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
is a provitamin that the body can form into vitamin A.
Beta carotene
The other provitamins are 7-dehydrocholesterol, which can be converted to (1) _______, and
tryptophan, which can be converted to (2) _______.
(1) Vitamin D
(2) Niacin
Rather than breaking down vitamins by ________, the body uses them in their original or slightly modified forms.
Catabolism
If the chemical structure of a vitamin is destroyed, its function is usually
Lost
The chemical structure of many vitamins is destroyed by heat, as when food is
Overcooked
Many vitamins function as ________, which combine with enzymes to make
the enzymes functional.
Coenzymes
Without enzymes and their coenzymes, many chemical reactions would occur _____ to support good health and life.
Too slowly
Vitamins B2 and B3, biotin, and pantothenic acid are critical for some of the chemical reactions involved in producing
ATP
Folate and vitamin B12 are required for ________ synthesis.
Nucleic acid
Vitamins A, B1, B6, B12, C, and
D are necessary for
Growth
Vitamin B1
Thiamine
Vitamin B2
Riboflavin
Vitamin B3
Niacin
Vitamin B5
Pantothenic acid
Vitamin B6
Pyridoxine
Vitamin B7
Biotin
Vitamin B9
Folate
Vitamin B12
Cobalamin
Vitamin C
Ascorbic acid
Vitamin A
Retinol
Vitamin D
Calciferol
Vitamin E
Tocopherol
Vitamin K
Phylloquinone
is necessary for the synthesis of proteins involved in blood clotting.
Vitamin K
vitamins, such as vitamins A, D, E, and K, dissolve in lipids and are absorbed from the intestine along with lipids. Some of them can be stored in the body for a long time. Because they can be stored, these vitamins can accumulate in the body to the point of toxicity.
Fat-soluble
vitamins, such as the B vitamins and vitamin C, dissolve in water. They are absorbed from the water in the intestinal tract and typically remain in
the body only a short time before being excreted in the urine.
Water-soluble
Vitamins were discovered at the beginning of the twentieth century. They were found to be associated with
certain foods known to protect people from diseases such as
Rickets and beriberi
are molecules, produced as part of normal metabolism, that are missing an electron.
Free radicals
The loss of an electron from a molecule is called
Oxidation
Free radicals can replace the missing electron by taking an electron from cell molecules, such as ______, ______, or ______, resulting in damage to the cell.
Lipids, Proteins, DNA
Damage from free radicals may contribute to aging and certain diseases, such as
Atherosclerosis and cancer.
substances called _________ may counteract these effects by donating an electron to free radicals and thus preventing the oxidation of cell components.
Antioxidants
Examples of antioxidants are
Beta carotene (provitamin A), vitamin C, and vitamin E.
RDA
Recommended Dietary Allowances
which are the nutrient intakes sufficient to meet the needs of nearly all people in certain age and gender groups.
RDA
consuming too much of some vitamins and minerals can be
Harmful
the long-term ingestion of 3–10 times the RDA for _________ can cause bone and muscle pain, skin disorders, hair
loss, and an enlarged liver.
Vitamin A
Consuming 5–10 times the RDA of _________ over the long term can result in calcium deposits in the kidneys, heart, and blood vessels
Vitamin D
Consuming more than 2 g of ________ daily can cause stomach inflammation and diarrhea.
Vitamin C
are inorganic nutrients that are necessary for normal metabolic functions.
Minerals
The minerals are divided into two
groups
Major minerals and trace minerals
The daily requirement for major minerals is _____ daily.
100 mg or more
The daily requirement for trace minerals is ______ mg daily.
less than 100
Minerals constitute about ____ of total body weight.
4-5%
Some minerals are components of other important molecules in the body, such as
coenzymes, a few vitamins, and hemoglobin.
are involved in a number of important functions, including establishing resting membrane potentials and generating
action potentials, adding mechanical
strength to bones and teeth, combining with organic molecules, and acting as coenzymes, buffers, and regulators of osmotic pressure.
