Chapter 7: Bones Flashcards
osteology
the study of bones
the skeletal system is composed of
bones, cartilage and ligaments
purpose of cartilage
covers many joint surfaces
purpose of ligaments
bone to bone
purpose of tendons
muscle to bone
Functions of the skeleton
support, protect, movement, electrolyte balance, acid-base balance, blood formation
what is osseus tissue
connective tissue with the matrix hardened by calcium phosphate and other minerals
what is mineralization or calcification
the hardening process of bone
Flat Bones
thin,, curved plates that protect soft organs. sandwich like construction. Diploe = spongy middle layer
Long Bones
longer than wide; crucial for movement
Short bones
aproxx equal in length and width
Irregular bones
elaborate shapes
skeleton = 3/4 of what and 1/4 of what
3/4 = compact bone…..1/4 = spongy bone
Another name for growth plate
Epiphyseal plate; epiphyseal line is where growth plates used to be
Osteogenic Cells
Stem cells found in endosteum and inner layer of periosteum. Contually multiply. Come from Mesenchyme
Osteoblasts
Bone-forming cells. Single layer under endosteum and periosteum. Stress tells osteogenic to increase the number of osteoblasts. Also secrete osteocalcin which stimulates insulin secretion
Osteocytes
Former osteoblasts that become trapped in the matrix they deposited
Osteoclasts
Bone dissolving cells found in bone surface. Develop from bone marrow stem cells (WBC/Monocytes)
Matrix
1/3 organic and 2/3 inorganic matter
Organic Matter of the matrix
synthesized by osteoblasts. Made of Collagen, carb-protein complex, glycosaminoglycans, proteoglycans and glycoproteins
Inorganic Matter of the matrix
85% hydroxyapatite, 10% calcium carbonate, 5% other minerals
Ceramic material
allows bone to support body weight without sagging
Polymer material
(protein) give the bones some flexibility
Bone Marrow
soft tissue occupying marrow cavities of long bones and small spaces of spongy bone
Red Marrow (Myeloid tissue)
hemopoetic- produces blood cells, in nearly every bone of children. In the skull, vertebrae, ribs, sternum, part of pelvic girdle and proximal heads of humerus and femur
Yellow Marrow
Fatty marrow that does now produce blood.
Ossification or Osteogenesis
the formation of bone
Bone develops how in the infant and fetus
Either intramembranous ossification (flat bones, long bones) or endochondral ossification (taking cartilage to create bone)
Bone Elongation
epiphyseal plate - cartilage transitions to bone
Interstitial growth - growth from within
Achondroplastic Dwarfism
long bones stop growing in childhood, failure of cartilage growth in metaphysis
Pituitary Dwarfism
lack of growth hormone, normal proportions with short stature
Bone Remodeling
Breakdown and rebuilding (absorption and deposition) occurs throughout life (10% of skeleton per year)
Wolff’s Law of Bone
architecture of bone determined by mechanical stress placed on it
Physiology of Osseus Tissue
involved in its own maintenance. Influences the rest of the body by exchanging minerals with tissue fluid. Disturbance of calcium homeostasis in skeleton disrupts function of other organ systems.
Mineral Deposition (mineralization)
Process in which calcium, phosphate and other ions are taken from blood and DEPOSITED in bone
Mineral Resorption
Process of dissolving bone and releasing minerals into the blood
Purpose of Phosphate
component of DNA, RNA, ATP, phospholipids and pH buffers
Purpose of Calcium
needed in Neuron communication, muscle contraction, blood clotting and exocytosis. 1,100 g in adult body (99% in bones). 18% exchanged with blood every year. 9.2-10.4 mg/dL in blood plasma
Purpose of minerals
Deposited in skeleton and withdrawn into the blood when they are needed for other purposes.
Hypocalcemia
deficient calcium in blood
Hypercalcemia
excessive calcium levels
Calcitonin
Secreted by C cells (clear cells) of thyroid gland when blood calcium levels are too high. Blood calcium levels are lowered 2 ways = Inhibit osteoclasts and Stimulates osteoblasts
Calcitriol
most active form of Vit D. Hormone that raises blood calcium levels
3 Hormones responsible for Calcium Homeostasis
Calcitriol, PTH and Calcitonin
PTH (parathyroid hormone)
secreted by PT glands on posterior surface. Released when calcium levels are low in blood.
Rickets
softness of bones in children
Osteomalacia
softness of bones in adults
Orthopedics
branch of medicine dealing with prevention and correction of injuries and disorders of bones, muscles and joints
Stress Fracture
break caused by abnormal trauma to a bone
Pathological Fracture
break in a bone weakened by disease ( such as bone cancer or osteoporosis)
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
Cast
used to stabilize and immobilize healing bones
Osteoporosis
most common bone disease; severe loss of bone density due to loss of matrix and minerals
Effect of estrogen on bones
maintains bone density in both sexes, inhibits resorption by osteoclasts
How to treat osteoporosis
ERT (estrogen replacement therapy), slows bone resorption (breakdown) but increases risk of breast cancer, stroke and heart disease.
PTH slows bone loss if injected daily
Also treat by exercise and diet