A&P Ch 23
Energy via GTP produced during enzymatic reactions
2 ATP
For each glucose molecule converted to two pyruvates, the anaerobic reaction sequence in glycolysis provides a net gain of _______
2 ATP for the cell
Oxidation
A gain of oxygen, or loss of hydrogen or electrons from an atom or molecule
Shivering thermogenesis
A gradual increase in muscle tone increases the energy consumption of skeletal muscle tissue throughout the body
Protein deficiency diseases are
A lack of one or more essential amino acids
Leptin is a
A peptide hormone produced by adipose tissue during the synthesis of triglycerides
Identify the fates of fatty acids
A source of energy or a component of triglycerides, glycolipids, phospholipids, prostaglandins, cholesterol, and steroids
Fat-soluble vitamins
A, D, E, K
Product of hydrogen ion diffusion within mitochondria
ATP
HDLs:
Absorb unused cholesterol from body tissues, returning it to the liver, where it may be packaged into new LDLs or excreted with bile salts in bile
Evaporation
Absorbs energy and cools the surface, where water changes from a liquid to a vapor
Period following a meal
Absorptive state
Nutrient pool
Accessible reserve of organic substrates that can be used for metabolic turnover or energy production
Common substrate for mitochondrial ATP production
Acetate
Catabolizing fatty acids by beta-oxidation results in the formation of what product?
Acetyl CoA
Pyruvate molecules are used by mitochondria after conversion to:
Acetyl CoA
Which molecule is a key reactant in both ATP production from fatty acids and lipogenesis?
Acetyl-CoA
Metabolism refers to
All the anabolic and catabolic reactions in the body
Milk and eggs are complete proteins because they contain _____
All the essential amino acids in sufficient quantities
The attachment of an amine group in the synthesis of an amino acid is called ____
Amination
The formation of glutamic acid from alpha-ketoglutarate is an example of
Amination
At rest, skeletal muscles increase the number of myofibrils using
Amino acids
Which nutrient in the nutrient pool is most often used to replace structural and functional components of the cell?
Amino acids
Amination
An ammonium ion is used to form an amino group that is attached to a molecule, yielding an amino acid
Phenylketonuria(PKU):
An inherited metabolic disorder resulting from an inability to convert phenylalanine to tyrosine
Cells in our body are constantly building new molecules to replace worn-out structures. This process is what part of cellular metabolism?
Anabolism
Synthesis of new organic molecules
Anabolism
The breakdown of glucose to pyruvate is
Anaerobic
Lack or loss of appetite
Anorexia
Water-soluble vitamins
B complex and C
Resting energy expenditure
Basal metabolic rate
The minimum resting energy expenditure of an awake, alert person is the ____
Basal metabolic rate
Lipids are useful as an energy reserve primarily because the process of ________ is so efficient
Beta oxidation
The process in which fatty acids are broken down into two-carbon fragments is ____
Beta oxidation
Emulsification
Bile salts break large lipid drops into tiny droplets
During the postabsorptive state,
Blood glucose begins to decrease, triggering the release of glucagon, which stimulates the liver to release glucose into the circulation
Glycogenolysis:
Breakdown of glycogen to glucose
Salivary amylase
Breaks down complex carbohydrates into a mixture of disaccharides and trisaccharide's
Source of mitochondrial CO2 production
CAC
Unit of energy
Calorie
Salivary amylase is a salivary enzyme that breaks down complex _______
Carbs
Breakdown of organic molecules
Catabolism
The process that breaks down organic substrates, releasing energy that can be used to synthesize ATP or other high-energy compounds, is ____
Catabolism
In resting skeletal muscles, a significant portion of their metabolic demand is met through the _____
Catabolism of fatty acids
When blood glucose concentrations are elevated, the glucose molecules are
Catabolized for energy
When blood glucose concentrations are elevated, the glucose molecules can be ____
Catabolized for energy, used to build energy reserves, and used for growth and tissue repair
Pancreatic alpha-amylase
Cholecystokinin release triggers its secretion; breaks down complex carbohydrates
Which lipoprotein carries dietary triglycerides to the liver?
