MINERALS

Question 1

in contrast, are simple elements with important roles in both structure and function.
Minerals also serve as cofactors in many important enzyme systems, and, in fact, sometimes
partner with vitamins in regulating essential metabolic functions. As was true for vitamins, an
excess of one mineral cannot remedy a deficit of another, making it important to eat a wide
variety of foods.

Answer 1

Minerals

Question 2

Elements present in
water find their way into rocks and soil; through plants they find their way to animals and humans.
At one time our access to these elements depended on luck where we happened to live
because most people obtained all of their food from nearby farms. However, with expanding
knowledge of how these elements are incorporated into foods, plus the fact that much of the
food we eat is grown outside of our immediate surroundings, people living in all parts of the world
have the potential to receive adequate mineral nutrition.

Answer 2

Cycle of Minerals

Question 3

Calcium and phosphorus give strength to bones and body frame. Iron provides the core
for the heme in hemoglobin that carries oxygen to the tissues and returns carbon dioxide to the
lungs for excretion.

Answer 3

Structural

Question 4

Ionized sodium and potassium exercise control over body water. Iodine is a necessary
constituent of the thyroid hormone that sets the rate of metabolism in the cells. Iron is a cofactor in
the mitochondrial enzyme system that supplies our body with energy. Some minerals such as iron
contribute to structure and function. Far from being static and inert, minerals are active participants
in many systems that support life.

Answer 4

Metabolic

Question 5

All vitamins are required in very small
amounts, but minerals vary depending on their role. A man weighing 150 lb has almost 3 lb of
calcium in his body, most of it in the skeleton. This same man contains only about 3 g (oz) of
iron, found mainly in the hemoglobin of red blood cells.

Answer 5

The differing amounts of vitamins and minerals

Question 6

The term
________ refers to the proportion of a food nutrient that can be successfully absorbed and made
available for body use.

Answer 6

bioavailability

Question 7

In some plants, minerals are bound in chemical complexes and not easily
released. Oxalates in green leafy vegetables and phytates in whole grains bind minerals and prevent
their absorption.

Answer 7

Binding substances:

Question 8

Most minerals are better absorbed in an acid environment.

Answer 8

Gastric acidity:

Question 9

Iron cannot be absorbed in the ferric form; it must first be reduced to ferrous iron for
absorption to take place.

Answer 9

Chemical form:

Question 10

Some foods, such as tea, contain substances that interfere with the absorption
of certain minerals.

Answer 10

Other foods in the meal:

Question 11

If you are a woman, your body is about __% to
__% water; if you are a man, then it is about ___%
to __% water.

• Men have higher water content because they
  have proportionately more muscle and less fat.
• Muscle contains more water than any other tissue
  except blood. Women have proportionately less
  muscle and more fat, which is lower in water
  content.

Answer 11

50% to 55%, 55% to 60%

Question 12

Body water has many roles.
* Much of our body form comes from the turgor water provides for tissues.
* Cell water furnishes the fluid environment for the vast array of chemical reactions that
sustain life.

• Medications are dissolved in body fluids.
• The evaporation of water from the skin is an important means of regulating body
  temperature.

Answer 12

Functions of Body Water

Question 13

The average adult processes _____of water each day. Water enters and leaves the body
by various routes, controlled by the thirst mechanism and regulatory hormones.

Answer 13

2.5 to 3 L

Question 14

• Water enters the body in three forms:

Answer 14

• As preformed water taken in as water or in other beverages
• As preformed water in food
• As metabolic water produced by cell oxidation

Question 15

• It is estimated that __% of fluid intake comes from water and beverages and 19% comes from food.
• Plain water contributes about a third of the total and other beverages about half.
• Many common foods contain large amounts of water.
• Metabolic water contributes less to total water than do beverages or food.
• All water, regardless of source, is of equal value in meeting fluid needs.

Answer 15

81

Question 16

• Water leaves the body via the kidneys, skin, and lungs, as well as through fecal elimination
• Vomiting and diarrhea bring abnormal fluid losses and serious clinical problems if prolonged.
• Abnormal loss of body fluid is especially dangerous for infants and children, whose bodies
  contain a greater proportion of water. More of their body water is outside the cells and more
  easily lost.
• Water retention associated with heart failure or ______ disturbances requires immediate
  medical attention. Intake and output must remain in balance to sustain normal hydration levels.

Answer 16

electrolyte

Question 17

Several minerals act as major electrolytes in controlling body fluid compartments. In this role
they are called electrolytes because they are free in solution and carry an electrical
charge. Free, charged chemical forms are also called ions, a term that refers to atoms,
elements, or groups of atoms that in solution carry either a positive or negative electrical
charge.
* An ion carrying a positive charge is called a cation: examples are sodium (Na+), the major
cation in extracellular water; potassium (K+), the major cation in intracellular water; calcium
(Ca+2); and magnesium (Mg).
* An ion carrying a negative charge is called an anion: examples are chloride (Cl−),
bicarbonate (HCO), phosphate (HPO), and sulfate (SO). By virtue of their small size these
ions or electrolytes can diffuse freely across cell membranes and create forces that control
the movement of water.

Answer 17

Electrolytes

Question 18

• Albumin and globulin, ___- _____of large molecular size, influence the movement of
  water in and out of capillaries. In this function these plasma proteins are called colloids.
• Because of their large size, plasma proteins cannot pass through the capillary membrane
  into the interstitial fluid. Instead they remain in the blood vessels, where they exert __________ to maintain vascular blood volume. We will learn more about this
  process a bit later.

