Unit 4 : Body Systems and Digestion

Question 1

Epiglottis

Answer 1

a flap located at the start of the esophagus which prevents food from entering the lungs.

Question 2

Sphincter

Answer 2

a circular muscle surrounding, and able to close, a body opening. The stomach has two sphincters: one at the start of the stomach and one at the end.

Question 3

Duodenum

Answer 3

he first part of the small intestine, the site at which foods are subjected to the action of bile and pancreatic juices, and where the breakdown of proteins, carbohydrates, and fats begins.

Question 4

Jejunum

Answer 4

the first two-fifths of the small intestine beyond the duodenum; its principal function is absorption of digested material.

Question 5

Ileum

Answer 5

the last segment of the small intestine that precedes the large intestine and functions in the absorption of nutrients.

Question 6

Digestion

Answer 6

defined as the breakdown of food into absorbable forms, through mechanical and chemical action.

Question 7

bolus

Answer 7

a swallowed food mass

Question 8

Segmentation

Answer 8

This is the periodic squeezing of the circular muscles in the segments of the intestine. This squeezing creates a rhythmic motion allowing a thorough mixing of the intestinal contents with digestive juices and enabling better contact with the absorption surface of the intestinal wall.

Question 9

Chemical digestion

Answer 9

Refers to the chemical breakdown of nutrients into basic absorbable units by digestive enzymes. These enzymes are secreted by specialized glands in the mouth, stomach, and pancreas, and by the epithelial cells of the small intestine.

Question 10

Enzymes

Answer 10

pecialized proteins that facilitate the conversion of one substance into another without the enzyme being altered. They are vitally important in thousands of chemical reactions in the body. Digestive enzymes break down food into small molecules that can be absorbed.

Question 11

Monosaccharide

Answer 11

a single-sugar molecule (e.g., glucose, fructose)

Question 12

Disaccharide

Answer 12

a pair of monosaccharides linked together (e.g., maltose, lactose, sucrose).

Question 13

Polysaccharide

Answer 13

numerous monosaccharides (up to thousands) linked together (e.g., starch).

Question 14

Disaccharidase

Answer 14

enzyme involved in hydrolyzing (breaking down) a specific disaccharide into its monosaccharide components.

Question 15

Amino acid

Answer 15

the building block of proteins.

Question 16

Dipeptide

Tripeptide

Answer 16

two amino acids bonded together.

three amino acids bonded together.

Question 17

Polypeptide

Answer 17

many (10 or more) amino acids bonded together; polypeptides form proteins.

Question 18

Fatty acid

Answer 18

the building block of fats.

Question 19

Glycerol

Answer 19

the “backbone” to which fatty acids are attached to produce a glyceride.

Question 20

Monoglyceride

Answer 20

a molecule of glycerol with one fatty acid attached.

Question 21

Diglyceride

Answer 21

a molecule of glycerol with two fatty acids attached.

Question 22

Triglyceride

Answer 22

a molecule of glycerol with three fatty acids attached; triglycerides are the predominant form of fat in the diet and in the body.

Question 23

Emulsified fat

Answer 23

fat droplets dispersed and stabilized in a watery solution with the help of emulsifiers (e.g., bile).

Question 24

pH

Answer 24

a measure of how acidic or alkaline a solution is. Acids have a low pH (about 0.5 for a strong acid to 4 for a weak acid). Neutral solutions have a pH of 7. Alkaline solutions have a pH from 9 (weak alkali) up to about 13.5 (strong alkali).

Question 25

Lipase

Answer 25

breaks emulsified fat down into monoglycerides, free fatty acids, and glycerol.

Question 26

Amylase

Answer 26

breaks starch and polysaccharides down into maltose; and disaccharidases break disaccharides down into monosaccharides.

Question 27

Hydrochloric acid

Answer 27

is produced in the stomach. It functions primarily to assist in the hydrolysis, or chemical breakdown, of protein to smaller peptides by creating the acid conditions needed by the enzyme pepsin, a protease enzyme, which is also secreted by the stomach. Hydrochloric acid is a strong acid (pH 2 or below) that can kill most food-borne bacteria entering the body. To protect the stomach from auto-digestion by acidic gastric juice, the cells of the stomach wall secrete a thick, slimy mucus that coats the wall. Mucus also lubricates the food.

Question 28

Bicarbonate

Answer 28

secreted by the pancreas, neutralizes stomach acid that reaches the small intestine.

Question 29

Bile

Answer 29

is produced by the liver and stored in the gallbladder. Fat in the diet stimulates the gallbladder to squirt bile into the duodenum. Bile is not an enzyme but an emulsifier, causing fat to form a suspension in the watery medium of the GI tract so that enzymes can break fat into its component parts. Bile is also essential for the absorption of fat by the intestinal mucosa.

