compa lecture3 skeletal system intro slides
TRANSCRIPT
The Skeletal System:
IntroductionIntroduction
Joel M. Chavez, PhD Biology (Cand.)
Functions of the skeletal system
• Gives shape
• Supports the body’s weight
• Provides a system of levers & together with
muscles produces movementmuscles produces movement
• Protects soft body parts
Organization of skeletal tissues: On the basis of
function
Exoskeleton
Keratinized exoskeleton (epidermal)
Bony exoskeleton (dermal)
Skeleton
Endoskeleton
Bony endoskeleton
Cartilaginous endoskeleton
Notochord
Organization of skeletal tissue: On the basis of
position
Cranial Skeleton
Splanchnocranium
Chondrocranium
Dermatocranium
Skeleton
Dermatocranium
Postcranial Skeleton
Axial skeleton
Vertebral column
Notochord
Appendicular skeleton
Limbs
Girdle
Histology of the skeletal system
Connective tissue
• Fibrous connective tissue
• Loose connective tissue
• Mesenchyme
• Adipose
Skeletal system
• Cartilage
• Hyaline• Adipose
• Areolar
• Hematopoetic tissue
• Myeloid/lymphoid tissue
• Blood
• Cartilage
• Hyaline
• Elastic
• Fibrous
• Bone
• Hyaline
• Elastic
• Fibrous
• Bone
Histology of the skeletal system
Comparisons Bone Cartilage
Type of cells Osteocytes Chondrocytes
Matrix composition Calcium phosphate Chondroitin sulfate
Type of
vascularization
Vascular Avascular
Degree of structural
organization
Highly organized
into osteons/
Haversian systems
Usually less
organized
Surface covering Periosteum Perichondrium
Bone• Specialized connective tissue
• Osteocytes are either– Osteoblast – bone forming cells
– Osteoclast – bone removing cells
• Composed of calcium phosphate in the form of hydroxyapatite– Invertebrate skeleton is composed of calcium
phosphate (also known as aragonite or calcite)
• Only present in vertebrates• Only present in vertebrates
• Said to have evolved due to the need to deposit calcium, phosphate and other minerals to maintain proper metabolic functioning
• Grows throughout the lifetime of fishes, amphibians and reptiles
• Growth stops in birds and mammals when adult size is reached
Germ Layer Origins of the Skeleton
Neural crest
• Cartilage and bones
EctodermEpimere
• Parts of the brain
Mesoderm
• Cartilage and bones of the lower jaw
• Odontoblasts
• Parts of the brain case
• Vertebral column
Hypomere
• Limbs
• Pharyngeal arches
Classification of Bones
Based on embryonic
development
Endochondral
• Also known as
Based on visual Appearance
Cancellous or
Based on position
• Also known as replacement bones
Intramembranous
Cancellous or spongy
Compact bone
Cortical
Medullary
Introductory Embryology
Origin of the Germinal Layers
Human Development
Human Development
Early Embryonic Development
Early Embryonic Development
Early Embryonic Development
Early Embryonic Development
Germ Layer
Derivatives
Comparative Embryogenesis
Human Development
Human
Development