NSCI 2114 Exam #2
proteases
Classification of enzymes that catalyze the hydrolysis of protein
According to the current dietary recommendations, what is the maximum percentage of total energy intake that added sugar should contribute in the diet?
25
Approximately how many different species and subspecies of bacteria live in a healthy GI tract?
400
What is the Daily Value for protein based on a 2000-kcalorie intake?
50 grams
What is the minimum daily amount of dietary carbohydrate necessary to spare body protein from excessive breakdown?
50-100 grams
What is the percent digestibility of most plant proteins?
70-90%
essential amino acids
9 amino acids that the body cannot synthesize; they must be obtained through dietary sources
True or False: Animal products are a good source of incomplete protein.
False. Animal proteins are considered complete proteins because they contain all nine essential amino acids.
True or False: The first step in the chemical digestion of protein occurs in the mouth with the enzyme protein.
False. Chemical digestion of protein begins in which the stomach with the enzyme pepsin, which is secreted by the chief cells lining the stomach.
True or False: Growing children are in a state of negative nitrogen balance.
False. Growing children are in a state of positive nitrogen balance, which means that more nitrogen is being retained by the body than excreted in the urine.
True or False: Carbohydrates are a main cause of obesity.
False. Kilocalories, not carbohydrates, are the main culprit behind most weight gain. In fact, some high-fiber carbohydrates can actually help people lose weight.
True or False: Eating too much protein is associated with high blood cholesterol levels.
False. Protein itself doesn't raise blood cholesterol levels. It depends on the type of protein food you consume.
True or False: Irritable bowel syndrome is caused by an allergy to gluten.
False. The cause of irritable bowel syndrome is not known, but low fiber diets, stress, consumption of irritating foods, and intestinal motility disorders are all suspected factors.
True or False: The primary function of protein is to provide energy to the cells.
False. The primary function of protein is to build new tissues and repair proteins that have been degraded or sloughed off in the body.
True or False: Sugar causes hyperactivity in children.
False. There is insufficient evidence to suggest that eating sugar causes hyperactivity or other behavioral problems in children.
True or False: Aspartame causes cancer in humans.
False. There is no scientific evidence to support claims that aspartame causes cancer or other health problems in humans.
True or False: Most babies are born lactose intolerant.
False. In fact, infants have higher amounts of lactase, the enzyme necessary for lactose digestion, due to their initial diet of breast milk. As people get older, however, their bodies produce less of this enzyme, which can result in the condition of lactose intolerance.
True or False: The lymphatic system transports all nutrients through the body once they've been absorbed.
False. Lymph only transports fat-soluble components. Blood transports water-soluble materials.
pepsin
Active protease that begins the digestion of proteins in the stomach
An individual who has PKU should not consume which sugar substitutes?
Aspartame
Which of the following is a characteristic of hormones? A. Inactivate bacteria B. Act as messenger molecules C. Coordinate visual response D. Act as buffers in the bloodstream
B. Act as messenger molecules
Which of the following stimulates the pancreas to release bicarbonate-rich juice? A. Gastrin B. Secretin C. Glucagon D. Gastric-inhibitory peptide
B. secretin
What is a typical response of the body to changes in blood glucose?
Blood glucose levels that fall too low signal the release of glucagon.
epiglottis
Cartilage at the back of the tongue that closes off the trachea during swallowing
goblet cells
Cells throughout the GI tract that secrete mucus
True or False: Proteins are made up of 20 essential amino acids.
False. Of the 20 amino acids that make up protein, nine are considered essential and 11 are nonessential.
True or False: Diarrhea is always caused by bacterial infection.
False. Though foodborne illness can cause diarrhea, the condition can also result from an adverse reaction to certain foods, medications, or other compounds.
peristalsis
Forward, rhythmic motion that moves food through the digestive system. It is a form of mechanical digestion because it influences motion, but it does not add chemical secretions.
crypts
Glands at the base of the villi; they contain stem cells that manufacture young cells to replace the cells of the villi when they die
How is glucose absorbed?
Glucose is absorbed by passive diffusion.
refined grams
Grain foods that are made with only endosperm of the kernel. The bran and germ have been removed during milling.
whole grains
Grain foods that are made with the entire edible grain kernel: the bran, endosperm, and the germ
What is the function of hydrochloric acid in the digestive process?
HCl activates pepsinogen to pepsin.
gastrin
Hormone released from the stomach that stimulates the release of acid
pepsinogen
Inactive protease secreted by the chief cells in the stomach; this enzyme is converted to the active form called pepsin in the presence of HCl
gastric pits
Indentations or small pits in the stomach lining where the gastric glands are located; gastric glands produce gastric juices
large intestine
Lowest portion of the GI tract, where water and electrolytes are absorbed and waste is eliminated
What transports fat-soluble nutrients to the blood?