Minerals
People ingest minerals alone or in combination with organic molecules, as well as obtain them from both _____ and _____ sources.
Animal, plant
Mineral absorption from _____ can be limited because the minerals tend to bind to plant fibers.
Plants
are often added to refined breads and cereals to compensate for their loss during the refinement process.
Minerals and vitamins
A _________ can provide all the vitamins and minerals required for good health for most people.
Balanced diet
Some nutritionists, however, recommend taking a once-a-day multiple _________ supplement as insurance because many people’s diets are not balanced.
Vitamin and mineral
are dietary values that appear on food labels to help consumers plan a healthful diet.
Daily values
are based on the 1968 RDAs
for certain vitamins and minerals.
Reference Daily Intakes (RDIs)
are set for total fat, saturated fat, cholesterol, total carbohydrate, dietary fiber, sodium, potassium, and protein.
Daily Reference Values (DRVs)
RDIs have been set for four categories of people:
Infants, toddlers, people over 4 years of age, and pregnant or lactating women
Therefore, the RDIs and DRVs were combined to form the
Daily Vales
The Daily Values appearing on food labels are based on a ____ kcal reference diet, which approximates the weight maintenance requirements of postmenopausal women, women who exercise moderately, teenage girls, and sedentary men
2000
On large food labels, additional information is listed based on a daily intake of ____ kcal, which is adequate for young men.
2500
The Daily Values for energy-producing nutrients are determined as a percentage of daily kilocalorie intake:
60% for carbohydrates, 30% for total fats, 10% for saturated fats, and 10% for proteins.
The Daily Value for fiber is 14 g for each ____ kcal of intake.
1000
is the total of all the chemical
reactions that occur in the body.
Metabolism
includes the energy-releasing process by which large molecules are broken down into smaller molecules.
Catabolism
includes the energy-requiring process by which small molecules are joined to form larger molecules.
Anabolism
of nutrients begins during digestion when large molecules, such as polysaccharides and fats, are broken down for absorption by the small intestine.
Catabolism
The process of catabolism continues in the cells when the absorbed nutrients are further broken down for
ATP production
The energy derived from catabolism is
used to drive _______ and processes such as active transport and muscle contraction.
Anabolic reactions
occurs in all the body cells as they divide to form new cells, maintain their own intracellular structure, and produce molecules, such as hormones, neurotransmitters, and extracellular matrix molecules, for export.
Anabolism
Most ATP from glucose is generated in the
Electron Transport Chain
is a short-term energy-storage molecule that the body can store in LIMITED amounts
Glycolysis
are long-term
energy-storage molecules that the body can store in LARGE amounts.
Lipids
metabolism begins with _________, a series of chemical reactions in the cytosol that results in the break-down of glucose into two pyruvic acid molecules
Glycolysis
Glycolysis is divided into four phases:
- Input of ATP
- Sugar Cleavage
- NADH Production
- ATP and Pyruvic Acid Production
The first steps in glycolysis require the input of energy in the form of
Two ATP molecules
An ATP molecule is used in the process called ___________, where a phosphate group is transferred from ATP to glucose. This first step forms glucose-6 phosphate.
Phosphorylation
The glucose-6-phosphate atoms are rearranged to form
Fructose-6-phosphate
A second ATP molecule is then used to phosphorylate fructose-6 phosphate, producing
Fructose-1,6-bisphosphate
Fructose-1,6 bisphosphate is cleaved, or broken, into
Two 3-carbon molecules,
Glyceraldehyde-3-phosphate,
Dihydroxyacetone Phosphate
Dihydroxyacetone phosphate
is rearranged to form a second _________; consequently, two molecules of _________ result
Glyceraldehyde-3-phosphate
Each glyceraldehyde-3- phosphate molecule is oxidized (loses two electrons) to form
1,3 bisphosphoglyceric acid
Nicotinamide Adenine Dinucleotide (NAD+) is reduced (gains
two electrons) to
NADH
Glyceraldehyde-3-phosphate also loses _______, one of which binds to NAD+.
