NUTRITION 12: FINAL EXAM

Functions of water in the body

-solvent (& participates in metabolic reactions) -transports minerals throughout the body -lubricates and protects -regulates body temp. & pH -participates in metabolic reactions

Vit. D Synthesis & Activation Flow

1 - Sun, when UV light strikes the skin, 7-dehydrocholesterol (made from cholesterol in the body) is converted to Vitamin D (inactive). 2 - or via Consumption, when consumed in foods (inactive forms). ... inactive vit. D (skin/consumption) travels in the blood to the liver. 3 - Liver, Enzymes add a hydroxyl group (-OH) to Carbon number 25 (25-hydroxy Vit. D, what is found in supplements, inactive) 4 - Kidneys, enzymes add a hydroxyl group (-OH) to Carbon number 1 (active Vitamin D.)

Bone structure and remodeling process

1) resting bone surface 2) active osteoclasts attach to bone surface 3) osteoclasts break down, or resorb, bone 4) pre-osteoblasts move in to begin rebuilding bone 5) active osteoblasts engage in bone formation

Stimulating water intake

1. Thirst, caused by signals in the brain. 2. Mouth becomes dry because less water is available to make saliva 3. Dry mouth + signals causes thirst and motivates fluid intake. 4. As water is consumed, blood volume increases and solute concentration decreases, restoring water balance.

Osteomalacia

A Vitamin D deficiency disease in adults characterized by a loss of minerals from bones. Causes bone pain, muscle aches, and an increase in bone fractures. Weakened because not enough calcium is available to form mineral deposits needed to maintain their health. Can precipitate or exacerbate osteoporosis.

osteoporosis

A bone disorder characterized by a reduction in bone mass, increased bone fragility, and an increased risk of fractures. Caused by a loss of both the protein matrix and the mineral deposits of bone, resulting in a decrease in the total amount of bone.

angiotensin II

A compound that causes blood vessel walls to constrict and stimulates the release of the hormone aldosterone.

hydroxyapatite

A crystalline compound composed of calcium and phosphorus that is deposited in the protein matrix of bone to give it strength and rigidity.

bioavailability

A general term describing how well a nutrient can be absorbed and used by the body.

metallothionein

A group of proteins that bind metals, binds zinc and copper in intestinal cells, limiting their absorption into the blood. When zinc intake is high, metallothionein synthesis increases. Zinc in the mucosal cell binds to metallothionein, slowing its transfer into the blood this provides more opportunity for zinc to be exported back into the lumen when zinc intakes are high or for it to be lost if the mucosal cell dies.

Parathyroid hormone (PTH)

A hormone released by the parathyroid gland that acts to increase blood calcium levels

calcitonin

A hormone secreted by the thyroid gland that reduces blood calcium levels

Aldosterone

A hormone that increases sodium reabsorption by the kidney and therefore enhances water retention.

nonheme iron

A poorly absorbed form of iron found in both plant and animal foods that is not part of the iron complex found in hemoglobin and myoglobin. Another source of nonheme iron in the diet is iron cooking utensils, from which iron leaches into food. Leaching is enhanced by acidic foods. When consumed, stomach acid helps convert the ferric form of iron to the ferrous form, which remains more soluble when it enters the intestine and therefore is absorbed into the mucosal cells more readily. When consumed with foods containing acid (such as ascorbic acid aka, vitamin c), iron absorption is enhanced because the acid helps to keep iron in the ferrous form. Another dietary component that increases the absorption is meat such as beef, fish, or poultry. Dietary factors that interfere with the absorption include fiber, phytates, tannins, and oxalates. Absorption also depends on minerals (Mn, Zn, Cu)

heme iron

A readily absorbed form of iron found in animal products that is chemically associated with proteins such as hemoglobin and myoglobin. Not significantly affected by most dietary factors that affect nonheme absorption. When consumed, the iron-containing heme group is released from the proteins by protein-digesting enzymes. The heme binds to receptors on the surface of muscosal cells, allowing it to enter the cells, where the iron is released from the heme group.

Why water is a good solvent

A solvent is a fluid in which solutes can dissolve to form a solution. Water is an ideal solvent for some substances because it is polar (has both positive and negative charge). This polar nature of water allows it to surround other charged molecules and disperse them.

osteoclast

A type of cell responsible for bone breakdown.

osteoblast

A type of cell responsible for the deposition of bone.

superoxide dismutase (SOD)

A vital enzyme that protects the cell by neutralizing damaging superoxide free radicals. One form of the enzymes requires zinc and copper for activity, and another form requires manganese.

