Week 6 Digestive System

Question 1

What are the four main functions of the digestive system?

Answer 1

Ingestion, digestion (mechanical and chemical), absorption, defecation.

Question 2

What is the difference between extracellular and intracellular digestion?

Answer 2

Extracellular occurs in GI tract (outside cells), intracellular occurs inside cells (e.g., phagocytosis).

Question 3

What is mechanical digestion?

Answer 3

Physical breakdown of food via chewing, churning, segmentation.

Question 4

What is chemical digestion?

Answer 4

Enzymatic breakdown of macromolecules into absorbable units.

Question 5

What is propulsion?

Answer 5

Movement of food through GI tract via swallowing and peristalsis.

Question 6

What is the function of the buccal cavity?

Answer 6

Mastication, saliva secretion, bolus formation, and initial digestion of starch and some lipids.

Question 7

What enzymes are present in the mouth?

Answer 7

Salivary amylase (starch), lingual lipase (activated later in stomach).

Question 8

What are the functions of saliva?

Answer 8

Softens food, begins starch digestion, cleanses mouth.

Question 9

What are the stages of swallowing?

Answer 9

Buccal (voluntary), pharyngeal (involuntary), esophageal (involuntary).

Question 10

What prevents food from entering the nasal cavity during swallowing?

Answer 10

The soft palate and uvula rise to block it.

Question 11

What prevents food from entering the trachea?

Answer 11

The epiglottis closes over the larynx.

Question 12

What is the structure of the esophagus?

Answer 12

A muscular tube; upper 1/3 is skeletal muscle, middle is mixed, lower 1/3 is smooth muscle.

Question 13

What is peristalsis?

Answer 13

Sequential contraction of circular and longitudinal muscles to move food along GI tract.

Question 14

What are the main parts of the stomach?

Answer 14

Cardia, fundus, body, pylorus.

Question 15

What is chyme?

Answer 15

Partially digested, acidic food mixture formed in the stomach.

Question 16

What cells are found in gastric glands and what do they secrete?

Answer 16

Parietal cells (HCl, intrinsic factor), chief cells (pepsinogen), enteroendocrine cells (gastrin).

Question 17

What is the function of HCl?

Answer 17

Kills microbes, denatures proteins, activates pepsinogen.

Question 18

What is the function of pepsin?

Answer 18

Breaks proteins into peptides.

Question 19

What activates lingual lipase?

Answer 19

Acidic conditions in the stomach.

Question 20

What are the functions of the liver?

Answer 20

Produces bile, regulates metabolism, detoxifies, stores vitamins/minerals, processes nutrients via hepatic portal system.

Question 21

What is the hepatic portal system?

Answer 21

Blood from GI tract goes to liver for nutrient processing before entering general circulation.

Question 22

What is the function of the gallbladder?

Answer 22

Stores and concentrates bile, releases it into duodenum on stimulation.

Question 23

What are the functions of the pancreas?

Answer 23

Produces pancreatic juice (enzymes + bicarbonate), secretes insulin and glucagon.

Question 24

What does bicarbonate do in digestion?

Answer 24

Neutralizes acidic chyme to allow enzyme function in small intestine.

Question 25

What are the three parts of the small intestine?

Answer 25

Duodenum, jejunum, ileum.

Question 26

What increases surface area in the small intestine?

Answer 26

Circular folds, villi, and microvilli (brush border).

Question 27

What is segmentation?

Answer 27

Local contractions that mix chyme and increase contact with absorptive surfaces.

Question 28

What hormones are secreted by the small intestine?

Answer 28

Secretin (stimulates pancreatic juice), CCK (stimulates pancreatic enzymes and bile release).

Question 29

What are the four parts of the large intestine?

Answer 29

Cecum, colon, rectum, anal canal.

Question 30

What are the main functions of the large intestine?

Answer 30

Absorption of water, salts, vitamins; formation and elimination of feces.

Question 31

What is the role of gut bacteria?

Answer 31

Produce vitamins B and K, assist in fermentation.

Question 32

How is defecation controlled?

