Bones & Skeletal Tissue: Lecture Notes

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What are the 3 types of cartilage
*Hyaline
*Elastic
*Fibro
Functions of Hyaline cartilage
*Support
*Flexibility
*Resilience
Where is Hyaline cartilage found?
*Larynx
*Trachea
*Nose
Where is Elastic cartilage found?
*External ear
*Epiglottis
Where is Fibrocartilage found?
*Menisci
*Public Synthesis
*Intervertebral Discs
Facts about Fibrocartilage
*Limited
*Highly compressed with great tensile strength
*Collagen fibers
Ways that cartilage grows
*Oppositional
*Interstitial
*Calcification
Oppositional Growth
*Happens outside of cartilage
* Bones grow wider
*Cells within perichondrium secrete
Interstitial Growth
*Cells in the center
*Chondrocytes inside cartilage divide
*Secretes new matrix
*Expands cartilage from within
* Bones grow long ways
What are the functions of bones?
*Support
*Protection
*Movement
*Mineral storage
*Blood cell formation
What are the 5 shapes of bones?
*Long
*Short
*Flat
*Irregular
*Sesamoid
What are bone markings for?
*Attachment sites
*Joint surfaces
*Conduits for blood vessels and nerves
What are the two types of bone?
*Compact
*Spongy
What are the structures of a long bone?
*Diaphysis
*Epiphysis
What is the Diaphysis of a bone
*Tubular shaft
*Compact bone that surrounds medullary cavity
*Yellow bone marrow
What is the Epiphysis of a bone?
*Expanded ends of long bone
*Exterior compact bone
*Interior spongy bone
*Joint covered with articular cartilage
Epiphysial Line or Plate
Structure that separates diaphysis from epiphysis
Periosteum Layers
*Outer fibrous layer
*Inner osteogenic layer
*Nutrient foramena
Outer layer of periosteum
Made of dense regular tissue
Inner osteogenic layer
*Osteoblasts
*Osteoclasts
*Osteogeneror
Nutrient Foramena
Nerve fibers, blood & lymphatic vessels
Structure of short, irregular, & flat bones
*Outer layers
*Inner layer
*Diploe
*No diaphasis or epiphysis
*Contains red marrow between trabeculae
Outer layer of short, irregular, & flat bones
Thin plates of periosteum covered compact bone
Inner layer
*Endosteum covered spongy bone
*Diploe
Diploe
Little layer of spongy bone
Red Marrow
*Hematopoietic tissue
*In infants found in Medullary Cavity and all areas of spongy bone
*In adults found in diploe of flat bones and head of femur & Humerus
Lacunae
Little spaces that "house" Osteocytes
Microanatomy of compound bone
*Osteon aka Haversian System
*Haversian Canal
*Lamella
*Volkmann's Canal
Lamella
*Weight bearing column-like tubes
*Composed mainly of cartilage
*Collagen fibers go in different directions for flexibility
Volkmann's Canal
*Perpendicular to Haversian Canal
*Osteon into spongy bone
Haversian Canal
*Vertical canal
*Veins
*Arteries
*Nerves
Cells of bone
*Osteoprogenitor
*Osteoblasts
*Osteocytes
*Osteoclasts
Osteoprogenitor Cells
*Retains ability be mitotic
*Is a stem cell
*Produces Osteoblasts
Osteoblasts
*Cells that make bone from Calcium & Phosphate
*Makes Osteocytes
Osteocytes
*Mature bone cells
*In Haversian System
*Comes from Osteoclast
Osteoclasts
*Comes from Hematopoetic Stem Cells
*Breaks down bone
*Breaks down bone
What does there need to be a balance of for bones to work properly?
Osteoblasts & Osteoclasts
Canaliculi
Allows communication with Osteocytes & Central Canal
Osteogenesis & Ossification
*process of bone tissue formation
What does Osteogenesis & Ossification lead to?