Two H+
is referred to as an electron carrier molecule
NADH
The last four steps of glycolysis produce (1) _______ molecules and (2) _______ molecule from each 1,3 bisphosphoglyceric acid molecule.
(1) Two ATP
(2) One pyruvic acid
Since the previous step produced two 1,3-bisphosphoglyceric
acid molecules, this last step produces (1) _______ molecules
and (2) _______ molecules
(1) Four ATP
(2) Two Pyruvic Acid
Each glucose molecule that enters glycolysis forms _____________ molecules at the sugar cleavage
phase.
Two
glyceraldehyde-3-phosphate
Each glyceraldehyde-3-phosphate molecule produces
(1) _________, (2) __________, and (3) __________ molecule.
(1) Two ATP molecules
(2) One NADH molecule
(3) One pyruvic acid
The breakdown of each glucose molecule, therefore,
produces (1) ________, (2) ________, and (3) _________ mole-
cules.
(1) Four ATP
(2) Two NADH
(3) Two Pyruvic Acid
The start of glycolysis requires the input of two ATP molecules, the final yield of each glucose molecule is (1) ________, (2) ________, and (3) ________ molecules
(1) Two ATP
(2) Two NADH
(3) Two Pyruvic Acid
If the cell has adequate amounts of oxygen, the NADH and pyruvic acid molecules are used in _________ to produce ATP.
Aerobic Respiration
is the breakdown of glucose in
the absence of oxygen.
Anaerobic Glycolysis
In human cells, the breakdown of a glucose molecule in the absence of oxygen produces two molecules of ________ and two molecules of ____
Lactate, ATP
Anaerobic glycolysis can be divided into two phases:
Glycolysis
Lactate Formation
is first converted to lactic acid, a reaction that requires the input of energy from the NADH produced in step 3 of glycolysis.
Pyruvic Acid
In cells, lactic acid
usually releases a ____ and is converted to lactate, the ionized form of lactic acid.
H+
Lactate is released from the cells that produce it, and blood transports it to the
Liver
Thisprocess of converting lactate to glucose is called the
Cori Cycle
The oxygen necessary for synthesizing the ATP is part of the
Oxygen Deficit
Aerobic Respiration is the breakdown of glucose in the
presence of oxygen to produce
Carbon Dioxide
Water
36 ATP Molecules
Most of the ATP molecules required to sustain life are produced through
Aerobic Respiration
Aerobic Respiration can be considered in four phases:
(1) glycolysis (which is also the first phase of anaerobic glycolysis)
(2) acetyl-CoA formation
(3) the citric acid cycle
(4) the electron-transport chain
Recall that glycolysis, the first phase, produces pyruvic acid. In the second phase of aerobic respiration, pyruvic acid is converted to ________, releasing carbon dioxide in the process.
Acetyl-Coa
The pyruvic acid moves from the cytosol into a
Mitochondrion
A mitochondrion is separated into the intermembrane space and the matrix by
the
Inner mitochondrial membrane
Within the _______, enzymes remove a carbon and two oxygen atoms from the 3-carbon pyruvic acid molecule to form carbon dioxide and a 2- carbon acetyl group
Matrix
The acetyl group combines with _________
(CoA) to form acetyl-CoA.
Coenzyme A
For each two pyruvic acid molecules from glycolysis, _________ are formed
Two acetyl-CoA molecules
Two carbon dioxide molecules
Two NADH
The third phase of aerobic respiration is the __________, which is named after the 6-carbon citric acid molecule formed in the first step of the cycle.
Citric Acid Cycle
Citric acid cycle is also called the _______ after its discoverer, British biochemist Sir Hans Krebs.
Krebs Cycle
The citric acid cycle begins with the production of citric acid. This occurs when the 2-carbon acetyl-CoA, produced in the second phase, combines with a 4-carbon molecule called
Oxaloacetic acid
During the reactions of the
citric acid cycle, three important
events occur:
ATP Production
NADH and FADH2 Production
Carbon Dioxide Production
The fourth phase of aerobic respiration involves the _____________, which is a series of electron carriers in the inner mitochondrial membrane.
