Pg 131 Chondroblast -> Chondrocyte (Lacunae) Firm Ground Substance

Home , Chondroblast, Ground substance, Lacuna (histology), Long bone, Osteon

Figure 4.8g Connective tissues. Chondroblast ‐> Chondrocyte (Lacunae) Firm ground substance (chondroitin sulfate and water) Collagenous and elastic fibers (g) Cartilage: hyaline No BV or nerves

Description: Amorphous but firm Perichondrium (dense irregular) matrix; collagen fibers form an imperceptible network; chondroblasts produce the matrix and when mature (chondrocytes) lie in lacunae. Function: Supports and reinforces; has resilient cushioning properties; resists compressive stress.

Location: Forms most of the embryonic skeleton; covers the ends Chondrocyte of long bones in joint cavities; forms in lacuna costal cartilages of the ribs; cartilages of the nose, trachea, and larynx.

Matrix

Costal Photomicrograph: Hyaline cartilage from the cartilages trachea (750x).

Thickness? Metabolism? Copyright © 2010 Pearson Education, Inc. Pg 131 Figure 6.1 The bones and cartilages of the human skeleton. Epiglottis Support Thyroid Larynx Smooth Cartilage in Cartilages in cartilage external ear nose surface Cricoid Trachea Articular Lung Cushions cartilage Cartilage of a joint Cartilage in Costal Intervertebral cartilage disc

Respiratory tube cartilages in neck and thorax Pubic Bones of skeleton symphysis Meniscus (padlike Axial skeleton cartilage in Appendicular skeleton knee joint) Cartilages Articular cartilage of a joint Hyaline cartilages

(g) Cartilage: hyaline

Description: Amorphous but firm matrix; collagen fibers form an imperceptible network; chondroblasts produce the matrix and when mature (chondrocytes) lie in lacunae. Function: Supports and reinforces; has resilient cushioning properties; resists compressive stress.

Matrix glassy

Costal Photomicrograph: Hyaline cartilage from the cartilages trachea (750x).

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(h) Cartilage: elastic Description: Similar to hyaline cartilage, but more elastic fibers in matrix.

Function: Maintains the shape of a structure while allowing Chondrocyte great flexibility. in lacuna

Location: Supports the external Matrix ear (pinna); epiglottis.

Photomicrograph: Elastic cartilage from the human ear pinna; forms the flexible skeleton of the ear (800x).

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Description: Matrix similar to but less firm than that in hyaline cartilage; thick collagen fibers predominate.

Function: Tensile strength with the ability to absorb compressive shock.

Location: Intervertebral discs; pubic symphysis; discs of knee joint. Chondrocytes in lacunae Intervertebral discs Collagen fiber

Photomicrograph: Fibrocartilage of an intervertebral disc (125x). Special staining produced the blue color seen.

Pg 132

Compact Spongy bone Support bone Protection Blood formation Storehouse Movement

Central Perforating (Haversian) canal (Volkmann’s) canal Endosteum lining bony canals Osteon and covering trabeculae Hydroxyapatite (Haversian system) (calcium salts) Circumferential lamellae Bone Cells ‐osteoblast ‐osteocyte (a) Perforating (Sharpey’s) fibers ‐osteoclast Lamellae Periosteal blood vessel Periosteum Periosteum (dense irr.) Osteoblasts & clasts 2 types of bone Nerve Vein Artery Lamellae Central Canaliculi Lacuna (with canal osteocyte) Osteocyte Lacunae in a lacuna (b) (c) Interstitial lamellae osteoblast Pg 181 Copyright © 2010 Pearson Education, Inc. Figure 6.3 The structure of a long bone (humerus of arm). Spongy = Cancellous

Articular cartilage

Compact bone Proximal epiphysis Spongy bone Epiphyseal line Periosteum Endosteum Compact bone Medullary cavity (lined (b) by endosteum) Yellow Diaphysis Spaces contain Trabeculae marrow bone marrow Compact bone Periosteum Perforating ‐Ends of long bones (Sharpey’s) ‐Shaft of young fibers bones Nutrient ‐In flat, short and arteries Distal irregular bones epiphysis (a) (c) Pg 176 Copyright © 2010 Pearson Education, Inc. Figure 6.7 Microscopic anatomy of compact bone. Compact forms Compact Spongy bone bone shaft of long bones and a shell over spongy bone