Question 30

Absorption

Answer 30

can be defined as the passage of simple nutrients through the epithelial cells of the small intestine and into the blood stream or the lymphatic system. Carbohydrates, fats, and proteins are broken down into the basic building units to be absorbed. Vitamins and minerals are absorbed with virtually no change by the digestive enzymes. Water and alcohol are absorbed directly into the blood. absorption by the mucosal cells of the intestine

Question 31

chylomicron

Answer 31

I :"A lipoprotein formed in the small intestine that transports dietary fats and cholesterol through the lymphatic system to the bloodstream. " Fatty acids with long hydrocarbon chains (16 or more carbons) and fat-soluble vitamins cannot gain access directly into these capillaries; they cluster together in the intestinal cells to form large fat molecules to which special protein carriers are attached, forming a lipoprotein complex called a chylomicron. The chylomicrons are then taken up by the lymphatic system, in which they are transported through the lymph spaces, eventually reaching the thoracic duct, which terminates in a vein that leads to the heart. Ultimately, all nutrients end up in the bloodstream

Question 32

grehlin

Answer 32

a hormone secreted by the stomach that is thought to be a “hunger hormone.”

Question 33

digestive system

Answer 33

the body system composed of organs that break down complex food particles into smaller, absorbable products. The digestive tract and alimentary canal are names for the tubular organs that extend from the mouth to the anus. The whole system, including the pancreas, liver, and gallbladder, is sometimes called the gastrointestinal, or GI, system.

Question 34

digest

Answer 34

to break molecules into smaller molecules; a main function of the digestive tract with respect to food.

Question 35

absorb

Answer 35

to take in, as nutrients are taken into the intestinal cells after digestion; the main function of the digestive tract with respect to nutrients.

Question 36

peristalsis

Answer 36

a series of squeezing waves that start with the tongue’s movement during a swallow and pass all the way down the esophagus the wavelike muscular squeezing of the esophagus, stomach, and small intestine that pushes their contents along.

Question 37

segmentation

Answer 37

alternating forward and backward movement allowing for greater contact between the partially digested food and intestinal juices and enzymes, thus resulting in virtually complete digestion of the food we eat.

Question 38

sphincter

Answer 38

a circular muscle surrounding, and able to close, a body opening (prevent from creeping back up)

Question 39

chyme

Answer 39

the fluid resulting from the actions of the stomach upon food [Chyme bears no resemblance to the original food. The starches have been partly split, proteins have been uncoiled and clipped, and fat has separated from the mass.]

Question 40

pyloric valve

Answer 40

the circular muscle of the lower stomach that regulates the flow of partly digested food into the small intestine. Also called pyloric sphincter.

Question 41

small intestine

Answer 41

the seven-metre length of small-diameter intestine, below the stomach and above the large intestine, that is the major site of digestion of food and absorption of nutrients.

Question 42

large intestine (colon)

Answer 42

the portion of the intestine that completes the absorption process.

Question 43

large intestine (colon)

Answer 43

the portion of the intestine that completes the absorption process. [The colon’s task is mostly to reabsorb the water donated earlier by digestive organs and to absorb minerals, leaving a paste of fibre and other undigested materials, the feces, suitable for excretion. ]

Question 44

feces

Answer 44

waste material remaining after digestion and absorption are complete; eventually discharged from the body.

Question 45

gastric juice

Answer 45

the digestive secretion of the stomach.

Question 46

pH

Answer 46

a measure of acidity on a point scale. A solution with a pH of 1 is a strong acid; a solution with a pH of 7 is neutral; a solution with a pH of 14 is a strong base.

Question 47

mucus

Answer 47

a slippery coating of the digestive tract lining (and other body linings) that protects the cells from exposure to digestive juices (and other destructive agents). The adjective form is mucous (same pronunciation). The digestive tract lining is a mucous membrane.

Question 48

bile

Answer 48

an emulsifier, a cholesterol-containing digestive fluid made by the liver, stored in the gallbladder, and released into the small intestine when needed. It emulsifies fats and oils to ready them for enzymatic digestion

Question 49

emulsifier

Answer 49

a compound with both water-soluble and fat-soluble portions that can attract fats and oils into water, combining them.

Question 50

pancreatic juice

Answer 50

fluid secreted by the pancreas that contains both sodium bicarbonate, a neutralizing agent, and enzymes to digest carbohydrate, fat, and protein.

Question 51

bicarbonate

Answer 51

a common alkaline chemical; a secretion of the pancreas; also the active ingredient of baking soda.

Question 52

villi

Answer 52

fingerlike projections of the sheets of cells that line the intestinal tract. The villi make the surface area much greater than it would otherwise be

Question 53

microvilli

Answer 53

tiny, hairlike projections on each cell of every villus that greatly expand the surface area available to trap nutrient particles and absorb them into the cells