Key Terms
Lengthening
Chondrocytes divide at epiphyseal plate; new cartilage replaces old; osteoblasts replace cartilage with bone on diaphyse
Epiphyseal plate closure
~age 18 in females, ~age 21 in males; cartilage replaced by bone; bone stops lengthening
Thickening (appositional growth)
Osteoblasts add bone at surface; osteoclasts remove bone from inner surface; balance prevents excessive weight gain
Bone remodeling
Continuous throughout life; 5-7% of bone mass recycled every week
Bony callus
Fibrocartilage converts to spongy bone; bone ends firmly joined (~2 months) 4. Remodeling: osteoclasts and osteoblasts r
Cross-bridge cycle
1. Myosin head (cocked, high-energy; ADP + Pi attached) binds to exposed actin site 2.
Sequence
Neural signal -> ACh release -> depolarization -> calcium release -> cross-bridge formation -> contraction