Chapter 26: Nutrition & Metabolism Flashcards

Chapter 26 explains how nutrients are obtained and metabolized for energy, how hormones regulate appetite and fuel storage, how carbohydrates, fats, and proteins are processed to make ATP, and how metabolism contributes to body temperature regulation and overall homeostasis.

What is meant by the body's homeostatic set point for body weight?

It is the relatively stable body weight maintained when energy intake equals energy expenditure, influenced by genetics, metabolism, appetite regulation, and environmental factors.

Approximately what percentage of body weight variation between individuals is attributed to heredity?

About 30 - 50%

What are gut-brain peptides?

Hormones that communicate between the digestive tract and hypothalamus to regulate hunger and satiety.

Which appetite-regulating hormones are considered short-term regulators?

Ghrelin, Peptide YY (PYY), Cholecystokinin (CCK), and Amylin.

Which appetite-regulating hormones are considered long-term regulators?

Leptin and insulin.

Which hormone is known as the hunger hormone?

Ghrelin.

Where is ghrelin produced?

By parietal cells of the empty stomach.

How does ghrelin affect appetite?

It stimulates hunger and increases food intake.

Besides stimulating hunger, what other hormone release does ghrelin promote?

Growth hormone-releasing hormone (GHRH).

What is the primary function of Peptide YY (PYY)?

It promotes satiety and reduces food intake.

Where is Peptide YY produced?

Enteroendocrine cells of the ileum and colon.

Why is PYY called the "ileal brake"?

Because it slows stomach emptying and digestive transit.

Which hormone is released from the duodenum and jejunum and promotes satiety?

Cholecystokinin (CCK).

What are two appetite-related functions of CCK?

Suppresses appetite and signals fullness to the brain.

What hormone is secreted by pancreatic beta cells and suppresses appetite?

Amylin.

What is leptin?

A hormone secreted by adipocytes that decreases appetite in proportion to body fat stores.

What does an increase in body fat do to leptin secretion?

Increases leptin secretion.

What is the relationship between insulin and appetite regulation?

Insulin suppresses appetite similarly to leptin, although less powerfully.

Which hypothalamic nucleus is important for appetite regulation?

The arcuate nucleus.

What neurotransmitter stimulates hunger in the hypothalamus?

Neuropeptide Y (NPY).

Which hormone stimulates neuropeptide Y release?

Ghrelin.

Which hormones inhibit neuropeptide Y?

Leptin, insulin, and PYY.

What neurotransmitter promotes satiety?

Melanocortin.

Which hormones stimulate melanocortin release?

Leptin and CCK.

How do chewing and stomach filling influence appetite?

They temporarily suppress hunger.

Which neurotransmitter promotes carbohydrate cravings?

Norepinephrine.

Which neurotransmitter promotes fat cravings?

Galanin.

Which neurotransmitter promotes protein cravings?

Endorphins.

Define one calorie.

The amount of heat required to raise 1 g of water by 1 C.

What is a dietary Calorie?

One kilocalorie (1 Cal).

How many kcal are contained in 1 g of fat?

9 kcal.

How many kcal are contained in 1 g of carbohydrate?

4 kcal

How many kcal are contained in $1\text{ gram}$ of protein?

$4\text{ kcal}$.

What are empty calories?

Calories from substances such as sugar and alcohol that provide energy but few nutrients.

What is the difference between macronutrients and micronutrients?

Macronutrients are required in large amounts, whereas micronutrients are required in small amounts.

Which nutrients are considered macronutrients?

Carbohydrates, fats, proteins, and water.

Which nutrients are considered micronutrients?

Vitamins and minerals.

What are essential nutrients?

Nutrients that cannot be synthesized adequately by the body and must be obtained through diet.

Where are carbohydrates stored in the body?

Liver glycogen, muscle glycogen, and blood glucose.

Which cells depend heavily on glucose?

Neurons and red blood cells.

Which hormones regulate blood glucose concentration?

Insulin and glucagon.

What is the RDA for carbohydrates?

$130\text{ g/day}$.

What are the three dietary monosaccharides?

Glucose, fructose, and galactose.

What is the normal blood glucose concentration?

$70\text{--}110\text{ mg/dL}$.

What are the major dietary polysaccharides?

Starch, glycogen, and cellulose.

What is dietary fiber?

Indigestible plant material that resists digestion.

What is the recommended daily intake of fiber?

$30\text{ g/day}$.

What effect does soluble fiber have on cholesterol?