Electron Transport Chain
The H+ cannot simply diffuse down the concentration gradient but must pass through certain channels formed by an enzyme called
ATP Synthase
As the H+ diffuses down the concentration gradient, energy is released that is used to produce ATP. This process is called ___________ because the chemical formation of ATP is coupled to a diffusion force similar to osmosis.
Chemiosmosis
are the body’s main energy-storage molecules.
Lipids
In a healthy person, lipids are responsible for about (1) ____ of the body’s energy storage, and (2) _______ accounts for about 1%.
(1) 99%
(2) Glycogen
Although ________ serve as an energy source, they are not considered storage molecules because their breakdown normally involves the loss of molecules that perform other functions.
Proteins
Triglycerides are the main lipid stored in _______ tissue
Adipose
Between meals, when triglycerides are broken down in adipose tissue, some of the fatty acids produced are released into the blood, where they are called
Free Fatty Acids
Other tissues, especially _____________, use the free fatty acids as a source of energy.
Skeletal muscle and the liver
The metabolism of fatty acids occurs by ___________, a series of reactions in which two carbon atoms are removed from the end of a fatty acid chain to form acetyl-CoA.
Beta Oxidation
Acetyl-CoA can enter the citric acid cycle and be used to generate
ATP
Acetyl-CoA is also used in __________, the
formation of ketone bodies.
Ketogenesis
Two acetyl-CoA molecules combine to form a molecule of __________, which is converted mainly into β-hydroxybutyric acid and a smaller
amount of acetone.
Acetoacetic acid
Acetoacetic acid, β-hydroxybutyric acid, and acetone are called
Ketone Bodies
Excessive production of ketone bodies is called
Ketosis
Ketone bodies are acidic, if the increased number of ketone bodies exceeds the capacity of the body’s buffering systems, _______, a decrease in blood pH,
can occur
Acidosis
Examples of conditions that increase lipid metabolism are
Starvation Impact,
Diets consisting mainly of proteins and lipids with few carbohydrates,
Untreated Diabetes Mellitus
Ketone bodies
are excreted by the ________ and diffuse into the alveoli of the
lungs.
KIdneys
The synthesis of nonessential amino acids usually begins with
Keto Acids
Unlike glycogen and triglycerides, ________ are not stored in the body.
Amino acids
is the inadequate intake of nutrients or the inability to metabolize or absorb nutrients.
Starvation
Starvation has a number of causes, including
Prolonged fasting
Anorexia
Deprivation
Disease
During the _____ phase of starvation, blood
glucose levels are maintained through the production of glucose from glycogen, lipids, and proteins.
First
In the second phase, which can last for several weeks, ______ are the primary energy source.
Lipids
The third phase of starvation begins when the lipid reserves are depleted and the body switches to _______ as the major energy source.
Proteins
In oxidative deamination, or deaminization, an ________ is removed
from an amino acid (usually glutamic acid), leaving ammonia and a keto acid.
Amine Group
Enzymes in the liver convert _______- (beverage alcohol) into
acetyl-CoA; in the process, two NADH molecules are produced.
Ethanol
Each gram of ethanol provides ______ of energy.
7 kcal
Chronic alcohol abuse can result in ________
of the liver, which involves lipid deposition, cell death, inflammation, and scar tissue formation.
Cirrhosis
The body experiences
two major metabolic states:
Absorptive State
Postabsorptive State
is the period immediately after a meal, when nutrients are being absorbed through the intestinal
wall into the circulatory and lymphatic systems
Absorptive State
The absorptive state usually lasts about __ hours after each meal, though the rate of absorption declines after 1–2 hours.
4
occurs late in the morning, late in the
afternoon, or during the night after each absorptive state is concluded
Postabsorptive state
is the total amount of energy produced and used by the body per unit of time.
