GIT - Lecture 2 Flashcards

1
Q

Endocrine secretions move into the…

A

blood

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2
Q

Exocrine secretions move into the…

A

lumen of the gut

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3
Q

ANS – “modulates” ENS activity via

A

LONG, EXTRINSIC REFLEXES

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4
Q

ENS regulates GIT via

A

ANS – “modulates” ENS activity via LONG, EXTRINSIC REFLEXES – synaptic connections with ENS neuronsSHORT, INTRAMURAL REFLEXES

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5
Q

What causes activation of the ANS?

A

signals at the level of the gut that send sensory afferents to the CNS

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6
Q

What is the pathway of long extrinsic reflexes?

A
  1. chemoreceptors, osmoreceptors, mechanoreceptors
  2. afferent neurons
  3. central nervous system
  4. efferent autonomic neurons (S or PS)
  5. nerve plexus
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7
Q

Where do efferent autonomic neurons synapse?

A

nerve plexus

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8
Q

Where do long extrinsic reflexes happen?

A

outside the gut wall

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9
Q

What are 2 direct ways we can activate the ANS?

A
  1. sight, smell, taste of food
  2. emotional state
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10
Q

The ___ modulates the activity of the ENS.

A

ANS

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11
Q

Parasympathetic is ___, whereas sympathetic is ___.

A

excitatory, inhibitory

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12
Q

Parasympathetic may also ___ inhibitory neurons.

A

excite

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13
Q

Sympathetic may also ___ inhibitory neurons.

A

inhibit

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14
Q

The activities of the GIT are integrated for high functional efficiency by which 2 mechanisms?

A

neural and hormonal mechanisms

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15
Q

What do non-GIT hormones influence?

A

growth and development of GIT

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16
Q

What do GIT hormones influence?

A

activities outside the GIT

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17
Q

What is released by glands in the stomach during fasting?

A

ghrelin

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18
Q

What does ghrelin activate?

A

hypothalamic “feeding centre”

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19
Q

What does ghrelin stimulate?

A

hunger and increases apetite

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20
Q

What is released by fat cells with overeating?

A

leptin

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21
Q

What does leptin activate?

A

hypothalamic “feeding centre”

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22
Q

What does leptin induce?

A

satiety and decreases apetite

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23
Q

What is DES?

A

diffuse endocrine system

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24
Q

Where is the DES scattered?

A

among cells in the mucosa

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25
What is the largest, most diverse endocrine system in the body?
DES
26
What are the 5 important GI hormones?
- gastrin - CCK - secretin - GIP - VIP
27
What are the 3 different modes of hormone regulation?
autocrine, paracrine and endocrine effects
28
What is the autocrine effect?
the hormone released by an endocrine cells have effects on cells that release that hormone
29
What is the paracrine effect?
the hormone released by paracrine cells have effects on nearby cell
30
What is the endocrine effect?
the hormone released by the endocrine cells move through the capillary and have effects on target tissues
31
What are GIT regulatory hormones classified as?
peptides
32
Where are GIT regulatory hormones released from? Where do they go?
mucosa into portal blood
33
How do GIT regulatory hormones go to portal blood?
through the hepatic portal vein
34
What is the pathway of GIT regulatory hormones?
1. mucosa 2. portal blood 3. liver 4. heart 5. systemic circulation 6. target cells
35
What are the 2 targets of GIT regulatory hormones?
excitatory and inhibitory
36
What do GIT regulatory hormones interact with?
one another and with neurotransmitters
37
What are the 2 effects that GIT regulatory hormones have?
1. synergistic 2. antagonistic
38
What happens during motility?
propulsion and physical breakdown
39
Which layer of the GIT is important during motility?
muscularis externa (longitudinal and circular fibers)
40
What contributes to variations of flow in the GIT?
1. gradients of pressure 2. variations in resistance
41
What creates gradients of pressure in the GIT?
coordinated contractions of muscular elements in the GIT wall
42
What are the 2 types of motility that the circular muscles produce?
segmentation and peristalsis
43
What is segmentation good for?
mixing
44
What is peristalsis good for?
propulsion
45
What is flow in the GIT mainly driven by?
gradients in pressure
46
Normally, is there resistance in the GIT?
there is little to none
47
Why are sphincters closed at rest?
to prevent the contents moving from one part of the GIT to another
48
What would happen if the lower esophageal sphincter was open?
there will be stomach acid moving to the esophagus which could lead to heartburn
49
What kind of flow is in the GIT?
slow
50
What direction does food move in the GIT?
aboral direction
51
What does aboral mean?
food is moving away from the mouth
52
Why is there little/no resistance in the GIT?
because the sphincters always open at the appropriate time
53
Why is swallowing highly regulated?
because we don't want food to move up into our nose
54
What is the scientific term for swallowing?
deglutition
55
What are the 4 phases of deglutition?
1. oral 2. pharyngeal 3. esophageal 4. gastric
56
Which phase of deglutition is the only one that is voluntary?
oral
57
What conveys food from the mouth to the esophagus through a process called deglutition?
the pharynx
58
What organ transports food into the stomach?
esophagus
59
What 2 sphincters of the esophagus must be relaxed in order for food to be transported?
the upper and lower esophageal sphincters
60
What happens during the oral phase?
transport of food from the mouth to the pharynx
61
What is a sticky mass of food called?
bolus
62
What closes off the nose during the oral phase so that food doesn't go up to the nose?
the soft palate
63
What closes off the airway when swallowing food?
the epiglottis
64
The voluntary aspect of swallowing happens via what kind of processing?
cortical processing
65
What is activated when you decide you want to swallow?
deglutition center
66
What kind of reflexes is found in the deglutition centre?
involuntary reflexes
67
Where in the brain is the deglutition centre found?
medulla
68
What happens to the pharyngeal receptors during the pharyngeal phase?
they stretch
69
What is the pharynx?
the region where respiratory and digestive tracks cross
70
Why do people who have strokes have trouble swallowing?
because it involves a lot of coordination
71
What happens to the vocal chords in the larynx during the pharyngeal phase?
reflective contraction
72
What happens to the glottis when the larynx closes it?
it becomes closed
73
During the pharyngeal phase, UES ___ and pharyngeal muscle ___.
relaxes, contracts
74
Why do pharyngeal muscles contract?
to push bolus across the relaxed UES into the esophagus
75
What are the steps during the pharyngeal phase?
1. passages to nose, mouth, and trachea blocked 2. apnea 3. UES relaxes 4. pharynx muscles contract
76
What happens to respiration during the pharyngeal phase?
it is briefly inhibited