An Introduction to the Skeleton Flashcards
body system that shows broad outlines of vertebrate phylogeny (fossil record)
Skeleton
Skeletal framework of vertebrates purpose
- Shape
- Support
- Protection
- Muscle attachment for locomotion
Type of skeleton
Primitive trait
Teeth and membrane bones of skull among higher chordates are dermal
Exoskeleton (dermal skeleton)
Type of skeleton
Distinguishing characteristic of chordates
Appears much earlier in ontogeny in organisms that have both exo- and endoskeletons
Endoskeleton
components of mainly mineralized connective tissue deposited in collagen (matrix)
Bone
Cartilage
Enameloids
Dentin
connects bones to bones and holds them in place
Ligaments
connects muscles to bones
Tendons
Formation of Mineralized Structures
mesenchyme turns into Fibroblast, Scleroblast, Myoblast
Fibroblast turns into collagen
Myoblast turns into Muscle
Cells
Scleroblast turns into Osteoblast (bone), Chondroblast (Cartilage), Odontoblast (Dentin), Ameloblast (Enamel)
Steps in Formation of Skeletal Tissues
Fibroblasts -> Fibrils -> Collagen Fibers -> Collagen Bundles -> Dense Connective Tissue -> Deposition of Minerals
Embryonic skeleton of higher vertebrates (temporary) and main skeleton of lower vertebrates (permanent)
Usually replaced by bone in higher vertebrates
Specialized (avascular) connective tissue of chondrocytes dispersed in spaces (lacunae) in a matrix
No canaliculi and no blood vessels of its own
Cartilage
cartilage matrix
chondromucin
Cartilage are surrounded by the __________ which is a dense connective tissue
perichondrium
Cartilage are Generally mesodermal (mesenchyme) in origin except for what regions
head and gill region (from neural crest cells)
Steps in Formation of Cartilage
Chondroblast -> mucopolysaccharides in matrix -> formation of perichondrium -> addition of cartilage from perichondrium, fibroblasts and chondroblasts -> transformation to become chondrocytes
Types of Cartilage
Hyaline
Fibrous
Elastic
Calcified
Types of Cartilage
most abundant, least differentiated and precursor of replacement bone, found chiefly on articular surfaces of bones
Hyaline
Types of Cartilage
intervertebral discs and attachment of tendons and ligaments
Fibrous
Types of Cartilage
in external ear and epiglottis
Elastic
Types of Cartilage
formed when calcium salts are deposited within the interstitial substance of hyaline cartilage or fibrocartilage
Calcified
Specialized (vascular) connective tissue made up of calcified bone matrix
Bone
bones are synthesized and maintained by what cells
Specialized (vascular) connective tissue made up of calcified bone matrix
what component of bones are the calcium hydroxyapatite crystals composed off calcium, phosphate and hydroxyl ions
Inorganic component
what component of bones are the type I collagen with amorphous ground substance
Organic component
Bones are Bound together by water and __________ as cementing substance
mucopolysaccharides
Types of Bone Cells
Osteogenic cells/scleroblasts
Osteoblasts
Osteocytes
Osteoclasts
Stem cells derived from mesenchyme
Give rise to all connective tissues
Osteogenic cells/scleroblasts
Bone formation and growth regulation
Secrete organic and mineral substances for ossification
Osteoblasts
Osteoblasts surrounded by its own intercellular deposits
Maintain cellular activities of bone tissue
Osteocytes
Contains enzymes for bone resorption (release of ion stores)
Contain hormone receptors for its own regulation
Osteoclasts
Functions of Bone
Support of soft tissues and muscles
Locomotion
Protect vital organs (skull, ribs, vertebrae)
Hematopoiesis: RBC production in bone marrow
Reservoir of calcium and phosphate
Classification of Bones
Shape
Structure
Function
Origin
Position
Classification According to Shape
Long bone
Short bones
Sesamoid bones
Flat bones
Irregular bones
Classification According to Shape
characteristic of the limbs
Long bone
Classification According to Shape
confined to the carpal and tarsal regions
Short bones
Classification According to Shape
present near free moving joints
Sesamoid bones
Classification According to Shape
found in limb girdles and in the head
Flat bones
Classification According to Shape
vertebral column, skull bones that are not flat and hip bones
Irregular bones
Classification According to Shape
formed due to additional ossification centers in or near sutures of the flat bones of the human cranium
sutural bone