physiology - general

Question 1

what is motility

Answer 1

mechanical activity mostly involving smooth muscle (skeletal muscle is involved in mouth to upper oesophagus and anal sphincter)

Question 2

what is digestion

Answer 2

chemical breakdown by enzymatic hydrolysis of cole foodstuffs to smaller, ABSORBABLE units

Question 3

what is absorption

Answer 3

transfer of the absorbable products of digestion from the digestive tract to the blood or lymph

Question 4

what does circular muscle contraction cause in the GI tract

Answer 4

lumen becomes narrower and longer

Question 5

what does longitudinal muscle contraction cause in the GI tract

Answer 5

intestine becomes shorter and fatter

Question 6

what does muscularis mucosa contraction cause in the GI tract

Answer 6

change in absorptive and secretory area of mucosa (mixing activity)

Question 7

how many sphincters are there? name them

Answer 7

1. upper oesophageal (UOS)
2. Lower oesophageal (LOS)
3. pyloric sphincter
4. ileocaecal valve
5. internal anal sphincter
6. external anal sphincter

Question 8

which sphincters are comprised of smooth muscle

Answer 8

Lower oesophageal (LOS) pyloric sphincter
ileocaecal valve
internal anal sphincter

Question 9

which sphincters are comprised of skeletal muscle

Answer 9

upper oesophageal (UOS)
external anal sphincter

Question 10

what are the organs associated with the alimentary canal

Answer 10

mouth and oropharynx
oesophagus
stomach
small intestine (duodenum, jejunum, ileum)
large intestine (caecum, appendix, colon)
rectum and anus

Question 11

what are the accessory structures associated with the alimentary canal

Answer 11

salivary glands
pancreas
liver and gall bladder

Question 12

what are the major motility patterns in the GI tract (5)

Answer 12

peristalsis
segmentation
colonic mass movement 
migrating motor complex 
tonic contractions

Question 13

what is peristalsis

Answer 13

a wave of relaxation followed by contraction that normally proceeds along the gut in an aboral direction

Question 14

what triggers peristalsis

Answer 14

distension of the gut wall

Question 15

what is tonic contractions

Answer 15

sustained contractions
low pressure = organs with major storage function (e.g stomach)
high pressure = sphincters

Question 16

what is migrating motor complex

Answer 16

powerful sweeping contractions from stomach to terminal ileum

Question 17

what is colonic mass movement

Answer 17

powerful sweeping contraction that forces faeces into the rectum

Question 18

what is segmentation

Answer 18

(mixing/churning)

rhythmic contractions of the circular muscle layer that mix and divide luminal contents

Question 19

stimulation of the parasympathetic innervation of the GI tract causes what

Answer 19

increased gastric, pancreatic and small intestinal secretion
increased blood flow
increased smooth muscle contraction

Question 20

inhibition of the parasympathetic innervation of the GI tract causes what

Answer 20

relaxation of some sphincters

receptive relation of the stomach

Question 21

stimulation of the sympathetic innervation of the GI tract causes what

Answer 21

increased sphincter tone

Question 22

inhibition of the sympathetic innervation of the GI tract causes what

Answer 22

decreased motility
decreased secretion
decreased blood flow

Question 23

who does electrical activity occur in the stomach, small and large intestine

Answer 23

slow waves

detailed: rhythmic patterns of membrane depolarisation and repolarisation that spreads from cell to cell via gap junctions

Question 24

what does the slow wave electrical activity determine

Answer 24

max frequency, direction and velocity of rhythmic contractions

basic electrical rhythm (BER)

Question 25

what is the slow wave electrical activity driven by

Answer 25

interstitial cells of cajal (ICCs)

pacemaker cells are also interspersed between the smooth muscle cells

Question 26

when would contraction occur (in relation to slow wave)

Answer 26

if the slow wave amplitude is sufficient to trigger SMC AP

Question 27

where is the enteric nervous system (ENS) located within the GI system

Answer 27

myenteric (Auerbach’s) plexus

submucous (Meissner’s) plexus

Question 28

where is the enteric nervous system (ENS) located within the GI tissue

Answer 28

intrinsic