Answer 18

Plasma Proteins, colloidal
osmotic pressure (COP)

Question 19

Other organic compounds small in size such as glucose, urea, and amino acids diffuse freely in
and out of the various fluid compartments but do not influence movement of water unless
they are present in abnormally large concentrations.
* Such a situation occurs in patients with uncontrolled diabetes mellitus, when large amounts of
glucose being excreted in the urine cause an abnormal osmotic diuresis or excess water
output.

Answer 19

Organic Compounds of Small Molecular Size

Question 20

Water and solutes move across the separating membranes according to the physiologic
mechanisms that handle fluid shifts. These mechanisms include osmosis, diffusion, active
transport, and pinocytosis.

Answer 20

Membranes

Question 21

activity of that solution.
* It is the number of particles, not the size of the particles that deter- mines chemical combining
power, so electrolytes are measured according to the total number of particles in solution.
* Each particle contributes chemical combining power according to its valence, not its total
weight. The unit of measure commonly used is the equivalent. Because we are talking about
very small amounts, these measurements are expressed in milliequivalents (mEq), or
thousandths of an equivalent.
* This term refers to the number of ions cations and anion in solution in a given volume of body
fluid. It is expressed as the number of milliequivalents per liter (mEq/L).

Answer 21

Measurement of Electrolytes

Question 22

Electrolytes are distributed in body water compartments in a definite pattern. According to
biochemical and electrochemical laws, a stable solution must have equal numbers of positive
and negative particles. This means it must be electrically neutral. When shifts or losses occur,
compensating shifts and gains must follow to maintain this balance of essential electrochemical
neutrality.

Answer 22

Electrolyte Balance

Question 23

Ionized sodium is the chief cation of ECF, and ionized potassium is the chief cation of ICF. These
two electrolytes control the amount of water retained in each compartment.
* Shifts in water from one compartment to the other reflect changes in the ECF concentration of
these electrolytes. The terms hypertonic and hypotonic refer to the electrolyte concentration of
the water outside the cell. When surrounded by a hypertonic solution, water flows out of the cell
and the cell becomes dehydrated and shrinks in size.
* When the cell is surrounded by a hypotonic solution, water flows into the cell, causing it to swell
and eventually burst if the situation is not corrected.

Answer 23

Electrolyte Control of Body Hydration

Question 24

Water is constantly circulating through the blood vessels to reach cells; fluid must move out of the
vessels to service the tissues and then be drawn back into the vessels to maintain normal transport
flow. Two opposing pressures control the movement of water and solute across capillary
membranes: (1) the hydrostatic pressure (blood pressure) of the capillary blood flow and (2) the
COP from plasma proteins (mainly albumin).
* The flow of water, nutrients, and waste to and from the cells occurs by the shifting balance of
these two pressures. It works as a filtration process driven by the differences in osmotic pressure on
either side of the capillary membrane.
* When blood first enters the capillary system, the existing blood pressure forces water and small
solutes such as glucose out into the tissues to bathe and nourish the cells. The plasma proteins,
however, are too large to pass through the pores of the capillary membrane and now exert the
greater COP that draws fluid and waste materials back into the capillary circulation. This process is
called the capillary fluid shift mechanism. It is one of the most important homeostatic mechanisms
in the body for maintaining water balance, without which cells would die. Low serum albumin
disrupts this process. Low concentrations of serum albumin lower the COP with the result that less
fluid is drawn back into the capillary circulation, leading to fluid retention in the tissues and
edema.

Answer 24

Capillary Fluid Shift Mechanism

Question 25

Just as plasma proteins in the capillaries provide COP to maintain the volume of the ECF, cell
protein provides the osmotic pressure that maintains the volume of the ICF.
* Electrolytes also play a role with ionized potassium guarding water within the cell and ionized
sodium guarding water outside the cell. This balance supports the sustaining flow of water, nutrients,
metabolites, and waste in and out of cells.

Answer 25

Cell Fluid Control

Question 26

The posterior lobe of the pituitary gland secretes the antidiuretic hormone (ADH), also called
vasopressin. It controls the reabsorption of water by the kidneys according to body need, acting
as a water-conservation mechanism. In times of threatened or actual loss of body water, this
hormone is released to retain precious fluid.
* ADH is secreted in response to (1) an increase in the con- centration of particles in the ECF as
measured by receptors in the hypothalamus and (2) decreased blood volume and blood pressure
as measured by receptors in the major arteries. Secretion of ADH causes an increase in water
reabsorption in the kidney tubule, thereby decreasing the amount of fluid lost via the urine. When
ECF concentration and blood volume have returned to normal, ADH secretion is reduced. ADH
levels rise in situations when fluid is lost through heavy sweating, fever, or major blood loss.

Answer 26

Antidiuretic Hormone

Question 27

is the sodium-conserving hormone associated with the renin-angiotensin-aldosterone
system, but it also exerts secondary control over body water.
* Renin, an enzyme secreted by the kidney in response to reduced blood volume acts on
angiotensin, an enzyme in the plasma, which triggers the release of aldosterone from the adrenal
cortex.
* Aldosterone acts on the kidney to reabsorb sodium, but in the process water is also reabsorbed,
restoring normal blood volume.
* The ADH and aldosterone systems work cooperatively to maintain normal hydration and are
continuously present at low levels.
* Both are activated by injury, surgery, or other physiologic stress bringing about losses of body

Answer 27

Aldosterone