The Digestive System

Question 1

Catabolic reactions

Answer 1

Reactions that break down molecules to supply energy

Question 2

Anabolic reactions

Answer 2

The synthesis of macromolecules

Question 3

Digestion

Answer 3

The breakdown of polymers (peptides, fats, starch) into their building blocks

Question 4

GI motility

Answer 4

The rhythmic contraction of GI smooth muscle
Controlled by the enteric nervous system
Can be increased or decreased by hormonal input
Serves two purposed: mixing of food and movement of food down the gut

Question 5

Functional syncytium

Answer 5

When one cell has an action potential and contracts, the impulse spreads to neighboring cells

Question 6

Peristalsis

Answer 6

Orderly contraction of muscles in the GI tract resulting in movement of food down the GI tract

Question 7

Bolus

Answer 7

Ball of food moving through the GI tract

Question 8

Enteric Nervous System

Answer 8

Is a branch of the autonomic nervous system that helps to control digestion via innervation of the GI tract, pancreas, and gall bladder

Question 9

Myenteric plexus

Answer 9

Found between the circular and longitudinal muscle layers and helps primarily to regulate gut motility

Question 10

Submucosal plexus

Answer 10

Found in the submucosa and helps to regulate enzyme secretion, gut blood flow, and ion/water balance in the lumen
Sparse in the esophagus and anus

Question 11

GI secretion

Answer 11

Stimulated by food in the gut and by the parasympathetic nervous system
Inhibited by sympathetic stimulation

Question 12

Exocrine glands

Answer 12

Secrete their products (digestive enzymes) into ducts that drain into the GI lumen

Question 13

Endocrine glands

Answer 13

Ductless glands
Their secretions (hormones) are picked up by capillaries and thus enter the bloodstream

Question 14

Acinar cells

Answer 14

Specialized epithelial cells found in the exocrine glands

Secrete products which pass into ducts

Question 15

Gastric glands

Answer 15

Secrete acid and pepsinogen

Question 16

Goblet cells

Answer 16

Specialized mucus-secreting cells found along the entire GI tract

Question 17

Mucus

Answer 17

A slimy liquid that protects and lubricates the gut

Question 18

Mucus membrane

Answer 18

Any body surface covered with mucus

Question 19

The three role of the mouth

Answer 19

Fragmentation (mastication), lubrication (saliva), some enzymatic digestion (salivary amylase)
Participates in innate immunity

Question 20

Saliva

Answer 20

Contains salivary amylase (ptyalin) - smallest fragment yielded by salivary amylase is the disaccharide
Lingual lipase (fat digestion)
Lysozyme - attacks bacterial cell walls

Question 21

Three purposes of the stomach

Answer 21

Partial digestion of food, regulated release of food into the small intestine, and destruction of microorganisms

Question 22

Effects of low gastric pH

Answer 22

Destruction of microorganisms, acid-catalyzed hydrolysis of many dietary proteins, and conversion of pepsinogen to pepsin

Question 23

Pepsin

Answer 23

Enzyme secreted by chief cells in the stomach wall

Catalyzes proteolysis

Question 24

Zymogen

Answer 24

An inactive precursor

Question 25

Chyme

Answer 25

Food mixed with gastric secretions

Question 26

Lower esophageal sphincter

Answer 26

Prevents reflux of chyme into the esphagus

Question 27

Pyloric sphincter

Answer 27

Prevents the passage of food from the stomach into the duodenum

Question 28

Cholecystokinin

Answer 28

Secreted by the epithelial cells in the wall of the duodenum Secreted in response to fats in the duodenum - causes the pancreas to secrete digestive enzymes, stimulates gallbladder contraction, and decreases gastric motility

Question 29

Gastrin

Answer 29

Secreted by G cells in the stomach wall Stimulated acid and pepsin secretion and gastric motility Stimulated by food in the stomach and parasympathetic stimulation

Question 30

Histamine

Answer 30

Binds to parietal cells to stimulate acid release | Released in response to gastrin and stretching the stomach wall

Question 31

Villi

Answer 31

Macroscopic projections in the wall of the small intestine Capillaries in the villus absorb monosaccharides and amino acids Small lymphatic vessels called lacteals absorb dietary fats Peyer's patches confer immunity to gut pathogens and toxins

Question 32

Microvilli

Answer 32

Microscopic foldings of the cell membranes of individual intestinal epithelial cells

Question 33

Brush Border

Answer 33

Luminal membrane of the small intestine

Question 34

Two functions of bile

Answer 34

Vehicle for the disposal of waste products by the liver | It is essential for the digestion of fats

Question 35

Enterokinase

Answer 35

Activates the pancreatic zymogen trypsinogen to trypsin

Question 36

Brush border enzymes

Answer 36

Hydrolyze the smallest carbohydrates and proteins into monosaccharides and amino acids

Question 37

Secretin

Answer 37

Released in response to acid in the duodenum - causes the pancreas to release large amounts of a high-pH aqueous buffer (HCO3-) - neutralizes HCl released by the stomach

Question 38

Enterogastrone

Answer 38

Decreases stomach emptying

Question 39

Ileum

Answer 39

Responsible for the absorption of vitamin B12 when complexed with intrinsic factor which is released by the parietal cells of the stomach

Question 40

Importance of colonic bacteria

Answer 40

The presence of large numbers of normal bacteria helps keep dangerous bacteria from proliferating, due to competition for space and nutrients Colonic bacteria supply us with Vitamin K, which is essential for blood clotting

Question 41

Somatostatin

Answer 41

Inhibits many digestive processes

Question 42

Three hormones that can raise blood sugar levels

Answer 42

Glucagon, epinephrine, cortisol

Question 43

Bile

Answer 43

Composed of bile salts, cholesterol, and bilirubin Emulsifies large fat particles in the duodenum Help fatty particles to diffuse across the intestinal mucosal membrane

Question 44

Ghrelin

Answer 44

Stimulate appetite

Question 45

Leptin

Answer 45

Secreted in response to increase triglyceride levels and works to suppress appetite until appropriate levels are restored

Question 46

Peptide YY

Answer 46

Reduces appetite