Chylomicrons
6-carbon molecule
Citric acid
The first step in the sequence of enzymatic reactions in the tricarboxylic acid cycle is the formation of ____
Citric acid
The reaction in which an acetyl group from acetyl-CoA is attached to a four-carbon molecule in the mitochondrial matrix produces a six-carbon molecule of
Citric acid
Vitamin B6 (pyridoxine)
Coenzyme in amino acid and lipid metabolism
Vitamin B9 (folic acid)
Coenzyme in amino acid and nucleic acid metabolism
Vitamin B7 (biotin)
Coenzyme in many pathways; deficiency results in fatigue, muscular pain, nausea, dermatitis
Vitamin B1 (thiamine)
Coenzyme in many pathways; excessive levels cause hypotension
Carry hydrogen atoms to the ETC
Coenzymes
Glycogen forms
Compact, insoluble granules
Lipoprotein lipase
Complex protein that breaks down the chylomicrons and releases fatty acids and monoglycerides that can diffuse into the interstitial fluid
Low-density lipoproteins
Complexes that deliver cholesterol to peripheral tissues
High-density lipoproteins
Complexes that return cholesterol to the liver, where it is extracted and packaged, or excreted with bile salts in bile
Direct transfer of heat energy through physical contact:
Conduction
Balanced diet:
Contains all the ingredients needed to maintain homeostasis and prevent malnutrition
____________ accounts for roughly 15 percent of the body's heat loss indoors
Convection
Anabolism
Converts smaller molecules into larger ones
Dipeptidases break dipeptides apart and release individual amino acids, which are absorbed by epithelial cells of the small intestine through two mechanisms, facilitated diffusion and ___________
Cotransport
Heat conservation mechanism that conducts heat from deep arteries to adjacent deep veins in the limps:
Countercurrent exchange
ETC proteins
Cytochromes
Poisons like cyanide bind to ____, thereby preventing the transfer of electrons to oxygen
Cytochromes
If the cells are catabolizing amino acids for energy, what is the first step in amino acid catabolism?
Deamination
Removal of amino group
Deamination
In amino acid metabolism, identify the processes by which the amino group is removed
Deamination or transamination
Lack of neuropeptide Y in the hypothalamus affects the control of appetite:
Decrease appetite
Conservation of body heat via the vasomotor center
Decreased blood flow to the dermis reduces losses by radiation and convection
Vitamin B3 (niacin)
Deficiency results in a condition called pellagra; part of NAD, involved in multiple pathways
Vitamin B2 (riboflavin)
Deficiency results in epithelial and mucosal deterioration; part of FAD, involved in multiple pathways
Incomplete protein:
Deficient in one or more of the essential amino acids
LDLs:
Deliver cholesterol to body tissues
Conduction
Direct transfer of energy occurs through physical contact
Buffers from the pancreas and liver moderate the pH of the arriving chyme in which region?
Duodenum
ATP produced anaerobically examples
During peak levels of physical activity, at all times in red blood cells, or when a tissue is temporarily deprived of oxygen
Identify when most of the CO2 is released during the complete catabolism of glucose
During the CAC
When do ketone bodies form?
During the postabsorptive state, when lipids and amino acids are broken down in the liver
The flow and transformation of energy
Energetics
Lingual lipase:
Enzyme that attacks triglycerides, breaking them down into monoglycerides and fatty acids
What is the term for an amino acid that either cannot be synthesized or is not synthesized in adequate amounts in the body?
Essential amino acid
Vitamin K
Essential for liver synthesis of prothrombin and other clotting factors
The mechanism of heat loss that involves the skin and alveoli of the lung is ___
Evaporation
Why is hypervitaminosis involving water-soluble vitamins relatively uncommon?