It lowers blood cholesterol and LDL levels.

What effect does insoluble fiber have on stool?

It increases bulk, softens stool, and speeds intestinal transit.

Why are lipids considered the body's major energy reserve?

They provide twice as much energy per gram as carbohydrates or proteins and are compactly stored.

Which vitamins require dietary fat for absorption?

Vitamins A, D, E, and K.

What are the three essential fatty acids?

Linoleic acid, linolenic acid, and possibly arachidonic acid.

What foods are rich in saturated fats?

Meat, dairy products, and egg yolks.

What foods are rich in unsaturated fats?

Vegetable oils, nuts, and seeds.

What are lipoproteins?

Protein-coated lipid transport particles that carry fats through blood.

List the four major lipoproteins from lowest to highest density.

Chylomicrons → VLDL → LDL → HDL.

What is the primary role of chylomicrons?

Transport dietary fats from the intestine to body tissues.

Where are chylomicrons formed?

Small intestine absorptive cells.

What is the function of VLDL?

Delivers triglycerides from the liver to adipose tissue.

How is LDL formed?

When triglycerides are removed from VLDL.

Why is LDL called "bad cholesterol"?

High LDL contributes to cholesterol deposition in arteries.

Why is HDL called "good cholesterol"?

It removes excess cholesterol from tissues and returns it to the liver.

What total cholesterol level is considered desirable?

Less than $200\text{ mg/dL}$.

What are the major functions of proteins?

Structure, movement, enzymes, receptors, antibodies, transport, and plasma osmotic balance.

What is the RDA for protein?

$46\text{--}56\text{ g/day}$.

Name the eight essential amino acids.

Isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine.

What is a complete protein?

A dietary protein containing all essential amino acids in sufficient amounts.

Give examples of complete proteins.

Meat, eggs, and dairy products.

Why are beans and rice considered complementary proteins?

Together they provide all essential amino acids.

What is positive nitrogen balance?

Nitrogen intake exceeds nitrogen loss, supporting growth.

What is negative nitrogen balance?

Nitrogen loss exceeds intake, causing tissue breakdown.

What are the major functions of calcium and phosphorus?

Formation of bones and teeth.

Why is iron essential?

Required for hemoglobin and myoglobin synthesis.

What mineral is part of stomach acid?

Chloride.

Which vitamins are water-soluble?

Vitamin C and B-complex vitamins.

Which vitamins are fat-soluble?

Vitamins A, D, E, and K.

What are the three major pathways of glucose catabolism?

Glycolysis, aerobic respiration, and anaerobic fermentation.

Where does glycolysis occur?

Cytoplasm.

What is the net ATP yield from glycolysis?

$2\text{ ATP}$.

What are the products of glycolysis?

$2\text{ pyruvate}$, $2\text{ ATP}$, and $2\text{ NADH}$.

What is the purpose of anaerobic fermentation?

To regenerate $\text{NAD}^{+}$ so glycolysis can continue without oxygen.

What molecule is produced during anaerobic fermentation in muscle?

Lactic acid.

Why is lactic acid production called oxygen debt?

Oxygen is later required to convert lactic acid back into usable metabolic products.

What organelle carries out aerobic respiration?

Mitochondria.

What is acetyl-CoA?

The molecule that links glycolysis to the citric acid cycle.

What is another name for the citric acid cycle?

Krebs cycle.

What is the final electron acceptor in the electron transport chain?

Oxygen.

What molecule is produced when oxygen accepts electrons and hydrogen ions?

Water.

What enzyme synthesizes ATP during chemiosmosis?

ATP synthase.

Approximately how much ATP is produced from complete aerobic oxidation of one glucose molecule?

$32\text{--}38\text{ ATP}$.

What is glycogenesis?

Formation of glycogen from glucose.

Which hormone stimulates glycogenesis?

Insulin.

What is glycogenolysis?

Breakdown of glycogen into glucose.

Which hormones stimulate glycogenolysis?

Glucagon and epinephrine.

What is gluconeogenesis?

Synthesis of glucose from non-carbohydrate sources.

What is lipogenesis?

Formation of fat from carbohydrates or amino acids.

What is lipolysis?

Breakdown of triglycerides into glycerol and fatty acids.

What is beta-oxidation?

Breakdown of fatty acids into acetyl-CoA units.

What hormone dominates the absorptive state?

Insulin.

What hormone dominates the postabsorptive state?

Glucagon.