Skeletal and Muscle Systems Part 2 Flashcards
Congenital Diseases of Bone
- Osteogenesis Imperfecta
- Achrondoplasia
- Osteopetrosis
General Terms
see below
Dysostoses
- congential malformations of bone
-Aplasia- absence of bone
-Supernumerary- extra bones
Abnormal fusion of bones
Dysplasias:
- abnormalities of bone osteogenesis
- —-mutations affecting bone or cartilage growth
Examples of dysplasias:
- Osteogenesis imperfect
- Achrondoplasia
- Osteopetrosis
Osteogenesis Imperfecta (OI) Brittle bone disease
● Cellular pathophysiology -Etiology is Genetic mutation -Defective synthesis of Collagen type 1 -----Extracellular bone matrix -----Skin, joints, eyes -Phenotype has broad range -Inadequate supply of bone- fragile skeleton
4 Clinical Classifications
See below
Type 1 OI:
Normal lifespan
Modest increase fracture rate in childhood that decreases in puberty
Blue Sclerae so that underlying choroid visible
Hearing loss
Small misshapen teeth
Type II OI:
- Fatal pre or immediately post-partum due to in utero fractures
Achrondroplasia
● Cellular pathophysiology
- Etiology is genetic mutation
- Fibroblast growth factor receptor 3 (FGFR3) is activated
- Activated FGFR3 inhibits chondrocyte proliferation
- Suppression of epiphyseal growth plate expansion long bones
- Long bone growth stunted
- All bones that develop from cartilaginous framework
Achrondoplasia: Clinical
-Clinical Major Cause of Dwarfism: - Disproportionate shortening of proximal extremities -Bowed legs -Lordosis
Severe cases can lead to perinatal death from respiratory failure
Osteopetrosis (Stone Bone)
● Cellular pathophysiology
-Etiology is genetic mutations
-Rare
-Exact molecular cause of osteoclast dysfunction not certain.
-Defective Osteoclast-mediated bone resorption
(Normally, the cells decalcify the matrix prior to matrix digestion.)
-Bone abnormally hard and structurally unsound with tendency to break.
Osteopetrosis : Clinical
- Fractures
- Compression of cranial nerve that leads to related problems
- Recurrent infections due to reduced marrow space affecting hematopoiesis
- Hepatosplenomegaly due to extramedullary (outside the marrow) hematopoiesis
Osteopenia
• Not a disease
• Condition of Low Bone Mass
– T score between -1 and -2.5
• Diagnosed by Bone Density test
• 34 mil women and 12 mil men
• Could develop Osteoporosis if prevention strategies not taken.
– Especially if person has Osteoporosis risk factors
Osteoporosis
• Disease • Porous bones that are fragile • Can be prevented and treated • 44 million Americans, 17 billion dollars – 80% are women • 1 of 2 women • 1 of 8 men lose trabecular bone volume (spongy interior matrix) (up to 20%) excess resorption
Types of Osteoporosis
See below
Type 1: Postmenopausal Osteoporosis
- women 51-75 yr, accelerated bone loss, especially trabecular
- common fractures of vertebrae and distal femur
Type II: Senile Osteoporosis
- Men and women greater than 71
- Proportional loss corticol and trabecular
- Common fx’s of vertebrae and distal femur
Type III: Secondary Osteoporosis
- Men and women any age
- Secondary to other such as drug therapy and diseases
Table 21: Broken into Categories of Generalized Osteoporosis
See Below
Primary
- Post menopause: MOST COMMON
- Senile - also most common
Secondary
- Endocrine
- Neoplasia
- GI disorders
- Disease Drugs
- Miscellaneous
Endocrine Disorders
- Hyperparathyroidism
- Hypogonadism
- Pituiatry tumors
- Diabetes type 1
- Addison Disease