L6- gastric motility

Question 1

an adaptation of the stomach to accommodate the food

Answer 1

• highly folded so it flattens out once the food is filled in and the intraluminal pressure increases
• the pressure increase rapidly if it’s filled near its max limit due to an interruption of vago-vagal reflex
• the reflex regulates the relaxation of the stomach

Question 2

3 phases of gastric motility

Answer 2

• propulsion
• grinding
• retropulsion

Question 3

what happens in propulsion

Answer 3

• liquids and smaller particles go into the pylorus

Question 4

what happens in grinding

Answer 4

• larger particles are retained in the antrum, causing a bulge in the stomach
• so they can be broken down into smaller pieces

Question 5

what happens in retropulsion

Answer 5

-those broken down particles go into pylorus into the duodenum

Question 6

functions of pylorus

Answer 6

• regulates emptying of gastric contents into the duodenum

- prevents duodenul contents back into the stomach

Question 7

3 phases of gastric emptying

Answer 7

-cephalic
-gastric
intestinal

Question 8

what happens in celphalic phase

Answer 8

approach of food in the mouth or the stomach

• vagus nerve inhibited so the stomach relaxes to a larger vol to accomodate the food
• inhibitory phase

Question 9

what happens in gastric phase

Answer 9

• excitatory phase
• stomach empties at a rate equal to the vol of it
• SM contraction causes relfex contraction of the stomach
• activation of pressure receptors inthe nerves
• gastrin released

Question 10

what happens in the intestinal phase

Answer 10

• inhibitory phase where the duodenum adapts to the contents filling
• ileogastric reflex - pressure receptors in the ileum due to food filling so it can delay gastric emptying fro digestion

Question 11

what molecules are released in response to

• low pH
• high fats
• high AAs
• high carbohydrates

Answer 11

pH - secretion activated and released
fats - CCK secretion increased
AAs- gastrin secretion increased
carbohydrates - GIP secretion increased

Question 12

functions of GIT so small and large intestine together

Answer 12

1. produces segmental contractions, not propulsive and mixes the food together
2. produces peristaltic contractions for propulsion, so the food can move in one direction
3. acts as storage for contents

Question 13

location of small intestine

Answer 13

• extends from stomach to colon

- responsible for digestion and absorption

Question 14

functions of small intestine

Answer 14

-mixing, propulsion and release of chyme into colon

Question 15

types of motility in the small intestine in the fed state

Answer 15

• segmentation

- peristalsis

Question 16

what is segmentation

Answer 16

-rings of circular muscle at the intervals which contract or relax for mixing food

Question 17

what is peristalsis

Answer 17

muscle of the GIT contracting and relaxing to propels the food froward

Question 18

what complex or mechanism is involved in fasted state

Answer 18

migrating motor complex (MMC)

Question 19

what is MMC

Answer 19

• rhymatic contractions
• makes sure that the gut is clean by moving the food along due to the contraction of the muscles
• the activity of the MMC is its highest at the start of jejujum and then decreases as you go along the jejujum

Question 20

benefits of MMC

Answer 20

• prevents bacterial overgrowth and stops the batceria from going into the small bowel
• removes undigested contents in the guts

Question 21

2 reflexes in ileum and the functions of them

Answer 21

• ileogastric reflex - decreases gastric motility
• gastroileol reflex - increased gastric activity increases ileal motility and movement of chyme
• mediated by ENS

Question 22

what’s ileocaecal sphincter

Answer 22

• seperate ileum from colon
• controls the flow of ileal contents into the colon
• mediated by ANS and ENS and regulated by luminal contents and pressure

Question 23

colon features

Answer 23

has no villi and low SA

• has longitudal muscle
• split up into ascending, transverse, descending and sigmoid

Question 24

function of colon

Answer 24

• gut microbiota, environment for beneficial bacteria to synthesise bacteria
• absorb fluid and electrolytes, FAs
• storage
• regulates release of faecal material
• secretes mucus and ions

Question 25

sites in colon for absorption and storage function

Answer 25

• proximal for absorption

- distal for storage

Question 26

types of contractions involved in colon motility

Answer 26

• colonic rhythmic phasic contractions

- giant migrating contractions

Question 27

what is colonic rhythmic phasic contractions

Answer 27

• fluid contents slowly becomes sloid in the sigmiod colon as the water is absorbed
• uses ST and LT contractions to acheive this

Question 28

what is giant migrating contractions

Answer 28

rapid contractions to push the contents during a big movement
- move it to the rectum

Question 29

what controls motility in the colon

Answer 29

indigestible material elicit motility and activates pressure receptors like cellulose, gums
-mediated by myentric plexus

Question 30

what part of the colon does PNS innervate

Answer 30

cecum,acsending and transverse through vagus nerves

Question 31

what part of the colon does SNS innervate

Answer 31

-descending,sigmoid, rectum and anal via pelvic nerves

Question 32

mechanism of reflex contraction of the rectum for pooing

Answer 32

• poo enters the rectum and causes distension (makes it bigger and stretches it
• internal anal sphincter need to relax so PNS defaecation reflex helps this
• results in peristaltic waves and internal anal sphincter relaxes
• then involventary contraction of the external and internal anal sphincter occurs, pushing the poo out

Question 33

types of laxatives

Answer 33

• stimulant
• saline or osmotic
• faecal softener
• bulk forming laxatives