Nutrition, Metabolism, and Temperature Regulation Flashcards
are the substances taken into the body that are used by the cells of the body to produce energy, to provide building blocks for new molecules, and to function in other chemical reactions.
Nutrition
is considered an important
component of our diet even though we cannot digest it. Instead, _____ adds to the bulk of feces, which stimulates normal motility of the large intestine.
Fiber
Nutrients are divided into six major classes:
(1) Carbohydrates
(2) Lipids
(3) Proteins
(4) Vitamins
(5) Minerals
(6) Water
are the major organic nutrients. They must be broken down by enzymes into their components during digestion before they can be absorbed by the small intestine.
Carbohydrates, Lipids, and Proteins
are required in fairly substantial quantities.
Carbohydrates, Lipids, Proteins, and Water
are required in only
small amounts.
Vitamins and Minerals
are absorbed by the digestive tract without being digested.
Vitamins, Minerals, and Water
are substances that must be ingested because the body cannot manufacture them at all or cannot manufacture adequate amounts of them.
Essential Nutrients
The essential nutrients include
certain amino acids and fatty acids,
most vitamins, minerals, water, and a few carbohydrates.
Other nutrients are necessary; if they are not part of the diet, they can be synthesized from the essential nutrients. Most of this synthesis takes place in the _____, which has a remarkable ability to transform and manufacture molecules.
Liver
is the amount of energy (heat) necessary to raise the temperature of 1 g of water 1°C.
calorie (cal)
is 1000 calories and is used to express the larger amounts of energy supplied by foods and released through metabolism.
Kilocalorie (kcal)
A kilocalorie is often called a
Calorie (with a capital C)
Most of the kilocalories supplied by food come from
Carbohydrates, Proteins, or Lipids (Fats)
For each gram of carbohydrate or protein the body metabolizes, about _____ of energy are released.
4 kcal
contain more energy per unit of weight than carbohydrates and proteins and yield about 9 kcal/g.
Fats
About 95% of the lipids in the human diet are
Triglycerides
Triglycerides, which are sometimes called _________, consist of three fatty acids attached to a glycerol molecule.
Triacylglycerols
Triglycerides are often referred to as (1) ____, which are solid at room temperature, or (2) ____, which are liquid at room temperature.
(1) Fats
(2) Oils
Fats and oils can be categorized as ________ or ________ depending on the types of bonds in the fatty acid.
Saturated, Unsaturated
have only single covalent bonds between the carbon atoms of their fatty acids.
Saturated fats and oils
have one or more double covalent bonds between the carbon atoms of their fatty acids
Unsaturated fats and oils
fats include olive and peanut oils
Monounsaturated
fats are in fish, safflower, sunflower, and corn oils.
Polyunsaturated
The “starting” point for determining the location of the double bonds is the _____ end of the fatty acid.
Omega (methyl)
The first double bond of an (1)_____ fatty acid starts three carbon atoms after the omega end; an (2)_____ fatty acid starts after six carbons; and an (3)______ fatty acid starts after nine carbons
(1) Omega-3
(2) Omega-6
(3) Omega-9
To saturate an unsaturated oil, the oil can be __________, which means that hydrogen gas is bubbled through the oil to produce a change in molecular shape that solidifies the oil.
Hydrogenated
The more _________ the product, the harder it becomes at room temperature
Saturated
These processed fats are usually referred to as
Trans fats
Unprocessed polyunsaturated fats are found mostly in the _______, which means the hydrogen atoms are on the same side of the carbon-carbon double bond in their fatty acids
Cis form
During hydrogenation, some of the hydrogen atoms are transferred to the opposite side of the double bond to make the _________, characterized by one hydrogen atom on one side of the double bond and another on the opposite side.
Trans form
raise the concentration of low-density lipoproteins and lower the concentration of high-density lipoproteins in the blood. These changes are associated with a greater risk for cardiovascular disease.
Trans fatty acids
The remaining 5% of lipids include _________ and _________, such as lecithin
Cholesterol and Phospholipids
is a steroid found in high concentrations in liver and egg yolks, but it is also present in whole milk, cheese, butter, and meats. ________ is not in plants.
Cholesterol
major components of plasma membranes, are found in a variety of foods, including egg yolks.
Phospholipids
Triglycerides are important sources of energy that can be used to produce
ATP
After a meal, excess triglycerides that are not immediately used are stored in ________ or the ________.
