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Gastrointestinal > 6. Motility of the GI Tract > Flashcards

6. Motility of the GI Tract Flashcards

(53 cards)

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1
Q

3 phases of DEGLUTITION/SWALLOWING

A
  1. ORAL
  2. PHARYNGEAL
  3. OESOPHAGUS
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2
Q

is PHASE 1 (ORAL) of DEGLUTITION voluntary or involuntary

A

VOLUNTARY

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3
Q

is PHASE 2 (PHARYNGEAL) of DEGLUTITION voluntary or involuntary

A

INVOLUNTARY

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4
Q

is PHASE 3 (OESOPHAGEAL) of DEGLUTITION voluntary or involuntary

A

INVOLUNTARY

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5
Q

what happens in PHASE 1 DEGLUTITION

A

ORAL:
- Food BOLUS formed by MASTICATION
- TONGUE moves UP and BACKWARD

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6
Q

Muscles in TONGUE are CONTROLLED by which CRANIAL NERVE

A

12 - HYPOGLOSSAL

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7
Q

what happens in PHASE II DEGLUTITION

A

PHARYNGEAL:
- SOFT PALATE RISES
- EPIGLOTTIS CLOSES (down)
- PHARYNX CONTRACTS
- UPPER OESOPHAGEAL SPHINCTER (UOS) RELAXES (opens oesophagus)

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8
Q

RECEPTORS of the PHARYNX that detect the food and send signals to Brain Stem to UOS to RELAX (and all actions of pharyngeal phase)

A

TACTILE/DISTENSION RECEPTORS

  • MECHANORECEPTORS
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9
Q

What happens in PHASE III DEGLUTITION

A

OESOPHAGEAL:

  • UOS CONTRACTS (reflex after food enters stomach, so oesophagus closed again to prevent gastric reflux)
  • Bolus moved by PERISTALSIS
  • LOWER OESOPHAGEAL SPHINCTER (LOS) RELAXES and opens (LOS is smooth muscle)
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10
Q

CRURAL DIAPHRAGM role in DEGLUTITION

A
  • (skeletal) MUSCLE that SURROUNDS LOS (sling around it)

CONTRACTS to OPEN, so food can pass into stomach

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11
Q

REFLEXES and NERVES used to OPEN LOS

A

VAGAL REFLEX and VAGAL PHRENIC REFLEX

VAGUS NERVE - VAGAL AFFERENT to BRAIN STEM
VAGAL EFFERENT to LOS

PHRENIC NERVE to CRURAL DIAPHRAGM

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12
Q

how does the PHRENIC NERVE stimulate the CRURAL DIAPHRAGM to CONTRACT and OPEN the LOS

A
  • STIMULATES ACETYLCHOLINE RELEASE
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13
Q

how do VAGAL EFFERENT FIBRES cause RELAXATION of LOS

A
  • VAGAL EXCITORY FIBRES (VEF) switched OFF
    (no Ach release)
  • VAGAL INHIBITORY FIBRES (VIF) switched ON
    -> release VASOACTIVE INTESTINAL POLYPEPTIDE (VIP) and NITRIC OXIDE (NO)

therefore relax LOS

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14
Q

to RELAX LOS, VAGAL INHIBITORY FIBRES are SWITCHED ON and RELEASE:

A

VIP (VASOACTIVE INTESTINAL POLYPEPTIDE)
& NO (NITRIC OXIDE)

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15
Q

what causes PERISTALTIC CONTRACTIONS in the STOMACH

A

PACEMAKER ZONE

  • in FUNDIC region (fundus)
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16
Q

order of GASTRIC MOTILITY (how food passes in stomach)

A
  1. FUNDUS : PACEMAKER ZONE for PERISTALSIS - mix and churn
  2. CORPUS (body) : ACID SECRETIONS
  3. ANTRUM : MUSCULAR PUMP - contracts vigorously to further mix
  4. PYLORIC SPHINCTER: OPENS when PRESSURE in PYLORIS INCREASES

-> food to duodenum
4.

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17
Q

the ANTRUM of the STOMACH has what ROLE

A

MUSCULAR PUMP
- contracts vigorously to further mix food before it goes to small intestine

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18
Q

the CORPUS (body) of the STOMACH has what ROLE

A

ACID SECRETIONS

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19
Q

where is the PACEMAKER ZONE in the STOMACH

A

FUNDUS

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20
Q

what is RETROPULSION in the STOMACH

A

when PYLORIC SPHINCTER is still CLOSED, food PUSHED BACK and there is MORE MIXING

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21
Q

which part of the STOMACH acts as a MUSCULAR PUMP

A

ANTRUM

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22
Q

what are the PACEMAKERS of the GUT

Study These Flashcards
A

INTERSTITIAL CELLS of CAJAL

(ICC CELL NETWORK)

(in the circular and longitudinal muscle layers of gut wall and submucosa)
(have gap junctions)

23
Q

what do the INTERSTITIAL CELLS of CAJAL allow for in the GUT

Study These Flashcards
A

SLOW WAVE MECHANISM conducted to smooth muscle
-> SMOOTH MUSCLE CONTRACTION

(ACTION POTENTIALS)

24
Q

what causes DEPOLARIATION of membranes and hence ACTION POTENTIALS in the GUT (depolarisation pacemaker currents)

