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Chapter 6 Skeletal System

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Skeleton
Bony framework that supports and protects organs and allows movement of the body.
Periosteum
membrane on outside of bone
4 types of CT
1. Cartilage
2.Bone
3.Bone Marrow
4. Periosteum
Functions of Bone
Movement, Protection, Support, Mineral Storage, Hemopoeisis, Energy Storage
Movement
Bone provides leverage for muscle contraction
Protection
Bone protects internal organs from physical injury.
Support
Bone supports soft tissue and provides a point of attachment for skeletal muscles
Hemopoeisis
Blood cell production occurs in RED bone marrow
Energy storage
YELLOW bone marrow contain lipids, an important source of energy.
Axial portion
80 bones that arranged along the longitudinal axis of the body.
Appendicular portion
126 bones appendages
Classification of bones
Long bones, short bones, flat bones, irregular bones, suture bones, sesamoid bones.
Long bones
Longer than they are wide(femur)
Short bones
cube shaped(tarsals)
Flat bones
ribs, sternum, scapula, cranium
Irregular bones
complex shape(vertebrae)
Suture bones
found in cranium(coronal suture)
Sesamoid bones
small bones embedded in tendon (patella)
Proximal Epiphysis
proximal end of a long bone, which is spongy(cancellous) bone arranged in laticework of thin plates
Trabeculae
Laticework of thin plates in end of long bone
Diaphysis
shaft of long bone, which is compact bonce tissue made of concentric rings of hard bone
Distal epiphysis
distal end of a long bone, with the same structure as the proximal epiphysis
Metaphysis
(neck) area where the diaphysis joins the epiphysis
Epiphyseal plate
in growing long bones, a layer of hyaline cartilage that allows the diaphysis to grow in length.
Medullary cavity
where yellow bone marrow is found
Articular cartilage
found where two bones come together(joint). Thin layer of hyaline cartilage that coves the epiphyses. Function is to reduce friction at joint and absorb shock.
Periosteum
thin layer of dense CT membrane around the surface of a bone.
Function of periosteum
repair and nutrition of bone. Also tendons and ligaments attach to it.
Endosteum
membrane that lines the medullary cavity of the bone. It contains osteoprogenitor cells and osteoclasts.
Four types of cells in bone
Osteoprogenitor, Osteoblasts, osteocyte, osteoclast
Osteoprogenitor
Found in inner portion of the periosteum, in the endosteum and canals in bone that contain blood vessels. Function: to undergo mitosis and become osteoblasts.
Osteoblasts
cells that form bone tissue. They secrete collagen and matrix which calcifies to build bone tissue.
Osteocyte
Mature bone cells, the main cells of bone tissue. They maintain bone tissue by exchanging nutrients and wastes with the blood.
Living bone
bone cells and collagen fibers
Non-living bone
Hydroxyapatite
Hydroxyapatite
calcium, phosphorus, and chemical components of the matrix
Youth
1:1
Adult
1:2
Elderly
1:3
Bone remodeling
continuous ongoing replacement of old bone tissue with new bone tissue
Remodeling
osteoblasts are constantly forming new bone tissue, and osteoclasts are constantly destroying old bone tissue
Calcium homeostasis
calcium ion level in the blood is strictly regulated, regulated by parathyroid glands and thyroid gland
Parathyroid gland
secrete PTH, increased PTH equals increased blood calcium level
Thyroid gland
secretes the hormone calcitonin, increased calcitonin equals decreased blood calcium level
Repair of bone
1. Fracture Hematoma
2. Fibrocartilaginous callus
3. Bony callus
4.Remodeling
Fracture Hematoma
formation of a blood clot under skin
Fibrocartilaginous callus
organization of the fracture hematoma into granulation tissue called a procallus
Bony callus
Fibrocartilagious(soft) callus becomes bony(hard) callus.
Remodeling
restoration of the bone to near original structure and form
Compact (dense) bone
Consists of osteons with very little space between them
Composes bone tissue of the diaphysis
Function is to protect and support
Haversion canal
dark spot in the middle of compact bone
Spongy bone
1. Done NOT contain osteons
2. Consist of trabeculae surrounding many red-marrow filled spaces.
3. Found in short, flat and irregular bones and in the epiphyses of long bones.
Function is to store RED marrow and provide some support
Ossification
Bone formation
Epiphyseal plate
layer of hyaline cartilage in the metaphysis of growing bone
Structure of the epiphyseal plate
1. Zone of resting cartilage
2. Zone of proliferating cartliage
3. Zone of Hypertrophic cartilage
4. Zone of calcified cartilage
Zone of Resting cartilage
Anchors the epiphyseal plate to the bone of the epiphysis
Zone of Proliferating Cartilage
layer of chondrocytes stacked like coins in columns
Zone of Hypertrophic Cartilage
large chondrocytes, stacked in columns
Zone of Calcified cartilage
only a few cells thick. Calcified matrix, cements epiphyseal plate to the bone of the diaphysis.