A&P unit 4 - skeletal system

5 functions of the skeletal system

Support, protection, storage, manufacturing, movement

Bones

a solid matrix of living cells and fibers surrounded by calcium deposits

Classification of bones

by shape (flat, short, long, sesamoid, irregular)

Diaphysis

shaft, long part of bone

Epiphyses

ends of bone

Epiphyseal Plate/Growth plate

Inbetween epiphyses and diaphysis— a thin layer of internal cartilage

Articular Cartilage

located at the ends of the epiphyses and covers it with an external layer of cartilage. Provides smooth movement of joints and cushions from shock.

Medullary Cavity

In the diaphysis and has red bone marrow

Red bone marrow

Fills the medullary cavity (young people) New blood cells are produced here.

Yellow bone marrow

filled with adipocytes

Hematopoiesis

Production of new blood cells

Periosteum

Tough connective tissue that is the location of muscle attachment and bone repair. Makes up the outer layer of bone.

Compact Bone

Beneath the periosteum. dense, hard outer layer of bone tissue arranged into osteons.

Spongy Bone Layer

beneath compact bone and at the ends of long bones

Lattice of trabeculae

“little beams”, between this are spaces filled with marrow or blood vessels.

Spongy bone

A lattice of trabeculae found along lines of stress for perfect resistance from compression

Compact bone

arranged in cylinders called osteons.

Osteons

Arranged in concentric circles called lamellae

Lamallae

Surrounds a central/haversian canal that contains blood vessels and nerves

Central/Haversian Canal

Contains blood vessels and nerves

How are Haversian/Central canals connected?

connected by perforating/volkmann’s canals running perpendicularly.

Osteocytes

Mature bone cells make up the majority of the bone structure. Connected with tentacle-like canaliculi

Canaliculi

connects all bone cells, allowing them to receive nutrients and remove wastes

Both osteoclasts and osteoblasts

Line the Haversian canals and the surfaces of the compact & spongy bone

Osteoclasts

break down bone

osteoblasts

produce new bone

ossification

the process of incorporating calcium and minerals into cartilage to become bone

chondrocytes

cartilage cells

Organic Composition of bone

35% osteoid, provides flexibility and tensile strength required to keep bones from constantly breaking

Composition of bone

organic and inorganic

Inorganic composition of bone

65% mineral salts, christalline salts made of hydroxyapatites, provides bone strength and hardness

Brittle Bone Disease

lack of collagen causes this disease

Rickets

Lack of hydroxyapatite causes this

2 hormones that help in maintaining calcium levels

calcitonin and parathyroid hormone

Calcium is too low

Parathyroid glands produce PTH

Calcium is too high

Thyroid gland produces calcitonin

Repairing broken bone

1. hematoma forms, 2. callus forms. 3, callus ossifies, 4. Compact bone forms.

Hematoma forming

1st stage of repairing bone. Blood enters the wound. Cells begin to die. Phagocytes ingest dead bone cells and debris

Callus Forming

2nd stage of repairing bone. Blood vessels grow. Cartilage forms to hold the bone together

Callus ossifies

3rd stage of repairing bone. Spongy bone forms to replace the cartilage

Compact bone forming

4th stage of repairing bone. Osteoclasts form a larger medullary cavity. Spongy bone is converted to compact bone.

2 major sections of the skeleton

Axial and appendicular skeleton

Axial Skeleton

central axis of the body. Skull, ribs, sternum and vertebrae (80)

Appendicular Skeleton

Pectoral and Pelvic girdles. Bones of arms, legs, pelvis, and shoulders (126)

Bones found in axial skeleton

Cranium, mandible. cervical vertebrae, ribs, manubrium, sternum, thoracic verterae, lumbar vertebrae, sacrum coccyx

Bones of the cranium

frontal, sphenoid, ethmoid, temporal, parietal, occipital

Other major facial bones

nasal, lacrimal, maxilla, zygomatic, mandible.

Vertebral column

extends from the skull to the pelvis. provides support and protects the spinal cord running through it.

5 sections of the vertebral column

cervical, thoracic, lumbar, sacral, coccyx

Fused vertebrae

Sacral and coccyx

remaining vertebrae that arent fused

separated by intervertebral discs that provide cushioning and absorb shock.

Unfused vertebrae

cervical, lumbar, thoracic

function of primary convex and secondary concave curvatures of the spine

allows for better balance and distribution of weight throughout the body.

Bones found within appendicular skeleton

clavicle, scapula, humerus, radius, ulna, carpals, metacarpals, phalanges, pelvic girdle, femur, patella, tibia, fibula

Fibrous joints

immovable or slightly moveable, held together by fibrous connective tissue

Cartilaginous Joints

Immovable or slightly movable, held together by cartilage

Synovial Joints

Very moveable and has frictionless movement. Provides a range of movements based on the shape of the bones involved

Structure of synovial joints

*Joint capsule filled with synovial fluid surrounding the end of the bones
-synovial membrane and articular cartilage line the joint cavity
* ligaments attach the bones of the joint.

ligaments

connect bone to bone

tendons

connect muscle to bone

pivot joint

between c1 and c2 vertebrae

saddle joint

between trapezium carpal bone and first metacarpal bone

ball and socket joint

hip

condylar joint

between radius and carpal bones of wrist