DIGESTION

Question 1

What are the 3 main functions of the digestive system?

Answer 1

1. Digestion – break down food into absorbable nutrients 2. Absorption – move nutrients into blood/lymph 3. Excretion – remove waste & unabsorbed material

Question 2

Key facts about the GI tract length and transit time?

Answer 2

Length ≈ 10 meters; Transit time 24–72 hours (mouth to anus)

Question 3

What factors affect GI transit time?

Answer 3

Diet, physical activity, emotions, medications, illness

Question 4

Main secretions of the GI tract?

Answer 4

Mucus (lubricates & protects) + enzymes (speed up reactions)

Question 5

What happens in the mouth during digestion?

Answer 5

Teeth break food → salivary amylase (starch) + lingual lipase (fat) → forms bolus

Question 6

Role of epiglottis?

Answer 6

Flap of cartilage that closes airway during swallowing to prevent choking

Question 7

How does food move through the esophagus?

Answer 7

Peristalsis (wave-like contractions) moves food to stomach in 4–8 seconds

Question 8

What sphincter controls entry to stomach?

Answer 8

Lower esophageal sphincter

Question 9

What is the pH and role of HCl in stomach?

Answer 9

pH ~2.0; kills bacteria + unfolds (denatures) proteins

Question 10

What enzyme digests protein in stomach?

Answer 10

Pepsin (breaks proteins into polypeptides; from meat, milk, legumes)

Question 11

What is chyme?

Answer 11

Semi-liquid mixture of food + acid in stomach

Question 12

Stomach transit time and factors?

Answer 12

2–6 hours; faster with low-fat meals, slower with high-fat

Question 13

What substances are absorbed in stomach?

Answer 13

Water, alcohol, aspirin, acetaminophen

Question 14

How does stomach protect itself?

Answer 14

Mucus layer prevents self-digestion

Question 15

What do parietal cells produce?

Answer 15

HCl + intrinsic factor (needed for vitamin B12 absorption)

Question 16

Stomach muscle layers?

Answer 16

3 layers – longitudinal, circular, diagonal (for churning)

Question 17

Why is small intestine main site?

Answer 17

Primary site of digestion & absorption

Question 18

Movements in small intestine?

Answer 18

Peristalsis + segmentation (mixes chyme for better absorption)

Question 19

What does small intestine produce?

Answer 19

Intestinal juice (watery mucus + enzymes)

Question 20

What organs help small intestine?

Answer 20

Pancreas (enzymes + bicarbonate) + gallbladder (bile)

Question 21

Where do most nutrients go after absorption?

Answer 21

Into blood (most) or lymph (fats)

Question 22

Role of gallbladder?

Answer 22

Stores bile (made by liver); bile emulsifies fats for digestion/absorption; released by CCK signal

Question 23

Pancreas digestive secretions?

Answer 23

Bicarbonate (neutralizes acid) + enzymes: pancreatic amylase (starch), lipase (fats), trypsin & chymotrypsin (proteins)

Question 24

Pancreas hormones?

Answer 24

Insulin & glucagon (blood sugar regulation)

Question 25

Liver role in digestion?

Answer 25

Makes bile; processes absorbed nutrients

Question 26

Parts of large intestine?

Answer 26

6 parts: cecum, ascending, transverse, descending, sigmoid, rectum

Question 27

What does large intestine absorb?

Answer 27

Water, sodium, potassium

Question 28

Large intestine transit time?

Answer 28

Up to 24 hours

Question 29

Daily gas production in colon?

Answer 29

200–2,000 mL gas/day

Question 30

Microbiome facts?

Answer 30

38–100 trillion bacteria; ferments fibre → SCFA, B vitamins, vitamin K; SCFA = energy for colon cells

Question 31

Probiotic food examples?

Answer 31

Yogurt, kefir, kimchi, sauerkraut, dill pickles, olives in brine (live cultures)

Question 32

Factors influencing gut microbiome?

Answer 32

Diet, birth method (vaginal vs C-section), antibiotics, age, stress, genetics

Question 33

What is dysbiosis?

Answer 33

Imbalance of microbiota; linked to IBS, Crohn’s, ulcerative colitis, celiac, obesity, diabetes, heart disease, asthma, neurological issues

Question 34

Enzymes in mouth?

Answer 34

Salivary amylase (starch), lingual lipase (fat)

Question 35

Enzyme in stomach?

Answer 35

Pepsin (protein)

Question 36

Small intestine enzymes?

Answer 36

Pancreatic amylase (starch), lipase (fat), trypsin/chymotrypsin (protein), brush-border: maltase, sucrase, lactase

Question 37

Carb digestion summary?

Answer 37

Starts mouth (salivary amylase) → finishes small intestine (pancreatic amylase + brush-border → glucose, fructose, galactose)

Question 38

Protein digestion summary?

Answer 38

Starts stomach (pepsin) → continues small intestine (trypsin/chymotrypsin + peptidases → amino acids)

Question 39

Fat digestion summary?

Answer 39

Minimal mouth/stomach → main in small intestine (pancreatic lipase + bile → monoglycerides + fatty acids)

Question 40

Where are final products absorbed?

Answer 40

Mainly small intestine (monosaccharides, amino acids, fatty acids/monoglycerides)

Question 41

Absorption mechanisms?

Answer 41

Simple diffusion (fats, vitamin E – no energy); Osmosis (water); Facilitated diffusion (fructose – no energy); Active transport (glucose, galactose, amino acids, sodium – requires energy)

Question 42

Main absorption site & path?

Answer 42

Small intestine → blood or lymph → liver processing

Question 43

Dental problems & digestion?

Answer 43

Pain/loss reduces chewing → lower intake/absorption; prevent: brush/floss; treat: softer foods

Question 44

GERD (heartburn) causes & management?

Answer 44

Acid reflux into esophagus; eat smaller meals, avoid spicy/fatty/fried, garlic/onions/mint, alcohol, smoking; stay upright

Question 45

Key takeaway organs?

Answer 45

Small intestine = main digestion/absorption; Pancreas = bicarbonate + enzymes + insulin/glucagon; Gallbladder = bile for fats; Large intestine = water/electrolytes + microbiome + SCFA + vit K/B

Question 46

Role of mucus in GI tract?

Answer 46

Protects lining everywhere

Question 47

How does fibre help microbiome?

Answer 47

Feeds bacteria (soluble/insoluble/resistant starch) → produces SCFA & vitamins