GI Intro To The Struct Of GI tract and motility Flashcards Preview

Physiology > GI Intro To The Struct Of GI tract and motility > Flashcards

Flashcards in GI Intro To The Struct Of GI tract and motility Deck (51):
1

What are the compartments of the ailment are canal separated by

Sphincters

2

What su the motility and what are some types

Mechanical activity mostly involving smooth muscle
( except skeletal muscle at mouth, pharynx, upper oes and external anal sphincter)

Propulsive movements oral to aboral
Mixing movements -
Tonic contractions

3

What are secretion required for

Digestion
Protection

4

What do some sec contain

Water 'borrowed' plasma
Electrolytes - sodium, pottasium, chloride
Organic compounds - bile salts, mucus, enzymes

5

What is digestion

Chemical breakdown by enzyme hydrolysis of complex foodstuffs to smaller absorbable units

6

What is carb digestion usually mediated by and what is it broken down to

Polysacc --> monosacs such as glucose or galactose

7

What is the digestion of proteins mediated by and what are they broken down to

Mediated by proteases, dipeptides
Broken to amino acids, dipeptides see

8

What mediates fat digestion and what is it broken down to

Mediated by lipases
Conv to monoglycerides and free fatty acids

9

What are the layers on the digestive tract wall

Mucosa
Su mucosa
Muscular is external
Serosa

10

What is the mucosal layer

Epi cells
Exocrine cells
Endocrine gland cells
Lamina propria

11

What is in the sub mucosa layer

Connective tissue
Larger blood and lymp vessels
Glands
Myenteric nerve network

12

What is the muscularis external layer

Circular muscle layer
Myentericplexus
Longitudinal muscle layer

13

What is the Serosa layer

Connective tissue
Forms thin and sticky fluid lubricates outer surface

14

What is the gastrointestinal motility largely due to

Activity of smooth muscle (circular, longitudinal layers and muscularis mucosal)

Skeletal muscle imp - mouth, pharynx, upper oes, external anal sphincter

15

What action does the circular and longitudinal muscle do

Circular - lament narrow and longer
Longitudinal- shorter and fatter

16

How are adjacent smooth muscle cells coupled

Via gap junctions whic allow spread of electrical activity

17

How is the rhythm of the GI muscle cells

Intrinsic - enteric su mucosa plexus
Extrinsic autonomic nerves
Numerous hormones sec by endocrine cells of GI tract

18

How does spontaneous electrical activity portray in the intestines

Slow waves - rhythmic patterns of mem depo and repo that spread from cell to cell via gap junctions

19

What does the slow wave activity determine

Maximum frequency, direction and velocity of rythmic contractions

20

What are the slow waves driven by

Pacemaker cells interstitial cells of Cajal

21

Contraction only occurs if the slow waves.....

Amplitude sufficient trigger action potential in smooth muscle

22

Force is related to whatn

Number of action potentails discharged

23

Where are ICC's found

Between longitudinal and circular muscle layers and in the submucosa

24

What do the slow waves determine

The basal electrical rhythm

25

Not all slow waves trigger

Contraction

26

Whether slow wave amplitude aches threshold depends upon

Neural stimuli
Hormonal stimuli
Mechanical stimuli

27

How many slow waves/min are in the
Stomach
Small intestine
Large intestine

Stomach - 3 slow waves
Small intestine - 10-12 waves in duo, 8 in ileum
Large intestine - 8 in proximal colon, 16 distal colon

28

Where are the neurones of the gut found

In ganglia in the Myenteric and submucous plexuses

29

What connects the ganglia of the gut

Interganglionic fibre tracts

30

What is the alternative name for Myenteric and submucous plexuses

Myenteric - auerbachs
Submucous - meissners

31

What dos the enteric nervous system do

Coordinates muscular, secretive and absorptive activities

32

How does the enteric nervous system do what it does

Via
Sensory neurones specialised (mechanorecpe)
Inter neurones (majority, coordinating reflexes)
Effector neurones (excitatory and inhibitory Motor neurones supplying longitudinal and circular smooth muscle layers, sec epi, endocrine cells and blood vessels)

33

What so the parasympathetic innervation of the GI tract

Preganglionic (ACh) synapse in ENS
Excitatory - increased gastric, pans and small intestine sec, blood flow and smooth muscle contraction

Inhibitory - relaxation of some sphincters, receptive relaxation of stomach

34

What is the sympathetic innervation like in the GI tract

Preganglionic fibres (ACh) synapse at prevertebral ganglion
Postganglionic releasing (NA) innervate mainly enteric structures also other structures

Functionally less lmp than parasymp

Inhibitory - decreases motility, secretion and blood flow

35

What is an example of a local reflex

Peristalsis

36

What is an example of a short reflex

Intestino-intestinal inhibitory reflex
Local distension and command adjacent smooth muscle to relax

37

What is an example of a long reflex

Increase gastric activity
Increase propulsive activity in terminal ileum
Food detected and causes contraction of terminal ileum propelled to large intestine

38

What so peristalsis

A wave of contraction that normally proceeds along gut in a aboral direct triggered by distension of gut wall
Contraction behind bolus and relaxation in front

39

What is segmentation

Mixing or churning movements
Rhythmic contractions of the circular muscle layer that mix and divide luminal contents

40

Where does segmentation occur

In small intestine and large intestine in fed state where called haustration

41

What are tonic contractions

Sustained contractions found in the sphincters of the GI tract

42

How many sphincters of the GI tract

6

43

What does a sphincter consist of

Specialised circular general smooth muscle
Are exceptions

44

What do sphincters act as

one way valves maintaining a positive resting pressure relative to two structures (eg oes and stomach)

45

What is the upper esophageal sphincter made of and what does it do

Skeletal and relaxes to allow swallowing and closes during inspiration

46

What does the lower esophageal sphincter do

Relaxes to permit food into stomach
Closes to prevent reflux of gastric contents to esophagous

47

What dos the pyloric sphincter do

Regulates gastric emptying
Usually prevents duodenal gastric reflux

48

What does the illeocecal sphincter do

Regulates the flow of ileum to colon
Distension of ileum opens
Distension of proximal colon closes

49

What so the difference between the internal and external anal sphincters

Internal - smooth muscle
External - skeletal muscle

50

How are the two anal sphincters regulated

By the defecation reflex

51

What is the direction of the food bolus

Oral to aboral