chapter 23 a&p

Define insensible perspiration

Insensible perspiration is the evaporation of water from the skin and alveolar surfaces of the lungs

If vitamins do not provide a source of energy, what is their role in nutrition?

Vitamins play an important role in metabolic pathways by serving as coenzymes

Describe the role that hydrogen ion channels play in the generation of ATP.

Hydrogen ion channels are the passageways for the diffusion of hydrogen ions from the inner membrane space of the mitochondria to the matrix. This movement of hydrogen ions powers the production of ATP by ATP synthase

Describe the source of intestinal gas

Intestinal gas, or flatus, is generated by bacterial activities in the colon when indigestible carbohydrates stimulate bacteria gas production.

Predict the effect of peripheral vasodilation on a person's body temperature.

Vasodilation of peripheral vessels would increase blood flow to the skin and thus the amount of heat the body can lose. As a result, body temperature would decrease.

Define nutrition

absorption of nutrients from food

Identify the two classes of vitamins

fat soluble and water soluble

Define beta oxidation

is fatty acid catabolism that produces molecules of acetylCoA.

Which molecule is a key reactant in both ATP production from fatty acids and lipogenesis

Acetyl-CoA is a reactant molecule in ATP production and in the synthesis of most types of lipids

Identify when most of the CO2 is released during the complete catabolism of glucose.

Two thirds of the Co2 is released in the complete catabolism of glucose occurs during the citric acid cycle.

list the products of glycolysis

2 ATP, 2 NADH, 2 pyruvate

What is basal metabolic rate?

Basal metabolic rate is the minimum resting energy expenditure of an awake, alert person

Explain why carbohydrates are preferred over proteins and lipids as an energy source

Carbohydrates are the preferred energy source because proteins and lipids are more important as structural components of cells and tissues.

compare catabolism and anabolism

Catabolism is the breakdown of large molecules into smaller ones. Anabolism converts smaller molecules into larger one

Why do cells make new compound?

Cells make new compounds to maintain and repair structures, to support growth, and the build up nutrient reserves.

What two coenzymes transfer hydrogen atoms to the electron transport chain?

Coenzymes NAD and FAD transfer hydrogen atoms to the electron transport chain

How is heat loss different between conduction and convection

Conduction is the direct transfer of heat through physical contact. Convection is 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.

Name the heat conservation mechanism that conducts heat from deep arteries to adjacent deep veins in the limbs.

Countercurrent exchange is the heat conservation mechanism that results from deep arteries to adjacent deep veins in the limbs.

Why is digestion important?

Digestion is important because cells throughout the body rely on the organic molecules from the food we eat to produce energy and to replenish the intercellular nutrient pool.

How do the absorptive and post absorptive states maintain normal blood glucose levels?

During the absorptive state, insulin prevents a large surge in blood glucose after a meal by stimulation the liver to remove glucose from the circulation. During the post absorptive state, blood glucose begins to decrease, triggering the release of glucagon, which stimulates the liver to release glucose into the circulation.

Identify and briefly describe two eating disorders.

Eating disorders are psychological problems that result in inadequate food consumption(anorexia nervosa) or excessive food consumption followed by purging (bulimia)

Define energetics.

Energetics is the study of the flow of energy and its change from one form to another.

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.

Which hormone inhibits the satiety center and stimulates appetite in the short term?

Ghrelin, a hormone secreted by the gastric mucosa when the stomach is not full, inhibits the satiety center and stimulates appetite.

Explain the role of glycogen in cellular metabolism.

Glycogen is synthesized from excess glucose molecules by liver and muscle cells, and it serves as an intracellular glucose reserve.

Compare glycogenesis and glycogenolysis.

Glycogenesis is the formation of glycogen from glucose. Glycogenolysis is the breakdown of glycogen to glucose.

Explain when glycolysis is important in cellular metabolism.

