Chapter 6 - copy
Where are the triglycerides stored in the bone?
adipose cells of the yellow marrow
What is the diaphisis?
shaft or body of a long bone that is long, cylindrical, and main portion of the bone
What is the epiphyses?
the proximal and distal ends of the long bone
What are the functions of the skeleton system?
support, protect internal organs, assist in movement, mineral homeostasis, blood cell reproduction, stores triglycerides
What does the axis skeleton contain?
80 bones (cranium-8, face-14, hyoid bone-1, auditory ossicles-6, vertebral column-26, thorax(sternum-1, ribs-24)
What does the appendicular skeleton contain?
126 bones, pectoral(clavicle-2, scapula-2), upper limbs( humerus-2, ulna-2, radius-2, carpals16, metacarpals-10, phalanges-28), pelvic(coxal bone-2), lower limbs(femur-2, patella-2, fibula-2, tibia-2, tarsals-14, metatarsals-10, phalanges-28)
Long bone shape
greater in length than width
Short bone shape
cube-shaped
Flat bone shape
thin layers of parallel plates
Irregular bone shape
complex shape
Seasamoid bones shape
shaped like a sesame seed
What is a metaphyses?
region between the diaphysis and epiphyses, contains growth plate during growing ages then it becomes the epiphyses line
What is articular cartilage?
thin hyaline cartilage that covers the part of the epiphysis that forms an articulation with another bone
What reduces friction and shock to freely movable joints?
articular cartilage
What is the medulla cavity?
hollo, cylindrical space in the diaphysis that contains fatty yellow bone marrow and numerous blood vessels in the adult
What is the endosteum?
thin membrane that lines the medulla cavity containing a single layer osteoblasts, osteoclasts, and connective tissue
What is the periosteum?
tough, connective tissue sheath and blood supply that surrounds the bone surface where it is NOT covered by cartilage
What helps the bone w/ repairs, protection, nourishment, and muscle/ligament attachments?
periosteum
What is the periosteum made of?
outer fibrous layer of dense irregular connective tisse, inner layer of osteogenic of cells
What attaches to bone by peforating fibers (Sharpey's fiber) consisting of collagen fiber?
periosteum
Where are blood cells formed?
in between the trabeculae of the spongy bone in the adipose tissue
What determines a bone's hardness?
crystallized mineral salts
What determines a bone's flexibility?
collagen fibers
What conists of a layer of hyaline cartilage and allows the bone grow in length?
epiphyseal plate
What happens when the bone is done growing?
the epiphyseal plate is replaced with bone and then the epipyseal line is made
What is the most abundant chemical in the bone?
calcium phosphate
What is calcification?
when the mineral salts and collagen fibers harden in the bone that is initated by osteoblasts
What chemicals make up the bone?
extracellar matrix, calcium phosphate, calcium hydroxide, magnesium, fluoride, potassium, sulfate
What supplies the bone with blood and nerves?
Periosteal arteries and nerves enter diaphysis thru Volluman's canal and are accompanied by periosteal vein
How does the metaphysis and epipysis receive blood?
have own blood supply that enters along circular band between the growth plate and joint plate
How does the periosteal arteries and periosteal vein supply the bone?
they supply the superficial layer of cortex and connect w/ nutrient artery-if obstruction of artery, the vein can meet needs to both systems
What cells are in the bone?
osteoprogenitor cells, osteoblasts, ostesclasts, osteocytes
What is the only bone cell that can undergo cell division?
osteoprogenator cell
What develops when osteoprogenitor cells go through cell division?
osteoblasts
Where do bone cells derive from?
mesenchyme
Where do you find osteoprogenitor cells?
inner portion of periosteum, the endosteum, and bone canals that have blood vessels
What iniates calcification and is "bone-building" cells?
osteoblasts
What does osteoblast have to do with extracellar matrix?
to build the matrix, they synthesize collagen fibers and other organic components
How are osteoclasts formed?
when osteoblasts become surrounded by extracellar matrix and trapped in their own secretions
Where are osteoclasts located?
endosteum
What does osteoclasts do?
has lysomal enzyme and acids that digest protein and mineral components of the matrix
What is bone resorption?
breakdown of extracellar matrix that releases calcium from bone
Where are osteoclasts derived from?
the large cell comes from a fusion of monocytes
What are osteocytes?
mature bone cells, maintains bones daily homeostasis, main cell in bone tissue
Where are osteons found?
compact bone
How do osteons align?
parallel lines to length of diaphysis
How are osteons formed?
from concentric lamellae that surround a network of nerves and blood vessels called central canal
What are some of the features the compact bone have?
few spaces, strongest bone tissue, provides protection and support, resists stress cause by wt and movement. beneath peristeum, makes up most of diaphysis
Concentric Lamellae (compact bone)
rings of calcified matrix that surround a network of nerves and blood vessels called central (osteonic) canals and forms osteons
Central (osteonic) canal
network of nerves and blood vessels
Lacunae (compact bone)
small spaces between the concentric lamellae and contains osteocytes
Canaliculi (compact bone)
tiny channels that are filed with extracellar fluid that radiates out from the lacuna and provides routes for nutrients and oxygen and removes wastes
Interstitial Lamellae (compact bone)
areas between osteons and contains fragments of older osteons
Perorating Canals (compact bone)
where blood vessels and nerves penetrate the bone
Inner circumferential lamellae (compact bone)
lines the medullary cavity
Outer circumferential lamellae (compact bone)
lies deep to the periosteum and are connected to periosteum by perforating (Sharpey's) fibers
Called the "cancellous or trabecular" bone
spongy
Where is the spongy bone located?