Regulation of iron

A. Absorbed iron is 1) bound to storage protein ferritin OR 2) picked up by the transport protein transferrin B. Transferrin-iron complex deliver iron to cells 1) hemoglobin - carries oxygen in blood, 2) myoglobin - carries oxygen in muscle C. Iron losses 1) blood loss 2) shedding of cells from intestine, skin, urinary tract

How does fluoride function in the body?

About 80-90% of ingested fluoride is absorbed. Has a high affinity for calcium, so when consumed with milk or other high-calcium foods, the fluoride forms an insoluble salt with calcium and absorption is reduced. Associated with calcified tissues such as bones and teeth. When fluoride is incorporated into the hydroxyapatite crystals of tooth enamel, it makes the enamel more resistant to the acid that causes decay. After teeth are formed, fluoride is no longer incorporated into the enamel, but fluoride ingested in food, water, and supplements is secreted in saliva, which continually bathes the teeth which prevents cavities by reducing the amount of acid produced by bacteria, inhibiting the dissolution of tooth enamel by acid and increasing enamel remineralization after acid exposure.

iodine toxicity

Acute toxicity can occur with very large doses of iodine. Chronically high intakes of iodine can cause an enlargement of the thyroid gland that resembles goiter (underactive thyroid gland, elevated TSH), can also occur if iodine intake changes drastically.

What dietary factors reduce the risk of osteoporosis?

Adequate calcium intake is important for bone development and bone health throughout life. Maximize dietary calcium to achieve a high peak bone mass. Low intakes of Vit. D reduce calcium absorption, increasing the risk of osteoporosis. Diets high in phytate, oxalates, and tannins also reduce calcium absorption. High sodium has been implicated as a risk factor because high dietary sodium intake increases calcium loss in the urine. Supplements, drug/hormone treatments

Electrolyte functions in the body

Almost all electrolytes consumed in the diet are absorbed. These electrolytes help regulate fluid balance and are important for nerve conduction and muscle contraction.

Dietary treatment of iron deficiency anemia

Although diet is the ideal way to meet iron needs, supplements are often recommended for groups at risk for deficiency. Supplements contain nonheme iron, to enhance the absorption it should be consumed with foods containing vitamin C; taken with a meal containing meat, fish, or poultry, and not taken with dairy products, calcium supplements or substances that bind iron.

Regulation of Water, INTAKE = OUTPUT

Amount of water in the body remains relatively constant, but because the body does not store water, in order to maintain homeostasis, the water taken into the body must equal the amount of water lost from the body in urine, in feces, and through evaporation.

renin

An enzyme produced by the kidneys that converts angiotensin (inactive) to angiotensin II (active).

hemochromatosis

An inherited condition that results in increased iron absorption. Caused by a defect in the gene for hepcidin or other proteins involved in iron uptake, that allows excess iron to enter the circulation.

Cofactors (minerals)

An inorganic ion or coenzyme required for enzyme activity.

Iron Deficiency Anemia

An iron deficiency disease that occurs when the oxygen-carrying capacity of the blood is decreased because not enough iron is available to make adequate amounts of hemoglobin. Groups at risk: infants, children, adolescents women of reproductive age, pregnant women

transferrin

An iron transport protein in the blood.

myoglobin

An iron-containing protein in muscle cells that binds oxygen.

hemoglobin

An iron-containing protein in red blood cells that binds oxygen and transports it through the bloodstream to cells.

How do the kidneys regulate sodium, chloride and potassium?

Because water follows sodium by osmosis, the ability of the kidneys to conserve sodium provides a mechanism to conserve body water.

How does water transport nutrients throughout the body?

Blood, 90% water, transports oxygen and nutrients to cells. It then carries waste (carbon dioxide) away from the cells. Blood also distributes hormones and other regulatory molecules throughout the body so they can reach target cells. Water in urine helps to carry away waste products.

What are the regulatory roles of calcium?

Calcium in the body fluids plays critical roles in cell communication and the regulation of body processes. Calcium helps regulate enzyme activity and is necessary in blood clotting. Involved in transmitting chemical and electrical signals in nerves and muscles. Necessary for the release of neurotransmitters, which allow nerve impulses to pass from one nerve to another and from nerves to target tissues. Inside the muscle cells, calcium allows the two muscle proteins (actin and myosin) to interact to cause muscle contraction Calcium also plays a role in blood pressure regulation, possibly by controlling the contraction of muscles in the blood vessel walls and signaling the secretion of substances that regulate blood pressure.

Zinc toxicity

Can be toxic when consumed in excess of recommendations, can cause GI irritation, vomiting, loss of appetite, diarrhea, abdominal cramps and headaches.

fluoride toxicity

Can cause adverse effects in high doses. In children, can cause fluorosis characterized by black and brown stains and cracking and pitting of the teeth. In adults, can result in changes in bone that can be crippling, as well as changes in kidney function and possibly nerve and muscle function.

