The need for tissue engineering

Osteoporosis

The importance of calcium

  • Serum Ca is maintained at a few millimoles/liter
    • Controlled by hormones acting on bone, kidney and intestines
    • If blood Ca is too low nerves become more excitable, but transmission may be blocked at synapses- the net effect is muscular spasms which can be fatal if they involve respiration
  • Intracellular Ca levels are kept low by active transport:
    • Keep cytoplasmic Ca at a concentration a thousand times lower than serum Ca (about 0.1 micromoles/liter)
    • Necessary because high levels of cytoplasmic Ca kill cells- they activate enzymes that destroy proteins and other cell components

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