Digestive 2

Question 1

What are the main functions of the digestive system?

Answer 1

Digestion, secretion, absorption, and motility

Question 2

What are the two main parts of the digestive system?

Answer 2

Gastrointestinal (GI) tract and accessory organs

Question 3

List the layers of the alimentary canal wall.

Answer 3

Mucosa, submucosa, muscularis externa, and serosa/adventitia

Question 4

What does the mucosa layer consist of?

Answer 4

Epithelium, lamina propria, and muscularis mucosae

Question 5

What is the enteric nervous system (ENS)?

Answer 5

A network of neurons in the GI tract that controls gut function independently

Question 6

What controls salivary secretion?

Answer 6

Parasympathetic and sympathetic nervous systems

Question 7

What are the components of saliva and their functions?

Answer 7

Water (moistening), mucins (lubrication), α-amylase (starch digestion), lysozyme (antibacterial)

Question 8

How is chewing controlled?

Answer 8

Both voluntary via somatic nerves and reflex via mechanoreceptors in the mouth

Question 9

What are the functions of the stomach?

Answer 9

Storage, digestion, sterilisation, controlled delivery to small intestine, intrinsic factor production

Question 10

What are the three phases of swallowing?

Answer 10

Oral (voluntary), pharyngeal (reflex), oesophageal (peristalsis)

Question 11

What triggers receptive relaxation in the stomach?

Answer 11

Relaxation of the lower oesophageal sphincter and entry of bolus

Question 12

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

Answer 12

Parietal (HCl, intrinsic factor), Chief (pepsinogen), Mucous neck cells (mucus)

Question 13

What enzyme is involved in HCl secretion in the stomach?

Answer 13

Carbonic anhydrase

Question 14

What is the role of intrinsic factor?

Answer 14

Binds vitamin B12 for absorption in the ileum; deficiency causes pernicious anaemia

Question 15

What are the three phases of gastric acid secretion?

Answer 15

Cephalic, gastric, and intestinal

Question 16

What stimulates gastric acid secretion?

Answer 16

Vagal reflexes, gastrin, histamine (neurocrine, endocrine, paracrine mechanisms)

Question 17

What inhibits gastric acid secretion?

Answer 17

Enterogastric reflex, secretin, GIP, high acid or fat in duodenum

Question 18

What is the role of gastric mucus?

Answer 18

Protects stomach lining from acid and pepsin

Question 19

How does peristalsis differ between the stomach body and antrum?

Answer 19

Body: weak contractions; Antrum: strong contractions for mixing and propulsion

Question 20

What is the function of Brunner’s glands?

Answer 20

Secrete bicarbonate to neutralise acid in the duodenum

Question 21

What is the function of secretin?

Answer 21

Stimulates HCO3- secretion from the pancreas and liver in response to duodenal acid

Question 22

What are the three parts of the small intestine and their main functions?

Answer 22

Duodenum (neutralisation, digestion, iron), Jejunum (nutrient absorption), Ileum (NaCl/H2O absorption)

Question 23

How is the absorptive surface area of the small intestine increased?

Answer 23

By circular folds, villi, and microvilli

Question 24

What do villus and crypt cells absorb and secrete?

Answer 24

Villus: absorb nutrients; Crypt: secrete Cl- and water

Question 25

What enzymes digest disaccharides at the brush border?

Answer 25

Lactase, sucrase, maltase

Question 26

What is the difference between starch and cellulose?

Answer 26

Starch: α-1,4 bonds (digestible), Cellulose: β-1,4 bonds (indigestible without bacteria)

Question 27

How are glucose and galactose absorbed in the intestine?

Answer 27

Via SGLT1 (Na+-dependent transporter)

Question 28

How is fructose absorbed?

Answer 28

Via GLUT-5 and GLUT-2 transporters

Question 29

What enzymes digest proteins?

Answer 29

Proteases/peptidases

Question 30

How are amino acids absorbed?

Answer 30

Na+-dependent transporters like SAAT1

Question 31

How are di/tripeptides absorbed?

Answer 31

Via H+-dependent PepT1 transporter

Question 32

What generates gastric peristaltic waves?

Answer 32

Pacemaker cells in longitudinal muscle layer producing slow waves (BER)

Question 33

What are the two types of small intestine movement?

Answer 33

Segmentation and peristalsis

Question 34

What initiates segmentation?

Answer 34

BER from pacemaker cells in longitudinal muscle

Question 35

What is the migrating motility complex (MMC)?

Answer 35

Peristaltic activity moving undigested material to large intestine

Question 36

What hormone initiates MMC?

Answer 36

Motilin

Question 37

What is the gastroileal reflex?

Answer 37

Gastric emptying → increased ileal motility → opening of ileocaecal valve

Question 38

What are haustra?

Answer 38

Pouches formed by contractions of teniae coli in the colon

Question 39

What is the role of the large intestine?

Answer 39

Water absorption, forming faeces, housing microbiota, fermentation

Question 40

What is the defaecation reflex?

Answer 40

Rectal distension → reflex contraction → relaxation of internal sphincter, external under voluntary control