HAPPATH Lecture Module 2

• Characteristics of Bone

  - a special type of connective tissue

  - composed of proteinaceous organic matrix

  - consist largely of collagen

  - plus inorganic matrix (calcium phosphate salt aka hydroxyapatite)
• Function of Skeletal System

  - protection

  - support

  - movement

  - storage

  - blood cell production
• 4 Types of Bone Cells

  - osteocyte

  - osteoblast

  - osteogenic cell

  - osteoclast
• Type of Bone as to Texture

  - compact

  - spongy
• Compact Bone


  - type of bone as to texture found in the shafts of long bones

  - make up 80% of all bones
• Spongy Bone


  - type of bone as to texture found at the ends of long bones

  - make up 20% of all bone

  - contains red bone marrow and a network of bony trabeculae
• Epiphysis


  - end part of a long bone

  - site of spongy bone in the adult
• Diaphysis


  - aka shaft of a long bone

  - site of hemopoiesis in the adult
• Periosteum


  - protective layer

  - attachment for ligaments and tendons
• Yellow Marrow Cavity


  site of fat storage
• Epiphyseal plate


  site of longitudinal growth in a child/area where bone grow in length
• Hyaline cartilage


  - covers end of bones

  - stops bones from rubbing together

  - absorb shock

  - mostly intimately associated with bones

  - most of the bones in the body develop from it
• Intramembranous Ossification


  bone are formed in the connective tissue membrane
• Endochondral Ossification


  bones are developed from cartilage models
• Appositional growth

  formation of new bone on the surface of older bone or cartilage
• Intervertebral disks


  - made of cartilage, separate and cushion the vertebrae from each other

  - disk becomes compressed with incleasing age which decreases the distance between the vertebrae
• Wrist


  - carpus

  - relatively short region between the forearm and hand

  - composed of 8 carpal bones arranged into two rows of four each
• Carpal Tunnel Syndrome


  occurs frequently among people who use their hands a lot
• Factors affecting Bone Growth


  Nutrition

  - vitamin D

  - vitamin C

  
  

  Hormones

  - growth hormones

  - thyroid hormone

  - sex hormones
• Vitamin D


  - necessary for the normal absorption of calcium from intestines

  - body can synthesize or ingest vitamin d
• Rickets


  - a disorderin children due to insufficient vitamin d

  - bowed bones and inflammed joints
• Osteomalacia


  disease characterized by weak, soft or brittle bones in adults
• Vitamin C


  necessary for collagen synthesis by osteoblasts
• Scurvy


  - vitamin c deficiency in adults and children

  - marked by ulceration and hemorrhage in almost any area of the body because of the lack of collagen
• Growth Hormone


  a protein hormone released from the anterior pituitary gland under the control of the hypothalamus
• Dwarfism


  condition in which the person is abnormally short
• Pituitary Dwarfism


  results when abnormally low levels of pituitary growth hormone affects the whole body
• Achondroplastic dwarfism


  form of dwarfism which produces a person with a nearly normal sized trunk and head but shorter than noral limbs
• Giantism


  a condition of abnormally increased height that usually results from excessive cartilage and bone formation at the epiphyseal plate
• Acromegaly


  - caused by excess pituitary GH secretion

  - effects include increased in the diameter of all bones strikingly appatent in the face and hands
• Thyroid


  - required for normal growth of all tissues including cartilage

  - decrease in this hormone = decrease size of an individual
• Estrogen and Progesteron


  initially stimulate bone growth which accounts for the burst of growth at the time of puberty
• Bone Remodeling


  - replacement of old bone tissue by new bone tissue

  - occurs in adult skeleton

  - to maintain bone mass
• 5 phases of Bone Remodeling

  - bone resorption

  - bone reversal

  - bone formation

  - bone quiescence

  - bone activation
• Bone resorption


  - phase of bone remodelling

  - osteoclasts digests bineral matrix (old bone)
• Bone Reversal


  - phase of bone remodelling

  - end of resorption
• Bone formation


  - phase of bone remodelling

  - osteoblasts synthesize new bone matrix
• Bone quiescence


  - phase of bone remodelling

  - osteoblasts become resting bone lining cells on the newly formed bone surface
• Fractures


  - the breaking of bone or cartilage

  - determined by: energy of the event & strength of the bone
• Radius Fractures


  - it is the most commonly fractured bone in people over 50 years old resulting from an outstretched hand