Lecture 24 GI physio Motility

Question 1

what are the 4 processes of GI tract?

Answer 1

Motility
Secretion
Digestion
Absorption

Question 2

what are the functions of motility in GI tract?

Answer 2

Movement at controlled rate
Mechanical digestion
Mixing - food / secretions / enzymes
exposure to absorptive surfaces (contact)

Question 3

what does the Movement at controlled rate include?

Answer 3

propulsion

storage

Question 4

what does Mechanical digestion include?

Answer 4

ingestion / physical breakdown

increases SA

Question 5

what kind of muscle is in the Mouth?
what kind of muscle is in the esophagus?
what kind of muscle is in the Anus?

Answer 5

Mouth = skeletal
esophagus = both 
anus = skeletal

Question 6

what are the muscle layers for the basis of GI motility?

Answer 6

Muscularis mucosae
Circular muscle
Longitudinal muscle - shortening
Motility programmes

Question 7

what does the Muscularis mucosae do?

Answer 7

SA

Question 8

what does the Circular muscle do?

Answer 8

reduce diameter

Question 9

what does the longitudinal muscle do?

Answer 9

shortening

Question 10

What does GI smooth muscle is spontaneously active mean?

Answer 10

Contracts without external input

Basic electrical rhythm (BER) or slow wave
GI smooth muscle activity controlled / co-ordinated
Modulation (i.e. influenced by):

Question 11

whats Basic electrical rhythm (BER) or slow wave?

Answer 11

Spontaneous variations in membrane potential (pacemakers)

Produce action potentials

Result in contractions (if / when get to threshold)

Question 12

what is the GI smooth muscle activity controlled / co-ordinated by?

Answer 12

ENTERIC NERVOUS SYSTEM (ENS)
Controls strength of contractions
Co-ordinates motility patterns

Question 13

what does the ENTERIC NERVOUS SYSTEM (ENS) do?

Answer 13

controls GI smooth muscle activity.

coordinates GI smooth muscle to generate motility patterns.

Controls strength of contractions
Co-ordinates motility patterns

Question 14

what is GI smooth muscle Modulation (i.e. influenced by):?

Answer 14

External inputs – CNS e.g. vagus nerve
Hormones
Local factors e.g. stretch

Question 15

GI

what different motility patterns can occur generated by ENS?

Answer 15

Peristalsis

Segmentation

Question 16

ENS determines type of motility that occurs, hows it modified?

Answer 16

by stretch / nerves /hormones / local feedback loops (e.g. enterogastric reflex)

Question 17

what are the 2 types of motility patterns?

Answer 17

Fasting

Fed

Question 18

whats the Fasting motility pattern in GI tract?

Answer 18

Migrating motor complex (MMC)

Co-ordinated – stomach -> small intestine -> large intestine

4 - 5 hours after a meal
Repeated every ≈ 2 hours

3 periods

Question 19

whats the 3 periods of Fasting motility pattern in GI tract?

Answer 19

Inactivity
Intermittent activity
Intense activity

Question 20

whats the function of Fasting motility pattern in GI tract?

Answer 20

House keeping

Question 21

whats the Feeding motility patterns in GI tract?

Answer 21

storage
peristalsis
segmentation

Question 22

for Feeding motility patterns in GI tract, whats storage?

Answer 22

Mainly stomach

Relaxation of smooth muscle (distension)

Question 23

for Feeding motility patterns in GI tract, whats peristalsis?

Answer 23

Esophagus, stomach, small & large intestine

Propulsive

Question 24

for Feeding motility patterns in GI tract, whats segmentation?

Answer 24

Small and large intestine

Mixing & exposure to absorptive surfaces

Question 25

whats peristalsis?

Answer 25

Propulsion (+/- mixing) Oesophagus, Stomach, SI, LI Proximal squeeze, distal relax

Question 26

whats segmentation?

Answer 26

Mixing SI and LI Contract/relax circular muscle -> mix + contact

Question 27

what are some specific motility patterns?

