GI system

Question 1

Function of GI tract

Answer 1

Digestion and absorption of nutrients

Question 2

What cells are in the mucosal layer?

Answer 2

Epithelial cells
Lamina propria
Muscularis mucosae

Question 3

Function of lamina propria

Answer 3

Connective tissue
Blood and lymph vessels

Question 4

What does muscularis mucosae contraction cause?

Answer 4

Change in the shape of the epithelial layer

Question 5

What is the submucosal layer composed of?

Answer 5

Collagen
Elastin
Glands
Blood vessels

Question 6

What is the enteric nervous system?

Answer 6

Collection of nerve plexuses surrounding the gi tract

Question 7

Is the ENS intrinsic or extrinsic?

Answer 7

Intrinsic

Question 8

Are parasympathetic postganglionic neurones cholinergic or peptidergic or adrenergic?

Answer 8

Cholinergic & Peptidergic

Question 9

Are sympathetic postganglionic neurons cholinergic, peptidergic or adrenergic?

Answer 9

Adrenergic

Question 10

What are the 3 gi peptide classes?

Answer 10

Hormones
Paracrine
Neurocrine

Question 11

What is the gi hormone cascade?

Answer 11

Endocrine cell at the end of GI tract ->
Secretion ->
Portal circulation ->
Liver ->
Systemic circulation ->
Target cell

Question 12

What is the gi paracrine cascade?

Answer 12

Endocrine cell ->
Diffusion ->
Target cell

Question 13

What is the gi neurocrine cascade?

Answer 13

Neuron ->
Action potential ->
Target cell

Question 14

What is most contractile tissue in the gi tract?

Answer 14

Unitary smooth muscle electrically coupled via gap junctions

Question 15

What are the 2 subsections of contractions?

Answer 15

Phasic
Tonic

Question 16

What is a phasic contraction?

Answer 16

A periodic contraction or relaxation, lasting between 3-12 mins

Question 17

What is a tonic contraction?

Answer 17

A constant level of contraction/ tone due to slow waves

Question 18

What generates a true action potential?

Answer 18

An extension to threshold

Question 19

What is the gi pacemaker?

Answer 19

Interstitial cells of cajal

Question 20

What are low pressure organs separated by?

Answer 20

Sphincters

Question 21

What is the mastication muscle innervated by?

Answer 21

Mandibular nerve (V3) of cranial nerve 5

Question 22

What are the 3 phases of swallowing?

Answer 22

Oral
Pharyngeal
Oesophageal

Question 23

What is lubricated food ready for swallowing called?

Answer 23

Bolus

Question 24

What does saliva contain? What is

Answer 24

Alpha amylase to hydrolyse starch

Question 25

What are mechanoreceptors?

Answer 25

Receptors which relay sensory info to the brainstem

Question 26

What is the oesophagus lumen lined with?

Answer 26

Stratified squamous epithelia

Question 27

What is the swallowing reflex?

Answer 27

The upper oesophageal sphincter is closed -> This initiates primary peristaltic waves which coordinates sequential contractions

Question 28

What triggers a secondary peristaltic wave?

Answer 28

Continued distension causing contractions to move the bolus along

Question 29

What are the 3 motility phases in the stomach?

Answer 29

1. Receptive relaxation in orad 2. Caudad contraction 3. Gastric emptying

Question 30

What is force of contraction in the caudad region controlled by?

Answer 30

Due to action potentials

Question 31

What is chyme composed of?

Answer 31

HCL Pepsinogen Intrinsic factor Mucus

Question 32

Describe gastric emptying

Answer 32

Chyme empties through the pyloric sphincter into the small intestine

Question 33

Function of the small intestine

Answer 33

Digestion and absorption of nutrients

Question 34

How long (approx) is the small intestine?

Answer 34

6 1/2 meters long

Question 35

What are the sections of the small intestine?

Answer 35

Duodenum Jejunum Ileum

Question 36

What increases surface area in the small intestine?

Answer 36

Plicae Villi Microvilli

Question 37

Function of the pancreas

Answer 37

Excretes 1l of exocrine pancreatic secretion into duodenum per day

Question 38

What are the secretion phases in the pancreas?

Answer 38

Cephalic Gastric Intestinal

Question 39

Where are enzymes secreted from in the pancreas?

Answer 39

Acinar cells

Question 40

What is the cephalic phase initiated by?

Answer 40

Initiated by smell, taste and conditioning

Question 41

What is the gastric phase initiated by?

Answer 41

Initiated by distension of the stomach

Question 42

Where is bile produced?

Answer 42

In hepatocytes

Question 43

What is bile composed of?

Answer 43

Bile salts Pigments Cholesterol Bilirubin

Question 44

Function of the gall bladder

Answer 44

Stores, concentrates and ejects bile

Question 45

What can bile form to emulsify lipids?

Answer 45

Form micelles to aid digestion and absorption of lipids

Question 46

Function of CCK in the gallbladder

Answer 46

Contracts the gallbladder by relaxing the sphincter of Oddi

Question 47

What cells release serotonin in the small intestine? What for?

Answer 47

Enterochromaffin cells for peristaltic reflex

Question 48

What happens to material not absorbed in the small intestine?

Answer 48

Passes through ileocecal sphincter into the caecum of large intestine

Question 49

What process exposes Chyme to secretions?

Answer 49

Segmentation contractions opposing in circular and longitudinal layers

Question 50

What are the functions of the large intestine?

Answer 50

Absorbs water and electrolytes Makes and absorbs vitamins K&B Forming and propelling faeces (ferments indigestible foods)

Question 51

What is a crypt?

Answer 51

Glands that secrete mucus to protect the lining from digestive fluids