Calcification zone 5. Ossification (osteogenic) zone |
|
|
Resting (Quiscent) Zone |
Area of cratilage on epiphyseal side of epiphyseal plate that is relativly inactive
|
|
|
Profiferation (Growth) Zone |
-Area of cartilage on diaphysis side of epiphyseal plate that is rapidly dividing. -New cells formed move upward, pushing epiphysis away from diaphysis, causind lenghtening(Cartilage cells undergo mitosis) |
|
|
Hypertrophic Zone |
-Area with older chondrocytes closer to diaphysis. -Cartilage lacunae enlarge and erode, formaing interconnecting spaces(Older certilage enlarge) |
|
|
Calcification Zone |
Surrounding cartilage matrix calcifies; chondrocytes die and deteriorate
|
|
|
Ossification Zone |
New bone forms.
|
|
|
End of Adolocescence |
-Chondroblast divide less often. -Epiphyseal plate thins, then is replaced by bone.-Epiphyseal plate closure occurs when epiphysis and diaphysis fuse. -Bone lengthening ceases (females around 18, males around 21 yrs of age) |
|
|
Growth in Width (Thickness) |
-Growing bones widen as they lengthen through appositional growth (Can occur through life)-Bones thicken in response to increase stress from muscle activity or added weight. -Usually more building up than breaking down which leads to thicker, strong bones that is not too heavy |
|
|
Hormonal Regulation of Bone Growth: -Growth Hormone |
Most important hormone in stimulating epiphyseal plate activity in infancy and childhood (released by anterior pituitary gland)
|
|
|
Thyroid Hormone |
Modulates activity of growth hormones, ensuring proper proportions
|
|
|
Testoterone (males) and Estrogen (females) at PubertyPromote |
-Promote adolescent growth spurts. -End growth by inducing epiphyseal place closure. |
|
|
Abnormal skeletal growth. |
Causes by excesses or Deficits of any hormone
|
|
|
Bone Remodeling |
-Occurs at surface of both periosteum and endosteum. -About 5-7% of bone mass is recycled each week -Spongy bone replace every 3-4 years. -Compact bone replace every 10 years. -Consist of both: Bone deposit and bone resorption. |
|
|
Remodeling Unit
|
Pachets of adjacent osteoblasts and ostoclasts coordinate remodeling process |
|
|
Bone Deposits
|
-New bone matrix is deposited by osteoblasts. -Trigger for deposit not confirmed but may include: *mechanical signals *Increased concentration of calcium and phosphate ions for hydroxyapatite formation. *Matrix proteins that binds and concentrate calcium. *Appropriate amount of enzyme algalune phosphatase for mineralization. |
|
|
Osteoid Seam
|
Band of unmineralized bone matrix that marks area of new matrix.
|
|
|
Calcification Front
|
Abrupt transtion zone berween osteoid seam and older mineralized bone
|
|
|
Bone Resorption |
Is fuction os Osteoclast. -Secrete lysosomal enzymes and protons (H+) that digest matrix. -Acidity converts calcium salts to soluble forms |
|
|
Bone Resorption |
-Osteoclasts also phagocytize demineralized matrix. -Osteoclasts activation involves PTH (parathyoid hormone) and immune T cell proteins. |
|
|
Control of Remodeling |
Remodeling occurs continuosly but is regulated by genetic factors and two control loops: 1. Hormonal controls. 2. Responses to mechanical stress. |
|
|
Parathyroid Hormone (PTH) |
Produce by parathryoid glands os responses to low blood calcium levels. -Stimulates osteoclasts to resorb bone. -Calcium is relased into blood, raising levels. -PTH secretion stops when homeostatic calcium levels are reached. |
|
|
Calcitonin
|
Produced by parafollicular cells of thyroid gland in response to high levels of blood calcium levels. -Effects are negligible, but at high pharmacoligical doses ot can lower blood calcium levels temporarily. |
|
|
Hypocalcemia
|
Low levels of calcium cause hyperxcitablility |
|
|
Hypercalcemia
|
High levels of calcium cause nonresponsiveness.
|
|
|
Sustained High Blood Calcium Levels |
Can lead to deposits of calcium salts in blood vessels or kidney and formation of kidney stones.
|
|
|
Other Components for Hormonal Controls
|
Leptin: -Hormone relased by adipose tissue. -May play role in bone density regulation by inhibiting osteoblasts. Serotonin: -Neurotransmitter regulates mood and sleep; also interfere with osteoblasts activity. -Most serotonin made in gut. -Secreted into blood after a meal. -May inhibit bone turnover after a meal, so bone calcium is lock in when new calcium is flooding into bloodstream. |
|
|
Response to Mechanical Stress
|
Bones are stressed when weight bears on them or muscle pull on them.
|
|
|
Wolf's law states
|
That bones grow or remodel in response to demands placed on them. -Stress is usually off center, s bones tend to bend -Bending compresses one side, stretches other side. -Diaphysis is thickest where bending stresses are greatest. -Bone can be hollow because compression and tension cancel each other out in center of bone |
|
|
Wolf's law also explains:
|
-Handedness (right or left handed) results in thicker and strong bone of the corresponding upper limb.
