Calcium homeostasis Flashcards
What is calcium used for intracellular reactions
Release of hormones through exocytosis
Blood coagulation
Cell membrane stability
What is phosphates used in calcium homeostasis
Binds to calcium reducing the available free calcium
As blood calcium levels rise, blood phosphate levels fall
Phosphate concentrations are controlled by same systems that control blood calcium concentrations
What are the 3 pools of calcium
Bone
Intracellular calcium
Extracellular fluid
What does the regulation of calcium levels involve
Control of the movement of calcium between extracellular fluid
GI tract
Kidneys
Bone
GI tract features of calcium homeostasis
Source of calcium for the body
Absorption of across mucosa both passive diffusion and active transport pump
Pump becomes more active when dietary calcium is low
Kidneys feature in calcium homeostasis
Route of calcium excretion
Most calcium reabsorbed only 2% lost
What is the parathyroid gland
Main organ involved in calcium and phosphate homeostasis
What hormone does parathyroid gland secrete
Parathyroid hormone
What effect does PTH have on calcium and phosphate concentration in ECF
An increase in calcium and phosphate concentrations
What does PTH have direct effects on
Bone
Kidney
What does PTH have indirect effects on
GI metabolism
Calcitonin features
Hormone is released by cells of thyroid gland
Counterbalance for PTH because it decreases movement of calcium from bone and decreases extracellular fluid calcium concentrations
What is calcitonin secretion controlled by
Calcium
Importance of vitamin D
Comes from diet
Inactive and must be transformed by both the liver and kidney before it becomes active
Hypercalcaemia causes
Malignancy
Hyperparathyroidism
Fungal disease
Osteoporosis
Chronic renal disease
Progress rapidly to acute renal failure due to mineralisation