Adipose Tissue, Liver
In addition to storing energy, _________ surrounds and pads organs. _________ located under the skin is an insulator,
which prevents heat loss.
Adipose Tissue
Cholesterol is a component of the
plasma membrane, and it can be modified to form other useful molecules, such as ________ and ________.
Bile salts, steroid hormones
are necessary for lipid digestion and absorption.
Bile Salts
include the reproductive hormones estrogen, progesterone, and testosterone.
Steroid Hormones
which include prostaglandins and leukotrienes, are derived from fatty acids.
Eicosanoids
such as lecithin, are part of the plasma membrane and are used to construct the myelin sheath around the axons of neurons.
Phospholipids
is also found in bile and helps emulsify lipids.
Lecithin
Most of the carbohydrates humans ingest come from (1) _____. An exception is (2) _______, which is found in milk and other dairy products.
(1) Plants
(2) Lactose
are the most common monosaccharides in the diet.
Glucose and Fructose
Plants capture the energy in sunlight and use it to produce _______, which can be found in vegetables.
Glucose
are isomers of glucose
Fructose (fruit sugar) and galactose
When most of us think of sugar, we are probably thinking of the sugar you can buy in big bags in the grocery store. This is commonly referred to as
Table Sugar
Table sugar is actually the disaccharide
Sucrose
derived from germinating cereals, is composed of two glucose molecules.
Maltose (malt sugar)
consists of a glucose and a galactose molecule.
Lactose (milk sugar)
are polysaccharides, which consist
of many glucose molecules bound together to form long chains.
Complex Carbohydrates
Examples of common dietary polysaccharides include
Starch, Glycogen, and Cellulose.
is an energy-storage molecule found
primarily in plants (vegetables, fruits, and grains).
Starch
is an energy-storage molecule in animals and is located primarily in
muscle and in the liver.
Glycogen
forms plant cell walls.
Cellulose
During digestion, polysaccharides and disaccharides are split into monosaccharides, which are absorbed into the
Blood
Humans can digest starch and glycogen because our bodies produce _______ that break the bonds between the glucose molecules
of starch and glycogen.
Enzymes
Humans are unable to digest ________ because our bodies do not produce the enzymes that break the bonds between its glucose molecules.
Cellulose
As a consequence, the digestive tract is unable to absorb cellulose. Instead, cellulose provides _____, or “roughage,” thereby increasing the bulk of feces and making it easier to defecate.
Fiber
The _____ converts fructose, galactose, and other monosaccharides absorbed by the small intestine into glucose.
Liver
Glucose, whether absorbed from the digestive tract or synthesized in the liver, provides energy to produce _________ molecules.
Adenosine Triphosphate (ATP)
Because the _____ relies almost entirely on glucose for its energy, the body carefully regulates blood glucose levels.
Brain
Muscle and liver cells convert excess glucose into glycogen for
Storage
Cells can store only a limited amount of ________; therefore, any additional glucose is converted into lipids and
stored in adipose tissue.
Glycogen
can be rapidly converted back to glucose when energy is needed.
Glycogen
In addition to serving as a source of energy, sugars have other functions. They form part of
Deoxyribonucleic acid (DNA), Ribonucleic acid (RNA), and ATP molecules.
Sugars also combine with ________ to form glycoproteins, such as the glycoprotein receptor molecules on the outer surface of the plasma
membrane.
Proteins
According to the Dietary Guidelines Advisory Committee, the Acceptable Macronutrient Distribution Range (AMDR) for carbohydrates is _____ of total kilocalories
45–65%
Muscles are primarily protein, the use of proteins for energy can result in the breakdown of
Muscle Tissue
The extensive use of lipids for energy
can lead to
Acidosis
are recommended in the diet because
many starchy foods contain other valuable nutrients, such as vitamins and minerals.
Complex Carbohydrates
Foods primarily composed of ________, such as soft drinks and candy, are rich in carbohydrates but have few other nutrients.
Simple Sugars
A typical soft drink is mostly _______, containing 9 teaspoons of sugar per 12 oz can. Consuming these kinds of foods in excess usually results in
obesity and tooth decay.
Sucrose
The AMDR for lipids is _____ for adults
20–35%
The AMDR for lipids is _____ for children and adolescents 4 to 18 years of age
25–35%
The AMDR for lipids is _____ for children 2 to 3 years of age.
30–35%
Saturated fats should amount to no more than ___ of total kilocalories or be as low as possible.
10%
Most dietary fat should come from sources of
Polyunsaturated and monounsaturated fats
Essential fatty acids are used to synthesize ________ that affect blood clotting.
