functions of the bones
support
protection
movement
mineral storage
hematopoiesis
energy storage
how do bones support ?
-form framework of body
-support muscles, fat and skin
-maintain body shape and posture
how do bones protect us?
protect vital organs
-skull protects brain
-ribs protect heart and lungs
-vertebrae protect spinal cord
-pelvis protects reproductive and lower organs
how do bones help movements?
-act as attachement points for muscles
-allow mobility and flexability
-muscle contractions pull on bones= movement
mineral storage in bones
serve as a reservoir
-calcium, phosphorus
-minerals released from bones to blood as needed to maintain homeostasis
hematopoiesis
blood cell production
-occurs in red bone marrow
produces: RBC, WBC, platelets
Energy storage within bones
(mostly in long bones)
yellow bone marrow stores fat as an energy reserve
skeletal divisions
206 bones divided into 2 groups
-axial skeleton (80 bones)
-appendicular skeleton (126 bones)
general bone features
compact bone
-strong dense outer layer
-gives bones strength for supporting the body
general bone features
spongy bone
-inner less dense layer
-contains a speculated network called trabeculae
general bone features
medullary cavity
central cavity of long bones
-in kids= red marrow
-in adults= yellow marrow (red when needed )
general bone features
bone marrow
fills in the bony trabeculations of spongy bone
-red marrow= produces RBC
-yellow marrow= stores fat for energy
general bone features
periosteum
tough outer membrane covering bones (not joints)
-blood vessels and nerves exit the bone through this
general bone features
endosteum
thin membrane lining the internal bone surfaces and marrow cavity
why bones are living organs
-need blood and nerve supply
-blood vessels and nerves enter/exit through foramen (hole)
-veins exiting bones carry blood to body
nutrient foramen
small hole in periosteum
-allows nutrient artery to enter long bones
-supplies cancellous bone and marrow
ossification
term that applies to the development and formation of bones
bone development
begins in 2nd month of embryonic life
-two processes;
1) Intermembranous
2) Endochondral
intramembranous ossification
bone develops directly from embryonic tissue
-form flat bones (skull, mandible etc)
-bones not joined until after birth (form sutures)
endochondral ossification
bones that develop by replacing hyaline cartilage
-form short, irregular, and long
-occurs in TWO areas of development; PRIMARY and SECONDARY OSSIFICATION
endochondral ossification
primary ossification
begins before birth
-forms entire bulk of short and irregular bones as well as the central shaft of long bones
endochondral ossification
secondary ossification
occurs after birth
-seperate bones begin to develop at both ends of long bones
- ends are called epiphyses or epiphyseal plates
bone shape classifications
classified based on shape and function
long bones
short bones
flat bones
irregular bones
sesamoid bones
long bones facts
found only in limbs
-longer than wide
-act as levers, aid in movement
-femur, humerus, radius, tibia, metacarpals, metatarsals