Glycolysis is important when ATP must be produced anaerobically, for example, during peak levels of physical activity at all times in red blood cells, or when a tissue is temporarily deprived of oxygen.

When and how do ketone bodies form?

Ketone bodies form during the post absorptive 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 in to the circulation.

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.

Describe leptin and its effect on appetite.

Leptin is a peptide hormone produced by adipose tissue during the synthesis of triglycerides. It stimulates the satiety center and suppresses appetite

Where does most nutrient absorption occur?

Most nutrient absorption occurs in the small intestine, primarily in the jejunum.

Most of the absorbed nutrients enter into which blood vessel?

Most nutrients enter into a branch of the hepatic portal vein and are transported to the liver.

Describe the role of nonshivering thermogenesis in regulation body temperature.

Nonshivering thermogenesis involved the release of hormones that increase the metabolic activity of all tissues, resulting in an increase in body temperature.

Compare oxidation and reduction.

Oxidation is a gain of oxygen, or a loss of hydrogen or electrons from an atom or molecule. Reduction is the loss of oxygen, or gain of hydrogen or electrons from an atom or molecule.

Briefly describe phenylketonuria (PKU).

Phenylketonuria (PKU) is an inherited metabolic disorder resulting from an inability to convert phenylalanine to tyrosine

Define protein deficiency disease, and cite an example.

Protein deficiency diseases are nutritional disorders resulting from a lack of one or more essential amino acids. Kwashiorkor is an example of a protein deficiency disease.

What heat transfer process accounts for about one-half of a person's heat loss when indoors?

Radiation accounts for about one-half of a person's heat loss indoors.

Briefly describe the citric acid cycle, and explain its role.

The citric acid cycle is the reaction sequence that occurs in the matrix of 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.

What molecule forms the common substrate for the citric acid cycle?

The common substrate for the citric acid cycle in mitochondria is the 2ccarbon acetate ion, CH3COO-, which is attached to coenzyme A to form acetyl-CoA.

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 bloodstream as low-density lipoproteins (LDLs) or very low density lipoproteins (VLDLs).

List the reactant required and products generated by mitochondria.

The reactants required by mitochondria are a continuous supply of 2 carbon substrates and O2; the mitochondrial products are CO2, H20, and ATP.

Define balanced diet.

A balanced diet contains all the ingredients needed to maintain homeostasis and prevent malnutrition

Distinguish between a complete protein and an incomplete protein.

A complete protein meets the body's amino acid requirements An incomplete protein is deficient in one or more of the essential amino acids.

Describe the roles of LDLs and HDLs.

Low-density lipoproteins (LDLs) deliver cholesterol to body tissues, and high density lipoproteins(HDLs) absorb unused cholesterol form body tissues, returning it to the liver, where it may be packaged into new LDLs or excreted with bile salts in bile.

Explain the process of metabolic turnover.

Metabolic turnover is the process in which cells continuously replace their cellular components

What is the difference between a micelle and a chylomicron?

Micelles are 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

Define and describe the absorptive state

The absorptive state, lasting about 4 hours, is the period following a meal, when nutrient absorption is under way. During this time, insulin stimulates glucose uptake and glycogenesis, amino acid upate, and protein synthesis Androgens, estrogens, and growth hormone stimulate protein synthesis. Glycolysis and aerobic metabolism provide the necessary ATP.

In amino acid metabolism, identify the processes by which the amino group is removed.

The amino group is removed by the 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 (in the urea cycle), which is ultimately excreted in the urine

Describe the role of CCK release and its effects on proteins

The arrival of acid chyme in the duodenum triggers the release of CCK, which stimulates the production and release of inactive pancreatic proenzymes. Enteropeptidase, released from the duodenum, converts the pancreatic proenzymes 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

Of these-carbohydrates, lipids, or proteins-which releases the greatest amount of energy per gram during catabolism

The catabolism of lipids releases the greatest amount of energy per gram.

Define thermoregulation

homeostatic control of body temperature

Define 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.