anatomy of the GI tract Flashcards

1
Q

what regulates hunger and satiety

A
  • plasma glucose levels
  • hormones
  • stretch receptors in GI tract
  • stress, body temperature, food palatability
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2
Q

what hormones regulate hunger and satiety

A

leptin (produces in adipose tissue)
ghrelin (produces in stomach)
insulin (produces in pancreas)
glucagon (produces in pancreas)

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3
Q

what happens in a well fed/absorptive state

A
  • storage of fuels and protein synthesis
  • glycogen synthesis
  • insulin secretion - enhances glucose uptake and metabolism in cells, thereby reducing blood glucose
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4
Q

what happens in a post absorptive state

A
  1. glucagon - glycogen breakdown
  2. gluconeogenesis
  3. ketones produced for energy during fast
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5
Q

what happens when hungry

A

decrease in glucose, fat an protein.
signals in appetite centre in hypothalamus. triggers eating

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6
Q

what happens when full

A

increase of glucose, fat, protein and leptin
signals in satiety centre in hypothalamus.
stops hunger, triggers digestion

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7
Q

what happens to gastric emptying when we eat larger amounts of food

A
  • longer digestive phase
  • larger amounts of food empty slowly and then it speeds up
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8
Q

what controls gastric emptying

A

nutrition density

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9
Q

what does fat in the duodenum cause

A

the fundus to relax which lowers intragastric pressure

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10
Q

what do high fat meals do

A

influence the feeling of fullness for longer than a low fat meal of same energy content.
this influences intake at next meal and prolongs elevation of pH in stomach

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11
Q

what is cns composed of

A

brain and spinal cord

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12
Q

what does the peripheral nervous system do

A

connects CNS to limbs and organs

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13
Q

what is the autonomic nervous system composed of

A

division of PNS influencing function of organs

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14
Q

what is the enteric system composed of

A

the intrinsic nervous system of your GI tract

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15
Q

how are CNS and ENS connected

A

via the vagus nerve that runs from your brain stem down to your abdomen

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16
Q

what do the gut bacteria use the vagus nerve for

A

to transmit info to the brain

17
Q

are neurons present in the brain and gut

18
Q

where is serotonin prouced

A

brain and gut

19
Q

what do afferent neurons AKA sensory receptor neurons do

A

they carry nerve impulses away from receptors or sense organs towards the CNS

20
Q

what do efferent nerves aka motor/effector neurons do

A

they carry nerve impulses away from the CNS to effectors such as muscles/glands

21
Q

where is the enteric nervous system found

A

within the wall of the GI tract from oesophagus to anus

22
Q

what is the motor in function influencing muscle activity

A

the myenteric plexus

23
Q

what does the submucosal plexus do

A

it receives signals from epithelium and stretch receptors influencing secretory activity

24
Q

how is the ens subject to regulation via the pns and sns

A

fibres from both can synapse with neurones in the ens

25
how are nerve plexuses linked to the CNS by fibres activated
- stretch - chemical stimulation
26
what efferent innervation from the ANS does the ENS receive
- parasympathetic input (rest and digest) stimulates gut motility and secretory activity - sympathetic nerves (fight and flight) cause presynaptic inhibition of parasympathetic-induced contraction
27
what does segmentation in the small intestine allow
the mixing of food
28
what does peristalsis in the small intestine allow
the propulsion of food along the tract
29
what is the ideal gut transit time for food
anywhere between 12 and 48 hours
30
what happens if gut transit time is too fast
diarrhoea absorption of nutrients from food is affected
31
what happens if gut transit time is too slow
constipation can result in poor gut health
32
why do some drugs have side effects and what can this impact
due to their non-specific targeting, can impact drug transit time
33
examples of drugs that can cause constipation
- antacids - anticholinergics - antihypertensives
34
how can loperamide affect transit time
it works through actions on the myenteric plexus which decreases peristalsis