A&P: Bones
Sex Hormones
estrogen & testosterone, secreted in large amounts in puberty which dramatically accelerates bone growth
Ossification (osteogenesis)
*either endochondral or intramembraneous* formation/development of bone CT; begins in embryo
Epiphyseal Plate
*in the metaphysis* a growth plate composed of hyaline cartilage, provides lengthwise bone growth; turns into epiphyseal line in adults
Phosphate
ATP utilization and plasma membrane
Central Canal
Cylindrical channel at center of osteon and parallel to it; blood vessels and nerves extend through channel
Hemopoiesis
blood cell production, occurs in red bone marrow connective tissue,and stem cells form blood cells and platelets
Appositional Growth
bone growth in diameter or thickness; occurs within periosteum
Interstitial Growth
bone growth in length
Parallel Lamellae
bone matrix, osteocytes between lamellae, canaliculi radiate from lacunae
Skeletal System
bones of skeleton, cartilage, ligaments, connective tissue
Storage of Minerals and Energy Reserves
bones store body's reserve of calcium and phosphate (released as needed); lipids stored in yellow bone marrow of adult bones
Interstitial Lamellae
components of compact bone between osteons; are incomplete and have no central canal
Bone Matrix
composed of organic and inorganic components
Compact Bone
comprised of small cylindrical structures (osteons); oriented parallel to bone diaphysis
Articular Cartilage
covers joint surface, thin layer of hyaline cartilage,reduces friction, and absorbs shock in moveable joints
Irregular Bones
do not fit any other category (Ex: vertebrae, hip bones, some facial bones)
Diaphysis
elongated, cylindrical shaft; provides leverage and weight support; compact bone with thin spicules of spongy bone extending inward
Proximal Epiphysis
end of bone closet to appendage joint
Distal Epiphysis
end of bone farthest from appendage joint
Calcium
essential for muscle contraction, blood clotting, and nerve impulse transmission
Flat Bones
flat, thin surfaces (may be curved slightly), provide surfaces for muscle attachment (Ex: roof of skull, sternum, ribs, scapula)
Long Bones
greater in length than width; elongated with cylindrical shaft (diaphysis); found in upper and lower limbs;most common bone shape (Ex: humerus, femur, tibia)
Glucocorticoids
group of steroid hormones; released from adrenal cortex; regulates blood glucose level; high amounts increases bone loss
Medullary Cavity
hollow, cylindrical space within diaphysis; contains red marrow in children & yellow marrow in adults
Epiphysis
knobby region at each end of long bone; composed of outer thin layer of compact none (inner region of spongy bone); covered by articular cartilage
Short Bones
length nearly equal to width (Ex: carpals, tarsals, sesamoid bones, patella)
Osteocytes
mature bone cells; found in lacunae; maintain bone matrix
Mechanical Stress
occurs during weight-bearing movement/exercise; required for normal bone remodeling; causes an increase in synthesis of osteoid; causes increase in bone strength
Trabeculae
open lattice of narrow rods and plates of bones; bone marrow fills spaces; resistance to stresses
Organic Components of Bone Matrix
osteoid produced by osteoblasts (contains collagen protein & semi-solid ground substance); gives bone tensile strength by resisting stretching and contributes to bone flexibility
Growth Hormone (somatotropin)
produced by anterior pituitary gland; stimulates live to produce hormone-somatomedin (both stimulate cartilage growth in epiphyseal plate)
Metaphysis
region of mature bone between diaphysis and epiphysis
Perforating Canals (Volkmann)
resemble central canal, blood vessels and nerves travel through; perpendicular to central canals; connect central canals within different osteons
Concentric Lamellae
rings of bone CT; surround central canal; collagen fibers give bone strength and resilience
Circumferential Lamellae
rings of bone;either internal or external and both run the entire circumference of the bone
Inorganic Components of Bone Matrix
salt crystals, calcium phosphate, sodium, magnesium, sulfate - all interact with calcium hydroxide to form hydroxyapatite salt crystals; harden bone matrix and rigidity
Thyroid Hormone
secreted by thyroid gland; influences basal metabolic rate of bone cells; regulates normal activity at epiphyseal plates
Classes of Bones
short bones, long bones, irregular bones, & flat bones
Function of Bones
support/protection, movement, hemopoiesis, storage of mineral/energy reserves
Canaliculi
tiny,interconnecting channels within bone CT, extend from each lacuna, travel through lamellae and connect to lacunae and central canal; house osteocyte projections that allow intercellular contact; allow exchange of nutrients, minerals, gases, and wastes between blood vessels and osteocytes
Spongy Bone
trabeculae & parallel lamellae
