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Bones - Anatomy & Physiology (view source)

Revision as of 14:53, 6 January 2011

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==Overview==
 
==Overview==
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[[Image:Horse Skeleton.jpg|thumb|right|250px|Horse Skeleton - Copyright Nottingham]]
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Bone comprises the structure of the skeletal system and provides lever arms for locomotion. Bone also plays important roles in maintaining mineral homeostasis, as well as providing the environment for [[:Category:Haematopoiesis|hematopoesis]] in [[Bone Marrow|marrow]].
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Bone comprises the structure of the skeletal system and provides lever arms for locomotion. Bone also plays important roles in maintaining mineral homeostasis, as well as providing the environment for hematopoesis in marrow.
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'''Short bones''' - Endochondral ossification continues in the diaphysis, until only the cartilage rim remains.
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[[Image:Horse Skeleton.jpg|thumb|right|250px|Horse Skeleton - Copyright Nottingham]]
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'''Long bones''' - A secondary center of ossification develops in the epiphyses.
    
==Bone Growth==
 
==Bone Growth==
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[[Image:Growth plate.jpg|right|thumb|250px|<small><center>Growth plate (Image sourced from Bristol Biomed Image Archive with permission)</center></small>]]
 
===Length===
 
===Length===
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The '''epiphyseal growth plate (EGP)''' allows the [[Bones and Cartilage - Anatomy & Physiology#Types of Bone|bone]] to continue to grow in length after birth. The EPG is a region of continuous chondroblast differentiation and maturation and can be divided into five zones:
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The '''epiphyseal growth plate (EGP)''' is a transverse disc of cartilate between the two ossification centers and allows the bone to continue to grow in length after birth. It then closes. The EGP is a region of continuous chondroblast differentiation and maturation and can be divided into five zones:
    
# '''Germinal Zone''' - chondroblast division at a low rate, and self renewal.
 
# '''Germinal Zone''' - chondroblast division at a low rate, and self renewal.
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[[Image:Growth plate.jpg|right|thumb|250px|<small><center>Growth plate (Image sourced from Bristol Biomed Image Archive with permission)</center></small>]]
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==Bone Remodeling==
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==Bone Growth and Remodeling==
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'''Short bones'''- Endochondral ossification continues in the diaphysis, until only the cartilage rim remains.
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'''Primary''' bone has not yet been '''remodelled'''. It contains less mineral and more randomly arranged collagen fibers, known as trabecular organization. Remodelling of bone occurs by [[Haversian Systems|'''haversian canals''']]. The osteoclasts dig out the canal, followed by blood vessel invasion. Concentric lamellae are laid down and phased resorption happens concurrently.
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'''Long bones'''- A secondary center of ossification develops in the epiphyses.
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'''Epiphyseal Growth Plate'''
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The growth plate is a transverse disc of cartilate between the two ossification centers, and allows longitudinal growth to continue to maturity. It then closes. The cartilage of the epiphyseal growth plate is divided into: (from right to left on the magnified image)
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1. Resting (reserve) zone
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2. Proliferative zone
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3. Hypertrophic zone
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'''Primary''' bone has not yet been '''remodelled'''. It contains less mineral and more randomly arranged collagen fibers, known as trabecular organization. Remodelling of bone occurs by '''haversian canals'''. The osteoclasts dig out the canal, followed by blood vessel invasion. Concentric lamellae are laid down and phased resorption happens concurrently.
      
==Types of Bone==
 
==Types of Bone==
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==Composition of Bone==
 
==Composition of Bone==
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[[Image:Bone histo.jpg|right|thumb|250px|<small><center>Histological structure of bone (Courtesy of RVC Histology images)</center></small>]]
 
[[Image:Bone histo.jpg|right|thumb|250px|<small><center>Histological structure of bone (Courtesy of RVC Histology images)</center></small>]]
 
[[Image:Bone micro structure.jpg|right|thumb|250px|<small><center>Microscopic bone (Courtesy of RVC Histology images)</center></small>]]
 
[[Image:Bone micro structure.jpg|right|thumb|250px|<small><center>Microscopic bone (Courtesy of RVC Histology images)</center></small>]]
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Bone is a hard, highly specialised connective tissue . It consists of interconnected cells embedded in a calcified, collagenous matrix. It is a living, dynamic, responsive tissue, growing and remodelling throughout life.
 
Bone is a hard, highly specialised connective tissue . It consists of interconnected cells embedded in a calcified, collagenous matrix. It is a living, dynamic, responsive tissue, growing and remodelling throughout life.
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Bone is comprised of:
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Bone is composed of:
    
===Matrix===
 
===Matrix===
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2. '''Chondrogenic'''- inner, flattened cells that differentiate to chondrocytes.
 
2. '''Chondrogenic'''- inner, flattened cells that differentiate to chondrocytes.
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==Types of Cartilage==
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===Hyaline Cartilage===
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The most abundant in the body. It is normally blue-white, smooth with a moist surface and turns yellow and becomes thinner in old age. It is found in nose, trachea, bronchi, ventral ends of ribs and sternal attachment. It is surrounded by perichondrium. It is at sites of articulation to provide a resilient, frictionless surface that resists compression. It is also found at epiphyseal growth plates.
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===Elastic Cartilage===
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Elastic cartilage has a yellow appearance and is found in auricular cartilage, larynx, eustacian tube, and epiglottis. It is surrounded by perichondrium and has resiliance with added flexibility.
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===Fibrocartilage===
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Fibrocartilage has more collagen ('''Type I''') and less proteglycans than hyaline. It resists high tensional strain and is often in transition with hyaline. It is found in intervertebral discs, tendon/ligament attachment to bone, joint menisci, and articular surface of some joints (such as the temperomandibular). It has NO perichondrium.
      
==Links==
 
==Links==
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