Excessive amounts of these vitamins are readily excreted in the urine
The __________ soluble vitamins are absorbed primarily from the digestive tract along with specific contents of micelles
Fat
Beta oxidation
Fatty acid catabolism that produces molecules of acetyl-CoA
In the nutrient pool, which chemical is best suited for storage of energy content?
Fatty acids
What happens to a glucose molecule as a result of the reactions of glycolysis?
Formation of 2 molecules of pyruvic acid
Glycogenesis:
Formation of glycogen from glucose
What is an important energy source during periods of starvation, when glucose supplies are limited?
Free fatty acids
Stomach hormone
Ghrelin
The hormone ______ , which is secreted by the gastric mucosa, stimulates appetite
Ghrelin
Which hormone inhibits the satiety center and stimulates appetite in the short term?
Ghrelin
Glucose synthesis from smaller carbon chains is known as
Gluconeogenesis
If absorption by the digestive tract fails to maintain normal nutrient levels, triglycerides and glycogen reserves in the liver cells are broken down and ________ is released
Glucose
Neural tissue requires a continuous supply of
Glucose
Sucrase
Glucose + fructose
Lactase
Glucose + galactose
Maltase
Glucose + glucose
Glycolysis:
Glucose is broken down into two three-carbon molecules/chains
Glycogenolysis
Glucose is released from glycogen
Gluconeogenesis
Glucose is synthesized from smaller carbon chains
Glycogenesis
Glycogen is synthesized from glucose
The breakdown of glucose into 2 3-carbon molecules is
Glycolysis
Which process in the aerobic metabolism of glucose takes place in the cytosol?
Glycolysis
Explain when glycolysis is important in cellular metabolism
Glycolysis is important when ATP must be produced anaerobically
For which basic food group is it recommended that at least half of the total amount consumed be whole (unprocessed), in order to prevent a rapid rise in blood glucose and insulin levels?
Grains
ETC by-product
H2O
Excess cholesterol leaves somatic cells and is absorbed by __________, which then transport the cholesterol back to the liver
HDLs
Glycolysis
There is a net gain of two ATP molecules for each glucose molecule.
Homeostatic control of body temperature
Thermoregulation
What happens to the ammonium ions that are removed from amino acids during deamination?
They combine with CO2 to form urea
Why is glucose the primary energy source for cells?
It can be efficiently stored as glycogen, which forms compact, insoluble granules
Complete protein
It contains all the essential amino acids
Intestinal absorption of nutrients occurs in the
Jejunum
Fat catabolism
Ketone bodies
In the post absorptive state, liver cells break down lipids and amino acids, and as levels of acetyl-CoA increase, which compounds begin to form?
Ketone bodies
When glucose supplies are limited, the breakdown of fatty acids and some amino acids in liver cells elevates acetyl-CoA levels and results in the production of small organic acids called
Ketone bodies
What lipoproteins transport cholesterol to cells of the body?
LDL
The absorptive state
Lasts 4 hours, period after a meal when nutrient absorption is underway
Adipose tissue hormone
Leptin
The hormone released by adipose tissues as they synthesize triglycerides is
Leptin
Which peptide hormone stimulates the satiety center and suppresses appetite?
Leptin
Long term of regulation of appetite:
Leptin stimulates the satiety center
Where is cholesterol in chylomicrons extracted and packaged into low-density lipoproteins (LDLs), or excreted?
Lipid
Micelle:
Lipid-bile salt complexes (containing fatty acids, glycerol, and monoglycerides) formed in the intestinal lumen
Chylomicron
Lipid-protein complex that contains insoluble lipids
Carbohydrates (such as glucose) are generally preferred for catabolism because proteins and _________ are more important as structural components of cells and tissues
Lipids
What releases the greatest amount of energy per gram during catabolism?
