Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

MONOGASTRIC GI > 4.2 – Gastric Motility > Flashcards

4.2 – Gastric Motility Flashcards

1
Q

Motor function of the stomach:

A

-mix and store food
-initiate protein and fat digestion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the 4 anatomical regions of a ‘single compartment stomach’?

A

-fundus
-corpus (body) cardia
-antrum
-pyloric
*some discrepancies and inconsistences

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are the functional regions of the stomach?

A

-proximal
-distal
*separated by pacemaker band

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Fundic region in cat or dog:

A

-difficult to define unless in a well-fed state

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Differences between the stomach regions:

A

-variation in acid secretion not related to anatomical differences
-glandular and non-glandular tissues are variable across species

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the major protection against erosion by acid?

A

-mucous

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is gastric acidity of different species:

A

-humans fasting: 1.7
-dogs: 6.8 (almost neutral)
-rats and mice: 3.9-4.0
*huge differences between species

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are the 2 major functions and functional regions of the stomach?

A
  1. Storage: proximal region
  2. Grinding and sieving: distal region
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Overall, what is the role of the stomach?

A

*deliver food in an acceptable form and amount to the small intestine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Proximal stomach:

A

-weak continuous contractions
-provide gentle propulsion of material into distal stomach
-‘adaptive relaxation’
-minimal mixing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

‘adaptive relaxation’ of proximal stomach:

A

-enlargement
-especially in carnivores
-can fill and enlarge without increasing pressure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Distal stomach (antrum), intense slow wave activity steps:

A

-waves of peristalsis begins at junction between proximal and distal areas
>moves towards pylorus
-as approaches pylorus, it constricts and some ingesta is pushed back
-some finely ground and/or liquefied material is pushed through the pylorus and allowed to enter the duodenum
-between contractions=no gross movements

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Distension of the fundus:

A

-activates contraction
*major driver

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Cajal cells (interstitial cells of Cajal (ICC)) within the fundus during distension:

A

-stretched
>activate a smooth muscle contraction wave
*’pace maker’ cells (3 per minute)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Cajal cells are activated by:

A

-mechanosensitive (stretch)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Cajal cells are modulated by:

A

-ENS
>parasympathetic
>Cl exit and Ca entry

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

‘antral contraction’ of digestive contractions:

A

-contraction wave DOES go all the way through the antrum for a quick opening and closing fo the pylorus
*results in turning over and mixing contents AND a small release of stomach content into the duodenum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

‘mixing contraction’ of digestive contractions:

A

-contraction wave does NOT proceed all the way through the antrum to open the pylorus
-results in turning over and mixing of contents
*contraction wave does not result in relaxation of the pylorus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

The rate of food leaving the stomach ‘must match’ the rate at which:

A

-the food can be digested and absorbed by the small intestine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What regulates emptying of the stomach? (especially liquids)

A

-duodenal receptors responding to the composition of the meal
*water may leave the stomach almost immediately

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

When do digestible solids leave the stomach?

A

-after being reduced to particles ~2-3mm
>half after 2.5hrs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

When do digestible solids leave the stomach?

A

-indigestible solids = >5-7mm
>half after 4hrs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What are other factors that affects gastric emptying?

A

-volume
-osmolarity
-chemical composition
-caloric density (higher=slower)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

‘gastric tunnel’:

A

-along lesser curvature of stomach
-allows the shunting of water to bypass solids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What is the most powerful inhibitor of gastric emptying?

A

-lipids 12 to 18 carbons in length =held back the most

26
Q

Enteroendocrine cells in the upper duodenum release:

A

-cholecystokinin (CCK)

27
Q

When do enteroendocrine cells in the duodenum release CCK?

A

-when they sense the fats or AA that feed back to the stomach via the blood

28
Q

What does CCK do?

A

-inhibits gastric motility
-causes pyloric sphincter to contract more tightly

29
Q

What is the role of fats and proteins vs. CHO in satiety?