Study These Flashcards
A

CALCIUM INFLUX (Ca2+)

by L-TYPE CA2+ CHANNELS

25
where does the BASAL ELECTRICAL RYTHM (BER) of the GUT originate and what happens to result in CONTRACTIONS
- In ICC - when SPIKE POTENTIALS occur at MAXIMUM DEPOLARISATION of BER due to Ca2+ ENTRY -> results in contraction
26
what causes HYPERPOLARISATION/REPOLARISATION in BER
OUTWARD K+ CURRENTS (delayed)
27
ACTION POTENTIAL FREQUENCY can be INCREASED and DECREASED by which NEUROTRANSMITTERS
ACH - INCREASE NORADRENALINE - DECREASE
28
I
29
what are the 4 PHASES of the MIGRATING MYOELECTRIC COMPLEX (MMC)
I - QUIESCENCE II - RANDOM CONTRACTIONS III - BURST of CONTRACTIONS (MAXIMUM AMPLITUDE and DURATION) IV - RAPID DECREASE of CONTRACTIONS
30
Where does MMC Initiate / Occur
79% in ANTRUM of STOMACH (initiates here) 29% in DUODENUM
31
how much of MMC Occurs in the DUODENUM
29%
32
2 INTESTINAL MOVEMENTS that take place to move food
1. SEGMENTATION 2. PERISTALTIC REFLEX
33
what is SEGMENTATION in INTESTINES
ALTERNATE CONTRACTION and RELAXATION of ADJACENT SEGMENTS Back and forth movement - causes thorough MIXING of food contents fine digestion into SMALLER components that can be ABSORBED
34
as BOLUS passed through INTESTINES what is it RECOGNISED BY to trigger PERISTALSIS
DISTENSION / STRETCH ->RELEASES 5-HT (5-hydroxytryptamine) (serotonin)
35
when DISTENSION/STRETCH recognises BOLUS and RELEASES 5-HT what is the SIGNAL PATHWAY
signals in Intrinsic PRIMARY AFFERENT NEURONS (IPAN) (TK/ACH) -> along INTERNEURONES (ACH) EITHER -> EXCITORY MOTOR NEURONES (ACH/TK) OR -> INHIBITORY MOTOR NEURONES (VIP/NO)
36
how are the 2 ends of the BOLUS described as it passes through INTESTINES
ORAD (BEHIND, Mouth end) CAUDAD (IN FRONT, Tail end)
37
which END of the BOLUS CONTRACTS in INTESTINES
ORAD
38
what happens in CAUDAL END of the BOLUS in the INTESTINES
RELAXATION of CIRCULAR SMOOTH MUSCLE
39
what stimulates ASCENDING CONTRACTION of CIRCULAR SMOOTH MUSCLE in the ORAD end of the INTESTINES (behind bolus)
PRIMARY AFFERENT NEURONES -> INTERNEURONES (RELEASE ACH) -> EXCITORY MOTOR NEURONES RELEASE ACH / TK (tachykinin) causes contraction
40
what do EXCITORY MOTOR NEURONES RELEASE to cause CONTRACTION of INTESTINES SMOOTH MUSCLE (circular)
ACh / TK
41
what causes DESCENDING RELAXATION of the CIRCULAR SMOOTH MUSCLE at the CAUDAD end of INTESTINES (in front of bolus)
PRIMARY AFFERENT NEURONES -> INTERNEURONES (ACH) -> INHIBITORY MOTOR NEURONES RELEASE VIP (vasoactive intestinal polypeptide) / NO (nitric oxide) - RELAXING FACTORS
42
what RELAXING FACTORS are RELEASED by INHIBITORY MOTOR NEURONES to cause RELAXATION of INTESTINES SMOOTH MUSCLE in front of bolus
VIP / NO
43
PERISTALTIC REFLEX in INTESTINES has 2 actions
- ASCENDING CONTRACTION - DESCENDING RELAXATION
44
DISTENSTION / STRETCH in the INTESTINES as BOLUS passes causes RELEASE of:
5-HT (SEROTONIN)
45
name of the SEGMENTATION action in the LARGE INTESTINE
HAUSTRATION - mixing, absorption and stool formation
46
Strong PERISTALTIC WAVES SHIFT the INDIGESTIBLE MATERIAL in the COLON (LARGE INTESTINE) TOWARDS RECTUM. called:
MASS MOVEMENTS
47
MASS MOVEMENTS in the COLON are STIMULATED by
FOOD IN STOMACH and food in DUODENUM (new food entering)
48
STRETCH of the RECTUM causes:
REFLEX: COLON CONTRACTS to PUSH more indigestible material, RECTUM CONTRACTS INCREASE PRESSURE INTERNAL ANAL SPHINCTER RELAXES
49
RELEASE of what RELAXING FACTORS cause the INTERNAL ANAL SPHINCTER to RELAX
VIP (Vasoactive Intestinal Polypeptide) & ATP
50
EXTERNAL ANAL SPHINCTER is under what CONTROL
SOMATIC - VOLUNTARY (striated muscle) - RELAXES by PUDENDAL NERVE
51
MASS MOVEMENTS initiate what REFLEX
DEFAECATION REFLEX
52
what NERVE CONTROLS EXTERNAL ANAL SPHINCTER
PUDENDAL NERVE (S2-S4)
53
how is MOTILITY LEVEL in the COLON (LI) and RECTUM compared to SMALL INTESTINE
LOWER MOTILITY (4-6 waves per min)

Gastrointestinal (19 decks)

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