Keshan disease

Causes an enlarged heart and poor heart function. Now virtually eliminated by selenium supplementation, the disease itself is believed to be due to a combination of selenium deficiency and infection with a virus.

sodium-potassium pump

Cell membranes keep the majority of sodium outside the cell and potassium inside, but some sodium and potassium do leak across the membrane. The sodium-potassium pump maintains the concentration gradient by pumping sodium out of the cell and pumping potassium into the cell. Maintaining this is important for nerve conduction and muscle contraction, but requires a great deal of energy.

cholecalciferol

Chemical name for Vitamin D, can be formed in the skin of animals by the action of sunlight on 7-dehydrocholesterol

What lifestyle factors reduce the risk of osteoporosis?

Cigarette smoking and alcohol consumption both can decrease mass and increase the risk of bone fractures. Physical activity (weight-bearing exercise) which puts direct weight over the skeleton is good for bones. This mechanical stress stimulate the bones to become denser and stronger, increasing bone mass.

Mineral food sources

Come from both plant and animal sources. Most foods naturally contain minerals, present as a functional components of the plant or animal and are therefore present in consistent amounts. Some foods provide minerals that are added intentionally by fortification or accidentally through contamination. Dietary supplements are also a source of minerals. The concentrations of other minerals may vary depending on the mineral concentration in the soil and water at the food's source.

Bone structure

Consists of a framework or matrix made up primarily of the protein collagen. Imbedded in the protein matrix are solid mineral crystals known as hydroxyapatite. 2 types of bone: cortical(compact) bone trabecular (spongy bone)

Electrolyte Deficiency

Deficiencies can lead to electrolyte imbalance, which disrupts physiological functions throughout the body, leading to acid-base imbalance, poor appetite, muscle cramps, confusion, apathy, constipation, and eventually an irregular heartbeat. Water loss = depletion of electrolytes. If the electrolytes are not replaced along with the water, electrolyte imbalances can result.

cortical (compact) bone

Dense, compact bone that makes up the sturdy outer surface layer of bones. Accounts for about 80% of the skeleton.

DASH

Dietary Approaches to Stop Hypertension First intervention trial that showed the greatest reduction in blood pressure was found with a dietary pattern that is high in fruits and vegetables and includes low-fat dairy products and lean meat, fish, and poultry. This pattern provides plenty of fiber, potassium, magnesium, and calcium; is low in total fat and saturated fat; and is lower in sodium than the typical American diet.

goiter

Enlargement of the thyroid gland caused by a deficiency of iodine. Forms when reduced thyroid hormone levels cause TSH to be released, stimulating the thyroid gland to make more thyroid hormones. Because iodine is unavailable, thyroid hormones cannot be made and the stimulation continues, causing the thyroid gland to enlarge.

copper toxicity

Extremely rare but has occurred as a result of drinking from contaminated water supplies or consuming acidic foods or beverages that have . been stored in copper containers. Causes abdominal pain, vomiting, and diarrhea. Also shown to cause liver damage.

Anemia assessment

Ferritin (iron storage protein) - decreases in iron stores and plasma iron levels indicate iron depletion but do not meant the person has symptomatic iron deficiency anemia. Iron deficiency anemia occurs when there is too little iron to synthesize adequate amounts of hemoglobin (oxygen carrying protein). It results in red blood cells that are small and pale and unable to transport adequate amounts of oxygen. Anemia is the last stage of iron deficiency, iron depletion can be detected by blood tests that measure indicators of iron levels in the plasma and in body stores.

How does processing affect the minerals in food?

Food processing and refining can affect the mineral content of foods, it does not destroy but it can still cause losses. Processing also adds minerals (flavor, preservatives), enrichment of grains (iron), fortification. Some minerals enter the food supply inadvertently through contamination.

(mineral) Absorption capacity

For some minerals, almost all that is present in our food is absorbed, but for others, only a small percentage of what is consumed in absorbed.

Zinc food sources

Found in foods from both plants and animal sources. Zinc from animal sources is better absorbed than that from plants because the zinc in plants foods is often bound by phytates. Zinc is abundant in red meat, liver, eggs, dairy products, vegetables, and some seafood.

How does water lubricate and protect?

Functions as a lubricant and cleanser. Tears lubricate eyes, wash away dirt. Synovial fluid lubricates the joints. Saliva lubricates the mouth, making it easier to chew, taste, and swallow food. Water inside the eyeballs and spinal cord acts as a cushion against shock.

How does selenium function in the body?

Functions mostly through association with proteins called selenoproteins, including glutathione peroxidase, are enzymes that help protect cells from oxidative damage. Important for the function of the thyroid gland

How is zinc regulated?