A

-CHO: don’t activate CCK=can leave stomach earlier
-fats and proteins: remain in stomach and send signals back to the brain=satiety

30
Q

Gastric emptying of a solid meal:

A

-has a lag time of ~1hr
>protein solution takes longer than glucose solution

31
Q

Liquid vs. Particulate gastric residence time:

A

-liquid leaves fastest
-particulate residence time will depend on particle size and meal ingredient

32
Q

A large volume of food can be accommodated without an increase in:

A

-pressure
*during filling no or minimal contractions

33
Q

Regulation of emptying during digestive period after ‘filling’

A

-phase or slow tonic contractions of fundus
-increased peristalsis to allow mixing
*’tenderized’ food

34
Q

‘tenderized’ food is propelled into:

A

-pylorus by contractions that become forceful in the antrum
>pyloric contractions cause some food to be moved back for more mixing and some into duodenum
*pyloric sphincter and duodenum work in a co-ordinated fashion

35
Q

Pylorus acts as a:

A

-grinder
-filter
*facilitating and inhibiting gastric empty

36
Q

What are the 3 functional parts of the stomach?

A

-pressure pump
-peristaltic pump
-grinder

37
Q

Pressure pump:

A

-fundus and proximal corpus
-tonic
-ICC absent

38
Q

Pressure pump: increased inhibition/decreased excitation

A

-slow gastric emptying

39
Q

Pressure pump: reduced inhibition/increased excitation:

A

-impaired accommodation and fast gastric emptying

40
Q

Peristaltic pump:

A

-distal corpus and proximal antrum
-phasic
-ICC present

41
Q

Peristaltic pump: increased inhibition/decreased excitation

A

-impaired mixing
-slow gastric emptying of solids

42
Q

Peristaltic pump: reduced inhibition/increased excitation:

A

-fast gastric emptying of solids

43
Q

Grinder:

A

-terminal antrum and pyloric sphincter, pylorus
-phasic and tonic
-ICC present
-strong, phasic, nearly simultaneous

44
Q

Grinder: increased inhibition/decreased excitation

A

-impaired grinding
-duodeno-gastric reflux

45
Q

Grinder: reduced inhibition/increased excitation:

A

-outlet obstruction

46
Q

What is the migrating myoelectric complex MMC?

A

-‘special mechanism’ to empty fasting contents and/or larger particles from the stomach to the distal small intestine
-4 phases
*larger particles can not leave the stomach during normal contractions
*interdigestive period

47
Q

What is another term for MMC?

A

-interdigestive motility complex

48
Q

What happens in phase I of MMC?

A

-calm period
-slow waves and no spikes

49
Q

What happens in phase II of MMC?

A

-intermittent spikes
-some smooth muscle contraction

50
Q

What happens in phase III of MMC?

A

-big sweep
-intense burst of spikes with each slow wave=strong contractions
-pyloric sphincter relaxes and strong wave will go over the antrum=forces less digestible material into the duodenum
*both solids and liquids are completely emptied and go RAPIDLY to large intestine!

51
Q

What happens in phase IV of MMC?

A

-inhibition of contractile activity that merges with the next phase of digest period

52
Q

Carnivores MMC:

A

-stopped during feeding
-fed pattern looks like phase II

53
Q

Herbivores MMC:

A

-cyclic pattern is not interrupted during feeding
>some food is always passing through

54
Q

Omnivores MMC:

A

-dependent on diet

55
Q

What controls MMC?

A

-not fully understood
-requires neural and endocrine inputs

56
Q

What mediates inhibition of gastric emptying?

A

-enterogastric reflux (neural mechanism)
-enterogastrone (hormonal mechanism)
*may inhibit emptying when there are hypertonic, acidic or irritating contents in duodenum

57
Q

Mucosa of duodenum vs. gastric mucosa:

A

-mucosa od duodenum is more permeable than the gastric mucosa (less of a barrier function)

58
Q

Enterogastric reflux (neural mechanism):

A

-responding to chemical composition and digesta

59
Q

Enterogastrone (hormonal mechanism):

A

-responding primarily to fat (and AA) in the duodenum (via CCK)

60
Q

Different segments of the stomach are regulated by:

A

-distinct sub-circuits of the inhibitory and excitatory vagal circuits
-nature of smooth muscle (tonic or phasic)
-presence of interstitial cells of Cajal

MONOGASTRIC GI (24 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions