chapter 7: bone tissues

osteology

the study of bone

skeletal system

composed of bones, cartilages, and ligaments joined tightly to form a strong, flexible framework for the body

support, protection, movement, electrolyte balance, acid-base balance, blood formation

what is the seven roles of the skeleton?

osseous tissue

a connective tissue in which the matrix is hardened by the deposition of calcium phosphate and other minerals

mineralization

the hardening process

flat bones

what type of bones are the paired parietal bones that form the dome of the top of the head, the sternum (breast bone), scapula (shoulder blade), ribs, and hip bones?

long bones

what type of bones are the humerus, radius, ulna of the arm and forearm; the femur, tibia, fibula of the thigh and leg; and the metacarpals, metatarsals, and phalanges of the hands and feet?

short bones

what type of bones are the wrist and ankle?

irregular bones

what type of bones are the vertebrae and skull bones?

compact bone

the long bone is composed of an outer shell of dense white osseous tissue

marrow cavity

the shell that encloses a space, which contains bone marrow

spongy bone

at the ends of the bone, the central space is occupied by a more loosely organized form of osseous tissue

diaphysis

the shaft of a long bone

epiphysis

the expanded head at each end of the long bone

epiphyseal line

mature bones often exhibit what that is slightly denser spongy bone between the epiphysis and diaphysis

epiphyseal plate

a remnant of childhood growth zone called what

articular cartilage

the joint surface where one bone meets another is covered with a layer of hyaline cartilage called what?

nutrient foramina

blood vessels penetrate into the bone through minute holes

periosteum

a bone is covered with a sheath called what?

perforating fibers

some collagen fibers of the outer layer are continuous with the tendons that bind muscle to bone, and some penetrate into the bone matrix as what?

osteogenic

what layer is important to the growth of bone and healing of fractures?

endosteum

a thin layer of reticular connective tissue that lines the internal marrow cavity, covers all the honeycombed surfaces of spongy bone, and lines a canal system found throughout the compact bone

diploe

the spongy layer in the cranium

osteogenic cells

stem cells that develop from embryonic mesenchyme and then give rise most other bone cell types. they occur in the endosteum and inner layer of the periosteum.

osteoblasts

bone-forming cells that synthesize the organic matter of the bone and then promote its mineralization. they form rows in the endosteum and inner layer of the periosteum and resemble a cuboidal epithelium on the bone surface

osteocytes

former osteoblasts that have become embedded in the matrix they deposited

lacunae

osteocytes reside in cavities called what?

canaliculi

lacunae are interconnected by slender channels called what

dendrites

each osteocyte has delicate cytoplasmic processes that reach into the canaliculi to contact the processes from neighboring osteocytes

osteocalcin

osteoblasts and osteocytes secrete what hormone?

osteoclasts

bone-dissolving cells; they develop from the same bone marrow stem cells as blood cells

resorption bays

osteoclasts reside in pits called what

organic matter

synthesized by the osteoblasts, includes collagen and various protein-carbohydrate complexes such as glycosaminoglycans, proteoglycans, and glycoproteins

inorganic matter

85% hydroxyapatite, a crystallized calcium phosphate salt; 10% calcium carbonate; and many inorganic ions

spicules

spongy bone consists of a lattice of delicate slivers

trabecula

a thin plate or layer of tissue

bone marrow

soft tissue that occupies the marrow cavity of a long bone, the spaces amid the trabeculae of spongy bone, and the larger central canals

red bone marrow

tissue that produces blood cells; often described as hematopoietic tissue

yellow bone marrow

most red marrow in adults is replaced by what?

ossification

the formation of bone

intramembranous ossification

produces the flat bones of the skull, most of the clavicle, and part of the mandible

endochondral ossification

a process in which a bone develops from preexisting model composed of hyaline cartilage

endochondral

what type of ossification develops the vertebrae, ribs, sternum, scapula, pelvic girdle, and bones of the limbs

metaphysis

the transitional zone, facing each marrow cavity called what?

interstitial growth

cartilage growth from within, by the multiplication of chondrocytes and deposition of new matrix in the interior called what?

appositional growth

the deposition of new tissue at the surface

wolff’s law of bone

the architecture of a bone is determined by the mechanical stressed placed upon it, and the bone thereby adapts to withstand them

mineralization

a crystallization process in which calcium, phosphate, and other ions are taken from the blood plasma and deposited in bone tissue

ectopic ossification

abnormal calcification of tissues

calculus

a calcified mass in an otherwise soft organ

mineral resorption

the process of dissolving bone

hypocalcemia

a calcium deficency

hypercalcemia

a calcium excess

calcitriol

a form of vitamin D produced by the sequential action of the skin, liver, and kidneys

calcitonin

produced by a parafollicular (clear, C) cells of the thyroid gland; it is secreted when the blood calcium concentration too high

parathyroid hormone

raises the blood calcium concentration by stimulating bone resorption by osteoclasts, promoting intestinal absorption of calcium, and inhibiting urinary excretion of calcium

calcitonin

promotes mineralization and lowers blood Ca2+ concentration in children, but usually has little effect in adults; may prevent bone loss in pregnant and lactating women

calcitriol

promotes intestinal absorption of Ca2+ and phosphate; reduces urinary excretion of both; promotes both resorption and mineralization; stimulates osteoclasts activity

cortisol

inhibits osteoclast activity, but if secreted in excess, can cause osteoporosis by reducing bone deposition, inhibiting growth hormone secretion, and stimulating osteoclasts to resorb bone

estrogen

stimulates osteoblasts and adolescent growth; prevents osteoporosis

growth hormone

stimulates bone elongation and cartilage proliferation at epiphyseal plate; increases urinary excretion of Ca2+ but also increases intestinal Ca2+ absorption, which compenstates for the loss

insulin

stimulates bone formation; significant bone loss occurs in untreated diabetes mellitus

parathyroid hormone

indirectly activates osteoclasts, which resorb bone and raise blood Ca2+ concentration; inhibits urinary Ca2+ excretion; promotes calcitriol synthesis

testosterone

stimulates osteoblasts and promotes protein synthesis, thus promoting adolescent growth and epiphyseal closure `

thyroid hormone

essential to bone growth; enhances synthesis and effects of growth hormone, but excesses can cause hypercalcemia, increase Ca2+ excretion in urine, and osteoporosis

vitamin A

promotes glycosaminoglycan synthesis

vitamin C

required for collagen synthesis, bone growth, and fracture repair

stress fracture

a break caused by abnormal trauma to a bone

pathological fracture

a break in a bone weakened by some other disease, such as bone cancer or osteoporosis, usually caused by a stress that wouldn’t normally fracture a bone

closed reduction

a procedure in which the bone fragments are manipulated into their normal positions without surgery

open reduction and internal fixation

surgically exposing the fractured bone and using plates, screws, or pins to realign the fragments

osteitis deformans

excessive proliferation of osteoclasts and resorption of excess bone, with osteoblasts attempting to compensate by depositing extra bone

osteomyelitis

inflammation of osseous tissue and bone marrow as a result of bacterial infection

osteogenesis imperfecta

a defect in collagen deposition that renders bones exceptionally brittle, resulting in fractures present at birth or occurring with extraordinary frequency during childhood; also causing tooth deformity, and hearing loss due to deformity of middle-ear bones

osteosarcoma

the most common and deadly form of bone cancer