Lipids
Lipolysis
Lipids are broken down into pieces that can be either converted to pyruvate or channeled directly into the citric acid cycle
Lipid synthesis
Lipogenesis
The synthesis of lipids
Lipogenesis
Lipid breakdown
Lipolysis
Lipid transport
Lipoproteins
Lipids circulate through the bloodstream as
Lipoproteins and free fatty acids
Chylomicron:
Lipoproteins formed in intestinal epithelial cells and contain newly synthesized triglycerides, cholesterol, and other lipids surrounded by phospholipids and proteins
Earliest step of lipolysis
Lysosomal enzymes break down triglyceride molecules into one glycerol molecule and three fatty acids
What is the primary focus of nutritional processing in the postabsorptive state?
Maintaining blood glucose levels
Release of hormones; increased metabolism
Nonshivering thermogenesis
What is a response coordinated by the heat-gain center?
Nonshivering thermogenesis
Collection of all the cell's organic substances
Nutrient pool
Condition when cells preferentially break down carbohydrates
Nutrients abundant
Condition when cells preferentially break down lipids
Nutrients scarce
Final acceptor of electrons from the ETC
O2
A cell with excess carbohydrates, lipids, and amino acids will break down carbohydrates in order to _____
Obtain energy
The CAC:
Occurs in the matrix of mitochondria; organic molecules are broken down, carbon dioxide molecules are released, and hydrogen atoms are transferred to coenzymes that deliver them to the electron transport chain
Oxidative phosphorylation
Occurs within mitochondria in which hydrogen atoms are used to generate ATP
In terms of the movement of electrons, the gain of electrons is called reduction, whereas the loss of electrons is called _____
Oxidation
Process that produces over 90% of ATP used by body cells
Oxidative phosphorylation
The process that produces 90% of the ATP used by our cells is
Oxidative phosphorylation
When chyme arrives in the duodenum, cholecystokinin (CCK) release triggers the secretion of which enzyme?
Pancreatic alpha-amylase
Leptin
Peptide hormone released by adipose tissues as they synthesize triglycerides
Stimulation of vasomotor center
Peripheral vasoconstriction
Inhibition of vasomotor center
Peripheral vasodilation
Which nutritional/metabolic disorder results from an inability to produce specific enzymes involved in amino acid metabolism?
Phenylketonuria
The primary mechanisms for increasing heat loss from the body include
Physiological responses and behavioral modifications
Heat loss and heat gain involve the activities of many systems, which are coordinated by the thermoregulatory centers in the ____________ area of the hypothalamus
Preoptic
Vitamin E
Prevents breakdown of vitamin A and fatty acids
Although small quantities of lipids are normally stored in the liver, most of the synthesized triglycerides are exported and bound to _____
Proteins
Explain why carbohydrates are preferred over proteins and lipids as an energy source
Proteins and lipids are more important as structural components of cells and tissues
What chemical in the catabolism of glucose enters the mitochondria?
Pyruvate
More than 50% of the heat you lose indoors is attributable to
Radiation
What heat transfer process accounts for about one-half of a person's heat loss when indoors?
Radiation
Which primary mechanism of heat transfer results in the loss of more than 50 percent of the heat humans lose indoors?
Radiation
The processes involved in heat transfer between the body and the environment are
Radiation, conduction, convection, and evaporation
The reactants required and products generated by mitochondria:
Reactants required are 2-carbon substrates and O2; the mitochondrial products are CO2, H2O, and ATP
During the catabolism of glucose, some energy is captured by __________ molecules, while the rest of the energy is lost mainly as ____
Reduced; heat
What is the primary role of the citric acid cycle in the production of ATP?
Removal of electrons from substrates
CAC
Removes hydrogen atoms from organic molecules and transfers them to coenzymes
Vitamin D3
Required for normal bone growth, intestinal calcium and phosphorus absorption, and retention of these ions by the kidneys
The enzyme that breaks down complex carbohydrates into a mixture of disaccharides and trisaccharide's in the mouth is
Salivary amylase
Sweat gland activity; heat loss
Sensible perspiration
Vitamins role in nutrition:
Serve as coenzymes in metabolic pathways
Short-term mechanism of control of the hypothalamic satiety and feeding centers:
Several hormones of the digestive tract, including CCK, suppress appetite during the absorptive state
A person's BMR is influenced by
Sex, body weight, age
Result of increased skeletal muscle tone
Shivering thermogenesis
Glycogen reserves
Skeletal muscle
Where does most nutrient absorption occur?