Answer 32

Stretch receptors in rectum send signals to spinal cord; internal sphincter relaxes involuntarily, external sphincter under voluntary control.

Question 33

What assists defecation?

Answer 33

Voluntary contraction of abdominal muscles and closing of glottis (Valsalva's maneuver).

Question 34

What are the five essential nutrients?

Answer 34

Essential fatty acids, essential amino acids, water, vitamins, and minerals.

Question 35

What is an essential nutrient?

Answer 35

One that must be ingested because the body cannot make it or not in sufficient amounts.

Question 36

What are the essential fatty acids?

Answer 36

Linoleic and linolenic acid.

Question 37

How are carbohydrates absorbed?

Answer 37

As monosaccharides: glucose and galactose via Na+ co-transport; fructose via facilitated diffusion.

Question 38

How are proteins absorbed?

Answer 38

Amino acids by Na+ co-transport; di/tripeptides also absorbed actively; all exit cells via facilitated diffusion.

Question 39

How are lipids absorbed?

Answer 39

Short chains diffuse directly into blood; long chains form micelles, absorbed into cells, repackaged as chylomicrons, and enter lymph.

Question 40

What are the six macrominerals?

Answer 40

Calcium, phosphorus, potassium, sodium, chlorine, magnesium.

Question 41

What is the function of vitamin D?

Answer 41

Regulates calcium metabolism and absorption; essential for bone, clotting.

Question 42

What is the function of vitamin K?

Answer 42

Essential for blood clotting protein synthesis.

Question 43

What is the function of vitamin C?

Answer 43

Antioxidant; helps form connective tissue and heal wounds.

Question 44

What are B vitamins generally for?

Answer 44

Coenzymes in energy metabolism and RBC production.

Question 45

Where are fat-soluble vitamins stored?

Answer 45

In body fat and liver (A, D, E, K).

Question 46

Which enzymes digest carbohydrates?

Answer 46

Salivary and pancreatic amylase, maltase, sucrase, lactase.

Question 47

Where does carbohydrate digestion occur?

Answer 47

Mouth (starts), small intestine (major site).

Question 48

What is the end product of carbohydrate digestion?

Answer 48

Monosaccharides (mainly glucose).

Question 49

Which enzymes digest proteins?

Answer 49

Pepsin (stomach), trypsin, chymotrypsin, carboxypeptidase (pancreas), aminopeptidase, dipeptidase (brush border).

Question 50

Where does protein digestion begin?

Answer 50

In the stomach with pepsin.

Question 51

Where are brush border enzymes located?

Answer 51

On the microvilli of intestinal epithelial cells.

Question 52

Where does most lipid digestion occur?

Answer 52

In the small intestine by pancreatic lipase.

Question 53

What are bile salts?

Answer 53

Amphipathic molecules that emulsify fats for digestion.

Question 54

What are micelles?

Answer 54

Tiny lipid-bile salt droplets that transport digested fats to epithelial cells.

Question 55

What are chylomicrons?

Answer 55

Triglycerides and cholesterol coated with protein and phospholipids for lymphatic transport.

Question 56

Which enzymes digest nucleic acids?

Answer 56

Deoxyribonuclease and ribonuclease (pancreas), nucleosidases and phosphatases (brush border).

Question 57

How are nucleic acids absorbed?

Answer 57

Via active transport of their breakdown products into blood capillaries.

Question 58

What are the three phases of digestion?

Answer 58

Cephalic (neural anticipation), gastric (neural + hormonal), intestinal (neural + hormonal).

Question 59

Which nerve stimulates gastric secretion during the cephalic phase?

Answer 59

The vagus nerve.

Question 60

What hormone is released in the gastric phase?

Answer 60

Gastrin — stimulates acid and enzyme production.

Question 61

What hormones are released in the intestinal phase?

Answer 61

Secretin (stimulates bicarbonate), CCK (stimulates enzymes and bile).

Question 62

What is the enterogastric reflex?

Answer 62

Stretch of duodenum inhibits gastric emptying to prevent overload.