Calcium Homeostasis Flashcards
What happens if calcium levels are too low?
Osteoclast activity increases, release more calcium into the blood than osteoblasts need to take from the blood to make new bone
What happens if calcium levels are too high?
Osteoclast activity decreases. Osteoblasts remove more calcium from the blood than osteoclasts release.
Three hormones that regulate calcium homeostasis
Parathyroid hormone
Vitamin D
Calcitonin
Parathyroid hormone
The major regulator of Calcium
Located in the parathyroid gland
Sends signals to increase or decrease osteoclast activity
RANKL
What is produced when PTH bonds with osteoblasts/ stemcells?
RANK
When binding with RANKL, stimulates osteoblasts to become osteoclasts
Osteoprotegerin
Secreted by osteoblasts to inhibit osteoclast production
Calcitonin
Secreted from thyroid gland when blood calcium levels are too high.
Osteomyelitis
Bacterial infection in the bone
Results in devastating bone loss by causing apoptisys in osteoblasts and increased activity in osteoclasts.
Treated with 4-8 week course of antibiotics; in extreme cases, surgery and debridement of the dead tissues.
What hormones do osteoblasts produce
RANKL
OPG
What hormones do osteoclasts produce
RANK
OPG
Osteoprotegerin
Produced by osteoblasts
Inhibits osteoclast production
Why is bone matrix more brittle in older bones?
Decreased collagen production in the bones, which removes some of the bone’s flexibility.
When is bone denisity highest?
Around age 30
What is the rate of bone loss experienced after age 35?
.3-.5%
