part 1 skeletal system

• functions of the skeletal system

  • support
  • protection
  • leverage + movement
  • mineral storage
  • blood production
  • energy storage
• functions of the skeletal system

  • support: provides framework for body, attachment for skeletal muscles through tendons
• functions of the skeletal system

  • protection of soft vital organs (brain, heart, lungs, spinal cord)
• functions of the skeletal system

  • leverage + movement: muscles contract to pull on bones to provide movement at joints in the skeleton
• a tendon is a dense regular connective tissue that attaches muscle to bone
• functions of the skeletal system

  • mineral storage: contributes to bone strength, stores phosphorus (needed to build ATP, protein, DNA) + calcium (needed for neuron + muscle use)
• functions of the skeletal system

  • blood production: red marrow produces blood cells
  • children produce most blood in long bones (ex femur)
  • adults produce most blood in flat + irregular bones (ex ribs, skull, pelvis, vertebrae, sternum)
• functions of the skeletal system

  • energy storage: yellow marrow stores lipid (fat = energy source)
• bones are rigid, calcified, supportive structures
• joints (articulates) are areas where bones connect other bones, allowing or preventing movement
• cartilage is a flexible but firm connective tissue that protects and cushions bones

  • hyaline cartilage protects the ends of bones and aids bone development
  • fibrocartilage is thick disks supporting spinal vertebrae
• adult skeleton usually has 206 bones
• babies are born with 300 bones

  • fuse together with aging, some cartilage / soft tissue develops into bone
  • allows for flexibility in during birth
• the two types of bone are compact bone and spongy bone
• compact bone is protective dense bone tissue structured into tightly packed columns of bone tissue
• spongy bone is small, needle-like pieces of bone with many open spaces

  • bone marrow is good for storage + blood cell formation
• the two divisions of the skeletal system are axial and appendicular
• the axial skeleton is the skull and bones that support the vertebral column, ribs, sternum

  • vertical axis of the body
  • protects vital organs in chest and CNS
• the appendicular skeleton is the limbs and all bones associated including hips, fingers
• the six classifications of bones are long, short, flat, irregular, sesamoid, and sutural
• long bones are longer than they are wide + fairly strong

  • mostly compact bone for strength
  • ex femur, tibia, fibula, humerus, fingers, toes
• short bones are as wide as they are tall + generally cube shaped

  • mostly spongy bone
  • ex wrist, ankle
• flat bones are thin, flattened, usually curved

  • thin layers of compact bone around middle layer of spongy bone
  • ex cranial, sternum, rib, scapula, ilium of coxal
• irregular bones is a catch all for complexly shaped

  • vertebrae, many facial bones, hip bones
• sesamoid bones are small bones usually located inside tendons, shaped like sesame seed

  • patella, ball of big toe
• sutural bones are small bones that sometimes form within suture joints of the skull
• functions of bones

  • support the body
  • protection of soft organs
  • storage of minerals and fats
  • blood cell formation (hematopoiesis)
• diaphysis is the shaft of a long bone

  • composed of compact bone
  • contains the periosteum, medullary cavity, and arteries
• periosteum is the outside covering of the diaphysis

  • fibrous connective tissue membrane
  • secured to underlying tissue via sharpey's fibers
  • location of bone stem cells
• medullary cavity

  • cavity in shaft
  • contains yellow marrow (mostly fat) in adults
  • contains red marrow (blood cell formation) in infants
• arteries supply bone cells with nutrients
• the epiphysis describes the ends of bones

  • composed of spongy bone
  • red marrow for blood cell formation
• epiphyseal line or plate

  • area for bone growth (ossification)
  • plate in youth, line in adults
• articular cartilage

  • covers external surface of epiphysis
  • made of hyaline cartilage
  • decreases friction at joints
• an osteon is a unit of compact bone
• an osteon contains lamellae, lacunae, canaliculi, central canal, perforating canal
• lamellae are concentric rings of bone matrix around the central canal
• lacunae are cavities containing osteocytes, arranged between lamellae
• canaliculi are tiny canals between lacunae that form a transport system for osteocytes to exchange materials
• the central canal is the opening in the center of an osteon that carries blood vessels and nerves