03b: GI Motility Flashcards

1
Q

There are two nerve plexi in GI tract. The myenteric plexus is in (X) tissue layer (be specific). Where is the second?

A

X = muscularis externa (between inner circular and outer long muscle layers)

Submucus nerve plexus in submucosa layer

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2
Q

Mastication’s purpose is to (increase/decrease) (X) of food.It is under (voluntary/involuntary) control.

A

Increase;
X = exposed surface area (to secretions)

Initially voluntary, but rhythmicity is reflexively maintained

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3
Q

What’s deglutition?

A

Transport/propulsion of bolus from mouth to stomach

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4
Q

Precise orchestration of movements of several structures is important in deglutition. List some nerves that are important here.

A
  1. CN VII, IX, X, XII;

2. Lingual and medial pterygoid nerves

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5
Q

Deglutition occurs in which phases?

A
  1. Oral
  2. Pharyngeal
  3. Esophageal
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6
Q

T/F: Initiation and continuation of swallowing is voluntary.

A

False - initiation is, but then swallowing is reflexly controlled

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7
Q

During swallowing, aka (X) phase of deglutition, (Y) closes (Z) so that food doesn’t go into nose.

A
X = oral
Y = soft palate (elevation)
Z = nasopharynx
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8
Q

During (X) phase of deglutition, UES opens to allow food into (Y). At this phase, it’s important to block food from entering which space(s)?

A
X = pharyngeal
Y = esophagus

Airways

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9
Q

Passage of bolus into airways is prevented via which mechanisms?

A
  1. Larynx elevated (glottis closed)
  2. Epiglottis tilts downward
  3. Respiration stops briefly
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10
Q

During (X) phase of deglutition, peristalsis is important for propelling food toward (UES/LES).

A

X = esophageal

LES

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11
Q

Normally, (X) (contraction/relaxation) prevents reflux of gastric contents.

A

X = LES

Contraction

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12
Q

The velocity of peristaltic wave is normally (X).

A

X = 3-5 cm/s

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13
Q

T/F: Liquids can bypass the peristaltic wave due to gravity.

A

Ture

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14
Q

The primary esophageal peristalsis is associated with (X). The secondary esophageal peristalsis is associated with (Y).

A
X = original swallowing 
Y = residual bolus or reflux
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15
Q

Control of deglutition is coordinated by swallowing center in (X) part of brain. Sensory afferent inputs via (Y) nerves and efferents via (Z) nerves.

A
X = medulla
Y = CN IX and X
Z = CN X
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16
Q

Initiation of peristalsis in upper portion of esophagus is innervated (directly/indirectly) by (X) nerve.

A

Directly;

X = vagus

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17
Q

T/F: A peristaltic wave, once initiated, can proceed in vagally denervated esophagus.

A

True

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18
Q

In lower 2/3 of esophagus, propagation of bolus (via peristalsis) is principally dependent on (X) nerves.

A

X = plexus of neurons in wall

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19
Q

Innervation of esophagus by (X) is absolutely necessary for proper motility.

A

X = myenteric plexus

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20
Q

LES is under neural control. Excitatory via (X), inhibitory via (Y). Both influenced by (Z).

A
X = Y = myenteric plexus
Z = vagus
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21
Q

T/F: Peristalsis only at lower esophagus will inhibit LES tone (opening of sphincter).

A

False - peristalsis at ANY level of esophagus

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22
Q

Vagus has excitatory influence on myenteric plexus via (X) NT and receptor. And it has inhibitory influence on myenteric plexus via (Y) NT and receptor.

A

Both excit and inhib preganglionic fibers from vagus release ACh and bind nicotinic receptors on myenteric plexus.

It’s the post-gang NT that make a difference

23
Q

Excitatory post-ganglionic fibers of myenteric plexus release (X) transmitter that binds (Y) receptors.

A
X = ACh;
Y = muscarinic
24
Q

Inhibitory post-ganglionic fibers of myenteric plexus release (X) transmitter that binds (Y) receptors.

A
X = NO and VIP (vasoactive intestinal peptide)
Y = no specific receptor..
25
Q

One symptom of pregnancy is gastric reflux/heartburn. This could be attributed to (lower/higher) levels of (X) hormone, which (increases/decreases) (Y).

A

Higher;
X = progesterone
Decreases;
Y = LES tone

26
Q

Immediately after LES relaxation, fundus and body of stomach (contract/relax). Is this neurally mediated?