Answer 27

chewing and swallowing gastric motility intestinal motility

Question 28

whats the function of motility in the mouth chewing?

Answer 28

Reduce size of food Mixing with saliva Taste

Question 29

for Motility in the mouth - Chewing, hows it controlled?

Answer 29

``` Voluntary - skeletal muscle Reflex control of: - Strength - Frequency - Occlusion - Side of chewing ```

Question 30

swallowing (deglutition) whats the function?

Answer 30

rapid transfer of material from mouth to stomach

Question 31

swallowing (deglutition) hows it controlled?

Answer 31

start voluntarily proceeds involuntary (reflex) co-ordination of multiple muscles need to protect airway

Question 32

swallowing (deglutition) hows it done in esophagus?

Answer 32

peristalsis (+/- gravity) | sphincters

Question 33

Gastric motility whats fasting?

Answer 33

Shrinks to small volume | Migrating motor complex

Question 34

Gastric motility Eating - delivery of food what Series of motility patterns occur associated with?

Answer 34

Storage Mixing Mechanical digestion Controlled delivery to intestine

Question 35

Gastric motility | storage in the proximal stomach

Answer 35

receptive relaxation | relaxation of proximal gastric smooth muscle

Question 36

Gastric motility storage in the proximal stomach whats receptive relaxation?

Answer 36

increase in stomach volume without increase in pressure initiated by swallowing - nervous reflex

Question 37

Gastric motility storage in the proximal stomach whats relaxation of proximal gastric smooth muscle?

Answer 37

reduced thickness - highly distensible

Question 38

Gastric motility | Peristalsis

Answer 38

peristaltic waves first 60 min gentle activity 60 - 300 min more intense activity

Question 39

Gastric motility Peristalsis whats peristaltic waves?

Answer 39

initiated on greater curvature ~ 3 /min spreads to antrum

Question 40

Gastric motility Peristalsis what causes 60 - 300 min more intense activity?

Answer 40

presence of products of digestion (amino acids) gastrin production stimulates contraction

Question 41

gastric motility whats the roles of peristalsis in the stomach?

Answer 41

propulsion combined with pyloric sphincter retropulsion mixing and mechanical digestion

Question 42

gastric motility Controlled delivery of chyme to duodenum

Answer 42

Regulation of gastric emptying through regulation of gastric motility Composition of food modifies rate of emptying Duodenum controls stomach

Question 43

gastric motility Controlled delivery of chyme to duodenum whats Composition of food modifies rate of emptying?

Answer 43

Solids slower than liquids | Fats slow gastric emptying

Question 44

gastric motility Controlled delivery of chyme to duodenum whats Duodenum controls stomach?

Answer 44

Hormonal - GIP Neural - Enterogastric reflex

Question 45

whats overall function of SI?

Answer 45

Chemical digestion of food | Absorption of nutrients, salts and water

Question 46

for Small intestinal motility whats the Functions of motility?

Answer 46

Mixing (chyme / chemicals / enzymes) Exposure to absorptive surfaces -> contact Propulsion (4-6 hours)

Question 47

for Small intestinal motility whats the motility patterns?

Answer 47

Fasting - migrating motor complex (MMC) Feeding - Mainly segmentation -> contact Peristalsis

Question 48

whats the function of LI (colon) motility?

Answer 48

Temporary storage of faeces | Regulation of the salt and water content of faeces

Question 49

for LI (colon) motility whats the motility patterns?

Answer 49

18-24 hours Inactivity Segmentation - Mixing and slow propulsion Mass movements - 3 - 4 time per day - Force faeces into rectum Defaecation - Reflex responses / Voluntary control - Brain / brain stem / spinal cord

Question 50

for LI (colon) motility whats segmentation?

Answer 50

Mixing and slow propulsion

Question 51

for LI (colon) motility whats Mass movements?

Answer 51

3 - 4 time per day | Force faeces into rectum

Question 52

for LI (colon) motility whats Defaecation?

Answer 52

Reflex responses / Voluntary control | Brain / brain stem / spinal

Question 53

whats formed after colectomy

Answer 53

ileostomy