GI tract is the major site fore regulation of zinc homeostasis (both the amount of zinc in the mucosal cells and the amount that leaves these cells for distribution to the rest of the body are regulated). The amount of zinc that is in the cytosol and is transported into the blood can be regulated by increasing or decreasing the synthesis of proteins that transport zinc into versus those that transport it back out of the mucosal cells. The amount of zinc that passes from the mucosal cell into the blood is also regulated by a metal-binding protein called metallothionein.

If high blood calcium is present, how does the body lower blood calcium?

If blood calcium levels are too high, the secretion of PTH is reduced which increases excretion of calcium by the kidney, decreases vitamin D activation (so less calcium is absorbed) and reduces calcium release from the bone. High blood calcium also stimulates the secretion of calcitonin from the thyroid gland, which acts primarily on bone to inhibit the release of calcium.

How are thyroid hormones controlled?

If blood levels drop, TSH is released from the anterior pituitary, which signals the thyroid gland to take up iodine and synthesize thyroid hormones (the thyroid gland grows larger to trap and absorb as much iodide as possible). When the supply is adequate, thyroid hormones can be made and their presence turns off the synthesis of TSH.

Define minerals

In nutrition, an element needed by the body in small amounts for structure and to regulate chemical reactions and body processes. Minerals may combine with other elements in the body, but they retain their chemical identity. Unlike vitamins, they are not destroyed by heat, oxygen, or acid. Humans need to consume more than 20 minerals to stay healthy.

Vit. D decreases blood calcium ...

In the kidneys (decreases excretion), if dietary calcium is unavailable, higher levels of Vit. D act at the bone & kidney with the PTH to return blood calcium to normal. @the bone, bone breakdown releases calcium into the blood. @the kidneys, Vit. D acts w/ PTH to increase the amount of calcium retained by the kidneys (inhibits).

How is water lost?

In urine, feces, through evaporation from the lungs and skin, and in sweat.

How does iodine function in the body?

Iodine is needed for the synthesis of thyroid hormones that help to regulate 1) growth 2) development 3) metabolic rate

Iron absorption

Iron from the diet is absorbed into the intestinal mucosal cells. The amount absorbed depends on whether the iron is heme or nonheme iron as well as on the presence of dietary components that enhance or inhibit iron absorption. Large intakes of iron from supplements can cause toxicity symptoms and interfere with the absorption of zinc and copper. Iron-containing supplements should only be taken only as suggested on the label or prescribed by a physician.

How does iron function in the body?

Iron in the body is essential for the delivery of oxygen to cells. It is a component of two oxygen carrying proteins (hemoglobin and myoglobin). Essential for ATP production (energy production). Also part of the enzyme catalase, which protects the cells from oxidative damage by destroying hydrogen peroxide before it can form free radicals.

iron toxicity

Iron promotes the formation of free radicals and causes cell death due to excess oxidation of cellular components. Acute -Taking a single large dose of iron can be life threatening, can damage the intestinal lining and cause abnormalities in body pH, shock, and liver failure. If too much iron enters the body, over time it accumulates in tissues such as the heart and liver. Most common cause of chronic iron overload is hemochromatosis, and overconsumption of iron supplements or a diet high in absorbable iron can also increase iron stores.

Electrolyte Toxicity

It is rare when water needs are met and kidney function is normal.

How do electrolytes affect muscle contraction?

Like nerve conduction, a similar mechanism causes the depolarization of the muscle cell membranes, leading to muscle contraction

If low blood calcium is present, how does the body raise blood calcium?

Low blood calcium causes the release of PTH from the parathyroid gland. PTH promotes calcium reabsorption by the kidney. PTH stimulates the activation of Vitamin D by the kidney, which then increases the amount of calcium absorbed from the GI tract. The active Vit. D also acts with PTH to stimulate calcium release from the bone and calcium retention by the kidney.

How does magnesium function in the body?

Magnesium is a cofactor for over 300 enzymes, and is necessary for the generation of ATP from carbs, fats, and protein. Magnesium is needed for the activity of the sodium-potassium pump, which is responsible for active transport of sodium and potassium across membranes (nerve & muscle contraction). Most magnesium is present inside cells, where it is the second most abundant positively charged intracellular ion (after potassium).

Functions of Vitamin D

Maintain levels of calcium and phosphorous in the blood that favor bone mineralization.

Major mineral

Mineral needed in the diet in an amount greater than 100mg/day or present in the body in an amount greater than 0.01% of body weight sodium, choloride, potassium

Trace mineral/trace element

Mineral required in the diet in an amount of 100mg or less per day or present in the body in an amount of 0.01% of body weight or less iron, copper, zinc, selenium, iodine, chromium, fluoride, manganese, molybdenum

How does mineral absorption (plants v. animals) affect bioavailability?

