6.1

Question 1

Parts of the digestive system

Answer 1

• mouth
• salivary glands
• esophagus
• stomach
• small intestine
• accessory organs: pancreas, liver, gall bladder
• large intestine
• rectum and anus

Question 2

Mouth (role in digestion)

Answer 2

• breaks food down mechanically
• voluntary

Question 3

Salivary glands (role in digestion)

Answer 3

• secrete saliva
• saliva breaks down food chemically (specifically starches: contains amylose)
• helps make bolus

Question 4

Esophagus (role in digestion)

Answer 4

• pathway for food to travel to the stomach
• movement of food by peristalsis (waves of muscle contractions)

Question 5

Stomach (role in digestion)

Answer 5

• further breaks down food
• contains HCl (stomach acid), helps break food down chemically: low pH breaks bonds, and kills foreign bacteria
• muscle contraction breaks down food mechanically
• enzyme pepsin helps break down protein (chemically)

Question 6

small intestine: duodenum (role in digestion)

Answer 6

• upper half of SI
• liver and gall bladder secrete bile which neutralizes the HCl and emulsifies fats
• contains amylases and lipase which digest carbohydrates and fats (pancreatic)
• trypsin digests polypeptides

Question 7

Small intestine: ileum (role in digestion)

Answer 7

• lower part of the SI
• nutrients absorbed into the blood through villi and microvilli

Question 8

Pancreas (accessory organ) (role in digestion)

Answer 8

• secretes enzymes such as lipase, amylase and protease into the SI
• neutralizes acidic chyme (food when it is btwn the stomach and SI) thru the use of sodium bicarbonate

Question 9

Liver (accessory organ) (role in digestion)

Answer 9

• secretes bile to break up lipid droplets
• bile is stored in gall bladder

Question 10

Gall bladder (accessory organ) (role in digestion)

Answer 10

• stores bile from liver

Question 11

Large intestine (role in digestion)

Answer 11

• absorbs water from food
• formation of feces

Question 12

Rectum and anus

Answer 12

• rectum stores feces
• anus releases feces

Question 13

Role of peristalsis in digestion

Answer 13

• peristalsis = series of muscle contractions which move food along the alimentary canal
• in SI, mixed enzymes and forces food to come into contact with the wall of the intestine
• food is moved very slowly in the intestines

Question 14

Main types of enzymes synthesized in the pancreas (and in pancreatic juice)

Answer 14

• amylase: digests starches
• lipase: digests lipids
• protease: digestes proteins and polylpeptides

Question 15

What controls the release of enzymes?

Answer 15

• hormones created and secreted by he stomach

Question 16

How are enzymes created?

Answer 16

• enzymes synthesized by the pancreas by the ribosomes on rER and processed by Golgi apparatus and secretes through exocytosis

Question 17

Specific enzymes (used for digestion) you should know (all destined for the SI and produced in the pancreas)

Answer 17

Made in pancreas:
- amylase: breaks down starch, produces maltose
- lipase: breaks down triglycerides, produces fatty acids and glycerols
- phospholipase: breaks down phospholipids, produces fatty acids, glycerol and phosphate (PO4 (-3))
- protease: (an example is pepsin) breaks down proteins, polypeptides, produces shorter peptides

Question 18

What kind of reaction breaks down/digestion of food molecules

Answer 18

hydrolysis, catabolic rxns

Question 19

Specific enzymes (used for digestion) you should know (all destined for the SI and produced in the small intestine)

Answer 19

• nuclease: breaks down DNA and RNA, produces nucleotides
• maltase: breaks down maltose, produces glucose
• lactase: breaks down lactose, produces galactose and glucose
• sucrase: breaks down sucrose, produces fructose and glucose
• exopeptidase: breaks down peptides, produces dipeptides
• dipetidase: breaks down dipeptides, produces amino acids

Question 20

Layers of small intestine
(Outer layers to inner layers)

Answer 20

• serosa: protective outer layer
• muscle layers (muscularis externa): inner circular and outer longitudinal muscle which perform peristalsis
• sub-mucosa: connective tissue (between mucosa and muscle)
• mucosa: inner lining, includes villi
• epithelial cells: single outer layer of cells on each villus

Question 21

Goblet cell in small intestine

Answer 21

• specialized cells on villi
• absorbs nutrients
• secrete mucus

Question 22

Lacteal in small intestine

Answer 22

• branch of lymphatic system
• allow rapid absorption and transport of lipids

Question 23

Membrane transport in SL: fatty acids/monoglycerides

Answer 23

• simple diffusion
• fatty acid only: facilitated diffusion via transmembrane proteins
• once inside epithelium cells, fatty acids and monoglycerides combine so that they cannot diffuse back into the lumen of SL

Question 24

Membrane transport: glucose

Answer 24

• facilitated diffusion via glucose channels
• large polar molecules: simple diffusion cannot occur

Question 25

Membrane transport: sodium

Answer 25

• active transport
• Na+ pumped into epithelial cells

Question 26

Membrane transport: sodium and glucose

Answer 26

• sodium glucose cotransporter facilitated diffusion
• Na+ and glucose transported together