Chapter 41

Question 1

essential nutrients

Answer 1

preassembled organic molecules and minerals
o Include essential amino acids, fatty acids, vitamins, and minerals
o Serve as substrates, coenzymes, and cofactors

Question 2

essential amino acids

Answer 2

amino acids that cannot be synthesized using enzymes and must be obtained from food
o Required in human diet: isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine.

Question 3

essential fatty acids

Answer 3

fatty acids that must be obtained from the diet (because we lack enzymes to form the double bonds)

Question 4

vitamins

Answer 4

organic molecules required in the diet in very small amounts
o Water soluble- B vitamins- which act as coenzymes and vitamin C
o Fat soluble- vitamin A and D

Question 5

minerals

Answer 5

inorganic nutrients that are required in small amounts

o Ex: iron and sulfur

Question 6

undernutrition

Answer 6

diets that fails to provide adequate sources of chemical energy

Question 7

epidemiology

Answer 7

the study of human health and disease at the population level
o Ex: Kids born to women of low socioeconomic status were more likely to have neural tube defects. (Lack of folic acid- vitamin B9 is responsible)

Question 8

mechanical digestion

Answer 8

increases surface available for chemical processes

Question 9

enzymatic hydrolysis

Answer 9

adding water to the fat molecule to break the covalent bond

Question 10

absorption

Answer 10

absorption of small molecules such as amino acids and simple sugars

Question 11

elimination

Answer 11

when undigested materials pass through digestive system`

Question 12

intracellular digestion

Answer 12

the hydrolysis of food inside vacuoles
o Occurs after cell engulfs food via phagocytosis or pinocytosis
o Newly formed vacuole fuses with lysosome

Question 13

lysosomes

Answer 13

organelles containing hydrolytic enzymes

Question 14

extracellular digestion

Answer 14

breakdown of food in compartments that are outside the animal’s body
o Allows animal to digest larger pieces of food

Question 15

gastricular cavity

Answer 15

opening which functions in digestion along with the distribution of nutrients throughout the body
o Glands inside secrete digestive enzymes
o Found in cnidarians (hydras) and flatworms

Question 16

alimentary canal

Answer 16

digestive tube extending between the mouth and anus
o Found in most animals
o Allows animal to ingest food while other meals are being digested

Question 17

peristalsis

Answer 17

alternative waves of contraction and relaxation in smooth muscle which push food along the alimentary canal
• Generally empty stomach contents into small intestine within 2-6 hours of meal

Question 18

sphincter

Answer 18

muscular layer forming ringlike valves which hold any type of biological opening closed
o Regulate passage of material between specialized compartments

Question 19

amylase (salivary glands)

Answer 19

enzyme found in saliva which hydrolyzes starch and glycogen into polysaccharides and the disaccharide maltose

Question 20

mucus (salivary glands)

Answer 20

viscous mixture of H2O, salts, cells, and mucins which protect the lining of the mouth from abrasion and lubricates food

Question 21

bolus

Answer 21

ball of food formed when tongue manipulates mixture of saliva and food

Question 22

pharynx

Answer 22

opens passageways to the trachea and the esophagus

Question 23

gastric juice

Answer 23

digestive fluid secreted by the stomach

Question 24

protease

Answer 24

a protein-digesting enzyme

Question 25

pepsin (protease)

Answer 25

protein-digesting enzyme which cleaves proteins into polypeptides • Formed by cutting small part of molecule off of pepsinogen and exposing the active site o Found in lumen only

Question 26

chyme

Answer 26

mixture of gastric juice and ingested food

Question 27

parietal cells

Answer 27

use ATP-driven pump to expel H ions into the lumen

Question 28

chief cells

Answer 28

release pepsinogen into the lumen

Question 29

pepsinogen

Answer 29

inactive form of pepsin released by chief cells

Question 30

small intestine

Answer 30

where most enzymatic hydrolysis of macromolecules from food occurs o Over 20 feet long o All folds in small intestine have a surface area 200-300m^2

Question 31

villi

Answer 31

fingerlike projections found in small intestine

Question 32

microvilli (villi)