Small intestine, mostly jejunum
Describe the role of CCK release and its effects on proteins
Stimulates the production and release of inactive pancreatic proenzymes
Balanced diets:
Supplies all ingredients to maintain homeostasis
Lipogenesis
Synthesis of lipids
Nutrition:
The absorption of nutrients from food
The period following a meal when nutrient absorption is underway is _____
The absorptive state
Deamination
The amino group is removed from an amino acid, and an ammonium ion is released
Transamination
The amino group of one amino acid is shifted to another molecule, yielding a different amino acid
Countercurrent exchange
The arrangement in which the deep veins lie alongside the deep arteries, trapping the heat close to the body core
Why are minerals, vitamins, and water classified as essential nutrients?
The body cannot synthesize these nutrients in sufficient quantities
Catabolism
The breakdown of large molecules into smaller ones
Catabolism refers to
The breakdown of organic substrates
Beta-oxidation
The catabolism of fatty acids to acetyl-CoA
Conduction:
The direct transfer of heat through physical contact
Insensible perspiration
The evaporation of water from the skin and alveolar surfaces of the lungs
Hypervitaminosis involving water-soluble vitamins is relatively uncommon because
The excess amount is readily excreted in the urine
Oxidative phosphorylation
The generation of ATP as the result of the transfer of electrons from the coenzymes NADH and FADH2 to oxygen by a sequence of electron carriers within mitochondria
Most of the absorbed nutrients enter into which blood vessel?
The hepatic portal vein and transported to the liver
Thermoregulation
The homeostatic control of body temperature
How do ketone bodies form?
The increased concentration of acetyl-CoA that results from their breakdown
What does the liver do with the chylomicrons it receives?
The liver absorbs chylomicrons, removes the triglycerides, combines the cholesterol from the chylomicron with recycled cholesterol, and alters the surface proteins
Reduction
The loss of oxygen, or gain of hydrogen or electrons to an atom or molecule
An individual's basal metabolic rate ideally represents _____
The minimum resting energy expenditure of an awake, alert person
Basal metabolic rate
The minimum resting energy expenditure of an awake, alert person
Describe the role that hydrogen ion channels play in the generation of ATP
The passageways for the diffusion of hydrogen ions from the inner membrane space of the mitochondria to the matrix; powers the production of ATP by ATP synthase
Metabolic turnover
The process in which cells continuously replace their cellular components
Leptin stimulates
The satiety center and suppresses appetite
Oxidative phosphorylation:
The stepwise passage of electrons by coenzymes embedded in the cristae of the mitochondrion releases energy
Energetics
The study of the flow of energy and its change from one form to another
ATP to initiate glycolysis
-2 ATP
The net result of one turn of the citric acid cycle is
1 ATP
Products of glycolysis:
2 molecules each of pyruvate, ATP, and NADH
What molecules forms the common substrate for the CAC?
2-carbon acetate ion, CH3COO−, which is attached to coenzyme A to form acetyl-CoA
ATP from NADH generated in the citric acid cycle
24 ATP
At which body temperature are the thermoregulatory capabilities of the body likely to be lost?
27 degrees C
ATP from FADH2 generated in the citric acid cycle
4 ATP
ATP from NADH produced in glycolysis
4 ATP
ATP produced during enzymatic reactions in the cytosol
4 ATP
The energy yield for carbohydrates is
4.18 cal/g
% of catabolic energy captured as ATP
40%
% of catabolic energy released as heat
60%
Basal metabolic rate (BMR) is
70 cal/hr or 1680 cal/day in the average individual
Convection
Heat loss to the air that overlies the surface of the body; accounts for roughly 15 percent of the body's heat loss indoors
Convection:
Heat loss to the cooler air in contact with the skin
The lipoprotein that transports cholesterol to the liver is ______
High-density lipoprotein
During open-heart surgery, what thermoregulatory changes is induced in the patient's body?
