DIGESTION AND ABSORPTION
Organic food forms are digested
- Hydrolyzed to inorganic phosphate by phosphatases
- Exception: phospholipids in micelles
- Exception: digestion-resistant phytic acid
Absorption typically by passive diffusion
- Active transport available for when intake is low
- Stimulated by vit D
- Absorption inhibitors
- Phytic acid
- Excessive Mg Al Ca
Ph in the blood
- Phospholipids delivered by chylomicrons
- Inorganic and other organic forms absorbed by facilitated diffusion
Cellular uptake passive
- largest amounts in bone and muscle
Excreted in urine
- influenced by diet, vit D, hormones, acid-base balance
FUNCTIONS and MECHANISMS
Bone mineralization
- PTH, calcitriol, calcitonin influence body Ph balance
- PTH impact of kidney is OPPOSITE Ca - Ph is excreted!
Nucleotide / nucleoside phosphatases
- structural roles
- energy storage and transfer
- intracellular second messenger
Phosphorylation in metabolism
- enzyme activation / deactivation
- vitamin activation
Phospholipids
- membrane structure and function
Acid-Base balance
- Ph main intracellular buffer
Oxygen availability
- 2,3 DPG mediates O2 release from Hg
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