Answer 32

microscopical projections found on the apical surface of each epithelial cell of a villus

Question 33

lacteal

Answer 33

vessels found at the core of each villus, part of the lymphatic system • Absorbs digested fats

Question 34

duodenum (small intestine)

Answer 34

where chyme from stomach mixes with digestive juices from pancreas, liver, and gallbladder. • The first 10 inches of the small intestine • Where most of digestion in small intestine occurs

Question 35

pancreas

Answer 35

aids in chemical digestion by producing an alkaline solution rich in bicarbonate o Bicarbonate neutralizes acidity of chyme, acting as a buffer o Contains enzymes which include trypsin and chymotrypsin (secreted in the inactive form- only in lumen)

Question 36

liver

Answer 36

site for detoxification of organic molecules

Question 37

bile

Answer 37

consists of bile salts which act as emulsifiers (detergents) that aid in digestion and absorption of lipids

Question 38

gallbladder

Answer 38

where bile is stored and concentrates

Question 39

hepatic portal vein

Answer 39

blood vessel that carries nutrient-rich blood away from villi and toward liver o Functions: • Allows liver to regulate distribution of nutrients to rest of body. • Allows liver to remove toxic substances before blood circulates.

Question 40

chylomicrons

Answer 40

globules formed when hydrolyzed fats are combined with triglycerides and coated with phospholipids, cholesterol, and proteins o Travel via blood (water-soluble)

Question 41

colon

Answer 41

completes reabsorption of water after small intestine

Question 42

cecum

Answer 42

pouch that is important for fermenting ingested material, especially plants • Relatively small in animals

Question 43

rectum

Answer 43

where feces are stored until they are eliminated

Question 44

appendix

Answer 44

fingerlike extension of the human cecum which plays minor role in immunity

Question 45

mutualistic symbiosis

Answer 45

the way vertebrates host large populations of mutualistic bacteria and protists in fermentation chambers in their alimentary canals o These microorganisms contain enzymes which digest compounds

Question 46

corpophagy

Answer 46

eating feces to get nourishing byproducts which passed through large intestine

Question 47

enteric division

Answer 47

branch of the nervous system which regulates peristalsis

Question 48

insulin

Answer 48

triggers uptake of glucose from blood into body cells, decreasing blood glucose concentration o Also functions to suppress appetite

Question 49

glucagon

Answer 49

promotes release of glucose into blood from energy stores, increasing blood glucose concentration

Question 50

pancreatic islet

Answer 50

Has alpha and beta cells which secrete hormones into interstitial fluid

Question 51

alpha cells (pancreatic islet)

Answer 51

make glucagon

Question 52

beta cells (pancreatic islet)

Answer 52

make insulin

Question 53

diabetes mellitus

Answer 53

when cells are unable to take up enough glucose to meet metabolic needs, even when blood glucose levels rise o Caused by insulin deficiency/decreased response to insulin o As a result, fat becomes the main substrate in cell respiration o Consequently, kidneys can’t absorb all the glucose so it gets excreted in urine o In severe cases, acid metabolites accumulate in blood, depleting Na+ and K+ ions from body

Question 54

Type 1 diabetes

Answer 54

insulin-dependent diabetes (high glucose levels) • Autoimmune disorder which results when immune system destroys beta cells of pancreas • Destroys ability of body to produce insulin • Treatment: insulin injections

Question 55

Type 2 diabetes

Answer 55

non insulin-dependent diabetes (high glucose levels) • When inulin is produced, but target cells fail to absorb glucose from blood • As a result, glucose levels remain elevated • Possible causes: heredity, excess body weight, lack of exercise • Most common form

Question 56

ghrelin

Answer 56

hormone secreted by stomach wall that triggers feelings of hunger o Can generally increase in dieters, making weight loss difficult

Question 57

leptin

Answer 57

suppresses appetite o Decreased body fat causes decrease in leptin level, increasing appetite o Produced by adipose tissue

Question 58

PYY

Answer 58

appetite suppressant secreted by small intestine after meals