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GI Week 1 > Oral and Esophageal Physiology > Flashcards

Oral and Esophageal Physiology Flashcards

1
Q

What is deglutition?

A

swallowing

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2
Q

What’s in saliva?

A

water
digestive enzymes (amylase, lipase, RNAse, DNAse)
mucins
defence molecules (lysozyme, IgA, lactoferrin, peroxidase, defensins)
growth factors
bicarbonate
sex steroids

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3
Q

Is saliva exocrine or endocrine?

A

mostly exocrine, but some may be secreted into the blood suggesting an endocrine role as well

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4
Q

Is saliva acidic or alkaline? hypertonic or hypotonic?

A

alkaline hypotonic

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5
Q

What cells control saliva flow rate?

A

myoepithelial cells

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6
Q

How does compositoin of saliva differ depending on what gland you’re looking at?

A

parotid is almost entirely serous
submandibular is mixed
sublingual is mainly mucous

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7
Q

What does ionic conentration of saliva depend on ?

A

flow rate

fast rate: saliva resembles plasma with higher HCO3

slow rate: duct has had time to make significant changes in ionic concentration but do not alter volume, so it sticks more HCO3 in exchange for Cl and more H in exhcnage for Na. THis is what makes it hypotonic

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8
Q

What are some stimuli that will trigger saliva production?

A

small, taste, sounds and sights via higher centers

pressure in the mouth

distention, esopahgitis and vomiting fmor lower centers

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9
Q

What are some stimuli that will inhibit saliva production?

A

sleep
fatigue
fear

(inhibit parasympathetics from the medulla)

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10
Q

What NTs does the parasympathetic nervous system act thorugh to increase secretion of saliva?

A

VIP and ACh on muscarinic receptors

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11
Q

What kind of saliva is promoted by parasympathetic stimulation?

A

watery saliva

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12
Q

What are some other things the parasympathetic system will promote in terms of saliva production?

A
  1. increased water saliva secretion
  2. increased enzyme and mucus secreiton
  3. increased rate of bicarb secreiton
  4. stimualtes glandular metabolism and growth
  5. increased blood flow to the gland
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13
Q

What NTs does the sympathetic nervous system work through to increased salivary secretion?

A

norepinephinr on beta1 and alpha1 adrenergic

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14
Q

What type of saliva is promoted by the SNS?

A

viscous saliva

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15
Q

What are some other things the SNS promotes in terms of saliva production?

A
  1. stimualtes secreiton fo enymes and mucous
  2. stimulates glandular metabolism and growth
  3. stimulates contraction of myofibrilblasts
  4. constricts blood vessels and decreases blood flow (this is why the saliva is viscous)
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16
Q

What activates the amylase in saliva? What does amylase do?

A

it’s activated by Cl- and hydrolyzes alpha14 glycosidic linkages in starch to release mono- and disaccharides

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17
Q

What will lingual lipase do?

A

start to break down triglycerides

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18
Q

Under what conditions will the digestive enzymes in saliva be increased?

A

during times of pancreatic insufficiency and neonates - if the pancreas isn’t gonna do it, someone has to…

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19
Q

In very general terms, how does taste happen?

A

taste ligands are dissolved in saliva and bind to recetors on the taste buds, activating G proteins and secondary messengers to trigger release of NTs onto primary sensory neurons

this signals taste to the nucleus tractus solitarius

20
Q

Can you get absorption in the oral cavity?

A

very little nutrient absorption, but some drugs are absorbed buccally or sublingually - good for them because htey can avoid first past metabolism

21
Q

What are some causes of xerostomia?

A

sjogren’s
lots of meds - muscarinic antagonists, decongestants, and antihistamines
head and neck radiation
dehydration
sialolithiasis
nerve damage related to injury or diabetes
postmenopausal hyposalivation

22
Q

What are some consequences of xerostomia?

