GI

Question 1

Layers of the GI tract (innermost to outermost)

Answer 1

Innermost mucosa
Submucosa
Muscularis externa
Outermost serosa

Question 2

Innermost mucosa 3 layers

Answer 2

1. Epithelial
2. Lamina propia
3. Muscularis mucosa

Question 3

Submucosa contains?

Answer 3

Connective tissue, larger blood vessels and lymphatic vessels and the submucosal plexus

Question 4

Muscularis externa composed of 3 layers

Answer 4

Inner circular muscle layer

Myenteric plexus between the two layers of muscle

Outer longitudinal muscle later
Myenteric plexus between the two layers of muscle

Question 5

Main function of the submucosal plexus?

Answer 5

Parasympathetic input, secretomotor innervation

Question 6

Myenteric plexus provides what innervation?

Answer 6

Motor innervation to the smooth muscle layers via sympathetic and parasympathetic input

Question 7

3 glands that produce saliva?

Answer 7

Parotid
Submandibular
Sublingual

Question 8

Sympathetic control of salivary production is via?

Answer 8

Cervical ganglionW

Question 9

What does sympathetic innervation cause in terms of saliva?

Answer 9

Increase protein secretion resulting in increased production of thick mucoid saliva.

Question 10

Parasympathetic control of saliva production controlled by?

Answer 10

Outflow coordinated by the medulla

-> innervation via facial and glossopharyngeal nerves

Question 11

Voluntary phase of swallowing

Answer 11

Buccal

Question 12

Two involuntary phases of swallowing

Answer 12

Pharyngeal and oesophageal

Question 13

Which nerves transmit impulses from the pharynx mechanoreceptors to the swallow centre?

Answer 13

Glossopharyngeal and vagus

Question 14

What does the stomach make food into to be released into the small intestine?

Answer 14

Chyme

Question 15

Parietal cells produce?

Answer 15

HCL and intrinsic factor

Question 16

Chief cells produce?

Answer 16

Pepsinogen

Question 17

G cells produce?

Answer 17

Gastrin

Question 18

Enterochromaffin like cells produce?

Answer 18

Histamine

Question 19

Surface mucous cells produce?

Answer 19

Mucus

Question 20

3 phases of gastric secretion

Answer 20

Cephalic, Gastric and intestinal

Question 21

Myenteric plexus role?

Answer 21

Major nerve supply to the gastrointestinal tract and controls GI tract motility.

Question 22

What triggers the cephalic phase ?

Answer 22

Sight, smell and taste of food, mediated by the action of the vagus nerve

Question 23

What triggers gastric phase?

Answer 23

Distension of the stomach and chemical composition of food

Question 24

Two pathways at work during the gastric phase to stimulate stomach secretory activity?

Answer 24

Stomach mechanoreceptors stretched
-> vagovagal -> medulla -> vagus nerve
AND -> local reflexes

Food chemicals and rising pH -> G cells secrete gastrin into the blood

Question 25

Pathway in the intestinal stage stimulating stomach secretory activity

Answer 25

Presence of low pH and partially digested food in the duodenum -> intestinal gastrin released

Question 26

Two pathways in the intestinal stage inhibiting stomach secretory activity

Answer 26

1. Distension of duodenum / presence of fatty acids / chyme -> local reflexes -> pyloric sphincter -> vagal nuclei in the medulla All stimulate the enterogastric reflex 2. Distension of duodenum / presence of fatty acids / chyme -> release of intestinal hormones

Question 27

What is added to duodenal chyme to allow it to be broken down further?

Answer 27

Water, bicarb and bile

Question 28

What creates the osmotic gradient in the small intestine?

Answer 28

sodium pump

Question 29

What happens to carbohydrate polysaccharides at the intestinal brush border to allow them to be absorbed?

Answer 29

Broken down by enzymes Maltase / isomaltase / sucrase / lactase

Question 30

Which transporter moves monosaccharides across the apical membrane in the GI tract?

Answer 30

SGLT1 inhibitors

Question 31

How do monosaccharides across the basal membrane in the GI tract

Answer 31

Facilitated diffusion (GLUT2) OR simple

Question 32

How are lipids packaged by bile acids to allow them to enter the aqueous layers surrounding the microvilli ?

Answer 32

Emulsified and then form micelles (hydrophobic lipid molecules in the centre, surrounded by bile acids)

Question 33

Main mechanisms of calcium extrusion from the GI tract?

Answer 33

The plasma membrane Ca2+ ATPase (PMCA) and the plasma membrane Na+/Ca2+ exchanger (NCX) are the two mechanisms responsible for Ca2+ extrusion.

Question 34

What facilitates the uptake of non-haem ferrous iron (Fe2+) from the intestinal lumen?

Answer 34

he transporter protein Divalent Metal Transporter 1 (DMT1), located on the apical surface of enterocytes

Question 35

Where are most pancreatic enzymes activated?

Answer 35

duodenum

Question 36

Secretion stimulates what in the pancreas?

Answer 36

Secretion of the alkaline-richh fluid from the ductal cells

Question 37

Cholecystokinin stimulates what in the pancreas?

Answer 37

Secretion of the enzyme rich fluid from the ductal calls

Question 38

Somatostatin inhibits what in the pancreas?

Answer 38

Secretion from both acinar and ductal cells

Question 39

Gastrin stimulates what in the pancreAs?

Answer 39

Acinar cells to secrete pancreatic enzymes

Question 40

What is CCK stimulated by?

Answer 40

The presence of fatty acids/monoglycerides and small peptides/amino acids in the duodenum

Question 41

CCK action

Answer 41

Increase production of bile stimulate release of stored bile increase pancreatic bicarbonate secretion stimulate pancreatic enzyme secretion inhibit gastric emptying, inhibit gastric acid production stimulate pepsinogen secretion

Question 42

Which types of cells release CCK?

Answer 42

I cells in the duodenum and jejunum

Question 43

Which types of cells release secretin?

Answer 43

S cells in the duodenum

Question 44

What stimulates secretin release?

Answer 44

A low pH and the presence of fatty acids in the duodenum

Question 45

Secretin actions

Answer 45

inhibit gastric acid secretion inhibit gastric emptying stimulate pepsinogen secretion stimulate pancreatic bicarbonate secretion increase pancreatic enzyme secretion increase bile production

Question 46

What is the portal triad composed of?

Answer 46

Portal arteriole Portal vein Bile duct (also contains lymphatic vessels and vagal parasympathetic fibres)

Question 47

The liver receives dual blood supply from?

Answer 47

Hepatic artery and portal vein

Question 48

Two main groups of bile constituents

Answer 48

Bile acid dependent and independent components

Question 49

The bile acid-dependent component is produced by... & what are they

Answer 49

Hepatocytes Bile acids, bile pigments and cholesterol

Question 50

The bile acid-independent component is made by the...

Answer 50

Ductal cells that line the bile ducts

Question 51

Enterohepatic circulation role?

Answer 51

The bile acid-independent component is made by the

Question 52

Bands of muscles in the large intestine wall called?

Answer 52

Taenia coli

Question 53

What innervates and caecum, ascending and transverse colon

Answer 53

Parasympa branches of the vagus nerve

Question 54

Role of intestinal bacterial flora (5)

Answer 54

Keep pathogenic bacteria at bay Convert conjugated bilirubin to unconjugated Synthesis of K, B12, thiamine and riboflavin Breakdown primary bile acids to secondary Break down cholestrol, some food additives and drugs

Question 55

Which monosaccharide isn't absorbed by Na+ transport in the intestine?

Answer 55

Fructose