John Flashcards
List the 5 functions of the honey skeleton
Structural support Facilitates articulate movement Protection of vital organs Houses the bone marrow Calcium reservoir
Describe the process of bone remodelling. How is this process different to bone modelling?
Bone modelling does not include resorption. Used to change the shape or size of bone.
1) osteoclasts are activated by load (osteocytes) or hormones and cytokines.
2) resorption of bone, bone us dissolved in acid within lacunae. Collagen broken down by professes.
3) osteoclasts die by apoptosis and are replaced by osteoblasts
4) osteoclasts produce osteoid, a type 1 collagen matrix
5) mineralisation, osteoblasts deposit hydroxyapatite onto osteoid.
Describe the role hormones play in the remodelling of bone.
PTH will increase bone resorption to free up more calcium in the circulation. Increase calcium absorption from gut, decrease excretion from kidney. Calcitonin will do the opposite.
Oestrogen increases bone remodelling
Growth hormone increases bone remodelling
Androgens increase bone remodelling
Lepton reduces bone mass
How does vitamin D impact bone homeostasis ?
Activated by 2 -OH groups and becomes calcidiol. Induces reduced calcium excretion from kidneys. Additional -OH group leads to calcium release from bones.
How does RANK and RANKL affect bone homeostasis?
Direct OB and OC precursor contact via RANK (receptor) and RANKL (ligand) leads to differentiation and fusion of of osteoclast precursors, resulting in an activated osteoclasts.
What are the 8 risk factors for getting osteoporosis ?
1) genetics
2) Smoking
3) inactivity
4) drugs
5) premature menopause
6) excess alcohol
7) diet
8) diseases
What are the risk factors for the development of osteoarthritis?
Age, breed, obesity, joint damage, genetics, excessive joint loading, inactivity, bone deformations, joint infections
Describe the 4 types of healing that can take place (john)
Regeneration (complete healing) Fibroplasia (complete function returns but is distinct from uninsured tissues Impaired healing (original function not achieved, healing incomplete) Fibrosis (inappropriate levels of connective tissue, function may be impaired)
List the 4 phases of wound repair. Briefly describe each stage
Vascular (increased permeability to allow cells to site. Fluid into tissue causing oedema. Initial vasoconstriction causes temporary ischaemia)
Inflammatory (recruitment of inflammatory cells)
Proliferative (keratinocytes become proliferative after coming into contact with type 1 collagen. Fibroblasts proliferate. Then differentiate into myofibroblasts. Granulation tissue.
Remodelling (epidermis restored, granulation tissue formed. Proliferative cells die, myofibroblasts contract to reduce wound size. Matrix remodelled over time)
What effects does histamine evoke after release from mast cells? What triggers its release?
Mast cells degranulate and release it in response to binding with IgE, complement or as a result of injury.
Causes vasodilation, chemotactic, activates capillary endothelium and increases permeability. Irritates nerve endings causing pain and itchiness