Central Perforating (Haversian) canal (Volkmann’s) canal Endosteum lining bony canals Osteon and covering trabeculae (Haversian system) Circumferential lamellae

(a) Perforating (Sharpey’s) fibers Lamellae Periosteal blood vessel Periosteum

Nerve Vein Artery Lamellae Central Canaliculi Lacuna (with canal osteocyte) Osteocyte Lacunae in a lacuna (b) (c) Interstitial lamellae Pg 181 Copyright © 2010 Pearson Education, Inc. Figure 4.8j Connective tissues.

(j) Others: bone (osseous tissue)

Description: Hard, calcified matrix containing many collagen fibers; osteocytes lie in lacunae. Very well vascularized. Central Bone supports and Function: canal protects (by enclosing); provides levers for the muscles Lacunae to act on; stores calcium and other minerals and fat; marrow inside bones is the site for blood cell formation (hematopoiesis). Lamella Location: Bones

Photomicrograph: Cross‐sectional view of bone (125x).

Proximal epiphysis Spongy bone Epiphyseal line (plate) Periosteum Compact bone Medullary cavity (lined by endosteum with clasts & Diaphysis blasts) Red-> Yellow

Intramembranous: skull bones, mandible, part of clavicle

Endochondral: Most bones of the body Bone is only deposited in an area with less highly specialized connective tissue.

Intramembranous mesenchyme ‐> Dense Irr. ‐> Spongy ‐> Compact C.T. Bone Bone (inside) Figure 6.5 Flat bones consist of a layer of spongy bone sandwiched between two thin layers of compact bone.

Spongy bone (diploë) Compact bone

Trabeculae

Layers?

Intramembranous mesenchyme ‐> Dense Irr. ‐> Spongy ‐> Compact C.T. Bone Bone (inside) Endochondral mesenchyme ‐> Hyaline ‐> Spongy ‐> Compact Cartilage Bone Bone Figure 6.9 Endochondral ossification in a long bone.

Week 9 Month 3 Birth Childhood to adolescence Articular cartilage Secondary ossification Spongy center bone

Epiphyseal Area of blood vessel deteriorating Epiphyseal cartilage matrix plate cartilage Hyaline cartilage Spongy Medullary bone cavity formation

Bone Blood collar vessel of Primary periosteal ossification center bud

12Bone collar Cartilage in the 3The periosteal 4The diaphysis elongates 5The epiphyses forms around center of the bud invades the and a medullary cavity ossify. When hyaline cartilage diaphysis calcifies internal cavities forms as ossification completed, hyaline model. and then develops and spongy bone continues. Secondary cartilage remains only cavities. begins to form. ossification centers appear in the epiphyseal in the epiphyses in plates and articular preparation for stage 5. cartilages.

Bone growth Bone remodeling In Length: Until In Width (appositional): end of puberty occurs throughout life Articular cartilage Cartilage grows here.

Epiphyseal plate Cartilage is replaced Bone is by bone here. resorbed here. Cartilage grows here. Bone is added by appositional Cartilage growth here. is replaced by bone here. Bone is resorbed here. Endochondral Intramembranous Copyright © 2010 Pearson Education, Inc. Achondroplasia Pg 185

Giantism Acromegaly Pituitary Dwarfism Figure 16.11a The parathyroid glands.

PTH -Low Blood Calcium Pharynx (posterior -Stimulates aspect) Osteoclasts, Kidneys

Estrogen ‐Reduced with menopause ‐Loss of bone mass Calcium Vitamin D Exercise Figure 6.16 The contrasting architecture of normal versus osteporotic bone.

Hematoma External Bony callus callus of spongy bone Internal New Healed callus blood fracture (fibrous vessels tissue and cartilage) Spongy bone trabecula 1 A hematoma forms. 2 Fibrocartilaginous 3 Bony callus forms. 4 Bone callus forms. remodeling occurs. Osteoclasts & Intramembranous & Endochondral Osteoblasts