Motility in the GI tract

Question 1

What are the three roles of motor activity in the GI tract?

Answer 1

Churns and mixes the food
Peristalsis moves the food in the right direction
Allows organs to act as reservoirs

Question 2

Name the four functions of the small intestine

Answer 2

Digestion
Absorption
Secretion
Motility

Question 3

What are the three functions of motility in the small intestine?

Answer 3

Mixing
Propulsion
Release into colon

Question 4

What are the three methods of motility in the small intestine?

Answer 4

Rhythmic phasic contractions
Segmentation
Peristalsis

Question 5

How does segmentation work?

Answer 5

Rings of circular muscle at intervals contract and then relax

Question 6

How does peristalsis work?

Answer 6

Sequential contractions of rings of circular muscle followed by sequential relaxation
Behind the bolus of food

Question 7

What is the migrating motor complex?

Answer 7

When in the fasting state, the migrating motor complex is the electrical activity that occurs every few hours

Question 8

What is the role of the migrating motor complex?

Answer 8

To propel particles greater than 2mm in diameter from the stomach into the duodenum
Remove residual content from small intestine
Stop colonic bacteria moving backwards

Question 9

What controls smooth muscle contraction?

Answer 9

Neurotransmitter (acetylcholine)
Hormones
Vasoactive intestinal peptide
Stretch (myogenic) reflex
Enteric nervous system

Question 10

What are the two types of movement in the ileum?

Answer 10

Ileogastric reflex

Gastroileal reflex

Question 11

What is the ileogastric reflex?

Answer 11

Ileal distension to decrease gastric motility

Question 12

What is the gastroileal reflex?

Answer 12

Increased gastric activity causing increased ill motility

Question 13

What does the ileocaecal sphincter separate?

Answer 13

The ileum and the colon

Question 14

What regulates movement through the ileocaecal sphincter?

Answer 14

Pressure proximal and distal to the sphincter

Question 15

What are taeniae coli?

Answer 15

3 muscular bands that run the length of the colon

Question 16

What are the functions of the colon?

Answer 16

Absorb large quantities of fluid and electrolytes
Absorb short chain fatty acids
Storage/reservoir function
Regulated release of faecal matter
Secrete mucus and ions
Home for beneficial bacteria

Question 17

What are the two types of motility in the colon?

Answer 17

Colonic rhythmic phasic contractions

Giant migrating contractions

Question 18

What controls motility in the colon?

Answer 18

Distension
Food contents (e.g. fibre)

Question 19

What are the four classifications of laxative?

Answer 19

Stimulant laxatives
Saline laxatives
Emollient laxatives
Bulk-forming laxatives

Question 20

What kind of muscle makes up the anal sphincter?

Answer 20

Internal anal sphincter - smooth, involuntary

External anal sphincter - striated, voluntary

Question 21

What are the stages to defaecation?

Answer 21

Faeces enter rectum and causes distension
Intrinsic defaecation reflex
Relaxation of internal sphincter
Conscious control of external sphincter