Karteikarten
Calcium
Karten in diesem Stapel (34)
- 1Intracellular [Ca2+]?approx. 1micromol/l
- 2Extracellular [Ca]?approx. 1mmol/l
- 3Reason for low [Ca]?Increase allows cascade of events to occur.
- 4Reason for high extracellular [Ca]?Bone mineralisation
Normal function of excitable tissue - 5Bone morphology?Trabecular bone inside, spongy.
Cortical bone outside, rigid. - 6Describe the change in Ca balance throughout life.Growth, pregnancy = +ve balance
Adulthood = neutral balance
Aging = slow -ve balance
loss in bone density - 7Bone function?Body support
Organ protection
Ca reservoir/mineral homeostasis
Endocrine function - osteocalcin, fibroblast GFactor 23
Haematopoiesis
Reverage for movement - 8Bone = ? % BW17%
- 9Order of 3 bone cells from outside in.Osteoblasts - Makes bone matrix
Osteocytes - Most abundant bone cell. May sense pressure during growth
Osteoclasts - Resorbs/degrades bone - bone turnover, releases minerals for collagenous protein breakdown - 10Which bone cell is related to macrophages?Osteoclasts
- 11Osteogenic cellsUndifferentiated bone cells, gives rise to osteoblasts and osteocytes.
- 12Are osteogenic cells responsible for formation of osteoclasts?No - Osteoclasts formed from monocytes and macrophages.
- 13What is an osteoiduncalcified bone matrix
- 14What is the mineral component of bone matrix?hydroxyapatite
Ca10(PO4)6(OH)2 - 15Role of hydroxyapatite?Provides rigidity and resistance to bone compression
- 16Osteoid mineralisation is dependant on?Vitamine D3 (1,25-(OH)2D3)
- 17What happens in Vit D3 deficiency for children? for adults?Rickets in children
Osteomalacia in adults - 18OsteomalaciaSoftening of bone from failing mineralization i.e. low Ca and Phosphate
Also occurs as a result of hyperparathyroidism which increases Calcium resorption from bones - 19Where is Alkaline Phospatase expressed?On osteoblast surface
- 20What are Alk Phos biomarkers of?Osteoblast activity i.e. bone formation
- 21Action of Alk Phos?Formation of inorganic phosphate ions by hydrolysing pyrophosphate (P2O7) -> 2 (PO4 3-)
Thus increasing local phosphate concentration - 22Why does pyrophosphate hydrolysis lead to bone formation?Pyrophosphate = bone mineralisation inhibitor
- 23Osteoclast formation occurs by?Fusion of monocytes and macrophages
- 24Characteristic of activated osteoclasts?Ruffled border formation
- 25How do osteoclasts resorb bone?Contains high levels of Carbonic Anhydrase for H+ formation from CO2 and H2O plus enzymes e.g. Cathepsin K (protease) which breaks down collagen matrix
- 26How do Osteoclast precursors become activated to become mature osteoclasts?RANK-RANKL interaction which forms NFkB
NFkB induces new gene transcription
*RANK = Receptor Activated Nucleate Kappa (Ligand) - 27OsteopetrosisIncreased bone mass/density due to abnormal osteoclasts = impaired resorption
Inheritedd condition
4 possible mutations - in CA, H+ pump, Cl channel or in Cathepsin K - 284 steps of bone remodelling cycleQuiescence
Resorption - 10 days
Reversal
Formation - 3 months
total 4-6 months - 29How often are skeleton renewed?7 yrs
- 30Where are calcitonin produced?C-cells of thyroidal folliclces
Lowers Ca level - reduce osteoclast activity?
No clear role in Ca homeostasis - 31Role of PTH (Ca absorption)Increased calcitriol formation by gut Ca absorption (indirect)
Increased distal tubule Ca absorption (direct) - 32Role of PTHPromotes loss of phosphate and bicarbonate
- 33Why does PTH induce loss of phosphate?PTH secretion = low Ca
Phosphate reacts naturally with calcium to form hydroxyapatite so phosphate loss = release of Ca - 34Why does PTH induce loss of bicarbonate?Loss of bicarbonate = increased H+ production = competes with Ca on Albumin = release of bound Ca
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- Beschreibung
- Karteikarten am Calcium, erstellt von suzukan am 17/12/2014.
- Erstellt von
- suzukan · Dez 2014
- Aktualisiert
- 19 Feb 2016
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- 10
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