Chapter 7 - Bones Flashcards
cartilage
covers many joint surfaces of mature bone
ligaments
hold bones togetther at joints
tendons
attach muscle to bone
functions of skeleton
- support
- protection
- movement
- electrolyte balance: phosphate/calcium levels
- acid-base balance: buffers blood against large pH changes by altering phosphate and carbonate salt levels
- blood formation: red bone marrow is producer of blood cells
flat bones
- thin, curved plates
- protect soft orgrans
- ex. skull bones
long bones
- longer than wide
- rigid levers acted upon muscles; crucial for movement
short bones
- approximately equal in length and width
- glide across one another in multiple directions
irregular bones
- elaborate shapes that do not fit into other categories
compact bone
dense outer shell of bone
spongy bone
- loosely organized bone tissue
- found in the center of ends and shafts of long bones and in the middle of nearly all others
- covered by compact bone
anatomy of a long bone
diaphysis
elongated, cylindrical shaft
anatomy of a long bone
epiphysis
knobby region, joint, surface for bone to bone articulation, tendon and ligament attachment
anatomy of a long bone
metaphysis
region found between the diaphysis and epiphysis, contains the epiphyseal growth plate
anatomy of a long bone
epiphyseal line
remnant of the growth plate, made of a thin layer of compact bone
general features of bones
articular cartilage
layer of cartilage that covers joint surface; allows joint to move more freely
general features of bones
nutrient foramina
minute holes in the bone surface that allows blood vessels to penetrate
(little holes)
general features of bones
periosteum
external sheath covering most of bone
* outer fibrous layer of collagen
- some fibers continuous with tendons
- perforating fibers: penetrate into bone matrix
* inner osteogenic layer of bone-forming cells
- important to bone growth and healing of fractures
osteogenic cells
stem cells found in endosteum and inner layer of periosteum
* arise from embryonic mesenchyme
* multiply continuously and give rise to most other bone cell types
osteoblasts
bone forming cells
* hardens when minerals are deposited
* stress stimulates osteogenic cells to multiply repidly and increase the number of osteoblasts which reinforce bone
** osteocalcin:** hormone stimulates insulin secretion of pancreas
osteocytes
osteoblasts that have become trapped in the matrix
* act as strain sensors: when stressed, produce biochemical signals that regulate bone remodeling
osteoclasts
blone-dissolving cells found on bone surface
* cells often reside in resorption bays
* dissolving bone is part of bone remodeling
* repairs microfractures, releases minerals into blood, reshapes bones in response to use/disuse
bone marrow
soft tissue occupying marow cavities of long bones and small spaces of spongy bone
red marrow (myeloid tissue)
- contains hemopoietic tissue (which produces blood cells)
- in children: found in every bone
- adults: found in skull, vertebrae, ribs, sternum, pelvic gridle
calcium homeostasis
- phosphate is a component of DNA, RNA, ATP, phospholipids, and pH buffers
- calcium needed in neuron communication, muscle contraction, blood clotting, and exocytosis
minerals deposited into skeleton, withdrawn when needed for above purposes ^
calcitriol
- most active form of vitamin D
- produced by actions of skin, liver, and kidneys
- hormone that raises blood calcium level
rickets/osteomalacia
inadequate calcitriol results in abnormal softness of bones in children and adults
calcitonin
secreted by the thyroid gland when blood calcium levels rise too high
* lowers blood calcium concentration
* may inhibit bone loss in pregnant and lactating women
parathyroid hormone
PTH: secreted by parathyroid glands
* released when calcium levels low in blood
orthopedics
branch of medicine dealing with prevention and correction of injuries and disorders of bones, joints, and muscles
achondroplastic dwarfism
- long bones stop growing in childhood
- normal torso, short limbs
- failure of cartilage growth in metaphysis
- spontaneous mutation produces mutant dominant allele (doesn’t have to have a genetic componet)
pituitary dwarfism
- lack of growth hormone
- normal proportions with short stature
anabolic steroid affect on bone
- cause growth to stop
- epiphyseal plate “closes” prematurely
- results in short adult stature
stress fracture
break caused by abnormal trauma to a bone (ex. in a fall)
pathological fracture
- break in bone weakened by disease (such as bone cancer or osteoporosis)
- usually caused by a stress that would not break a healthy bone
4 types of bone fractures
- nondisplaced
- displaced
- comminuted: shatter plates
- greenstick: bends then splinters
fractures
4 steps of the healing process
- hematoma formation
- soft callus formation
- hard callus formation
- bone remodeling
closed reduction
procedure in which bone fragments are manipulated into their normal positions without surgery
open reduction
involves surgical exposure of the bone and the use of plates, screws, or pins to realign the fragments
cast
normally used to stabilize and immobilize healing bone
osteoporosis
the most common bone disease
* severe loss of bone density
* estrogen: maintains bone density in both sexes; inhibits resorption by osteoclasts
* postmenopausal white womens at greatest risk
* young female athletes with low body fat, stop ovulating
treatments of osteoporosis
ERT: estrogen replacement therapy slows bone resorption, but increases risk of breast cancer, stroke, heart disease
Drugs: fosamax, actonel: destroy osteoclasts
PTH: slows bone loss if given as daily injection (2 year max = leads to bone cancer
Prevention = best treatment = exercise