Minerals in animal products are generally better absorbed than those in plant foods. Difference in absorption is due to the fact that plants contain substances such as phytates (phytic acid), tannins, oxalates and fiber that bind minerals in the GI tract and can reduce absorption.

Calcium

Most abundant mineral in the body, provides structure to bones and teeth and has essential regulatory roles. 1-2% of adult body weight 99% is found in bones and teeth 1% found in body fluid

How do electrolytes affect nerve conduction?

Nerve impulses are created by a change in the electrical charge across cell membranes. Stimuli (such as a touch or presence of neurotransmitters) increase the cell membrane's impermeability to sodium, allowing it to rush into the cell which then reverses (depolarizes) the charge of the cell membrane at that location and an electrical current is generated. Once the nerve impulse passes, the original membrane potential is restored by another change in cell membrane permeability --- the original distribution of sodium and potassium is restored by the sodium-potassium pump in the cell membrane.

Hypertension symptoms/consequences

No outward symptoms but can lead to atherosclerosis, heart attack, kidney disease, and early death.

Water Deficiency: Dehydration

Occurs when water loss exceeds water intake, causing a reduction in blood volume which impairs the body's ability to deliver oxygen and nutrients to cells and remove waste products. Chronic mild dehydration also impairs health, increases the risk of kidney stones and UTI's. Causes prolonged constriction of the blood vessels, which can increase the risk of high blood pressure and stroke. More severe dehydration can require medical attention. Dehydration due to diarrhea is a leading cause of death in children under 5 years old in the developing world. Symptoms: Early symptoms include headache, fatigue, loss of appetite, dry eyes and mouth, and dark-colored urine. Without water, an average person can survive for only a few days compared to about eight weeks without food.

How does copper function in the body?

Once absorbed, copper binds to albumin (protein in the blood) and travels to the liver, where it binds to the protein ceruloplasmin for delivery to other tissues. It must be transported bound to proteins because free copper ions can act as pro-oxidants (triggering oxidation and leading to cellular damage). Copper functions in a number of important proteins and enzymes that are involved in iron and lipid metabolism, connective tissue synthesis, maintenance of heart muscle, and the functioning of the immune and central nervous systems. Essential component in a form of the antioxidant enzyme superoxide dismutase. Also plays a role in cholesterol and glucose metabolism, needed for the synthesis of the neurotransmitters norepinephrine and dopamine and several blood-clotting factors.

What is the function of phosphorus in the body?

Phosphorus, along with calcium, forms hydroxyapatite crystals that provide rigidity to bones. A component of the water-soluble head of phospholipid molecules, which form the structure of cell membranes. Major constituent of DNA and RNA. Essential for energy metabolism.

selenoproteins

Proteins that contain selenium as a structural component of their amino acids. Selenium is most often found as selenocysteine, which contains an atom of selenium in place of the sulfure atom. Selenoproteins help protect the thyroid gland from reactive oxygen species, and selenium-containing enzymes are needed for the synthesis of the thyroid hormones, which regulate basal metabolic rate.

Sodium and Chloride Homeostasis

Regulated to some extent by the intake of both water and salt. When salt intake is high, thirst is stimulated to increase water intake. When salt intake is very low, a "salt appetite" causes the individual to crave salt.

What is sodium's role in regulating blood pressure?

Regulates extracellular fluid volume, when the concentration of sodium in the blood increases, water follows by osmosis, causing an increase in blood volume. Changes in blood pressure trigger the production and release of proteins and hormones that affect the amount of sodium...as well as the water (retained by the kidneys).

Selenium toxicity

Result from oversupplementation or high levels in the food supply. Symptoms include skin rash, fatigue, irritability, brittle hair; brittle, thickened fingernails and toenails, leading to nail loss in some cases; and a garlic odor on the breath and skin.

Copper food sources

Richest dietary sources of copper are organ meats and shellfish, but most of the copper we consume is from legumes, nuts and seeds, and whole-grain breads and cereals.

Vitamin D Deficiency can cause...

Rickets, in children. Osteomalacia, in adults

Food sources of electrolytes

Salt = 40% sodium + 60% chloride Sodium - Processed foods contain high amounts of sodium. Potassium - Unprocessed foods such as fruits, vegetables, whole grains, and fresh meats. Chloride - Sodium chloride, aka table salt

Food sources of Selenium

Seafood, kidney, liver, and eggs are excellent sources of selenium. Grains, seeds, and dairy products are good sources. Selenium content of plant foods depends on the selenium content of the soil and the content of animal products is affected by the amount of selenium in their feed.

