Ch. 3

Front 1

gut

Back 1

the gastro-intestinal system

Front 2

gastro-intestinal (GI) system

Back 2

the digestive system and its accessory organs

Front 3

motility

Back 3

the process of moving food through the gut

Front 4

peristalsis

Back 4

the rhythmic contraction of circular muscles surrounding the gut in such way as to move food forward

Front 5

segmentation

Back 5

contraction of muscles surrounding the gut in such a way as to mix it with GI secretions

Front 6

chyme

Back 6

the fluid mass of food in the intestinal lumen

Front 7

bolus

Back 7

a mass of food in the gut

Front 8

Sphincters

Back 8

rings of muscles that act as valves, blocking or restricting flow

Front 9

esophagus

Back 9

the passage connecting the mouth and the stomach

Front 10

reflux

Back 10

flow of stomach acid back into the esophagus, resulting in heartburn

Front 11

pyloric sphincter

Back 11

the valve controlling the flow of chyme from the stomach into the small intestine

Front 12

ileocecal valve

Back 12

valve separating the ileum from the colon

Front 13

rectum

Back 13

final organ of the digestive tract, acting as a reservoir before elimination

Front 14

secretion

Back 14

synthesis and release of substances by cells in response to stimuli

Front 15

denature

Back 15

to act on protein in such a way as to change its chemical and physical properties, so that its configuration or shape is different

Front 16

protease

Back 16

enzyme responsible for protein digestion

Front 17

bile

Back 17

a secretion of the liver, stored in the gall bladder that emulsifies dietary lipid

Front 18

emulsifier

Back 18

a substance that breaks fat droplets suspended in a water-based medium into smaller particles, and keeps them in suspension

Front 19

digestion

Back 19

the chemical and mechanical breakdown of foods and of complex nutrient molecules into simpler components

Front 20

peptides

Back 20

short chains of amino acids; smaller than a protein

Front 21

triglycerides

Back 21

primary form of lipid in the diet. Formed of three fatty acids on a glycerol backbone

Front 22

monoglycerides

Back 22

digested form of triglycerides. These and free fatty acids are formed from lipid digestion. Composed of one fatty acid on a glycerol base.

Front 23

churning

Back 23

muscular contractions of the gut, particularly the stomach, that grind food and mix it with secretions

Front 24

Absorption

Back 24

movement of nutrients from the intestinal lumen into the mucosal cells

Front 25

lumen

Back 25

the interior of the gut

Front 26

mucosa

Back 26

the cells of the gut lining

Front 27

passive diffusion

Back 27

absorption of nutrients that does not require the input of energy. Driven by a concentration gradient

Front 28

diffusion

Back 28

a movement of molecules from an area of high concentration to an area of low concentration.

Front 29

concentration gradient

Back 29

a change in concentration of a substance over a distance

Front 30

facilitated diffusion

Back 30

movement of molecules across a membrane in the direction of a concentration gradient, aided by proteins embedded in the membrane

Front 31

active transport

Back 31

absorption of nutrients against a concentration gradient, requiring the input of energy

Front 32

endocytosis

Back 32

absorption of large nutrient molecules involved the engulfing of the molecule by a portion of the cell membrane

Front 33

antibodies

Back 33

a component of the immune system made from protein

Front 34

amylase

Back 34

enzyme responsible for starch (amylose) digestion

Front 35

lipase

Back 35

enzyme responsible for lipid digestion

Front 36

small intestine

Back 36

digestive organ responsible for most chemical breakdown of foods and most absorption

Front 37

duodenum

Back 37

initial segment of the small intestine

Front 38

jejunum

Back 38

middle section of the small intestine

Front 39

ileum

Back 39

terminal segment of the small intestine

Front 40

villi

Back 40

microscopic fingers lining the surface of the intestinal lumen. Responsible for nutrient absorption. They greatly increase surface area of the intestine

Front 41

brush border

Back 41

the intestinal villi

Front 42

microvilli

Back 42

hair like projections on the surface of the villi that increase surface area

Front 43

large intestine

Back 43

digestive organ mostly responsible for water reabsorption from chyme

Front 44

colon

Back 44

the large intestine

Front 45

transit time

Back 45

the amount of time food spends in passage through the gut