MSK case Flashcards
Functions of the musculoskeletal system: (6)
- Protects organs
- Stores and releases fat
- Produces blood cells
- Stores and releases minerals
- Facilitates movement
- Supports the body
Mineral phase of bone:
- Hydroxyapatite (a calcium phosphate)
Organic phase of bone:
- Collagen and other proteins
Bone cells: osteochondral progenitor cells
- Undifferentiated stem cells
Bone cells: Osteoblasts
- Make new bone
Bone cells: osteocytes
- Maintain the activity of the bone
Bone cells: Osteoclasts
- Reabsorb (remove) bone
Types of bone: (2)
- Cortical bone
- Trabecular bone
Bone and calcium:
- Role of bones
- Amount of calcium
- Bone is the main body store of calcium
- Body contains approximately 1Kg of calcium and 99% of that is bone
Calcium regulation: Parathyroid hormone
- Secretion
- Action on kidney :Ca, Ph, VitD
- Action on bone
- Secreted from the parathyroid glands
- Actions on the kidney:
. Increases Ca Resorption in distal tubules
. Increases Phosphate excretion
. Increases formation of active vitamin D - Actions on bone:
. Stimulates bone Resorption
Vitamin D sources:
- Mostly formed from the action of UV light on the skin
- Also found in some foods (oily fish)
- Highly fat soluble, large amounts stored in the adipose tissue
Vitamin D activation pathway: - 2 Reactions - Liver: cholecalciferol to ..... - Kidney: ...... to active vit D Regulated by the enzyme:
- 2 hydroxylation reactions
- In the liver:
Cholecalciferol to calcidiol - In the kidney:
Calcidiol to active vitamin D - regulated by the enzyme 1a-hydroxylase
Actions of vitamin D:
- Bone
- Intestine (Ca,Ph)
- Bone: stimulates bone resorption
- Intestine:
. Stimulates calcium absorption
. Stimulates phosphate absorption
Calcitonin:
- Secretion
- Effect
- Secreted by parafollicular cells of the parathyroid gland
- Opposes the effect of PTH
Regulation of low calcium levels:
- Parathyroid gland releases PTH
- Calcium levels increase
Bone density:
- A measure pf the amount of minerals present in the bone
Factors effecting bone density: (3 main)
- Availability of substrates . Ca intake, Ca absorption, PTH functionality - Physiological factors . Exercise, BMI, smoking - Biochemical factors . Hormones
Groups that require calcium supplementation:
- Vegans
- Lactose intolerance
Bone density after menopause:
- Decreases
Macroscopic bone structures: (2)\
- Axial
- Apendicular
- Axial: skull, spine, ribs
- Appendicular: Limbs, pelvis, shoulders
Osteology:
- E
- M
- D
- Epiphysis: ends of the long bone
- Metaphysis: Wide part of the bone. Growth occurs here
- Diaphysis: long part of the bone (shaft)
Cortical bone: (4)
- Type
- Skeletal weight %
- Organisation
- Turnover rate
- Compact bone
- 80% skeletal weight
- Organised into Haversian systems
- Slow turnover
Cancellous bone: (5)
- Type
- Density
- Wolff’s law
- Turnover rate
- Function
- Spongy/trabecular
- Less dense
- Remodels due to Wolff’s law
- High turnover
- Haematopoiesis
Haematopoiesis:
- The formation of bloods cellular components
Osteoblast products:
- Type 1 collagen
- ALP - initiates calcification
- Calcium phosphate
Osteocytes further:
- Positioning
- Derivation
- Causes
- Lie within lacunae in mature bone
- Derived from osteoblasts
- Responsible for bone maintenance
Wolff’s Law:
- Bones will adapt based on the stress or demands placed on them
Primary bone healing: (2)
- Absolute stability + compression
- No callus
Secondary bone healing:
- Relative stability
- Callus formation