SKELETAL SYSTEM

• FUNCTION OF SKELETAL SYSTEM?

  • acts as a physical barrier, protecting your body from bacteria, infection, injury and sunlight
• SKELETAL SYSTEM

  • body's most important support structure
  • gives the body its shape and holds your organs in place
  • help in movement -create new blood cells
  • store minerals
• Conodonts

  • An important group of early vertebrates with tooth-like structure, representing the earliest expression of a mineralized skeleton
• Skeleton

  • unique because of its ability to Mineralize

  • > essential to give them strength and structure for body support and function
• Bone mineralization

  • Organic bone matrix becomes filled with calcium phosphate Nanocrystals. - mediated by Osteoblasts
• Osteoblasts

  • composed of mineralized bones, connective tissue and of ligaments, tendons, and joints
• Where are minerals confined?

  • Collagen - fibril consist of proteins that disposed in dense bundles

  → form a compact matrix where mineralizing constituents of cartilage or bone are deposited
• BONES

  • tissue consisting of collagenous fibers/matrix impregnated with hydroxyapatite crystals, cementing substance, and osteocytes in lacunae that are usually connected by canaliculi.
• VOCABULARY

  • hydroxyapatite crystals calcium, phosphate, and hydroxylions

  • cementing substance - composed of water and mucopolysaccharides that binds the crystals to the matrix

  • osteocytes -former osteoblasts that have been trapped in the matrix they formed

  • lacunae - cavities where the osteocytes stay

  • canaliculi- channels that connect lacunae
• Bone Tissue

  Osteon - consists of a osteonic (haversian)canal, which i s surrounded by lamellae of matrix.
• SPONGY BONE VS COMPACT BONE

  Spongy Bones

  • Also called as cancellous bones
  • Light, spongy, and soft in nature Made up of trabeculae
  • Fill the inner layer of the most bones
  • Forms the end or epiphyses of long bones

  Compact Bones

  • Also called cortical bones
  • Heavy, tough, and compact ni nature
  • Made up of osteons
  • Fill the outer layer of the most bones
  • Forms the shaft or diaphysis of long bones
• SKELETON

  SKELETON

  A) BONE

  B) CARTILAGE

  C) DENTIN

  D) ENAMEL

  E) AMELOBLAST

  F) ODONTOBLAST

  G) CHONDROBLAST

  H) OSTEOBLAST

  I) COLLAGEN

  J) FIBROBLAST

  K) SCELROBLAST

  L) MYOBLAST

  M) MUSCLE CELLS

  N) MESENCHYME

  
• STRUCTURE OF MUSCLES

  A) SKELETAL

  B) SMOOTH

  C) CARDIAC

  
• BONE TISSUE


  BONE TISSUE

  A) LACUNAE

  B) CANALICULI

  C) CENTRAL CANAL

  D) LAMELLAE

  E) INTERSTITIAL LAMELLAE

  F) CEMENT LINE

  G) LACUNAE

  
• Periosteum

  Surrounded by a Periosteum

  • separates the bone from surrounding structures
  • contains small blood vessels that provide nourishment to the outer cortex of bones.

  A) COMPACT BONE

  B) SPONGY BONE

  
• Three types of cells contribute in bone homeostasis:

  • Osteoblasts are bone-forming cell
  • Osteoclasts resorb or breakdown bone
  • Osteocytes are mature bone cells.
• Bone homeostasis

  An equilibrium between osteoblasts and osteoclasts maintains bone tissue

  A) osteoclast

  B) OSTEOBLAST

  C) osteocyte

  D) osteoid

  
• BONE DEVELOPMENT AND

  GROWTH

  ● Ossification (Osteogenesis)

  ▪ process of bone formation by osteoblasts.

  ● Intramembranous ossification (formation of membrane bone)

  ▪ Development from fibrous membranes.

  ▪ Involved in forming flat bones.

  ● Endochondral ossification (formation of replacement bone)

  ▪ Development from hyaline cartilage.

  ▪ Involved in forming bones except mentioned above bones.

  ● Long bones continue to lengthen until adolescence.

  ▪ Increase width through appositional growth.
• BONE REMODELING

  • Replacement of old bone tissue to new.
  • Bone deposition by osteoblasts.
  • Bone resorption by osteoclasts.
  • Bone became stronger and thicker when subjected to stress.

  A) Quiescent

  B) activation

  C) resorption

  D) formation

  E) mineralisation

  
• CARTILAGE

  ● resembles bone as it is formed also within a

  matrix of collagenous connective tissue.

  DIFFERENCE TO BONE

  ● Intercellular matrix contains sulfated mucopolysaccharide instead of hydroxyapatite crystals.

  ● Has no canaliculi and blood vessels on its own.
• CARTILAGE FORMATION

  • Mesenchyme differentiates into chondroblasts.
  • Chondrification organizes a bounding membrane called perichondrium.
  • Cartilage is laid down within the blastema by mesenchyme from the perichondrium (appositional growth) and by fibroblast and chondroblasts through (interstitial growth).
  • Chondroblasts become chondrocytes after being trapped in lacunae.
• TYPES OF CARTILAGE

  Hyaline cartilage:

  • Least differentiated and precursor of replacement bone.
  • Little remained after growth of replacement bone has ceased.
  • transformed into fibrocartilage, elastic cartilage, or calcified cartilage.
• TYPES OF CARTILAGE

  Fibrocartilage:

  • Cartilage with exceptionally thick, dense collagenous bundles in the interstitial matrix.

  ▪ Ex. Intervertebral discs of mammals
• TYPES OF CARTILAGE

  Elastic cartilage:

  • Network of elastic fibers

  ▪ Ex. Found in pinna of the ear, walls of outer ear canal, epiglottitis of mammals.
• TYPES OF CARTILAGE

  Calcified cartilage

  • Formed when calcium salts are deposited within the interstitial substance of hyaline cartilage or fibrocartilage.

  ▪ Ex. Jaws of sharks
• TYPES OF CARTILAGE

  TYPES OF CARTILAGE

  A) HYALINE

  B) FIBROCARTILAGE

  C) ELASTIC CARTILAGE

  
• TENDONS, LIGAMENTS, AND JOINTS

  Tendons and Ligament:

  • Consists of packed collagens.
  • Aponeuroses (if wide and flat)
  • Becomes mineralized (Turkeys - ossified tendons)

  Tendons – connect muscle with bones.

  Ligaments – connects bones to bones.

  Joint (arthrosis) – where two bones meet.

  A) TENDON

  B) BONE

  C) LIGAMENT

  
• TENDONS, LIGAMENTS, AND JOINTS

  Joint (arthrosis) – where two bones meet.

  Types of joints

  ● Synarthrosis – immobile joint

  ● Amphiarthrosis – slightly moveable joint

  ● Diarthrosis – freely moveable joint

  A) SYNARTHROSIS

  B) AMPHIARTHROSIS

  C) DIARTHROSIS

  
• LEARNING CHECK

  LEARNING CHECK

  A) TENDON

  B) LIGAMENT

  C) BONE

  
• LEARNING CHCK

  LEARNING CHECK

  A) YELLOW

  B) BLUE