Zinc Deficiency: acrodermatitis enteropathica

Seen in individuals with a genetic defect in zinc absorption and metabolism. Symptoms include poor growth and development, skin rashes, hair loss, diarrhea, neurological changes, impaired reproduction, sexual maturation and reduced immune function.

Why does copper deficiency lead to anemia?

Severe copper deficiency is relatively rare. The most common manifestation of copper deficiency is anemia. Due to the importance of copper-containing proteins in iron transport, because even if iron is sufficient, iron cannot be transported out of the intestinal mucosa.

How is blood calcium levels regulated?

Slight changes in blood calcium levels trigger responses that quickly raise or lower them back to normal.

Name 3 major electrolytes

Sodium Potassium Chloride

How is electrolyte balance regulated?

Sodium and Chloride Homeostasis Potassium Homeostasis The kidneys are the primary regulator of sodium, chloride, and potassium balance in the body. Excretion of these electrolytes in the urine is decreased when intake is low and increased when intake is high.

How is aldosterone released?

Stimulated by high blood potassium, low blood sodium, or angiotensin II

fluoride deficiency

Susceptibility to tooth decay is more common.

Selenium deficiency

Symptoms include muscular discomfort, weakness, poor immune function, and cognitive decline. Predisposition to Keshan disease (cardiac tissue becoming fibrous).

Potassium Homeostasis

The amount of potassium in the body is also tightly regulated. If blood levels begin to rise, mechanisms are activated to stimulate the cellular uptake of potassium. The short-term regulation prevents the amount of potassium in the extracellular fluid from getting lethally high. The long-term regulation of potassium balance depends on aldosterone release, which causes the kidneys to excrete potassium and retain sodium.

Iron Homeostasis

The body regulates the amount that enters the blood from the mucosal cells of the GI tract and stores or transports it. The amount of iron in the body is controlled primarily at the intestine, when iron enters the mucosal cells of the SI it can be bound to the iron storage protein ferritin or transferred into the blood and picked up by the iron transport protein transferrin. Iron that remains bound to ferritin is excreted in the feces when mucosal cells die and are sloughed off into the intestinal lumen. The amount of iron transported from the mucosal cells to the rest of the body depends on body iron needs. The primary regulator of iron homeostasis is a peptide hormone called hepcidin released by the liver.

(mineral) How does nutritional status and life stage affect mineral bioavailability?

The body's need for a mineral may also affect how much of that mineral is absorbed. Life stage can also affect absorption. For example, calcium absorption doubles during pregnancy when the body's needs are high.

Why electrolytes are needed for nerve conduction?

The concentration gradient of sodium and potassium across nerve cell membranes is important for the conduction of nerve impulses. An electrical charge (membrane potential) exists across nerve cell membranes because the number of negative ions inside is greater than the number outside because the cell membrane allows more positively charged ions to leak out of the cell than into the cell.

ceruloplasmin

The major copper-containing protein in the blood, converts iron into a form that can bind to transferrin for transport from body cells.

ferritin

The major iron storage protein.

peak bone mass

The maximum bone density attained at any time in life, usually occurring in young adulthood.

Regulation of water begins with...

The need to consume water is triggered by the sensation of thirst, thirst is caused by dryness in the mouth as well as signals from the brain (hypothalamus). Decrease in blood volume, increase in solute concentration

Competition among minerals

The presence of one mineral can also interfere with the absorption of another. Although this is generally not a problem when whole foods are consumed, a large dose of one mineral from a dietary supplement may interfere with the absorption of other minerals.

Bone remodeling

The process whereby bone is continuously broken down and re-formed to allow for growth and maintenance. Bone is formed by cells (osteoblasts) and broken down in a process called bone resorption, by cells called osteoclasts. During bone formation, the activity of osteoblasts exceeds that of the osteoclasts. When bone is broken down, the osteoclasts resorb bone more rapidly than the osteoblasts can rebuild it.

sodium-potassium pump & sodium

The pumping of sodium ions across cell membranes is also linked to nutrient transport. Example, glucose and amino acids are transported by systems that depend on the movement of sodium ions across cell membranes.

trabecular (spongy bone)

The type of bone forming the inner spongy lattice that lines the bone marrow cavity and supports the cortical shell.

How is water loss regulated?

To maintain water balance, the kidneys regulate the amount of water excreted in the urine, functions like a filter. As blood flows through the kidneys, water molecules and other small molecules move through the filter and out of the blood, while blood cells and large molecules are retained in the blood. Some of the water and other molecules filtered out are reabsorbed into the blood, and the rest is excreted in the urine. Summary: when plasma (blood) volume decreases, solute concentration increases > low saliva > dry mouth. brain (hypothalamus) connects "thirst" with water intake.

