Digestive System

Question 1

two-way digestive system

Answer 1

Platyhelmenthes (flatworms) – planarians; food goes into the gastrovascular cavity, digested intracellularly and absorbed, waste expelled through the one hole

Question 2

annelid (segmented worm) digestion

Answer 2

mouth - esophagus - crop - gizzard - intestine - anus

crop: stores food
gizzard: mechanically digests (grinds) food w/ rocks

Question 3

two parts of human digestive tract

Answer 3

alimentary canal (tube where the food passes through) and glands that secrete enzymes

Question 4

mouth

Answer 4

mechanical digestion (chewing)
chemical digestion: six salivary glands secrete saliva
saliva: water, mucus, and salivary amylase
water & mucus: dissolve and lubricate food
salivary amylase: breaks down starches into disaccharide maltose
moves to pharynx and esophagus

Question 5

bolus

Answer 5

food after being chewed in mouth

Question 6

esophagus

Answer 6

tube carrying bolus to stomach

Question 7

epiglottis

Answer 7

flap that closes trachea to prevent choking

Question 8

peristalsis

Answer 8

muscular contractions that push bolus to stomach

Question 9

cardiac sphincter

Answer 9

valve that prevents stomach contents from entering esophagus (heartburn)

Question 10

stomach

Answer 10

mechanical digestion (churning)
chemical digestion: pepsin + hydrochloric acid
hydrochloric acid: creates low pH (less than 2) for pepsin, kills bacteria
pepsin: main enzyme in stomach, IS PRODUCED as pepsinogen, turns into pepsin when in low pH; begins protein digestion
mucus: protects stomach walls from acid (ulcer)

Question 11

chyme

Answer 11

food after stomach

Question 12

pyloric sphincter

Answer 12

controls exit of chyme (stomach to small intestine)

Question 13

small intestine

Answer 13

main site of chemical digestion!
duodenum: top of small intestine where most chem. digestion takes place
jejunum & illeum: where amino acids and sugars are absorbed (after duodenum)

Question 14

duodenum

Answer 14

liver produces bile, which is stored in gallbladder
bile: emulsifies fats – breaks fats down into smaller globules, creating larger surface area so that enzymes can digest fat faster
pancreas produces enzymes and a base to neutralize the stomach acid
small intestine secretes remaining enzymes

Question 15

jejunum & illeum

Answer 15

absorption
villi: small “fingers” that efficiently absorb sugars & proteins (think big surface area)
Lipids are processed in cells of lining before entering the lymphatic system

Question 16

large intestine

Answer 16

(colon) reclaims water

e. coli live here and produce vitamin K

Question 17

rectum

Answer 17

stores feces before elimination

Question 18

lipase

Answer 18

digests fats into glycerol and fatty acids (lipids)

Question 19

trypsin and chymotrypsin

Answer 19

digest polypeptides further (proteins)

Question 20

pancreatic amylase

Answer 20

digests polysaccharides to disaccharides (carbs)

Question 21

maltase, lactase, sucrase

Answer 21

break down disaccharides into monosaccharides

Question 22

aminopeptidases

Answer 22

complete polypeptide digestion by breaking off individual amino acids (s. intestine)

Question 23

minerals needed

Answer 23

iron (hemoglobin); iodine (thyroid hormone); calcium (bones); sodium, chlorine, potassium (many body fluids); phosphorus (nucleic acids)

Question 24

vitamins needed

Answer 24

Vitamin A (vision), Vitamin B complex (cellular resp., DNA replication), Vitamin C (collagen production, immune system), Vitamin D (bone growth and calcium absorption), Vitamin E (healthy red blood, liver and kidney), Vitamin K (aids blood clotting)

Question 25

vitamin solubility

Answer 25

Vitamins A, D, E, and K: fat-soluble
Vitamins B (complex) and C: water-soluble

Question 26

What’s that word that means to break something down with water in a chem. reaction?

Answer 26

hydrolyze

Question 27

intracellular digestion (WHO, how)

Answer 27

amoeba (phagocytosis), paramecia (protists; ciliated oral groove); create food vacuole, then lysosome fuses with vacuole and digests food

Question 28

cnidarian digestion

Answer 28

release enzymes into water-filled cavity for extracellular digestion, also do intracellular digestion

Question 29

duodenum enzymes

Answer 29

Pancreas: lipase (fats), chymotrypsin and trypsin (amino acids/proteins – produced in inactive forms until s. intestine!!!), pancreatic amylase (polysaccharides)
S. Intestine: maltase, lactase, sucrase (disaccharides), aminopeptidases (finishes amino acids after trypsin and chymotrypsin)