BIOL 1051H Chapter Notes - Chapter 11: Homeostasis, Sarcolemma, Isotonic Contraction
Document Summary
Chapter 11: muscle and bone: bone is a dynamic structure, growing tissue and constantly being renewed. 10% of our skeleton is renewed every 10 years. Calcium homeostasis: hypocalcemia: deficient calcium in blood. Causes overly excitable nervous system and tetany (muscle spams) Caused by vitamin d deficiency, diarrhea, thyroid tumors, underactive parathyroid glands. Pregnancy and lactation increases risk: hypercalcemia: excessive calcium levels, makes ion channels less responsive, nerve and muscle are less excitable. Can cause emotional disturbance, muscle weakness, sluggish reflexes, and cardiac arrest. Three important hormones that help regulate calcium in our bodies: calcitriol: raises blood calcium levels, most active form of vitamin d. Produced by actions of skin, liver, and kidneys: vitamin d3 (inactive) liver calcidiol kidney calcitriol (active form of vitamin d) Increases calcium absorption by small intestine, and from skeleton. Stimulates osteoblasts to release rankl, a chemical that stimulates production: parathyroid hormone (pth): raises blood calcium of more osteoclasts. Stimulates osteoblasts to secrete rankl, increasing osteoclast population.