*Formation of bony skeletons in embryos
*Bone growth until early adulthood
*Bone thickness, remodeling, & repair
Bony Skeleton Formation Facts & Types
*Begins at 8 weeks development
*Intramembranous Ossification
*Endochondral Ossification
Intramembranous Ossification Summary
Bone development from fibrous membrane
Endochondral Ossification Summary
Bone forms by replacing Hyaline cartilage
Intramembranous Ossification Information
*Formation of most of the flat bone of skull & clavicals
*Fibrous connective tissue membranous are formed by Mesenchymal cells
*Formation of bone within membrane sheet
4 Basic Steps of Intramembranous Ossification
1) Ossification center appears in the fibrous connective tissue
2) Bone matrix secreted
3) Woven bone & periosteum form
4) Compact bone forms
Endochondral Ossification Information
*Begins at about 8 weeks gestation
*Uses hyaline cartilage model
*Requires breakdown of hyaline cartilage prior to ossification
Stages of Encochondral Ossification
1) Bone collar
2) Cavitation of hyaline cartilage
3) Periostial bud & spongy bone form
4) Formation of Medullary Cavity
5) Secondary ossification centers
6) Ossification of epiphyses
7) Hyaline cartilage only in epiphyseal plates
Growth Zone (in reference to post-natal bone growth)
* Cartilage cells undergo Mitosis
* Epiphysis pushed away from diaphysis
Epiphyseal Plate (in reference to post-natal bone growth)
The site of bone growth after birth
Transformation Zone (in reference to post-natal bone growth)
* It's the transition from cartilage to bone
* Older cells enlarge
* Matrix becomes calcified
* Cartilage cells die
Osteogenic Zone
New bone formation occurs
What hormones regulate skeletal growth?
* Growth hormone (HGH)
* Estrogen
* Testosterone
Growth Hormone (in reference to bone growth)
*Most important during infancy & childhood
* Stimulates epiphyseal plate
Estrogen & Testosterone (in reference to bone growth)
* Most important during puberty
* Causes growth spurts
* Stimulates epiphyseal plate closure
Bone Remodeling
* Periosteum
* Endosteum
* Osteoblasts
* Osteoclasts
Periosteum & Endosteum (in reference to remodeling)
Where the cells needed fro repair, replacement, & remodeling are
Osteoblasts (in reference to remodeling)
* Cartilage to bone
* Deposits bone to fix the bone
* Makes the bone
Osteoclasts (in reference to remodeling)
* Repairs
* Rebuilds bone to its proper form
Non-Displaced Fracture
Bone is in proper alignment
Displaced Fracture
Bone is out of alignment
Complete Fracture
Break is all the way across the bone
Incomplete Fracture
Break is not all the way across the bone
Transverse Fracture
Break line forms a right angle at bone long axis
Linear Fracture
Break line runs parallel to bone long axis
Simple Fracture
Bone not through skin
Compound Fracture
Bone goes through the skin
Comminuted Facture
Break is in multiple pieces
Spiral Fracture
* Slanted
* Indicative of abuse
Depressed Fracture
In the skull when a bone fragment is pushed down below normal level
Compression Fracture
In vertebrae, when one bone basically crushes the other one
Epiphyseal Fracture
Along line of epiphyseal, causing separation
Greenstick Fracture
* Only in children
* One side is broken, one side is bent
Bone Healing Stages Following a Fracture
1) Hematoma formation
2) Fibrocartilaginous Callus Forms
3) Bony Callus Forms
4) Bone Remodeling Occurs
In bone remodeling: Periosteum & Endosteum contains:
Cells for: repair, replacement, and remodeling
In bone remodeling: Osteoblasts:
Deposits bone to fix it (makes the bone)
In bone remodeling: Osteoclasts:
Repairs & rebuilds bone to its proper form
What stores calcium?
Osteoblasts
When is calcitonin released:
when blood calcium levels are too high
What does calcitonin do?
stimulates bone, GI (decreases absorption), kidneys (increases excretion aka you pee out the excess)
What are the hormonal mechanisms that control bone remodeling?
* Calcium Homeostasis
* Thyroid
* Parathyroid
When is the parathyroid hormone released?
when calcium levels are too low
Osteomalacia
* In adults
* Inadequate mineralization
* Ca or Vitamin deficiency
Rickets Disease
* In children
* Inadequate mineralization
Osteoporosis
* Bone reabsorption outpaces bone deposition
Paget's Disease
* Excessive bone formation and breakdown
* High ratio of woven to compact bone
Osteogenesis Inperfecta
* Synthesis of improper collagen fibers
* Brittle bone disease
* Not a problem with Ca
Wolff's Law
when a bone grows or remodels in response to the forces or demands placed upon it

trabeculae form along lines of stress