interior of short, flat, seasmoid, and irregular bones, covered by compact bone
What does the spongy bone form?
core of the epiphysea of long bone
What has lamellae arranged in irregular pattern of thin columns (trabecular)?
spongy bone
What does the spongy not have?
osteons, epiphyses, diaphysis
What is between the spaces of trabeculae?
red bone marrow that produce RBC or yellow marrow in adipose tissue
What happens when a bone is placed under stress?
increase deposition of mineral salts and increase in collage fibers, production occurs and bone will remodel itself to become stronger
How can bone tissue strengthen?
mechanical stress
What are the main mechanical stress put on bones?
pull of skeletal bones and pull of gravity
Why is Vit A important in bone growth/remodeling?
stimulates activity of osteoblasts
Why is Vit C important in bone growth/remodeling?
collagen synthesis and its the main bone protein
Why is Vit D important in bone growth/remodeling?
increase absorption of calcium
Why is Vit K important in bone growth/remodeling?
production of proteins; essential for blood clotting factors
Why is Vit B12 important in bone growth/remodeling?
osteoblast function; RBC production
What is ossification (osteogenesis) of bone?
process of bone formation
When does ossification happen?
embryological and fetal developement, bone growth before adulthood, bone remodel, healing of fracture
Intramembrane (ossification)
occurs in flat bones when a connective tissue membrane is replaced by bone
Endochondral (ossification)
replaces cartilage with bone in developing embryo and fetus
Interstitial growth (endochondral ossification)
continual chondrocytes cell division and secretion of the cartilage extracellar matrix resulting in increase in length
Appositional growth (endochondrial ossification)
occurs when chondroblasts in perichondrium deposit extracellar matrix on surface of cartilage model resulting in growth of cartilage in width
Demineralization (aging bone)
loss of calcium and other minerals from matrix
Brittleness (aging bone)
caused by decrease in rate of protein synthesis
What regulates calcium exchange?
Parathyroid hormone (PTH)
What is secreted when calcium level drops and osteoclasts are stimulated to increase bone resorption and calcium is increased?
Parathyroid hormone (PTH)
What stimulates calcitrol by the kidneys to increase calcium absorption in intestines?
Parathyroid hormone (PTH)
What decreased excretion of calcium through urination by stimulating tubular resportion of calcium?
Parathyroid hormone (PTH)
This is controlled by negative feed back..
Parathyroid hormone (PTH)
Calcitonin
causes negative feedback by inhibiting PTH, by inhibiting the action of osteoclasts which decrease blood calcium and blood phosphate levels
Zone of resting cartilage (epiphyseal plate)
anchors epiphyseal plate to emphysis bone, does NOT participate in cell growth, lies next to epiphysis and consists of scattered chondrocytes
Zone of proliferating cartilage (epiphyseal plate)
larger chondrocytes stacked like coins that divide and secrete matrix-these chondrocytes replace those that died at diaphyseal side of epiphyseal plate
Zone of hypertrophic resting cartilage (epiphyseal plate)
consists of large, maturing chondrocytes arranged in columns
What is the final "zone" for epiphyseal plate?
calcified cartilage
What do osteoblasts and osteoclasts do in the zone of calcified cartilage?
osteoclasts dissolve calcified cartilage, osteoblasts lay down bone matrix replacing th calcified cartilage
What happens to cartilage in zone of calcified cartilage?
calcified cartilage becomes the "new diaphysis" attached to the rest of to diaphysis of the bone
What is a few cells thick?
Zone of Calcified Cartilage
Reactive phase (bone repair)
cells die resulting in swellling and inflammation, phagocytes (neutrophils and macrophanges) and osteaocytes begin to removed dead and damage tissue
The "early infammatory phase"
reactive phase
Reparative Phase (bone repair)
fibroblast produce collage fibers at fractue site, cells form chrondoblasts and form fibrocartilage and collage fibers form to bridge broken bone ends, osteogenitator develop to osteoblasts which begin to produce spongy bone trabeculae that join living and dead sections of bone, fibrocartilage is converted to spongy bone and callus which is called bony callus
Bone remodeling phase (bone repair)
last step-bony callus is remodeled, dead sections are resorbed osteoblasts, compact bone replaces spongy bone
osteoarthiritis
degeneration of articular cartilage so bones end touch causing friction of bones which worsens the condition, common in the elderly
osteoporosis
bone resorption outpaces bone deposit, cause due to calcium lost in urine, feces and sweat is more than calcium absorbed in diet. tx calcium and vitamin D, wt bearing exercise, hormone therapy, bone building meds
osteomalacia
adult form of rickets, new bone formed in remodeling does NOT calcify, bone fractures commone. tx vitamin D and sun exposure
Rickets
inadequate calcification of bone matrix due to deficiency in Vit D, occurs in children, soft rubbery bones, causes bowed legs and deformities in pelvis. tx vit D and sun exposure
osteomyelitis
infection of bone caused by Staph aureos, usually from surgeries, open fractures, penetrating wounds, UTIs, upper resp infection, adjacent tissue infection(diabetics) tx antibiotics, surgery
IGFs(insulin-like growth factors)-(hormones in bone growth)
produce liver and bone tissue
Growth hormone (hormones in bone growth)
promotes genera body growth including bones
Thyroid hormones (T3, T4) (hormones in bone growth)
stimulate osteoblasts
Insulin (hormones in bone growth)
increase synthesis of bone proteins
Sex hormones (hormones in bone growth)
promotes growth spurts, makes femine/masculine characteristics in bones, induces epiphyseal plate closure, ends longitude bone growth