Vitamin D Toxicity

Too much can cause high calcium concentrations in the blood and urine, deposition of calcium in soft tissues such as the blood vessels and kidneys, and cardiovascular damage. Does not result from overexposure to sunlight because it is regulated by the body. Oversuppplementation and overfortification can pose a toxicity risk.

Rickets

Vitamin D deficiency disease in children that is characterized by poor bone development because of inadequate calcium absorption. Weak bones & deformities such as narrow rib cages, bowed legs. Reduces bone mass, causes muscle pain and weakness and stunts growth.

How does water regulate pH (acid-base balance)?

Water and dissolved substances it contains are important for maintaining the proper level of acidity. Water serves as a medium for the chemical reactions that prevent changes in pH, and it participates in some of these reactions. Water is also needed as a transport medium to allow the respiratory tract and kidneys to regulate acid-base balance.

How does water regulate body temperature?

Water in blood helps regulate body temp. by increasing/decreasing the amount of heat lost from the surface of the body. Body temp. rises - blood vessels in the skin dilate, causing blood to flow close to the surface of the body where it can release some of the heat to the environment (i.e. fevers, sweat). When body temp. increases, the brain triggers the sweat glands in the skin to produce sweat, which is mostly water. As the water evaporates from the skin heat is lost, cooling the body. In a cold environment, blood vessels in the skin constrict, restricting the flow of blood near the surface and conserving body heat.

Water Toxicity: Overhydration

Water intoxication may occur with illness and during exercise. When the blood has too much water relative to the amount of sodium (hyponatremia) water moves out of the blood vessels into the tissues by osmosis, causing them to swell. Swelling in the brain can cause disorientation, convulsions, coma, and death. Symptoms: Early symptoms similar to dehydration (nausea, muscle cramps, disorientation, slurred speech, and confusion) so it is important to be able to distinguish between overhydration and dehydration. Symptoms will worsen and can results in seizure, coma, or death. **When working out, to avoid overhydration, beverages (gatorade), containing dilute solutions of sodium as well as sugar should be used to replace water losses.

How does water participate in metabolic reactions?

Water is involved in some of the chemical reactions of metabolism. Hydrolysis reactions break large molecules into smaller ones by adding water. Water also participates in reactions that join two molecules, dehydration reactions, a type of condensation reaction in which a molecule of water is lost.

How do electrolytes function in the body?

Water moves by osmosis in response to solute concentration, all body fluids are in osmotic balance. The concentration of specific electrolytes in body compartments differs dramatically. Potassium is the principal positively charged ion inside cells. Sodium is the most abundant positively charged electrolyte in the extracellular fluid. Chloride is the principal negatively charged extracellular ion. ***The different intracellular and extracellular concentrations are maintained by cell membranes and an active transport system called the SODIUM-POTASSIUM PUMP (sodium-potassium-ATPase)

Water reabsorption

When a high solute concentration is detected, the pituitary gland secretes ADH (Antidiuretic hormone), signals the kidneys to reabsorb water to reduce the amount lost in the urine. This reabsorbed water is returned to the blood, preventing the solute concentration in the blood from increasing further. Example - someone who has exercised strenuously and not consumed enough water

How do the kidneys regulate blood pressure?

When blood pressure decreases, the kidneys release the enzyme, renin, leading to the production of angiotensin II which increases the blood pressure both by causing the blood vessel walls to constrict and by stimulating the release of the hormone aldosterone, which acts on the kidneys to increase sodium (and chloride) reabsorption. Water follows the reabsorbed sodium, helping to maintain blood volume and blood pressure. As blood pressure increases, it inhibits the release of renin and aldosterone so that blood pressure does not continue to rise.

iron deficiency

When iron is deficient, hemoglobin cannot be produced. When not enough hemoglobin is available, the red blood cells that are formed are small and pale and unable to deliver adequate oxygen to the tissues. Early stages have no symptoms

How do the kidneys regulate blood levels of magnesium?

When magnesium intake is low, excretion in the urine is decreased. As intake increases, urinary excretion increases to maintain normal blood levels? This efficient regulation permits homeostasis over a wide range of dietary intakes.

How does high intakes of zinc affect copper absorption?

When zinc intake is high, it stimulates the synthesis of the protein metallothionein in the mucosal cells, although it binds zinc it binds to copper more tightly preventing it from being moved out of mucosal cells into the blood. Copper absorption is also reduced by high intakes of iron, manganese, and molybdenum. Large doses of antacids may also inhibit copper absorption, and over the long term, can cause copper deficiency.

How does zinc function in the body?

