KAAP Chapter 23
if vitamins do not provide a source of energy, what is their role in nutrition
play a role in metabolic pathways by serving as coenzymes
describe leptin and its effect on appetite
a peptide hormone produced by adipose tissue during the synthesis of triglycerides. It stimulates the satiety center and suppresses appetite
name the heat conservation mechanism that conducts heat from deep arteries to adjacent deep veins in the limbs
countercurrent exchange is in the heat conservation mechanism that results in the conduction of heat from deep arteries to adjacent deep veins in the limbs
identify the two classes of vitamins
fat soluble and water soluble
Define beta oxidation
fatty acid catabolism producing acetyl-CoA
Identify the fates of fatty acids
fatty acids may become a source of energy or a component of triglycerides, glycolipids, phospholipids, prostaglandins, cholesterol, and steroids
when and how do ketone bodies form
form during the postabsoprtive state, when lipids and amino acids are broken down in the liver. The increased concentration of acetyl CoA that results from their breakdown forms ketone bodies. Ketone bodies are not catabolized by liver cells, and they diffuse into the circulation
Define oxidative phosphorylation
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
describe the role of non-shivering 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
explain when glycolysis is important in cellular metabolism
it is important when ATP must be produced anaerobically, during peak levels of physical activity, at all times in red blood cells, or when a tissue is temporarily deprived of oxygen
how might a lack of neuropeptide Y in the hypothalamus affect the control of appetite
lack of neuropeptide Y, a hypothalamic neurotransmitter, would probably decrease appetite because it normally stimulates the feeding center
of these- carbohydrates, lipids, or proteins- which releases the greatest amount of energy per gram during catabolism
lipids
what molecule forms the common substrate for the citric acid cycle
2-carbon acetate ion, CH3COO-, which is attached to coenzyme A to form acetyl-CoA.
Identify when most of the CO2 is released during the complete catabolism of glucose
2/3s of CO2 is release in the complete catabolism of glucose occurs during the citric acid cycle
define protein deficiency disease
nutritional disorders resulting from a lack of one or more essential amino acids. Ex: Kwashiorkor
where does most nutrient absorption occur
occurs in the small intestine, jejunum
compare oxidation and reduction
oxidation: gain of oxygen, or loss of hydrogen or electrons from an atom or molecule Reduction: loss of oxygen, or gain of hydrogen or electrons to an atom or molecule
identify and briefly describe 2 eating disorders
psychological problems that result in inadequate food consumption (anorexia nervosa) or excessive food consumption followed by purging (bulimia)
what heat transfer process accounts for about 1/2 of a person's heat loss when indoors?
radiation accounts for about 1/2 of a person's heat loss indoors.
in amino acid metabolism, identify the processes by which the amino group is removed
the amino group is removed by deamination or transamination
what happens to the ammonium ions that are removed from amino acids during deamination
the ammonium ions combine with carbon dioxide to form urea which is ultimately excreted in the urine
List the products of glycolysis
2 molecules of pyruvate 2 molecules of ATP 2 molecules of NADH
compare catabolism and anabolism
Catabolism is the breakdown of large molecules into smaller ones, whereas anabolism is buildup of large molecules from smaller building blocks.
how is heat loss different between conduction and convection
Conduction: direct transfer of heat through physical contact Convection: heat loss to the cooler air in contact with the skin. The air warmed by the skin rises and it is repeatedly replaced by cooler air until there is no difference in temperature
describe the roles of LDLs and HDLs
LDLs deliver cholesterol to tissues and HDLs absorb unused cholesterol and return it to the liver.