-Curved bones are thickest where most likely to buckle. -Trabeculae form trusses along lines of stress. Large, bony projections occurs where heavy, active muscle attach. |
|
|
Control remodeling
|
-Mechanical stress causes remodeling by producing electrical signals when bone is deformed -Hormonal controls determine whether and when remodeling occurs in response to changin blood calcium levels, but mechanical stress determines where it occurs. |
|
|
Fractures
|
-Fractures are breaks. -During youth, most fractures result from trauma -In old age, most result from weakness of bone due to bone thinning. |
|
|
Position of bone ends after fracture: |
-Nondisplaced: Ends retain normal position
-Displaced: Ends are out of normal alignment. |
|
|
Completeness of break: |
-Complete: Broken all the way through.
-Incomplete: Not broken all the way through. |
|
|
Whether skin is penetrated:
|
-Open (compound): Skin is penetrated. -Closed (simple): Skin is not penetrated. Can also be described by location of fracture, external appearance, and nature of break. |
|
|
Fracture Tratment and repair
|
Treatment involves reduction, the realignment of broken bone ends. -Closed reduction: physician manipulates to correct position. -Open reduction: surgical pins or wires secure ends.
|
|
|
Immobilization
|
Immobilization of bone by cast or traction is needed for healing. -Time needed for repair depends on break severity, bone broken, and age of patient. |
|
|
Repair Involves four major stages |
-Hematoma formation -Fibrocartilaginous callus formation -Bony callus formation -Bone remodeling |
|
|
1.Hematoma Formation:
|
-Torn blood vessels hemorrhage, forming mass of clotted blood called a Hematoma. -Site is swollen, painful, and inflamed.
|
|
|
2.Fibrocartilaginous Callus formation |
|
|
|
3.Bony callus Formation |
|
|
|
4. Bone Remodeling
|
|
|
|
Bone Disorders
|
Imbalances between bone deposit and bone resorption underlie nearly every disease that affects the human skeleton.
|
|
|
Three major bone Diseases:
|
-Osteomalacia and rickets -Osteoporosis -Paget's disease |
|
|
Fracture Type: |
-Bones are poorly mineralized -Osteoid is produced, but calcium salts not adequately deposited. -Result is soft, weak bones. -Pain upon bearing weight. |
|
|
Rickets (Osteomalacia of children) |
-Results in bowed legs and other bone deformities because bones ends are enlarged and abnormally long. -Cause: Vitamin D deficiency or insufficient dietary calcium. |
|
|
Osteoporosis |
-Is a group of diseases in which bone resorption exceeds deposits. -Matrix remains normal, but bone mass declines. -Spongy bone of spine and neck of femur most susceptible. (Vertebral and hip fractures common) |
|
|
Osteoporosis risk factors |
-Most often aged, postmenopausal women. (Estrogen plays a role in bone density, so when levels drop at menopause, women run higher risk) - Men are less prone due to protection by the effects of testosterone. -Petite body form -Diet poor in calcium and protein. -Smoking -Insuficiente exercise to stress bone, |
|
|
Paget's Disease (pagetic bone) |
-Excessive and haphazard bone deposits and resorption cause bone to be made fast and poorly. -Very high ratio of spongy to compact bone and reduced mineralization. -Usually occurs in spine, pelvis, fémur, and skull -Rarely occurs before age 40. -Treatment includes calcitonin and bisphosphonates. |
|
|
Developmental Aspects of Bone |
-Embryonic skeleton ossifies predictably, so fetal age is easily determined from X rays or sonograms. -most long bones begin ossifying by 8 weeks, with primary ossification centers developed by week 12 |
|
|
Developmental Aspects of Bone |
-Embryonic skeleton ossifies predictably, so fetal age is easily determined from X rays or sonograms. -Most long bones begin ossifying by 8 weeks, with primary ossification centers developed by week 12 |
|
|
Birth to Young Adulthood |
-At birth, most long bones ossified, except at epiphyses. -Epiphyseal plates persist through childhood and adolescence. -At ~ age 25, all bones are completely ossified, and skeletal growth ceases. |
|
|
Age-Related Changes in Bone |
-In children and adolescents, bones formation exceeds resorption. (Males tend to have greater mass than females) -In young adults, both are balanced. -In adults, bones resorption exceeds formation. |
|
|
Aged- Related Changes in Bone |
-Bone density changes over lifetime are largely determined by genetics. *Gene for vitamin D's cellular docking determines mass early in life and osteoporosis risk at old age. -Bone mass, mineralization, and healing ability decrease with age beginning in fourth decade. *Except bones of skull. *Bone loss is greater in whites and females. |
|
|
Comminuted Fracture |
-Bone fragments into three or more pieces. -Particularly common in the aged, whose bones are more brittle. |
|
|
Compression Fracture |
-Bone is crushed. -Common in porous bones (i.e, osteoporotic bones) subjected to extreme trauma, as a fall. (Crushed vertebrae) |
|
|
Spiral Fracture |
-Ragged break occurs when excessive twisting forces are applied to a bone. -Common sports fracture. |
|
|
Epiphyseal Fracture |
-Epiphyseal separates from the diaphysis along the Epiphyseal plate. -Tends to occur where cartilage cells are dying and calcification of the matrix is occurring. |
|
|
Depressed Fracture |
-Broken bone portion is pressed inward. -Typical of skull fracture. |
|
|
Greenstick Fracture |
-Bone breaks incompletely, much in the way a green twig breaks. Only one side of the shaft breaks; the other side bends. -Common in children, whose bones have relatively more organic matrix and more flexible than those of adults. |
