Quiz 3 Flashcards
Vitamin D Characteristics
Steroid derivative (also a seco-steroid Absorbed from a micelle and incorporated into the chylomicron in intestinal cells
Vitamin D functions
Regulator of bone mineral metabolism, blood calcium homeostasis, proliferation and growth, calcium metabolism, cell differentiation
Immunity: important for Cell Mediated Immunity & coordination of the immune response.
Calcium Function
Tightly regulated Structural component of bones and teeth Role in cellular processes Muscle Contraction Blood Clotting Enzyme Activation
Phosphorus Function
Structural component of bone teeth cell membranes phospholipids nucleic acids nucleotide co-enzymes ATP-ADP phosphate transferring system in cells pH Regulation
Phosphorus Regulation
Not tightly regulated
Influence absorption: Calcitriol, phytate, Excessive intake of Mg, Al, Ca
If high: we excrete FDF23 which decreases active Vit D. It also suppresses calcitriol which decreases Ca absorption
PTH: enhances active vit D to increase small intestine phosphorour absorption and increase Ca absorption.
Potassium Function
Water, electrolyte, and pH balances
Cell membrane transfer
Potassium Toxicity / Deficiency
Hyperkalemia
Hypokalemia (Serum K < 3.5 mEq)
Sodium Functions
Water, pH, and electrolyte regulation
Nerve transmission
Muscle contraction
Sodium Toxicity / Deficiency
hyponatremia
hypernatremia
Magnesium Functions
Component of bones
Role in nerve impulse transmission, protein synthesis
Enzyme cofactor
Iron Storage and transfer proteins
Functional Iron: mostly hemo and myoglobin. Also heme and nonheme enzymes.
Transports: transferrin (ferric iron). Also ferroportin
Stored: Ferritin and hemosiderin
Cystein acts as a chelator to enchance absorption
Iron is regulated at absorption
Extracellular fluid cations + anions
Sodium
Calcium
Chloride
Bicarbonate
Intracellular fluid cations + anions
Potassium
Magnesium
Phosphate
Regulation of Extracellular water volume and osmolarity
Aldosterone leads to Na retention and K excretion from kidney
ECF increased by aldosterone. This increase triggers a thirst response
Decreased blood volume triggers baroreceptors to tell hypothalamus to excrete vasopressin to up water retention
Extracellular Calcium Regulation
Three main hormones in the blood serum / plasma:
PTH: Increases ECF calcium concentrations through interactions with the kidney and bone.
Calcitriol: Improves Ca absorption in the intestine and brush border membrane.
Calcitonin: Lower serum calcium concentrations, suppress PTH production and release.