Prostaglandins
can be converted to arachidonic acid, an omega-6 fatty acid used to produce thromboxanes, which increase blood clotting.
Linoleic acid
can be converted to eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), omega-3 fatty acids that can be used to synthesize prostaglandins, which decrease blood clotting.
Alpha- linolenic acid
People who eat foods rich in EPA and DHA, such as herring, salmon, tuna, and sardines, increase the synthesis of _________ from EPA and DHA.
Prostaglandins
Those who eat these fish two or more times per week have a lower risk for heart attack than those who do not, possibly because of reduced blood clotting.
Herring, Salmon, Tuna, and Sardines
EPA and DHA are also known
to reduce blood _______ levels.
Triglyceride
People who do not like to eat fish can take _______ supplements as a source of EPA and DHA.
Fish oil
is a source of alpha-linolenic acid, from which EPA and DHA can be synthesized.
Flaxseed
Most of the ________ consumed in the diet is broken down in the digestive tract.
Lecithin
The _____ can manufacture all the lecithin necessary to meet the body’s needs, so taking lecithin supplements is
not necessary.
Liver
The essential fatty acids in the human diet include
Alpha-linolenic acid and linoleic acid
These fatty acids must be ingested because humans lack the enzymes necessary to synthesize them.
Alpha-linolenic acid and linoleic acid
are good sources of alpha-linolenic and linoleic acids.
Seeds, nuts, and legumes
(1) ________ is in the
green leaves of plants, and (2) _______ is in grains.
(1) Alpha-linolenic acid
(2) Linoleic acid
are chains of amino acids.
Proteins
Proteins in the body are constructed of
20 kinds of amino acids, which are divided into two groups:
Essential and nonessential
The body cannot synthesize ________, so they must be obtained in the diet.
Essential amino acids
The nine essential amino acids are
- Histidine
- Isoleucine,
- Leucine
- Lysine
- Methionine
- Phenylalanine
- Threonine
- Tryptophan
- Valine
which are necessary to construct our proteins, do not necessarily need to be ingested because they can be synthesized from essential amino acids.
Nonessential amino acids
is a food that contains adequate amounts of all nine essential amino acids
Complete protein
Examples of complete protein foods are
Meat, fish, poultry, milk, cheese, and eggs
Examples of incomplete protein foods are
Leafy green vegetables, grains, and legumes (peas and beans)
If two incomplete proteins, such as rice and beans, are ingested together, the amino acid composition of each complements the other, and a
_________ is created.
Complete protein
provides structural strength in connective tissue, as does keratin in the skin.
Collagen
The interactions of ______ and
______ make muscle contraction possible.
Actin, Myosin
regulate the rate of chemical reactions
Enzymes
hormones regulate many physiological processes
Protein
in the blood prevent changes in pH (buffers), promote blood clotting (coagulation factors), and transport oxygen and carbon dioxide (hemoglobin).
Proteins
move materials across plasma membranes, and other proteins in the plasma membrane function as receptor molecules.
Transport proteins
are part of the immune system response that protects against microorganisms and other foreign substances.
Antibodies, lymphokines, and complement
The body also uses proteins for
Energy
As an energy source, proteins yield the same amount of kilocalories as
Carbohydrates
If excess proteins are ingested, the energy in the proteins can be stored by converting their _________ into glycogen or lipids.
Amino acids
The AMDR for protein is ____ of total kilocalories.
10–35%
The _________ of proteins contain nitrogen, so saying that a person is in nitrogen balance means that the nitrogen content of ingested protein is equal to the nitrogen excreted in urine and feces.
Amino acids
A starving person is in ______ nitrogen balance because the nitrogen gained in the diet is less than that lost by excretion. In other words, when proteins are broken down for energy, more nitrogen is lost than is replaced in the diet.
Negative
A growing child or a healthy pregnant woman is in _______ nitrogen
balance because more nitrogen is going into the body to produce
new tissues than is lost by excretion.
Positive
are organic molecules that exist in very small quantities in food. These molecules are essential to normal metabolism
Vitamins
cannot be produced by the body and must be obtained through the diet.
Essential vitamins
The absence of an essential vitamin in
the diet can result in a
Deficiency disease
A few vitamins, such as ________, are produced by intestinal bacteria, and a few others can be formed by the body
from substances called provitamins.
Vitamin K
is a part of a vitamin that the body can convert into a functional vitamin.
Provitamin
