6 Bones and Skeletal Tissues: Part A

Cartilage © 2013 Pearson Education, Inc.

Skeletal Cartilages What do you find in all cartilage? Cell type? Other junk? © 2013 Pearson Education, Inc.

Skeletal Cartilages What do you find in all cartilage? Chondrocytes in lacunae Extracellular matrix What are the three types of cartilage? Hyaline Elastic Fibrocartilage What are the properties that make these different? Characteristic Fiber type Location © 2013 Pearson Education, Inc.

Cartilage Three types Hyaline cartilage Elastic cartilage Flexibility Contains a boat load of collagen Ex: articular, costal, respiratory, nasal cartilage Elastic cartilage Super flexible Collagen + mostly elastic fibers Ex: external ear and epiglottis Fibrocartilage Thick collagen fibers—has great tensile strength Ex: Menisci of knee; vertebral discs © 2013 Pearson Education, Inc.

Table for organization Type Property Fiber Type Examples Hyaline Flexibility Collagen Costal cart., trachea Elastic Super flexible Collagen + elastic Ext. ear, epiglottis Fibro Tensile strength, cushion Thick collagen Vertebral discs, menisci of knee © 2013 Pearson Education, Inc.

Figure 6.1 The bones and cartilages of the human skeleton. Epiglottis Thyroid cartilage Larynx Cartilage in external ear Cartilages in nose Cricoid cartilage Trachea Articular cartilage of a joint Lung Costal cartilage Cartilage in intervertebral disc Respiratory tube cartilages in neck and thorax Pubic symphysis Bones of skeleton Axial skeleton Meniscus (padlike cartilage in knee joint) Appendicular skeleton Cartilages Articular cartilage of a joint Hyaline cartilages Elastic cartilages Fibrocartilages © 2013 Pearson Education, Inc.

What are the two types of growth? Growth of Cartilage What are the two types of growth? Growth in length? Growth in girth? Appositional growth “Girth” Cells secrete matrix against external face of existing cartilage. Interstitial growth “Length” Chondrocytes divide (through lacunae) to secrete new matrix, expanding cartilage from within the bone. © 2013 Pearson Education, Inc.

Compare and Contrast Appositional Growth Interstitial Growth Addition to surface Osteoprogenitor cells Bone Solid matrix Increases in thickness Addition within Chondroblasts Cartilage Denser matrix Increases the length © 2013 Pearson Education, Inc.

How can we remember this? Terms Pnemonic Appositional Growth Growth in width Interstitial growth Length A.G.I.L.E © 2013 Pearson Education, Inc.

Classification of Bones © 2013 Pearson Education, Inc.

Classification of Bones 206 named bones in skeleton Divided into two groups Axial skeleton Appendicular skeleton © 2013 Pearson Education, Inc.

Questions: Is the pelvic girdle part of the appendicular skeleton or the axial skeleton? To which skeleton is the shoulder girdle connected? © 2013 Pearson Education, Inc.

Classification of Bones by Shape What are the classifications based on shape? Long bones Short bones Flat bones Irregular bones Bone Type Description Long Longer than wide Short Cube shaped (carpals/tarsals) Sesamoid (patella) Flat Thin, slightly curved Irregular Complicated shapes © 2013 Pearson Education, Inc.

Figure 6.2 Classification of bones on the basis of shape. Flat bone (sternum) Long bone (humerus) Irregular bone (vertebra), right lateral view Short bone (talus) © 2013 Pearson Education, Inc.

Functions of Bones What are the important functions of bone? Support/protect Movement Storage Production How does the skeleton carry out these functions? i.e. what are some examples? Function Examples Support/Protect Spine, Rib Cage Movement Voluntary movements Storage Minerals (Ca and P), Growth Factor, Fats Production Hematopoiesis, hormone production © 2013 Pearson Education, Inc.

Functions of Bones Mineral and growth factor storage Calcium and phosphorus Growth factors (GF) reservoir Hormone production Osteocalcin Regulates bone formation Protects against Obesity Glucose intolerance Diabetes mellitus © 2013 Pearson Education, Inc.

What are the two major types of bones? Gross Anatomy What are the two major types of bones? Compact Spongy Bone Type Descriptions Compact Dense outer layer; smooth and solid Spongy Trabeculae, “like a sponge” © 2013 Pearson Education, Inc.

Spongy bone (diploë) Compact bone Trabeculae of spongy bone Figure 6.3 Flat bones consist of a layer of spongy bone sandwiched between two thin layers of compact bone. Spongy bone (diploë) Compact bone Trabeculae of spongy bone © 2013 Pearson Education, Inc.

Structure of Typical Long Bone What are the two main regions of a long bone? Diaphysis (“Shaft”) Compact bone surrounding medullary cavity Epiphyses (“Ends”) External compact bone; internal spongy bone Cartilage covers articular surfaces What type? D E © 2013 Pearson Education, Inc.

Still talking long-bones What is unique about the epiphyseal line? Only found in long bones Remnant of childhood bone growth What is the difference between the epiphyseal plate and epiphyseal line? © 2013 Pearson Education, Inc.

Compare and Contrast Cartilage Found in children Epiphyseal Plate Epiphyseal Line Cartilage Found in children Trauma can result in improper growth Bone Found in adults Sign that growth has stopped

Figure 6.4a The structure of a long bone (humerus of arm). What are the two major types of membranes surrounding bone? Periosteum Endosteum Proximal epiphysis Periosteum Medullary cavity (lined by endosteum) Diaphysis Distal epiphysis © 2013 Pearson Education, Inc.