A

Relax;

Yes - myenteric plexus

27
Q

As stomach fills, it (relaxes/contracts) because the smooth muscle (shortens/lengthens) under mechanical stress. This phenomenon is formally called (X).

A

Relaxes;
Lengthens;
X = stress-relaxation

28
Q

(X) portion of stomach displays periodic peristaltic contractions.

A

X = antrum (distal portion)

29
Q

T/F: When the stomach is empty, contractions at the antrum never occur.

A

False - some contraction occasionally

30
Q

The (X), located in (Y) part of stomach, initiate(s) “slow wave” depolarizations that are propagated toward (Z) part of stomach.

A
X = pacemaker (interstitial cells of Cajal)
Y = middle of greater curvature
Z = pyloric sphincter
31
Q

BER (basic electrical rhythm) of stomach is fired at frequency of (X). The activity can be observed in (fundus/body/antrum) of stomach.

A

X = 3-4/min

Body and antrum

32
Q

The BER is conducted to and propagated by cells within (X). It defines which properties of peristaltic contractions?

A

X = smooth muscle (NOT myenteric plexus)

Frequency and direction

33
Q

T/F: Slow wave depolarization associated with BER are subthreshold oscillations.

A

True

34
Q

T/F: During the fed state, initiation of BER results in contraction.

A

False - AP “spikes” bring BER depolarizations to threshold

35
Q

In smooth muscle, the (X) activity determines the amount of tension developed.

A

X = frequency of AP spikes

36
Q

T/F: Though distension doesn’t affect BER frequency, vagal activity does.

A

False - neither do

37
Q

Vagal activity will (increase/decrease) (velocity/tension) of smooth muscle peristalsis.

A

Increase;

Tension (AP spike frequency)

38
Q

Gastrin is (hormone/NT) that triggers (increase/decrease) in (BER/spike activity). You’d expect this to correspond to increased (X) transmitter release.

A

Hormone;
Increase;
Spike activity

X = Ach

39
Q

As bolus moves toward pyloric sphincter, the pressure on it (increases/decreases) so that most chyme can move into (X).

A

Increases;
X = back into/remains in stomach

Only smallest particles of chyme enter duodenum

40
Q

What’s the main function of retropulsion of chyme in stomach?

A

Shearing force homogenizes chyme mechanically

41
Q

Distension of duodenum generally (increases/decreases) stomach emptying. This is known as (X) reflex.

A

Decreases;

X = entero-gastric

42
Q

Homogenization of chyme in small intestine is carried out by (X)-like segmentation contractions. Does peristalsis occur at all?

A

X = ring (annular)

Only locally, if at all

43
Q

The BER in duodenum is (X) and in ileum is (Y).

A
X = 12/min
Y = 8/min
44
Q

T/F: The BER is only found in the stomach.

A

False - though in other parts of GI tract, BER frequency is different

45
Q

MCC (Migrating myoelectrical complex) is the phenomenon when:

A

GI tract undergoes intense peristaltic contractions every 80-90 min during inter-digestive periods

46
Q

The housekeeping role of GI tract is left to (X). This allows sweeping of residual food particles, secretions, and bacteria out of tract.

A

X = MCC (Migrating myoelectrical complex)

47
Q

Abdominal gurgling is attributed to (X).

A

X = MCC (Migrating myoelectrical complex)

48
Q

T/F: Unlike BER, MCC of stomach is coupled to that of intestine.

A

True

49
Q

Residual, (digested/undigested) chyme enters large intestine via (X), which is normally (open/closed) and is under control of (Y).

A

Undigested;
X = ileocecal valve
Closed;
Y = myenteric plexus

50
Q

Contraction of ileum near ileocecal sphincter (contracts/relaxes) it, as does gastric activity. This is referred to as (X) reflex.

A

Relaxes;

X = gastro-ileal

51
Q

Distention of cecum (relaxes/contracts) ileocecal valve.

A

Contracts

52
Q

List the two dominant types of contraction that occur in colon

A
  1. Annular constrictions

2. Peristalsis

53
Q

(X) contraction type in colon leads to sacculations known as (Y), which slice through fecal material.

A
X = annular
Y = haustra
54
Q

Segmental contraction of rectum tends to propel contents (antero/retro)grade into (X) space. Thus, rectum is usually (empty/full).

A

Retrograde;
X = sigmoid colon
Empty