A

increased risk for opportunistic infections
halitosis due to production of hydrogen sulfide by bacteria and accumulation of dead cells
decrease in oral pH leading ot tooth decay
decrease in tasting ability
problems with speech
dysphagia promoting poor nutrition

23
Q

How can we treat xerostomia?

A

sugar gree gum
artficiial saliva
swich meds
parasympathomimetics like pilocarpine (but avoid due to side effects)

24
Q

What prevents the bolus from entering the nasal cavity?

A

the soft palate lifts up to close off the nasopharynx

25
Q

What are the steps that occur in the oral phase of swallowing?

A
  1. soft palate elevates
  2. the tongue pushes the bolus back to activate the mechanoreceptors
  3. the larynx moves up and forward
  4. the UES is still tonically contracted
26
Q

What happens during the second phase of swallowing?

A
  1. breathing is inhibited as the bolus passes the closed airway
  2. the epiglottix folds down to prevent material from entering the trachea
  3. longitudinal muscles of posterior pharynx contract
  4. relaxation of cricopharygeal muscle leads to opening of distal pharynx and UES
27
Q

Again, what causes the UES to open?

A

relaxation of the cricopharygneal muscle

28
Q

What muscles contract to get the bolus down into the esophagus?

A

the longitudinal muscles of the posterior pharynx

29
Q

What happens during the esophageal phase of swallowing?

A

easy

the food just moves into the esophagus and gets propelled by peristaltic waves

also aided by gravity, but it’s not necessary

30
Q

What occurs in the esophagus associated with swallowing?

A

primary peristalsis, or the esophageal phase

31
Q

What happens to sphincter pressures during a swallow?

A

they’re higher than atmostpheric before and then fall during swallow

32
Q

WHat happens to esophageal pressure as peristalsis occurs?

A

pressure increases as the peristaltic wave sweeps down the esophagus

33
Q

How long may the esophagela phase last?

A

10 seconds

34
Q

What will mechanoreeptors sense to trigger contraction above and relaxation below?

A

distension of the esophagus or changes in pH

35
Q

How does the force and speed change with larger or colder boluses?

A

propelled with greater force, but slower

harder to get them down

36
Q

Describe how the circular and longitudinal muscles differ in their action during peristalsis?

A

circular muscles contract downstream and relax downstream

longitudinal relax upstream and contract downstream

37
Q

What happens if a bolus gets stuck? How does it get down?

A

secondary peristalsis occurs

it’s smooth muscle contraction elicited by distension of esophagus or acid in the esophagus via the enteric neruons

you get a very strong peristaltic wave starting just above the obstruction

38
Q

What are retrograde movements and when do they occur?

A

when thing go back up the other way

eructation, vomiting and regurgitation - they require relaxation of the UES and LES< but DO NOT require additional esophageal movements - the stomach is what creates the upward force

39
Q

What happens with diffuse esophageal spasms?

A

they’re uncorodinated contractions that don’t push food down - can cause a lot of pain and regurgitation

40
Q

What’s the term for painful contractions of the esophagus?

A

nutcracker esophagus

41
Q

What are the things a sword swallower needs to be able to do?

A 
Need to hyperextend neck
Inhibit pharyngeal reflex
Flip epiglottis
Relax upper and lower 
esophageal sphincters
42
Q

What neurons control the LES?

A

enteric plexus of nerves

43
Q

What are some substances that will reduce LES tone?

A 
chocolate
peppermint
caffeine
alcohol
fatty meals
progesterone
isoproterenol
secretin
VIP
NO
Neurotensin
PGE1
CCK
44
Q

What are some substances that will increase LES tone?

A 
protein meal
ACh
phenylephrine
serotonin
gastrin
pancreatic polypeptide
substance P
motilin
Neuropeptide Y
45
Q

What about pregnancy increases risk for GERD?

A

increased progresterone leads to decreased LES tone

46
Q

What’s the baseline loss in achalasia?

A

loss of myenteric ganglion cells, resulting in a loss of VIP and NO, so the LES is always constricted

GI Week 1 (13 decks)

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