Lymph vessels
What are the fiber needs for an individual between the ages of 19 and 50?
Male: 38 grams Female: 25 grams
What are the three brush border enzymes that hydrolyze carbohydrates in the small intestine?
Maltase, lactase, and sucrase
galactose
Monosaccharide that links with glucose to create the dissaccharide found in dairy foods
segmentation
Muscular contractions of the small intestine that move food back and forth, breaking the mixture into smaller and smaller pieces and combining it with digestive juices
upper esophageal sphincter
Muscular ring located at the top of the esophagus
passive diffusion
Process of absorbing nutrients freely across the cell membrane
active transport
Process of absorbing nutrients with the help of a carrier molecule and energy expenditure
transport
Process of moving absorbed nutrients throughout the body through the circulatory and lymph systems
Absorption
Process of moving nutrients from the GI tract into the circulatory system
enterohepatic circulation
Process of recycling bile from the large intestine back to the liver to be reused during fat digestion
Propulsion
Process that moves food along the gastrointestinal tract during digestion
How do proteins differ from carbohydrates and lipids?
Proteins differ from carbohydrates because they contain nitrogen found in the amine group. All 3 macronutrients contain carbon, hydrogen, and oxygen. The chains of glucose units or fatty acids vary in lengths similar to proteins.
What is an example of an incomplete protein?
Proteins from plant sources
What are 2 examples of a complete protein?
Soy protein and protein from animal products
microvilli
Tiny projections on the villi in the small intestine
True or False: Consuming a diet inadequate in protein may lead to a disease called kwashiorkor.
True. A diet that is inadequate in protein results in kwashiorkor, characterized by edema and body wasting.
True or False: The primary function of the large intestine is to absorb water.
True. After food has been completely broken down and its nutrients absorbed in the small intestine, it passes into the large intestine, where water and electrolytes continue to be absorbed.
True or False: The body can use protein as a source of glucose.
True. Amino acids can be converted to glucose through gluconeogenesis.
True or False: Obese individuals are more likely to develop type 2 diabetes.
True. Being overweight or obese can increase one's chances of developing type 2 diabetes.
True or False: The major function of bile is to emulsify fats.
True. Bile emulsifies fat by breaking up the large globules into smaller fat droplets.
True or False: Soda and other sugar-sweetened beverages play a big role in Americans' rising rate of obesity.
True. Much of the added sugars and excess kilocalories in the American diet come from sodas and other sugary beverages. Consuming more kilocalories than are necessary to meet energy needs causes weight gain.
True or False: Proteins are chemically different from carbohydrates or lipids because they contain nitrogen.
True. Proteins are the only macronutrients that contain nitrogen.
True or False: Hormones play an important role in digestion.
True. Several hormones, including gastrin, secretin, cholecystokinin (CCK), and gastric inhibitory peptide help regulate digestion.
True or False: Sugar causes teeth decay.
True. Simple carbohydrates, especially added sugars, encourage the growth of acid-producing bacteria in the mouth, which in turn promote dental caries.
True or False: Americans do not consume enough fiber.
True. The average American consumes about half the amount of fiber that's recommended daily.
True or False: Saliva can alter the taste of food.
True. The enzyme salivary amylase, found in saliva begins digesting carbohydrate during chewing; hence, starchy foods will begin to taste sweet as they are broken down.
True or False: Without mucus, the stomach would digest itself.
True. The stomach secretes a powerful acid, HCl, that is critical to digestion. The acid is also strong enough to damage the stomach wall, so a thick layer of mucus protects it.
True or False: Whole grains are more nutrient dense than refined grains.
True. Whole grains contain more fiber and nutrients than refined grains, which have had much of the grain kernel removed during processing.
True or False: Feces contain a high amount of bacteria.
True. Fecal matter consists of 50 percent bacteria, while the rest is undigested food, water, and sloughed intestinal cells.
True or False: Hydrochloric acid denatures protein in the stomach.
True. When proteins arrive in the stomach, hydrochloric acid uncoils them, revealing the peptide bonds that connect the amino acids.
endocytosis
Type of active transport in which the cell membrane forms an indentation, engulfing the substance to be absorbed
When is gluconeogenesis stimulated?