Zinc is the most abundant intracellular trace element, found in the cytosol, in cellular organelles, and in the nucleus. Zinc is secreted in pancreatic and intestinal juices, which enter the lumen of the intestine. When low, zinc enters the GI tract can be reabsorbed and recycled. When high, less is reabsorbed and more is therefore eliminated in the feces. Zinc is involved in the functioning of over 300 different enzymes and many cellular activities, , regulates gene expression (RNA & DNA), influences hormonal regulation of cell division (needed for the growth and repair of tissues), activity of the immune system and the development of sex organs and bone. Taste perception

iodine absorption

absorbed completely and rapidly from the GI tract in the form of iodide ions, can be eliminated from the body by excretion in the urine.

What affects mineral bioavailability?

absorption capacity nutritional status & life stage competition among minerals other substances present (ascorbic acid, binders such as phytates & oxalates)

What factors affect the risk of osteoporosis?

age, gender, hormone levels, genetics and lifestyle

What vital roles does calcium play in the body?

bone health nerve transmission muscle contraction release of hormones

oxidative damage

damage caused by highly reactive oxygen molecules that steal electrons from other compounds, causing changes in structure and function.

Symptoms of Iron Deficiency Anemia

fatigue, weakness, headache, decreased work capacity, an inability to maintain body temperature in a cold environment, changes in behavior, decreased resistance to infection, adverse pregnancy outcomes, impaired development in infants, and an increased risk of lead poisoning in young children. Many of these symptoms are due to the role of iron in energy metabolism and oxygen transport.

Extracellular fluids

fluid secreted by glands (saliva) and other digestive secretions, and fluid in the eyes, joints, and spinal cord, blood plasma, lymph and the fluid between cells (interstitial fluids)

sources of fluoride

fluoride is present in small amounts in almost all soil, water, plants, and animals. Richest dietary sources are fluoridated water, tea, toothpaste, and marine fish consumed with their bones.n Cooking utensils also affect food fluoride content, cooked with Teflon can pick up fluoride from the Teflon, whereas aluminum cookware can decrease fluoride content. Fluoride is absorbed into the body in proportion to its content in the diet.

Define hypertension

high blood pressure Blood pressure that is consistently elevated to 140/90 millimeters of mercury or greater.

thyroid-stimulating hormone (TSH)

hormone that stimulates the synthesis and secretion of thyroid hormones from the thyroid gland.

Distribution of body water

in adults, ~60% of total body weight intracellular fluid, ~2/3 water inside cells extracellular fluid, ~1/3 water outside cells

lumen

inside cavity of a tube, such as the GI tract

iodine food sources

iodized salt, seafood, bread, dairy products, plants grown in iodine-rich soil.

Name food sources that are good sources of magnesium.

leafy greens (spinach, kale). Nuts, seeds, bananas, and the germ and bran of whole grains. Increased calcium in the diet decreases the absorption of magnesium, as well as the presence of phytate.

Vitamin D increases blood calcium by...

parathyroid gland releases PTH, stimulates kidneys to convert to active Vitamin D. Enters blood and travels to major target tissues (intestinal cells, bone & kidney). @intestinal cells, Vit.D increases production of intestinal calcium and calcium binding proteins needed for the active transport of dietary calcium in the body.

Hepcidin

peptide hormone released by the liver. When body iron levels are low, little hepcidin is released, allowing intestinal mucosal cells to transfer iron into the blood where it binds to transferrin. High levels of iron cause hepcidin release. When hepcidin concentrations increase, iron is not transported out of the mucosal cells and instead remains within the cells bound to ferritin. Hepcidin also inhibits cells that store iron from releasing iron into the blood when iron levels are high.

Name the compounds that can bind to minerals and decrease their absorption.

phytate (phytic acid) tannin oxalate

Electrolytes

positively and negatively charged ions that conduct an electrical current in solution. In nutrition, it commonly refers to the three principal electrolytes in body fluids: sodium, potassium, and chloride Sodium/Potassium, positive charge Chloride, negative charge

iodine deficiency

reduces the production of thyroid hormones, metabolic rate slows with insufficient thyroid hormones causing fatigue and weight gain. Most obvious outward sign of deficiency is an enlarged thyroid gland called a goiter (simple goiter). Can cause a condition called cretinism in offspring, characterized by symptoms such as developmental disability, deaf mutism, and growth failure. Iodine deficiency during childhood and adolescence can also result in goiter and impaired cognitive and motor development.

What are the functions of a mineral?

structure regulation cofactors, necessary for enzyme activity. Many minerals serve more than one function. To maintain health, the overall diet must contain enough of each of the minerals in the correct proportions. The wrong amounts or combinations can cause deficiency or toxicity.