Hypothermia
The most important factor of good nutrition is obtaining nutrients _____
In sufficient quantities and qualities
Predict the effect of peripheral vasodilation on a person's body temperature
Increase blood flow to the skin and thus the amount of heat the body can lose; body temperature would decrease
Respiratory heat loss
Increased evaporative heat losses occur through the lungs
Vasodilation and shunting of blood
Inhibition of the vasomotor center occurs
General role of satiety center
Inhibits feeding center
Where in the cell does the electron transport chain occur?
Inner mitochondrial membrane
Lung and epithelial water loss
Insensible perspiration
Absorptive state hormone
Insulin
In most tissues, the transport of glucose into the cell is dependent on the presence of a carrier protein that is stimulated by
Insulin
During the absorptive state,
Insulin prevents a large surge in blood glucose after a meal by stimulating the liver to remove glucose from the circulation
Before the large vitamin B12 molecule can be absorbed, it must be bound to ___
Intrinsic factor
Role of nonshivering thermogenesis in regulating body temperature:
Involves the release of hormones that increase the metabolic activity of all tissues, resulting in an increase in body temperature
Nonshivering thermogenesis
Involves the release of hormones that increase the metabolic activity of all tissues
The source of intestinal gas:
Is generated by bacterial activities in the colon when indigestible carbohydrates stimulate bacterial gas production
Explain the role of glycogen in cellular metabolism
Is synthesized from excess glucose molecules by liver and muscle cells, and it serves as an intracellular glucose reserve
What happens to oxygen when it functions as the final electron acceptor in the electron transport system?
It becomes part of a water molecule
Vitamin A
Maintains epithelia; supports immune system; promotes growth and bone remodeling
Complete protein:
Meets the body's amino acid requirements
All the chemical reactions that occur in an organism are called ____
Metabolism
Which part of the cell is most heavily involved in energetics?
Mitochondria
Where in the cell does the CAC occur?
Mitochondrial matrix
Lingual lipase
Monoglycerides + fatty acids
What two coenzymes transfer hydrogen atoms to the electron transport chain?
NAD and FAD
What sources generates the most molecules of ATP?
NADH generated in the citric acid cycle
Appetite-regulating neurotransmitter
Neuropeptide Y
NAD, a key coenzyme used in the process of producing ATP, is produced from which water-soluble vitamin?
Niacin
Why do cells make new compounds?
To maintain and repair structures, to support growth, and to build up nutrient reserves
Why is digestion important?
To produce energy and to replenish the intracellular nutrient pool
If daily intake exceeds total energy demands, the excess energy is stored primarily as
Triglycerides in adipose tissue
All nutrients can be used by the mitochondria to provide energy. In what form are these nutrients "fed" into the mitochondria?
Two-carbon fragments
Amino acid catabolism
Urea formation
Gout
Uric acid
Most of the lipids absorbed by the digestive tract are immediately transferred to the
Venous circulation by the thoracic duct
Vitamin required for synthesis of visual pigments:
Vitamin A
A water soluble vitamin:
Vitamin C
Identify the water-soluble vitamin that functions as a coenzyme in many pathways and results in epithelial and mucosal deterioration if it occurs in deficient levels
Vitamin C (ascorbic acid)
Radiation
Warm objects lose heat energy; the heat emanating from the sun; the human body loses heat in the same manner; accounts for more than 50 percent of the body heat lost indoors
2 classes of vitamins:
Water soluable and fat soluable
Hydrogen atoms are used to generate ATP through oxidative phosphorylation, which occurs:
Within mitochondria
