Bone Health Regulation Flashcards
Bone mass peaks by what age?
Mid-20’s
How long does someone maintain their bone mass after reaching their peak?
10 years
After age 35, both men and women will lose ____-____% of their bone density per year. What is this part of?
0.3-0.5; the aging process
Less than ___% of bone loss during lifespan occurs before menopause.
50%
What accelerates bone loss rapidly in first postmenopausal decade?
Estrogen deficiency
Define bone turnover
Rates of deposition and absorption are equal so that total mass remains constant.
Bone turnover=
Remodeling
What percentage of bone mass turns over in a single year?
15%
What is the normal range of plasma calcium?
8.5-10.5 mg/dl
Describe what happens in hypocalcemia.
Increased neuromuscular excitability
Hypocalcemia results in increased neuronal membrane permeability to _____
Sodium
Hypocalcemia side effects
Muscle spasms, tetany, cardiac dysfunction
Tetany occurs at what plasma calcium level
6 mg/dl
Hypercalcemia results in _____ nervous system and muscle activity.
Depressed
Hypercalcemia occurs at what plasma calcium level?
12 mg/dl
Describe hyperpcalcemia side effects
Sluggish CNS reflexes
Constipation/lack of appetite due to depressed contractility of muscles in GI tract
What occurs above 17 mg/dl plasma calcium level?
Diffuse precipitation of calcium phosphate in tissues, leading to widespread organ dysfunction and damage.
Which hormone increases plasma calcium and maintains at 10mg%?
Parathyroid hormone
Which hormone increases calcium mobilization from bone to plasma?
Parathyroid hormone
Which hormone increases calcium reabsorption in renal tubules?
Parathyroid hormone
Three functions of Parathyroid Hormone
- Increases plasma calcium and maintains at 10mg%
- Increases calcium mobilization from bone to plasma
- Increases calcium reabsorption in renal tubules.
What is the hormonal form of vitamin D?
Calcitrol
What hormone is produced by the kidneys in response to stimulation by the parathyroid hormone?
Calcitrol
Two functions of Calcitrol
- Increases calcium absorption from intestine
2. Limits calcium excretion when blood calcium levels are low.
Which hormone increases calcium absorption from the intestine?
Calcitrol
Which hormone limits calcium excretion when blood calcium levels are low?
Calcitrol
Alternate name for Thyrocalcitonin
Calcitonin
Where is calcitonin produced?
Thyroid gland
What hormone reverses the action of parathyroid hormone?
Calcitonin
Increases in blood calcium stimulates what hormone?
Calcitonin
Which hormone lowers blood calcium by inhibiting bone resorption?
Calcitonin
Calcitonin _____ plasma calcium and phosphate levels
Decreases
What is used in medicine to treat hypercalcemia?
Calcitonin
What hormone is a minor regulator of blood calcium compared to the actions of PTH and calcitrol?
Calcitonin
How is vitamin D-3 formed?
In the skin, when cholesterol precursor 7-dehydroxycholesterol is exposed to ultraviolet light.
What is the primary action of vitamin D-3
Promote gut absorption of calcium by stimulating formation of calcium-binding protein within the intestinal epithelial cells
What hormone has a synergistic role with parathyroid hormone?
Vitamin D-3
Compared to PTH, ______ exerts a much slower regulatory effect on calcium balance.
Vitamin D-3
