Upper GI Tract Structure and Function Flashcards

1
Q

5 main constituents of saliva

A
  1. water
  2. mucins
  3. alpha-amylase
  4. electrolytes
  5. lysozymes
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2
Q

what is the purpose of water in saliva

A

to soften the food and dilute it

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3
Q

purpose of mucins in saliva

A

create mucousy consistency which acts as a lubricant

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4
Q

purpose of alpha-amylase in saliva

A

to breakdown polysaccharides

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5
Q

purpose of electrolytes in saliva

A

to maintain tonicity and pH

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6
Q

purpose of lysozymes in saliva

A

to kill bacteria by cleaving polysaccharides from their cell wall

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7
Q

3 pairs of glands of saliva secretion

A

parotid, submandibular and sublingual

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8
Q

what parasympathetic nerves stimulate salivation

A

facial and glossopharyngeal (VII and IX)

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9
Q

which nervous systems saliva is more watery

A

parasympathetic

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10
Q

which nervous systems saliva has a higher mucus content

A

sympathetic

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11
Q

which nervous systems saliva has a lower amylase content

A

parasympathetic

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12
Q

which nervous system produces a higher volume of mucus

A

parasympathetic

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13
Q

what stimulus acts on the para/symp systems for salivation

A

food in the mouth acting on chemoreceptors and pressure receptors

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14
Q

roughly how long is the oesophagus

A

25cm

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15
Q

four layers of oesophagus wall

A

mucosa, submucosa, muscularis externa and adventitia

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16
Q

what section of the oesophagus has no adventitia

A

abdominal (i.e. below diaphragm)

17
Q

what type of epithelium in the oesophagus

A

stratified squamous

18
Q

how does the muscle of the oesophagus change from top to bottom

A

skeletal in the top 1/3

smooth in the bottom 2/3

19
Q

where is the swallowing control centre

A

in the medulla, close to the respiratory control centre

20
Q

describe the process of swallowing

A

bolus pushed to back of throat by tongue –> pharyngeal reflex triggered –> pharyngeal muscles contract –> nasopharynx close off by soft palate moving up and back –> upper oesophageal spinchter relaxes –> epiglottis covers trachea –> UOS contracts –> perstaltic wave moves bolus through oesophagus –> LOS relaxes –> bolus enters stomach

21
Q

what is the voluntary action of swallowing

A

pushing the bolus to the back of the throat by the tongue

22
Q

what happens to the stomach when the bolus enters it

A

vagal reflexes triggered by the LOS relaxing causes the stomach to relax its smooth muscle

23
Q

how long does the oesophageal phase of swallowing last

A

about 10 seconds

24
Q

how can the stomach change volume without changing pressure

A

because it unpleats its folds in wall (rugae)

25
what is the pH of the stomach
~2
26
additional muscle layer of stomach
oblique
27
how does the oblique muscle layer aid digestion
by 'ringing out' the contents to create more mixing
28
stomach anatomy from top to bottom
LOS --> cardiac region --> fundus --> body --> pyloric region --> pyloric sphincter
29
innermost stomach muscle layer
oblique
30
outermost stomach muscle layer
longitudinal