Prayer Attendance Homework

Musculoskeletal System Ms. Doshi

Bone Structure Compact Bone Is composed of dense, hardened bone matrix Contains both organic and inorganic material Organic material: proteins (collagen fibers and glycoproteins) Inorganic material: Calcium, phosphate, and hydroxide (join to form hydroxyapatite crystals), as well as sodium, potassium, and magnesium ions. Hydroxyapatite crystals and collagen fibres give bone its strength.

Bone Structure: Microscopic The bony matrix is deposited (증착 Verb: 두다 , 퇴적시키다 , 보증금을 주다 , 낳다) in osteons (Haversian systems) Each osteon has a Haversian canal that has lamellae (circles of bony matrix) surrounding the canal. Inside the Haversian canals, there are blood vessels, nerve fibers, and lymph. The lacuna is a space inside the bone matrix. In these spaces (lacunae), are mature bone cells called osteocytes. Osteocytes help with bone maintenance. Canaliculi are small canals radiating (방사) from each lacuna. The canaliculi interconnect with each other and with Haversian canals. The canaliculi allow for exchange of nutrients and wastes.

Bone Cells Osteoblasts make and secrete the organic materials of the bone matrix. once they are surrounded by bone matrix, they become mature bone cells, osteocytes. Osteoclasts large, multinucleated cells that help in bone resorption. several = many

Questions Part 2-1

Bone Formation (Ossification) Two processes: endochondral ossification or intramembranous ossification. Endochondral ossification: Existing cartilage is replaced by bone. Example: long bone Intramembranous ossification: Mesenchymal (embryonic) connective tissue is transformed into, and replaced by, bone. Example: skull bones (except the mandible) http://m.youtube.com/watch?v=NM8zQLJ1ipQ

Bone Remodeling Bone matrix is dynamic (it continuously and simultaneously degrades and reforms) 2 processes for bone remodeling: bone reformation and bone resorption Bone reformation Inorganic ions (calcium and phosphate) are absorbed from the blood for use in bone formation Bone resorption the inorganic ions are released into the blood Vitamin D, and hormones, such as parathyroid hormone and calcitonin, help with regulating bone remodeling. Bone use and stress during exercise affect bone remodeling.

Joints Joints are connective tissue structures that join bones together. Immovable joints Bones that do not move relative to each other (서로에 대해 움직이지 않는다) are held in place by immovable joints Example: skull bones Movable joints Bones that move relative to each other (서로에 대해 이도) are held together by movable joints Movable joints are supported and strengthened by ligaments.

Movable Joint Synovial capsule (articular capsule) Synovial fluid surrounds the synovial (joint) cavity Synovial fluid Helps with movement Lubricates the joint Articular cartilage Reduces friction (마찰을 감소) during movement.

Questions Part 2-2