Nutrition Science Exam 4 Study Materials

The relationship between blood glucose and glucagon is analogous to the relationship between blood calcium and _____.

Parathyroid Hormone (PTH)

Biochemical tests are often required to assess status of specific nutrients.

Is blood calcium a good indicator of calcium status?

FALSE

What are known to enhance calcium absorption from the GI tract?

Lactose, stomach acid, vitamin D, pregnancy

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, what happens?

resorption of calcium from the bone increases, reabsorption of calcium from the kidney increases, parathyroid hormone is released, absorption of calcium from the intestine increases

What are some of the required major macro-minerals?

Calcium, Magnesium, Phosphorus, Potassium, Sodium, Chloride

What are the biochemical roles of minerals?

Minerals are inorganic and cannot yield energy

What minerals are more enriched in plants?

Potassium, and magnesium

What minerals are more available in animal products

Iron, zinc, calcium

TRUE or FALSE: minerals cannot be expended/destroyed by our bodies

TRUE

What are the two major regulation points?

Absorption and excretion

What metal can be toxic if not bound to specialized proteins?

Iron

What is the most abundant mineral in the body?

Calcium

What are Osteoblasts?

Are anabolic bone building cells that secrete protein collagen and deposits the minerals as hydroxyapatite

What are Osteoclasts:

Are catabolic bone destruction cells, that release acids and enzymes on bone surface

What are Osteocytes?

they are osteoblasts that become embedded in the matrix after building bones

What is blood coagulation?

formation of a blood clot, can cause stroke or thrombosis

What can enhance calcium absorption?

Vitamin D

What does calcium absorption mean?

refers to the movement of nutrients from the GI tract into blood (absorbed in small intestine)

What does calcium Reabsorption mean?

the movement of nutrients from the kidney filtrate back into the blood

What is calcium Resorption?

the movement of nutrients into the blood following the breakdown of a tissue (skeletal calcium)

What are the two main hormones that regulate blood calcium?

The PTH and calcitonin

What happens when blood calcium is high?

calcitonin is secreted to prevent calcium reabsorption from the kidney

What happens when blood calcium is low?

PTH is secreted to promote calcium reabsorption from the kidney and stimulate calcium resorption from by bone by osteoclasts

Insulin: glucose as _____ : Calcium

calcitonin

What does not enhance calcium absorption?

Oxalate

What is Osteoporosis?

Where production of new bone does not keep up with bone destruction (bones become fragile) is a silent disease

When does bone mass often peak at?

In our late 20s

Who are at higher risk for osteoporosis?

Women

What is the second most abundant mineral in the body?

Phosphorus

What is the role of phosphorus in the body?

Part of major buffer system, DNA and RNA, helps transport lipids in blood

What mineral maintains bone health?

Magnesium

What are good sources for Magnesium?

Legumes, nuts

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

What can indicate iron deficiency?

high total iron-binding capacity

What mutation can lead to hemochromatosis?

mutations leading to impaired production of hepcidin

What tests can serve as an early indicator of iron depletion?

Serum ferritin

What element can substitute for the hydroxyl group of hydroxyapatite?

Fluoride

The relationship between zinc and metallothionein is similar to the relationship between iron and ____.

Ferritin

What is Selenium?

a part of endogenous antioxidant system

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

What does copper bind to in the enterocytes?

Metallothionein (MT)

Where is excessive copper excreted to?

into bile

What is a rich source of iodine?

Seaweed

What can enhance iron absorption?

Vitamin C, gastric acid, consumption of animal tissue, increased iron requirements

What can excessive zinc cause?

Copper deficiency

What three elements compete in the intestinal absorption?

Zinc, iron, and copper

What are the proteins required for iron to function?

Hemoglobin, myoglobin, and iron enzymes

What is the iron transport protein?

Transferrin, carries iron in the circulation

What is divalent metal transporter (DMT)?

a transport located on the cell surface that allows iron to enter cells

What is Ferroportin?

Transporter that allows iron from the enterocyte into the blood (exit the cells)

What is the iron storage protein?

Ferritin

What is the main function of iron?

Oxygen carrier

What is the center of a protoporphyrin ring in heme?

Ferrous iron

When does myoglobin release oxygen in cells?

Releases oxygen when oxygen is needed for ATP production during muscle contraction

When do you lose iron?

through bleeding or small amount through bile

What is iron homeostasis regulated by?

Absorption

What is dietary iron that enters into the mucosal cells be stored by?

Ferritin

Is both heme and nonheme iron derived from animal flesh?

YES

What foods only have nonheme iron?

Plants

What is absorbed better heme or nonheme?

Heme

What inhibits iron absorption?

Calcium, fiber, whole grains, oxalate, polyphenols

Who needs the highest iron requirements?

Pregnant women

What is the average bioavailability of iron?

25%

What is serum ferritin?

Early indicator for iron status

What is transferrin saturation?

percent of transferrin that is saturated with iron

What is total iron-binding capacity?

refers to how much more iron the blood can bind

What are the biochemical indicators of iron deficiency?

- low serum ferritin

- low transferrin saturation

- high total iron-binding

What are the clinical signs of iron deficiency?

pale skin, fatigue, weakness

Is iron deficiency sufficient or necessary in causing anemia?

Sufficient

What is the deficiency of iron?

Anemia (a deficiency of hemoglobin)

What is hepcidin?

hormone produced in liver that regulates iron balance, sends a signal to destroy the transporter ferroportin

What is a nutrient-gene interaction?

Transferrin-R and Ferritin

What is the leading cause of accidental poisoning in children?

Acute iron overdose

What is hemochromatosis?

genetic disorder that is when the body fails to sense how much iron is present

Which of the following mutations could result in hemochromatosis?

Ferroporitn that is not responsive to hepcidin signals

What is zinc?

is essential structural and catalytic cofactor for many proteins, every living thing can't live without it

How is zinc homeostasis maintained?

absorption and excretion

Why does the pancreas use zinc?

to make digestive enzymes and secretes them into intestine

What happens if the bod does not need zinc?

Zinc will be excreted in shed intestinal cells

What releases zinc into albumin?

Metallothionein

What is Zinc finger?

a small protein structural motif that has one or more zinc ions in order to stabilize structure of DNA

What are the food sources of Zinc?

Red meats, oysters, milk products, whole grains, seafood

What are the two classes of zinc regulation?

Zip and ZnT transporteres

What is the intake transporter of zinc?

Zip4

Would Metallothionein prefer to bind to zinc or copper?

Copper

Iron is to ____ as Zinc is to metallothionein:

Ferritin

A defective (inactive) Zip4 can lead to what?

zinc deficiency

What is Acrodermatitis Enteropathica?

A genetic disease that causes inadequate zinc absorption.

What is an example of a nutrient-nutrient interaction?

Iron, zinc, and copper or zinc and vitamin A

What is copper?

a transition metal, helps produce hemoglobin, myelin, and melanin, and is redox active

What is the function of copper?

cofactor for metalloenzymes in redox reactions

What are the genetic diseases of copper metabolism?

Menkes disease (X-linked Cu deficiency) and Wilson Disease (autosomal recessive Cu toxicity)

What is the Cu uptake transporter?

CTR1

What are zinc, copper, and iron competing for?

the same transporter on the apical membrane

What does zinc and copper use as reservior?

Metallothionein

What does zinc and iron both use for transportation in the blood?

Transferrin