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Physiology > 3.2 Gastrointestinal Physiology > Flashcards

3.2 Gastrointestinal Physiology Flashcards

1
Q

what are the components of secretion and their function?

A

1) enzymes= digest nutrients and activate other enzymes
2) buffers= adjust pH and enzyme activation
3) fluids= media for digestion/absorption
4) mucus= lubrication and protection against enzymes and acids

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2
Q

mucus is made of?

A

mucopoly= saccharides, water, electrolytes

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3
Q

how much fluid do secretions make? how much do we take in?

A
  • secretions= 7 liters

* we drink= 2 liters

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4
Q

why do we NOT want enzymes in the gut when there is no food?

A

1) digest gut intead
2) requires energy
3) wasteful

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5
Q

neural and hormonal control of secretions are a result of 3 phases (aka stimuli) in stomach/SI. what are they?

A

1) cephalic= brain
2) gastric= stomach
3) intestinal= intestine

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6
Q

describe cephalic phase for secretions

A

sensory receptors and emotion receptors in the brain are stimulated by sights, sounds, smells, tastes, chewing, and emotion
*parietal cells release gastrin while motility increases

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7
Q

describe gastric phase for secretions

A

distension, acidity, AA and peptide in stomach

*CHL, gatrin, and pepsinogen secretion

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8
Q

describe intestinal phase for secretions

A

distension, acidity, osmolarity, fat, CHO, protein in the intestinal tract
*secretin, CCK, GIP, and pancreatic enzyme secretion

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9
Q

what affect does secretin, CCK and GIP have?

A
  • decrease GASTRIC secretions and motility

* increase intestinal secretions and motility (remember I:I)

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10
Q

in most parts of the body, sym and para do opposite things. But what about salivary glands?

A

they do the same thing

  • BOTH stimulate secretion (but with diff neurotransmitters and diff saliva concentration)
  • PARA more important (longer and stronger)
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11
Q

Parasympathetics on neural control of salivation?

preganglionic vs post?

A
  • effects are stonger and longer lasting
  • preganglionic fibers= branches of facial and glossopharyngeal nerves synapse with postganglionic fibers in or near glands (longer)
  • postganglionic fibers terminate on ACINAR cells and ducts (shorter)
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12
Q

Sympathetics on neural control of salivation for AFFERENT input?

A

afferent input from mechano-receptors and taste-buds to salivary nuclei via facial and glossopharyngeal nerves

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13
Q

Sympathetics on neural control of salivation for EFFERENT output?

A

efferent output from salivary nuclei to glands via facial and glosso

  • facial nerves go to submandibular and sublingual glands AND minor glands
  • glossopharyngeal nerves go to parotid glands
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14
Q

facial and glossopharengeal nerves innervate what glands?

A
  • facial nerves go to submandibular and sublingual glands AND minor glands
  • glossopharyngeal nerves go to parotid glands
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15
Q

why is sympathetic neural control of salivation not as important as para?

A

not as strong or long lasting

  • no major defect if lost
  • postganglionic sympathetic fibers come from superior cervical ganglion
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16
Q

3 phases/stimulation for salivation?

A

1) cephalic= brain
2) buccel= cheek
3) gastrointestinal =stomach/SI

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17
Q

cephalic stimulation for salivation?

A

involve sensory input from higher brain center that cause salivation
*conditioning like Pavlov dogs

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18
Q

buccal stimulation for salivation?

A

involve both chemical and mechanical stimuli in mouth

*sensory input conveyed via afferent fibers of facial and glossopharyngeal nerves

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19
Q

gastrointestinal stimulation for salivation?

A

involve both chemical and mechanical stimuli in GI tract

*sensory input conveyed from GI via vagal afferents (irritants, bowel blockages –> salivation; prier to vomiting)

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20
Q

mechano vs chemical stimuli in mouth

A
  • mechano= something IS there

* chemical= tells us WHAT is there (also gives indication of what type of saliva will come)

21
Q

what are the 2 types of salivary glands?

A

major and minor

22
Q

are salivary glands exocrine or endocrine?

A

exocrine glands

23
Q

define exocrine glands?

does acidic foods affect this?