When the diet is too low in carbohydrates
cecum
a pouch at the beginning of the large intestine that receives waste from the small intestine
enterocytes
absorptive epithelial cells that line the walls of the small intestine
edema
accumulation of excess water in the spaces surrounding the cells, which causes swelling of the body tissue
glucogenic amino acids
amino acids that can be used to form glucose through gluconeogenesis
glycemic load (GL)
amount of carbohydrates in a food multiplied by the amount of the glycemic index of that food
colon
another name for the large intestine
The primary treatment for ulcer caused by the presence of H. pylori is ____.
antibiotics
Pharynx
area of the GI tract between the mouth and the esophagus; also called the throat
gastroesophageal reflux disease (GERD)
backward flow of the stomach contents into the esophagus due to improper functioning of the LES, resulting in heartburn
hypoglycemia
blood glucose level that drops to lower than 70 mg/dl
glycosidic bond
bond that forms when two sugar molecules are joined together during condensation
amylopectin
branched chain of polysaccharides found in starch
ketone bodies
by-products of the incomplete breakdown of fat
Exchange of oxygen, nutrients, and waste materials takes place across the walls of small vessels called ____
capillaries
After you and your friend Dolores share pretzels and animal crackers, she announces that she wants to start digesting her food by watching television. You inform Dolores that:
carbohydrate digestion begins in the mouth through the action of amylase, so she has already begun digesting the snacks.
lumen
channel or inside space of a vessel such as the intestine or artery
What type of nutrient is starch?
complex carbohydrate
amino acid score
composition of essential amino acids in a protein compared with a standard, usually egg protein
What is the reaction that links two monosaccharides together?
condensation
What type of reaction is required to bind two molecules of glycine together and release a molecule of water?
condensation
alkalosis
condition in which the blood pH is too low due to a low concentration of hydrogen ions
acidosis
condition in which the blood pH is too low, generally due to the excessive hydrogen ions
ketosis
condition of increased ketone bodies in the blood
impaired glucose tolerance (prediabetes)
condition whereby a fasting blood glucose level is higher than normal, but not high enough to be classified as having diabetes mellitus
protein turnover
continual process of degrading and synthesizing protein
gluconeogenesis
creation of glucose from noncarbohydrate sources, predominantly protein
nitrogen balance
difference between nitrogen intake and nitrogen excretion
salivary amylase
digestive enzyme that begins breaking down carbohydrates (starch) in the mouth; other important enzymes during carbohydrate digestion include pancreatic amylase, maltase, sucrase, and lactase
maltose
disaccharide composed of 2 glucose units joined together
sucrose
disaccharide composed of glucose and fructose; also known as table sugar
lactose
disaccharide composed of glucose and galacose; also known as milk sugar
The process by which bile acts on fat so that enzymes can attack the fat is known as ____.
emulsification
limiting amino acid
essential amino acid that is in the shortest supply, relative to the body's needs, in an incomplete protein
What are cellulose, pectin, hemicellulose, and lignin?
fibers
What is/are the primary target organ(s) for the action of cholecystokinin?
gallbladder and pancreas
Which substance functions to control the release of hydrochloric acid to prevent excessive acidity?
gastrin
Which substance is known as blood sugar or dextrose?
glucose
What are 3 examples of hexose?
glucose, galactose, and fructose
enterogastrones
group of GI tract hormones, produced in the stomach and small intestine, that controls gastric motility and secretions
A person on a low-fiber diet is at increased risk for experiencing elevated rectal vein pressure leading to formation of ____.
hemorrhoids
peptide YY
hormone in the small intestine that reduces hunger
cortisol
hormone produced by the adrenal cortex that stimulates gluconeogensis and lipolysis
epineohrine
hormone produced by the adrenal glands that signals the liver cells to release glucose; also referred to as the "fight or flight" hormone
norepinephrine
hormone produced by the adrenal glands that stimulates glycogenesis and gluconeogenesis
gastric inhibitory peptide (GIP)
hormone produced by the small intestine that slows the release of chime from the stomach
ghrelin
hormone produced in the stomach that stimulates hunger
cholecystokinin (CCK)
hormone released by the duodenum that stimulates the gallbladder to release bile
glucagon
hormone secreted from the alpha cells of the pancreas that stimulates glycogenesis and gluconeogenesis to increase blood levels of glucose
secretin
hormone secreted from the duodenum that stimulates the stomach to release pepsin, the liver to make bile, and the pancreas to release digestive juices
growth hormone
hormone that regulates glucose metabolism by increasing glycogenolysis and lipolysis
glycogenolysis
hydrolysis of glycogen to release glucose
What is the most common cause for the development of ulcers?
infection from H. pylori.
gastroenteritis
inflammation of the lining of the stomach and intestines; also known as stomach flu
empty calories
kilocalories that provide little nutrition, such as those found in candy
protein energy malnutrition (PEM)
lack of sufficient dietary protein and/or kilocalories
hepatic portal vein
large vein that connects the intestinal tract to the liver and transports newly absorbed nutrients
What is the primary site for absorption of nutrients?
microvillus
glycemic index (GI)
rating scale of the likelihood of foods to increase the levels of blood glucose and insulin
What is the name of the inactive form of the protein-splitting enzyme in the stomach?
pepsinogen
elongation
phase of protein synthesis in which the polypeptide chain grows longer by adding amino acid
What would 20 amino acids bonded together be classified as?
