EXAM4 Flashcards
Required major (macro)minerals
need more than 100 mg/day
Calcium, phosphorus, magnesium, sodium, chloride, and potassium
Required trace minerals
need less than 100mg/day
iron, copper, iodine, selenium, chromium, manganese molybdenum, and zinc
Which of the following individuals is likely to have more osteoblast than osteoclast activity?
1-year-old Robby
The relationship between blood glucose and glucagon is analogous to the relationship between blood calcium and _____.
PTH
Biochemical tests are often required to assess status of specific nutrients.
Is blood calcium a good indicator of calcium status?
False
Factors that increase calcium absorption
- Active vitamin D hormone
- Lactose and other sugars
- Adequate protein intake
- Increase calcium needs (e.g. during pregnancy and infancy)
Factors that inhibit calcium absorption
- Lack of stomach acid
- Vitamin D deficiency
- High phosphorus intake
- Phytates: phytochemicals in the bran of whole grain
- Oxalates: in dark green leafy vegetables (spinach)
What is the bioavailability of a nutrient in food?
The amount of nutrient absorbed and ready to be used by the body.
Almost all (99%) of the calcium in the body is used to ______.
form hydroxyapatide
When blood calcium is low, _____ .
- parathyroid hormone is relased
- absorption of calcium from the intestine increases
- reabsorption of calcium from the kidney increases
- resorption of calcium from the bone increases
During rising blood calcium levels, the thyroid secretes what?
Calcitonin: Inhibits Vit D activation, prevents kidney reabsorption, and limits intestinal absorption to inhibit osteoclasts and lower blood calcium levels
Factors that decrease PBM:
- Lack of key minerals (Celiac, ED, etc)
- Smoking (↓ Ca2+absorption)
- Excessive alcohol
- Early menopause
- Abnormal absence of periods (amenorrhea)
Factors that enhance iron absorption
- Increased requirements
- Consumption of animal tissues – Meat Fish Poultry (MFP)
- Ferrous form (Fe2+) is better absorbed than ferric form (Fe3+)
- Heme iron is better absorbed
- Vitamin C increases absorption of non-heme iron by keeping iron in ferrous form
- Gastric acid reduces ferric iron to ferrous form
Factors that inhibit iron absorption
- Decreased requirements, ie. Good iron status (body doesn’t need more iron)
- Phytate in whole grains and legumes
- Oxalate in green leafy vegetables
- High fiber intake
- Polyphenols (e.g., tannins found in tea)
- Excessive intake or supplement of calcium, zinc, and manganese
Which of the following proteins carries iron through the blood to tissues?
Transferrin
When iron levels within cells are low, _____.
IRPs (Iron Regulatory Proteins) bind to the IREs (Iron Responsive Elements)
Which of the followings has a relationship to iron, similar to the relationship of insulin to glucose?
Hepcidin
Which of the following statements is correct?
- Hepaestin (ferroxidase) contains copper.
- Divalent metal transporter (DMT) transports reduced nonheme iron.
- Ferroportin facilitates cellular iron export.
Which of the followings indicates iron deficiency?
high total iron-binding capacity
Which of the following mutations could result in hemochromatosis?
Mutations leading to impaired production of hepcidin
To decrease the extent of iron deficiency in the U.S., some legislators propose a bill requiring that more foods, like fruit juices, are fortified with iron.
As an expert witness who is concerned about the prevalence of hemochromatosis, what position should you take?
Oppose the legislation because iron toxicity could occur in susceptible individuals since very little iron is lost once it has been absorbed.
Which of the following tests can serve as an early indicator of iron depletion?
Serum ferritin
The relationship between zinc and metallothionein is similar to the relationship between iron and ____.
ferritin
The relationship between iron and hepcidin is similar to the the relationship between calcium and ____.
calcitonin
Selenium is ____.
a part of endogenous antioxidant system
Which of the following statements regarding function of iron is correct?
- Iron is involved in the synthesis of several neurotransmitters.
- Iron is an oxygen carrier.
- Iron is required for energy metabolism.
- Iron is a cofactor of enzymes involved in oxidation/reduction reactions.
Zip 4 is a zinc transporter. What would be a proper response to a declining Zinc status in the expression and activity of Zip4 in the enterocytes?
Increase
Which of the following copper homeostasis mechanisms is correct?
- Copper can bind to metallothionein (MT) in the enterocytes.
- Excessive copper can be excreted into bile.
Which of the following statements regarding iodine is correct?
- Iodine is an essential component of thyroxine (T4) and triiodothyronine (T3).
- Iodine deficiency causes goiter.
- Maternal iodine deficiency could result in increased risk of congenital hypothyroidism (cretinism).
- Seaweed is a rich source of iodine.
Fluoride
can substitute for the hydroxyl group of hydroxyapatite.
Which of the following statements regarding iron absorption is correct?
- Gastric acid enhances iron absorption.
- Increased iron requirements enhance iron absorption.
- Vitamin C enhances iron absorption.
- consumption of animal tissues, containing heme-iron, enhance iron absorption
Which of the following statements is correct?
- Excessive zinc supplementation can cause copper deficiency.
- Zinc supplementation induces the expression of metallothionein.
- Dietary iron, copper and zinc can compete for intestinal absorption.
Nutrigenetics
Nutrient-gene interactions
- the study of genome/genetic of an individual modulate responses to health
- How genetic variations determine how we absorb, process, and metabolize nutrients
PKU, hemochromatosis (hepcidin mutations), AE (zip4), lactose intolerance, Menkes & Wilsons
Nutrigenomics
The study of how what you eat modulate expression of genes
Epigenetics
The study of heritable changes in phenotype caused by changes in gene expression that do not involve changes
Metagenomics
the study of genetic material from a mixed community of organisms
Microbiome
The combined genetic material of microorganisms in a particular environment
Microbiota
the microorganisms of a particular environment
Prebiotics
are the non-digestible food ingredients that stimulate the growth/activity of bacteria in the digestive systems in ways beneficial to health
Probiotics
live microorganisms that are intended to have benefits when consumed or applied to the body
Which of the following can regulate the distribution and composition of gut microbiota?
GI secretion, gastric acid, diet, synbiotics, GI motility, Mucus, oxygen tension, antimicrobial peptides,
Systemic
Iron regulates the expression of hepcidin, a hormone that regulates how much iron is released from cells, including hepatocytes, macrophages, and enterocytes. It determines how much iron is absorbed from diets.
Cellular
Iron regulates expression of several proteins important for iron metabolism, including transferrin receptor, and ferritin, to maintain cellular iron homeostasis
What mutation could result in hemochromatosis?
Ferroportin not responsive to hepcidin
Iron: Zinc:: _____ :Metallothionein
Ferritin
Insulin: glucose:: ____: calcium
Calcitonin
