bio chp#02

• Endoskeleton


  Skeleton that lies inside the body
• Human endoskeleton


  • Comprises of bones and cartilage
  • Provides shape of the body
  • Makes blood cells through red bone marrow
  • Protects internal organs
  • Stores minerals
• Osteology


  The branch of science that deals with the study of human bones
• Musculoskeletal system


  Bones and muscles attached to form a well-coordinated system
• Humans have around 300 bones at birth but due to fusion of some bones it becomes 206 in adults
• Bone


  • Toughest living structure
  • Composed of different cells
  • Major proportion is formed by collagen fibers and different types of cells
  • Other components include minerals and 10 to 20% water
• Collagen


  Fibrous protein that strengthens bone with calcium upon calcification or ossification
• Long bone


  • Has three distinct regions: epiphysis, diaphysis, and metaphysis
  • Epiphysis is a cancellous or spongy part of the bone
  • Diaphysis has an external cortical bone and internal medullary canal
• Osteon


  Small cylinders that make up cortical bone, each containing concentric layers of collagen and hydroxyapatite
• Haversian canal


  Contains the blood supply and innervations of the bone cells
• Medullary canal


  Hollow space in the center of the bone, lined by spongy or cancellous bone, containing bone marrow
• Periosteum


  Outer covering of the bone, allows for attachment of muscle connective tissue and provides pathways for blood and lymphatic vessels
• Endosteum


  Soft, thin layer that lines the inner cavity of long bones, contains progenitor stem cells
• Bone cells


  • Osteoblasts
  • Osteocytes
  • Osteoclasts
• Osteoblasts


  Progenitor cells that secrete matrix around themselves to form spongy bone which later become compact bone
• Osteocytes


  Mature cells that form the bones, direct osteoblasts to sites of damage to hasten healing
• Osteoclasts


  Break down the composite material in bones, helping in demineralization and repair
• Cartilage


  • Soft, flexible connective tissue
  • Lacks blood vessels, so grows and repairs slower than other tissues
  • Formed by chondroblast cells that divide to form chondrocyte cells
• Types of cartilage


  • Hyaline cartilage
  • Fibrocartilage
  • Elastic cartilage
• Hyaline cartilage has a smooth surface that allows tissues to slide easily, found between ribs and sternum, nose, and at bone surfaces in many joints
• Fibrocartilage is the hardest type, found in intervertebral discs, knee joints, and pectoral girdle
• Elastic cartilage is the most flexible and strong, found in the pinna of the ear, external and internal auditory tubes, epiglottis, and larynx
• Differences between bone and cartilage

  • Strength
  • Formation
  • Calcification
  • Covering
  • Protection
  • Water content
  • Blood cell formation
• Axial skeleton


  • On the central axis of the body
  • Comprises skull, vertebral column, and thoracic cage
• Bones of the axial skeleton

  • 28 skull bones
  • 1 hyoid bone
  • 26 vertebrae
  • 24 ribs
  • 1 sternum
• Cranial bones


  • Protect brain and provide attachment for essential receptor organs
  • Include 2 parietal, 2 temporal, 1 frontal, 1 occipital, 1 ethmoid, and 1 sphenoid bone
• Facial bones


  • Protect soft tissues of the face, help in breathing, eating, facial expressions, speech, and structure
• Auditory ossicles


  Six small bones that help transmit sound waves from the external environment to the inner ear
• Hyoid bone


  1. shaped bone that provides attachment for the tongue and muscles of the oral cavity
• Vertebral column


  • Protects spinal cord and serves as the site for blood cell production
  • Consists of 7 cervical, 12 thoracic, 5 lumbar, 1 sacrum, and 1 coccyx vertebrae
• Rib cage


  • Formed by ribs and sternum
  • 12 pairs of ribs, first 7 pairs are true ribs directly attached to sternum, last 5 pairs are false ribs
• Appendicular skeleton


  • Consists of 126 bones
  • Divided into pectoral girdle and associated forelimb bones, and pelvic girdle and associated hindlimb bones
• Pectoral girdle


  • Provides structural support to the upper region of the body
  • Consists of 2 clavicles and 2 scapulae
• Forelimb bones


  • 2 humerus, 2 radius, 2 ulna, 16 carpals, 10 metacarpals, 28 phalanges
• Pelvic girdle


  • Supports body weight, helps in movement, and protects pelvic viscera
  • Formed by 2 ilium, 2 pubis, and 2 ischium bones fused into 2 innominate or hip bones
• Hindlimb bones


  • 2 femur, 2 tibia, 2 fibula, 2 patella, 14 tarsals, 10 metatarsals, 28 phalanges
• Types of joints


  • Fibrous joints
  • Cartilaginous joints
  • Synovial joints
• Fibrous joints


  • Hold bones together by dense connective tissue containing collagenous fibers
• Cartilaginous joints


  • Join two bones articulated by hyaline or fibrocartilage
• Synovial joints


  • Most movable joints, consist of a joint capsule and synovial membrane that secretes synovial fluid