polypeptide
facilitated diffusion
process of absorbing nutrients with the help of a carrier molecule
glycogenesis
process of assembling excess glucose into glycogen in the liver and muscle cells
lipogenesis
process that converts excess glucose into fat for storage
albumin
protein produced in the liver and found in the blood that helps maintain fluid balance
incomplete protein
protein that is low in one or more of the essential amino acids
complete protein
protein that provides all the essential amino acids, along with some nonessential amino acids.
deamination
removal of the amine group from an amino acid
protein digestibility corrected amino acid (PDCAAS)
score measured as a percentage that takes into account both digestability and amino acid score and provides good indication of the quality of a protein
chyme
semiliquid, partially digested food mass that leaves the stomach and enters the small intestine
Disaccharidase enzymes that hydrolyze the disaccharides into monosaccharides are found in the ____.
small intestine
Bolus
soft mass of chewed food
chief cells
specialized cells in the stomach that secrete an inactive protein-digesting enzyme called pepsinogen
parietal cells
specialized cells in the stomach that secrete the gastric juices hydrochloric acid and intrinsic factor
ileocecal valve
sphincter that separates the small intestine from the large intestine
kwashiorkor
state of PEM where there is a severe deficiency of dietary protein
marasmus
state of PEM where there is a severe deficiency of kilocalories, which perpetuates wasting
glycogen
storage form of glucose in animals, including humans
amylose
straight chain of polysaccharides found in starch
catalysts
substances that aid and speed up reactions without being changed, damaged, or used up in the process
hexose
sugar that contains six carbons
naturally occurring sugars
sugars such as fructose and lactose that are found naturally in foods
added sugars
sugars that are added to processed foods and sweets
fructose
sweetest of all the monosaccharides; also known as fruit sugar or levulose
lymphatic system
system of interconnected spaces and vessels between the tissues and organs that contains lymph and circulates fat-soluble nutrients throughout the body
ferment
to metabolize sugar into carbon dioxide and other gases
transamination
transfer of an amino group from one amino acid to a keto acid to form a new nonessential amino acid
soluble fiber
type of fiber that dissolves in water and is fermented by intestinal bacteria
insoluble fiber
type of fiber that isn't dissolved in water or fermented by intestinal bacteria
resistant starch
type of starch that is not digested in the GI tract but has important health benefits in the large intestine
hepatic vein
vein that carries the blood received from the hepatic portal vein away from the liver
What is a byproduct of the condensation of two molecules of glucose?
water
What is the minimum amount of carbohydrates needed daily?
130 grams
Your friend Jill has just joined her community college soccer team. How much protein should she consume each day?
1.2-1.7 g/kg
nonessential amino acids
11 amino acids that the body can synthesize and that therefore do not need to be consumed in the diet
pancreas
A large gland located behind the stomach that releases digestive enzymes after a meal. This organ also secretes the hormones insulin and glucagon, which control blood glucose
Gallbladder
A pear-shaped organ located behind the liver. This organ stores bile produced by the liver and secretes the bile through the common bile duct into the small intestine
Which of the following regulates the pH of the stomach? A. Gastrin B. Insulin C. Secretin D. Cholecystokinin
A. gastrin
Which of the following is NOT an essential amino acid in human nutrition? A. Proline B. Threonine C. Methionine D. Tryptophan
A. proline
True or False: Carbohydrates are the least important macronutrient.
False. All macronutrients are essential for health, including carbohydrate, which is vital for numerous body functions.
True or False: Acid reflux is caused by gas in the stomach.
False. Acid reflux occurs when stomach contents pass back through the lower esophageal sphincter into the esophagus.
Name one feature of kefir.
It contains live bacterial organisms.
liver
Largest organ in the body, located in the upper abdomen. This organ aids digestion by secreting bile.
What is intestinal ischemia?
Reduced blood flow to the intestines
enriched grains
Refined grain foods that have folic acid, thiamin, niacin, riboflavin, and iron added
Villi
Small, fingerlike projections that line the interior of the small intestine
Celiac disease is caused by a reaction to gluten found in which foods?
Wheat, barley, and rye
small intestine
long coiled chamber that is the major site of food digestion and nutrient absorption
What amino acid supplement has been advertised in the popular media for treating herpes infections?
lysine
The gastrointestinal microbiome is comprised primarily of ____.
mucosa
Where is glycogen typically stored?
muscles and liver
lower esophageal sphincter (LES)
muscular ring located between the base of the esophagus and the stomach
lignin
noncarbohydrate form of dietary fiber that binds to cellulose fibers to harden and strengthen the cell walls of plants
cellulose
nondigestable polysaccharide found in plant cell wells
functional fiber
nondigestible polysaccharides that are added to foods because of a specific desired effect on human health
conditionally essential amino acids
nonessential amino acids, such as tyrosine and glycine, that become essential (and must be consumed in the diet) when the body cannot make them
