Skeletal System
Bones seen in everyday life
The Skeletal System
 A human system
 Organs?
 Functions?
 The bones of the skeletal system differ greatly from
one another
 Shapes
 Long
 Short
 Flat
 Irregular
 Sesamoid
Overview of the system
 Made up of osseous tissue
 Functions
 Support/Protection
 Movement
 Blood Cell
 Storage
 206 bones
Parts of a Long Bone
 Epiphysis
 Ends of bones
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Helps to articulate with other bones
Proximal/Distal
Hyaline Cartilage
 Diaphysis
 Shaft
 Periosteum
 Encloses bone
Bone Tissue
Within Long Bones
 Compact Bone
 Found in diaphysis
 Tightly packed tissue
 Spongy Bone
 Found in epiphysis
 Thin layers of bone
 Irregular connections results in lighter bones
Structure Contd.
 Medullary Cavity
 Hollow chamber filled with marrow


Red-Blood
Yellow- Fat
 Lined by the endosteum
 Like any other molecule, the specific shape determines a bone’s function
 Condyle/Epicondyle
 Crest
 Facet
 Foramen
 Fossa
 Fovea
 Head
 Process
 Spine
 Suture
 Trochanter
 Tubercle
 Tuberosity
 How do they all work?
 P.144
Bone Growth and Development
 Two types of bones
 Intramembranous
 Endochondral
 All bones start as connective tissue
 During fetal development, connective tissue is replaced
by bone tissue
 Bone Growth
Intramembranous
 Broad, flat bones of the skull
 Start off as layers of undifferentiated connective tissue
 Progenitor cells
 Osteoblasts
 Osteoclasts
 Osteocytes
 Ossification
Endochondral
 All other bones in the body
 Start off as masses of hyaline cartilage
 Change starts in center of bone
 Primary ossification
 Secondary ossification
 Epiphyseal plate
 Between two ossification centers
Bone Homeostasis
 Cycle of resorption and deposition of bone matrix
 Osteoclasts
 Osteoblasts
 Other factors
 Nutrition
 Exercise
 Hormonal Secretions

Blood Calcium Levels
 Examples?
Storage of Salts
 Calcium
 Stored as calcium phosphate in bones
 Homeostatic mechanism
 Blood calcium level=High

Thyroid releases calcitonin
 Osteoblasts deposit more calcium
 Osteoclast activity is inhibited
 Blood calcium level=Low
 Parathyroid releases PTH
 Osteoclasts break down bone to release calcium
 Negative Feedback
Support and Protection
 Support
 What bones support most of the body’s mass?
 Protection
 Which bones protect vital organs in the body?
 Where/which organs?
Body Movement
 How does our body move?
 Levers
 Fulcrum
 Load
 Effort
 Very inefficient

Why?
Movements within the Body
 Flexion
 Pronation/Supination
 Extension/Hyperextensio  Eversion/Inversion
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n
Dorsiflexion
Plantar Flexion
Abduction
Adduction
Rotation
Circumduction
 Retraction
 Protraction
Skeletal Organization
 Divided into two major portions
 Axial and Appendicular

Which is green/purple?
 Bones of the axial skeleton
 Cranium/Facial Bones
 Hyoid
 Vertebral Column

Sacrum/Coccyx
 Thoracic Cage

Ribs/Sternum
Organization Contd.
 Appendicular Skeleton
 Pectoral girdle
 Scapula/Clavicle
 Upper Limbs
 Humerus
 Radius/Ulna
 Carpals/Metacarpals/Phlanges
 Pelvic Girdle
 Hip Bones
 Lower Limbs
 Femur
 Tibia/Fibula
 Patella
 Tarsals/Metatarsals/Phalanges