Compare and Contrast Periosteum Endosteum White, double-layered membrane Fairly dense Covers external surfaces (except joint surfaces) Connected to bone by Sharpey's fibers Delicate Covers trabeculae of spongy bone Lines canals that pass through compact bone Contains osteogenic cells that differentiate into other bone cells © 2013 Pearson Education, Inc.

Endosteum Compact bone Periosteum Articular cartilage Proximal epiphysis Spongy bone Epiphyseal line Yellow bone marrow Periosteum Compact bone Compact bone Medullary cavity (lined by endosteum) Periosteum Perforating (Sharpey’s) fibers Diaphysis Nutrient arteries Distal epiphysis © 2013 Pearson Education, Inc.

Membranes: Periosteum What types of tissues will you find in and around bone? Many nerve fibers and blood vessels Anchoring points for tendons and ligaments © 2013 Pearson Education, Inc.

Marrow Tissue in Bones Found in spongy bone and diploe of flat bones Red Marrow Yellow Marrow Found in spongy bone and diploe of flat bones Forms RBC Found in medullary cavity Stores fats © 2013 Pearson Education, Inc.

Bone Markings © 2013 Pearson Education, Inc.

Why do we have different types of markings? Bone Markings Why do we have different types of markings? Sites of attachment Joint surfaces Conduits for blood vessels and nerves How can these be classified? Projections Depressions Openings © 2013 Pearson Education, Inc.

Depressions and openings Bone Markings Projections Most indicate stresses created by muscle pull or joint modifications Depressions and openings Usually allow nerves and blood vessels to pass © 2013 Pearson Education, Inc.

Table 6.1 Bone Markings (1 of 2) © 2013 Pearson Education, Inc.

Table 6.1 Bone Markings (2 of 2) © 2013 Pearson Education, Inc.

Microscopic Anatomy of Bone: Cells of Bone Tissue What are the different types of cells found in bone? Osteogenic cells Osteoblasts Osteocytes Bone lining cells Osteoclasts © 2013 Pearson Education, Inc.

Microscopic Anatomy of Bone: Cells of Bone Tissue What do each of these types do? Osteogenic cells Osteoblasts Osteocytes Bone lining cells Osteoclasts © 2013 Pearson Education, Inc.

Microscopic Anatomy of Bone: Cells of Bone Tissue What do each of these types do? Osteogenic cells precursor Osteoblasts “blast” Osteocytes “cytes” Bone lining cells “lining” Osteoclasts “clast” © 2013 Pearson Education, Inc.

Also called osteoprogenitor cells Osteogenic Cells Also called osteoprogenitor cells Mitotically active stem cells Found in periosteum and endosteum Differentiate into Osteoblasts Bone lining cells Persist as osteogenic cells © 2013 Pearson Education, Inc.

Osteoblasts “Bone-making cells” What do they secrete? Actively mitotic Mineralized bone matrix or osteoid Includes collagen and calcium-binding proteins Collagen = 90% of bone protein Actively mitotic © 2013 Pearson Education, Inc.

Osteogenic cell Osteoblast Stem cell Matrix-synthesizing Figure 6.5a–b Comparison of different types of bone cells. Osteogenic cell Osteoblast Stem cell Matrix-synthesizing cell responsible for bone growth © 2013 Pearson Education, Inc.

Bone Lining Cells: Osteocytes External bone surface: periosteal cells Lining internal surfaces: endosteal cells Where have we seen similar terms before? Periosteum Endosteum © 2013 Pearson Education, Inc.

Derived from hematopoietic stem cells that become macrophages Osteoclasts Derived from hematopoietic stem cells that become macrophages What does being a macrophage have to do with “clast” behavior? What makes their form fit function? Hint: it has to do with ruffled border. Ruffled border increases surface area for enzyme degradation of bone © 2013 Pearson Education, Inc.

Osteocyte Osteoclast Mature bone cell that monitors and maintains the Figure 6.5c–d Comparison of different types of bone cells. Osteocyte Osteoclast Mature bone cell that monitors and maintains the mineralized bone matrix Bone-resorbing cell © 2013 Pearson Education, Inc.

Artery with capillaries Structures in the Vein central canal Figure 6.6 A single osteon. Artery with capillaries Structures in the central canal Vein Nerve fiber Lamellae Collagen fibers run in different directions Twisting force © 2013 Pearson Education, Inc.

Microscopic Anatomy of Bone: Compact Bone Canals and canaliculi Central (Haversian) canal Runs through core of osteon Contains blood vessels and nerve fibers Perforating (Volkmann's) canals Canals lined with endosteum at right angles to central canal Lacunae—small cavities containing osteocytes Canaliculi—connect lacunae/lacunae and to central canal © 2013 Pearson Education, Inc.

Figure 6.7 Microscopic anatomy of compact bone. Spongy bone Central (Haversian) canal Perforating (Volkmann’s) canal Endosteum lining bony canals and covering trabeculae Osteon (Haversian system) Circumferential lamellae Perforating (Sharpey’s) fibers Lamellae Periosteal blood vessel Periosteum Nerve Vein Lamellae Artery Central canal Canaliculi Osteocyte in a lacuna Lacunae Interstitial lamella Lacuna (with osteocyte) © 2013 Pearson Education, Inc.

Microscopic Anatomy of Bone: Spongy Bone What is the arrangement in spongey bone called? Trabeculae Align along lines of stress No osteons Contain irregularly arranged lamellae and osteocytes interconnected by canaliculi BONUS: How does spongy bone get its nutrients? © 2013 Pearson Education, Inc.

Chemical Composition of Bone: Inorganic Components Hydroxyapatites (mineral salts) 65% of bone by mass Mainly of tiny calcium phosphate crystals in and around collagen fibers Responsible for hardness and resistance to compression © 2013 Pearson Education, Inc.