what two coenzymes transfer hydrogen atoms to the electron transport chain
NAD and FAD transfer hydrogen atoms to the electron transport chain
briefly describe PKU
PKU is an inherited metabolic disorder resulting from an inability to convert phenylalanine to tyrosine
explain why carbohydrates are preferred over proteins and lipids as an energy source
carbs are preferred because proteins and lipids are more important as structural components of cells and tissues
why do cells make new compounds
cells make new compounds to maintain and repair structures, to support growth, and to build up nutrient reserves
most of the absorbed nutrients enter into which blood vessel
enter into a branch of the hepatic portal veins and transported to the liver
describe the role of CCK release and its effects on proteins
it stimulates the production and release of inactive pancreatic proenzymes. Enteropeptidase released from the duodenum, converts the pancreatic proenzyme trypsinogen into the proteolytic enzyme trypsin. Trypsin then converts other proenzymes to yield chymotrypsin, carboxypeptidase, and elastase. Each of these enzymes attacks peptide bonds that link specific amino acids while ignoring others. As a result, they break down proteins into a mixture of dipeptides, tripeptides, and amino acids
predict the effect of a peripheral vasodilation on a person's body temperature
it would increase blood flow to the skin and thus the amount of heat the body can lose. As a result, body temperature would decrease
what is the difference between a micelle and chylomicron
micelle: lipid-bile salt complexes (containing fatty acids, glycerol, and monoglycerides) formed in the intestinal lumen. Chylomicrons are lipoproteins formed in intestinal epithelial cells and contain newly synthesized triglycerides, cholesterol, and other lipids surrounded by phospholipids and proteins
briefly describe the citric acid cycle and explain its role
reaction sequence that occurs in the matrix of the mitochondria. In the process, 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
define nutrition
the absorption of nutrients from food
define and describe the absorptive state
the period following a meal, when nutrient absorption is under way. During this time, insulin stimulates glucose uptake and glycogenesis, amino acid uptake and protein synthesis. Androgens, estrogens, and growth hormone stimulate protein synthesis. Glycolysis and aerobic metabolism provide the necessary ATP
explain the process of metabolic turnover
the process in which cells continuously replace their cellular components
define energetics
the study of the flow of energy and its changes from one form to another
How do the absorptive and post-absorptive states maintain normal blood glucose levels?
absorptive: insulin prevents a large surge in blood glucose after a meal by stimulating the liver to remove glucose from the circulation. post-absorptive: blood glucose begins to decrease, triggering the release of glucagon, which stimulates the liver to release glucose into the circulation
which molecule is a key reactant in both ATP production from fatty acids and lipogenesis
acetyl-CoA isa reactant molecule in ATP production and in the synthesis of most types of lipids
describe the role that hydrogen ion channels play in generation of ATP
are the passageways for the diffusion of hydrogen ions from the inner membrane space of the mitochondria to the matrix. This movement powers the production of ATP by ATP synthase
Why is digestion important?
cells throghout your body rely on the organic molecules from the food we eat to produce energy and to replenish the intracellular nutrient pool
dinstinguish between a complete protein and an incomplete protein
complete: meets the body's amino acid requirements incomplete: deficient in one or more of the essential amino acids
define balanced diet
contains all the ingredients needed to maintain homeostasis and prevent malnutrition
list the reactants required and products generated by mitochondria
continuous supply of 2-carbon substrates and O2; the mitochondrial products are CO2, H2O, and ATP
which hormone inhibits the satiety center and stimulates appetite in the short term
ghrelin
explain the role of glycogen in cellular metabolism
glycogen is synthesized from excess glucose molecules by the liver and muscle cells and it serves as an intracellular glucose reserve
compare glycogenesis and glycogenolysis
glycogenesis: the formation of glycogen from glucose glycogenolysis: the breakdown of glycogen to glucose
define insensible perpsiration
insensible perspiration is the evaporation of water from the skin and alveolar surfaces of the lungs
describe the source of intestinal gas
intestinal gas, flatus, is generated by bacterial activities in the colon when indigestible carbs stimulate bacterial gas production
Define thermoregulation
the homeostatic control of body temperature
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. Newly synthesized complexes are released into the blood stream as low-density lipoprotein or very low density lipoproteins
what is basal metabolic rate
the minimum resting energy expenditure of an awake, alert person.