A
  • secrete products into ducts that open onto some internal or external surface
  • basal secretion rate: 0.4 ml/min (stimulation via acidic foods: 4-8 m/min= 20x faster)
24
Q

endocrine vs exocrine

A
  • endocrine= secrete directly into blood (GIP, CCK, Secretin)
  • exocrine= secret into duct system and THEN into circulation (saliva)
25
Q

why do we need a great supply of blood to make saliva?

A

bc just about everything in saliva comes from blood

we take stuff out of blood, move it across cells, make osmotic load and draw out water

26
Q

what are the major salivary glands?

A

1) parotids
2) submandibular (aka submaxillaries)
3) sublinguals -directly below tongue

27
Q

do major or minor glands produce more saliva?

A

major glands produce 90-95% of saliva

28
Q

name a few minor salivary glands?

A 
lingual
labial
palatine
buccal
*located throughout mouth, share duct systems, 5-10% of saliva produced
29
Q

what is a ‘secretory unit’ from a gland structure?

A

acinus cells AND duct system

30
Q

order gland structure and cells?

A

1) acinus -make stuff
2) intercalated duct cells -acinar cell wanna-bes
3) granular tubules
4) striated duct
5) excretory duct - carries secretions to oral cavity

31
Q

define acinus

A

a cluster of acinar cells, which produce most of the fluid and macromolecuels of saliva

32
Q

what are the two types of acinar cells?

A

1) serous
- –watery, contain PTYLIN, and RICH IN PROTEINS
2) mucous
- –slimey, secrete glycoproteins mucins and glycopolysaccharides

33
Q

parotid glands made of what type of cells?

A

serous acinar cell

34
Q

submandibulars made of what type of cells?

A

serous AND mucous acinar cells

35
Q

sublingual glands made of what type of cells?

A

serous AND mucous acinar cells

36
Q

minor glands made of what type of cells?

A

MOSTLY muscous acinar cell; but is technically mixed; share duct

37
Q

what does the duct system do?

A

1) carries acinar cells to the mouth (passageway)

2) alters secretions (saliva that enters oral cavity isn’t the same as what was produced by acinar cells)

38
Q

what are the 3 types of duct cells? and what do they drain into?

A

1) intercalated
- - drain into striated ducts
2) striated
- - drain into excretory ducts
3) excretory
- - drain into mouth

39
Q

Acinar cells synthesis and package?
transport what ions?
produce?

A
  • syn and package proteins
  • transport Na+, K+, Cl-, HCO3-
  • move water via osmosis
  • produce ISOTONIC saliva
40
Q

what type of saliva do acinar cell produce? means what?

A

produce ISOTONIC saliva

*means about the same ion concentration as plasma

41
Q

are duct cells considered to ‘make’ saliva?

A

yes… becuz they alter it

42
Q

duct cells reabsorb and secrete what?

produce what type of secretion?

A
  • reabsorb Na+ and Cl-
  • secrete HCO3- and K+
  • produce HYPOTONIC secretion rich in HCO3-
43
Q

intercalated duct cells are most similar to what other cells?

A

acinar cells in structure and function than to other duct cells

44
Q

what type of model is saliva production?

A

two stage

45
Q

describe the two stage model of saliva production?

***very important

A

1) acinar cells and intercalated duct cells secrete ISOTONIC primary saliva
2) striated and exretory duct cells extract Na+/Cl- and ADD HCO3-/K+ making a HYPOTONIC secondary secretion

46
Q

why are tear and sweat glands so salty?

A

they DO NOT have duct cell reclaim of Na+ like salivary glands do

47
Q

what cells make primary and secondary saliva?

A
  • primary= acinar and intercalated duct cells

* secondary= striated duct and excretory duct cells

48
Q

difference in pH of primary and secondary saliva?

A
  • primary= isotonic

* secondary= hypotonic

49
Q

what is Heidenhain’s Law?

A

the FASTER the salivary flow rate the MORE ISOTONIC saliva will be
*the longer saliva is in duct system, then the more Na+ the duct cells can reabsorb

Physiology (42 decks)

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