Small intestine

Question 1

What is the purpose of motility in the small intestine?

Answer 1

1. mixes intestinal contents
2. brings contents to mucosa for absorption
3. propels contents further down GI tract

Question 2

What are the 2 main types of contraction in the SI?

Answer 2

Segmentation: to mix chyme
Peristaltic: to propel food

Question 3

What 2 parts of the GI tract are under voluntary control?

Answer 3

Upper oesophageal sphincter (swallowing)

External anal sphincter (defecation)

Question 4

What do sympathetic (post-ganglionic) and parasympathetic (pre-ganglionic) nerves do in the GIT?

Answer 4

Sympathetic: inhibitory nerves to non-sphincteric muscle

Para: excitatory to non-sphincteric muscle

Question 5

What are interstitial cells of Cajal?

Answer 5

Like pacemaker cells of the GIT, they interact with smooth muscle and set the rate for slow waves (BER)

Question 6

What substances allow segmentation to occur?

Answer 6

Ach (vagal) and substance P: contract proximal end

NO and VIP: relax distal end

Question 7

What is achalasia?

Answer 7

Disorder of the oesophagus, involving uncoordinated/absent contraction of oesophageal smooth muscle or incomplete relaxation of the LOS, causing swallowing disturbances.

Question 8

What is the pathophysiology of achalasia?

Answer 8

Loss of inhibitory nitrinergic neurons in the myenteric plexus of the oesophagus, due to inflammatory destruction causing loss of peristalsis

Question 9

What neurons are affected in achalasia?

Answer 9

Selective loss of post-ganglionic inhibitory neurons means there is no inhibition of contraction in LOS by VIP/NO.
Excitatory post-ganglionic cholinergic neurons remain, giving high LOS tone.

Question 10

What is aperistalsis?

Answer 10

Loss of latency gradient, allowing sequential contractions by NO

Question 11

What are the signs/symptoms of achalasia?

Answer 11

Dysphagia
Regurgitation
Weight loss
Retrosternal pain

Question 12

Investigations in achalasia?

Answer 12

Barium swallow.
High resolution manometry
Endoscopy.

Question 13

How can achalasia be treated?

Answer 13

Rigiflex balloon dilatation: mechanical dilation of LOS cia endoscope
Heller’s myotomy: cut muscles to LOS
Per-oral endoscopic myotomy: inner circular muscle of LOS divided through a submucosal tunnel

Question 14

What is gastroparesis?

Answer 14

Delayed gastric empyting

Question 15

What are the causes of gastroparesis?

Answer 15

Idiopathic
Diabetes w macrovascular disease
Post-viral/surgical complications 
Opiates
Females

Question 16

Symptoms of gastroparesis?

Answer 16

Abdominal pain
Nausea and vomiting
Weight loss
Early satiety

Question 17

How is gastroparesis managed?

Answer 17

Small meals frequently
Liquid meals
Nutritional support

Question 18

What meds can be used in gastroparesis?

Answer 18

D2 antagonists
Motilin agonists
5HT4 agonists

Question 19

How long does food take to get from the pylorus to ileocaecal valve?

Answer 19

3-5 hours

Chyme moves @ 1cm/min

Question 20

What is chronic intestinal pseudo-obstruction?

Answer 20

Signs of mechanical obstruction, without any occlusion.
Neuropathic/myopathic causes e.g. problems in Cajal cells

May need parenteral feeding

Question 21

What is acute post-operative ileus?

Answer 21

Constipation and intolerance of oral intake, in absence of mechanical obstruction after surgery.
Pain and discomfort if prolonged.

May need open surgery or delayed enteral nutrition.

Question 22

What is acute colonic pseudoobstruction?

Answer 22

Ogilvies syndrome
Large bowel parasympathetic dysfunction, common after cardiothoracic and spinal surgery.

May need gut rest, IV fluids, NG decompression

Question 23

How long does transit take from the caecum to rectum ?

Answer 23

1-2 days (shorter in men)

Question 24

What drugs can reduce GI motility?

Answer 24

Opiates

Anticholinergics

Loperamide: gut-selective Mu receptor agonist; decreases tone and activity of myenteric plexus so slows colonic transit.; increased absorption so can be used in diarrhoea

Question 25

What drugs can increase GI motility?

Answer 25

Laxatives: alter electrolyte balance

Prucalopride: gut-selective 5HT4 receptor agonist

Linaclotide: minimally absorbed guanylate C receptor agonist: increases Cl and bicarbonate secretion into lumen to speed transit

Question 26

What can cause incontinence (excessive rectal distension)?

Answer 26

Acute/chronic diarrhoea
Chronic constipation
Anal sphincter weakness (e.g. pudendal nerve damage)

Question 27

What can cause anorectal constipation?

Answer 27

Hirschsprungs disease: nerve damage decreasing transit

Obstructive defecation(paradoxical contraction)

Rectocoele: tear

Anal fissure

Question 28

What is scleroderma?

Answer 28

Multi-system autoimmune disease, structural/functional abnormalities.
Weak LOS, aperistalsis, oesophagitis.

No pressure at LOS on HRM

Question 29

How is scleroderma treated?

Answer 29

PPIs and surgery to ‘create’ achalasia

Question 30

What is nutcracker oesophagus?

Answer 30

Excessive contraction In oesophageal smooth muscle

Pain on swallowing and dysphagia

Question 31

What is diffuse oesophageal spasm?

Answer 31

Uncoordinated oesophageal contractions

Dysphagia or regurgitation

Question 32

What are the 4 phases of MMCs?

Answer 32

1. Prolonged quiescence
2. Increased frequencu of contractility
3. Few mins of peak electrical/mechanical activity
4. Decreased activity

Question 33

What hormone regulates MMCs?

Answer 33

Motilin

Question 34

What is motilin?

Answer 34

Peptide hormone made by M cells of SI, at 90 minute intervals, to increase GI motility and cleanse the gut for the next meal.

Question 35

What does motilin do?

Answer 35

Stimulates contraction of gastric fundus.