Metabolic Rate
A molecule of ATP exists for less than _______ before it is degraded back to ADP and inorganic phosphate.
1 minute
One liter of oxygen consumed by the body is estimated to produce ____ kcal of energy.
4.825
A pound of body fat (adipose tissue) provides about
____ kcal.
3500
Metabolic energy is used in three ways:
Basal Metabolism
Thermic effect of food
Muscular activity
is the energy needed to keep the
resting body functional.
Basal Metabolic Rate
A typical Basal Metabolic Rate
for a 70 kg (154-pound) male is
38 kcal/m2/h
In the average person, basal metabolism accounts for about ___ of energy expenditure.
60%
people have a higher BMR than
older people because of increased cell activity, especially during growth.
Younger
Males have a greater BMR than
females because men have proportionately more (1) _______ tissue and less (2) _______ tissue than women do.
(1) Muscle
(2) Adipose
During pregnancy, a woman’s BMR can increase ___ because of the metabolic activity of the fetus.
20%
The second component of metabolic energy is used for activities
involved in digestion and absorption of food.
Thermic effect of food
The energy cost of these events accounts for about ___ of the body’s energy expenditure.
10%
consumes about 30% of the body’s energy.
Muscular Activity
sometimes called
inborn errors of metabolism, are a large class of genetic disorders that result in
biochemical defects.
Metabolic Disorders
is the total amount of energy liberated by the complete catabolism of food.
Free Energy
The average normal __________- is considered to be
37°C (98.6°F) when measured orally and 37.6°C (99.7°F) when
measured rectally.
Body Temperature
Our bodies exchange heat with the environment in a number of ways, including
Radiation
Conduction
Convection
Evaporation
is the gain or loss of heat between two objects that are not in physical contact.
Radiation
is the exchange of heat between objects in direct contact with each other, such as the bottoms of the feet and the floor.
Conduction
is a transfer of heat between the body and
the air or water, as the air or water moves across the surface of
the skin.
Convection
is the conversion of water from a liquid to a gas, a process that requires heat.
Evaporation
is maintained by balancing heat gain with heat loss.
Body Temperature
If heat gain exceeds heat loss, body temperature
Increases
If heat loss exceeds heat gain, body temperature
Decreases
Obesity can be further classified according to the number and size of
Adipocytes
adipocytes are both more numerous
and larger than normal.
Hyperplastic Obesity
results from a normal number of adipocytes that have increased
in size.
Hypertrophic Obesity
This type of obesity,
which is associated with massive obesity, begins at an early age.
Hyperplastic Obesity
This more common type of obesity is
associated with moderate obesity and typically develops in adults.
Hypertrophy Obesity
Body temperature regulation is an example of a _________ system controlled by a set point.
Negative-feedback
elevated body temperature, develops when heat gain exceeds the body’s ability to lose heat.
Hyperthemia
Hyperthermia can result from
Exercise
Exposure to hot environments
Fever
Anesthesia
is characterized by wet, cool skin due to heavy sweating.
Heat Exhaustion
is more severe than heat exhaustion because it results from a breakdown in the normal negative-feedback mechanisms
of temperature regulation.
Heat Stroke
is the development of a higher than normal body temperature due to invasion of the body by microorganisms or other foreign substances.
Fever
Lymphocytes, neutrophils, and macrophages release chemicals called _________, such as certain interleukins,
interferons, and tissue necrosis factor.
Pyrogens
In people who have the inherited muscle
disorder _______________, certain
general anesthetics cause sustained, uncoordinated muscle contractions.
Malignant Hyperthermia
is an induced elevation in local or general body temperature
sometimes used to treat tumors and infections.
Therapeutic hyperthermia
If heat loss exceeds the body’s ability to produce heat, body temperature falls below normal.
Hypothermia
is a decrease in body temperature to 35°C (95°F) or below.
Hypothermia
is sometimes
used to slow the metabolic rate during surgical procedures, such as heart surgery.
Therapeutic Hypothermia
