Flashcards in Lecture 18: Minerals Deck (65):
What are the nine essential macro minerals?
What are the 9 essential trace minerals?
What are the functions and daily requirements of phosphorus?
Component of ATP, DNA, RNA, phospholipids
What are the functions and daily requirements of magnesium?
Cell metabolism (ATP synthesis !!)
What are the functions of sulfur?
Critical for protein function and cell metabolism
Component of organic molecules
How do Ca, P, Mg, and S get taken up into the intestine?
Ca = active, passive absorption
Mg = active, passive absorption
P = active
S = part of organic molecules
Where is there active absorption of calcium?
What mediates calcium uptake into the intestines?
Important for low concentrations of Ca
What factors increase TRPV6 expression and activity?
How is calcium actively exported ?
When is passive intestinal calcium absorption important?
Normal and high calcium levels
What are major regulators of calcium homeostasis and their effects?
Vitamin D = inc. calcium
Parathyroid hormone = inc. calcium
Calcitonin = dec. calcium
What are causes of calcium deficiency ?
Impaired absorption due to small intestinal inflammation (celiac disease, IBD)
what are symptoms of calcium deficiency?
What is the treatment for calcium deficiency?
Dietary adjustments, calcium supplements
What chronic diseases are associated with calcium?
Low calcium = inc. risk for HPT
More calcium = lower risk for colon cancer
What is the safe upper limit of calcium to reduce risk of hypercalcemia?
What is hypercalcemia?
Associated with increased risk of
Calcification of soft tissues
What are food sources of phosphorus?
Is there passive absorption of phosphorus?
Where does phosphate absorption take place?
Duodenum and jejunum
How is phosphorus taken up into the cell?
Na-dependent phosphate cotransporter (SLC)
What are causes of phosphate deficiency?
Dietary insufficiency = RARE
Impaired intestinal absorption (from Al-containing antacids)
What are the symptoms of phosphate deficiency?
Neuromuscular = weakness, lethargy, bone pain
What is the treatment for phosphate deficiency?
Infusion therapy + treatment strategy for underlying disease
What food sources does magnesium come from?
What does magnesium do?
Participates in a lot of metabolic reactions:
DNA and protein synthesis
Where is magnesium absorbed?
Jejunum and ileum
How does magnesium get taken up into cell actively?
Magnesium channel = TRPM6/7
How is Mg excreted actively?
Is Mg brought into the cell passively?
Yes @ high [Mg]
What are causes of magnesium deficiency?
Protracted diarrhea, vomiting
Some diuretic drugs
Dietary deficiencies very RARE
What are symptoms of magnesium deficiency?
Neuromuscular and psychiatric symptoms
What is the treatment for magnesium deficiency ?
Oral magnesium salts
Treat underlying problem
What are the clinically most important trace minerals?
What are the dietary requirements of trace minerals?
What are common trace mineral deficiencies?
What are the functions of iron, zinc, copper and iodine?
Fe = oxygen transport, enzyme functions
Zn = enzyme functions
Cu = enzyme functions
I = thyroid hormones
Characterize intestinal uptake of the clinically important trace minerals (Fe, Zn, Cu, I)
Active transport of ionized forms
What food sources does iron come from?
Legumes, whole grain, enriched grains
Is there a passive paracellular pathway for intestinal absorption of iron?
Is there a passive paracellular pathway for intestinal absorption of copper?
Where does absorption of iron occur?
Duodenum and proximal jejunum
What must happen before iron can be absorbed?
Iron needs to be reduced to Fe2+
How is iron taken up by cells?
Proton-coupled divalent metal transporter = DMT1
How is iron exported?
Ferroportin = SLC40A1
Iron gets oxidized for transportation!
What is transferrin?
Oxidized iron + apotransferrin
Found in circulation
What is ferritin?
Iron storage complex
Forms when there is excess intracellular iron
Why is ceruloplasmin important?
Oxidizes iron so it could be ready for transport via transferrin
What is hepcidin and what does it do?
Hepcidin is a peptide hormone made in the liver when there is high iron and inflammation
Hepcidin will induce ferroportin degradation to block iron export from epithelial cells
What are causes of iron deficiency?
Decreased iron intake/absorption: inadequate diet*, malabsorption due to small intestine destruction, systemic inflammation
Inc. iron loss: menses, acute and chronic blood loss
Inc. iron demand: pregnancy, infancy, adolescence
What are symptoms of iron deficiency?
What is the treatment for iron deficiency?
Oral iron therapy
Parenteral iron therapy
Describe iron overload and toxicity
Hemochromatosis (from genetic defects in hepcidin, etc)
Characterized by: excess iron storage in liver, pancreas, adrenals and thyroid
Too much iron absorption without enough excretion
Why is too much iron bad?
Oxidative damage to membranes, proteins, DNA
Particularly to liver and heart
What are food sources of copper?
What is copper important for?
Required for oxidation of iron (for iron absorption)
Neural development + function
How is copper taken up into cell?
Copper transporter 1 (CTR1)
How is copper exported?
Copper transport ATPase (ATP7A)
What is copper mostly found bound to in the plasma?
Loss of which transporters can lead to copper-related diseases?
ATP7A => Menkes disease
ATP7B => Wilson disease
What does loss of ATP7A affect?
Intestine, kidney, brain
What does loss of ATP7B affect?
How do loss of ATPases relate to copper levels?
ATP7A loss = too little copper
ATP7B loss = too much copper