Bone and Joint Histology

Bone & Joint Histology ________________ Bone * It is a specialised connective tissue. * Osteogenic cells ⇒ osteoblast (makes matrix, active when young, and after fracture) ⇒ osteocyte ⇒ osteoclast (functions in resorption, breakdown of bone matrix) (makes cavities) (from blood monocyte) Bone Functions * Framework for support of the skeleton * Protection: brain, spinal cord, lungs and heart * Levers for muscles attached to them via tendons * Reservoir for minerals e.g. calcium, magnesium, phosphates etc. Bone Matrix * Components * Extracellular matrix (ground substance and fibres) consists of inorganic material (65%) e.g. calcium phosphate, calcium carbonate, magnesium, sodium, potassium, bicarbonate, fluoride, citrate, sulfate, and hydroxide. * Minerals give bone hardness and rigidity * Organic component (35%) mostly type I collagen (95%)- gives bone slight flexibility; and ground substance e.g. GAGs with proteoglycans, which contain chondroitin and keratin sulfates which give bone resilience * Development 1. Bone starts as osteoid, which is collagen and GAG’s with no minerals 2. Bone becomes mineralised (immature, primary, or woven bone). It is the first bone to appear in development and in repair after fractures 3. Bone starts to remodel as the adult form (mature, secondary, lamellar) Bone Cells . Osteoprogenitor (osteogenic) cells: from

  • Word count: 1755
  • Level: University Degree
  • Subject: Medicine and Dentistry
Access this essay

What is Hypophosphatasia?

HYPOPHOSPHATASIA INTRODUCTION; Hypophosphatasia is a rare disorder characterised by low levels of serum alkaline phosphatase activity resulting in abnormal phoshorylated metabolites and varying skeletal abnormality. Ratbun first described it in 1948, but since then reports have come from countries all over the world. DIFFERENT FORMS OF HYPOPHOSPHATASIA; Hypophosphatasia is classified into six sub groups. All six exhibit a varying skeletal abnormality. These include: . Adult form - occurring in middle age. 2. Childhood form - affecting children seven and upwards. 3. Odonto - affects infants and children. 4. Perinatal - affects pregnant women. 5. Infantile - Infants (6months -7 years) are effected by the; Infantile, Pseudo and Odonto forms. These then persist in adult life 6. Pseudo Hypophosphatasia- is an extremely rare form of the disease. Adult form ? Symptoms: - Premature teeth loss, - Slowness in walking with tiredness. - Pain in legs and feet. ? Diagnosis: - Stress fractures in the feet, thighs or hips. ? Prognosis: - Involves extraction of the secondary teeth. Childhood form ? Symptoms - Premature loss of teeth (before the age of five). - Waddling gait. - Pain stiffness with muscle weakness in limbs. - Bowed legs or knocked knees. - Short stature. ? Diagnosis - Enlargement of the wrists and ankles. Infantile form ?

  • Word count: 1387
  • Level: University Degree
  • Subject: Medicine and Dentistry
Access this essay