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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
why do we need a great supply of blood to make saliva?
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
what are the major salivary glands?
1) parotids 2) submandibular (aka submaxillaries) 3) sublinguals -directly below tongue
27
do major or minor glands produce more saliva?
major glands produce 90-95% of saliva
28
name a few minor salivary glands?
``` lingual labial palatine buccal *located throughout mouth, share duct systems, 5-10% of saliva produced ```
29
what is a 'secretory unit' from a gland structure?
acinus cells AND duct system
30
order gland structure and cells?
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
define acinus
a cluster of acinar cells, which produce most of the fluid and macromolecuels of saliva
32
what are the two types of acinar cells?
1) serous - --watery, contain PTYLIN, and RICH IN PROTEINS 2) mucous - --slimey, secrete glycoproteins mucins and glycopolysaccharides
33
parotid glands made of what type of cells?
serous acinar cell
34
submandibulars made of what type of cells?
serous AND mucous acinar cells
35
sublingual glands made of what type of cells?
serous AND mucous acinar cells
36
minor glands made of what type of cells?
MOSTLY muscous acinar cell; but is technically mixed; share duct
37
what does the duct system do?
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
what are the 3 types of duct cells? and what do they drain into?
1) intercalated - - drain into striated ducts 2) striated - - drain into excretory ducts 3) excretory - - drain into mouth
39
Acinar cells synthesis and package? transport what ions? produce?
* syn and package proteins * transport Na+, K+, Cl-, HCO3- * move water via osmosis * produce ISOTONIC saliva
40
what type of saliva do acinar cell produce? means what?
produce ISOTONIC saliva | *means about the same ion concentration as plasma
41
are duct cells considered to 'make' saliva?
yes... becuz they alter it
42
duct cells reabsorb and secrete what? | produce what type of secretion?
* reabsorb Na+ and Cl- * secrete HCO3- and K+ * produce HYPOTONIC secretion rich in HCO3-
43
intercalated duct cells are most similar to what other cells?
acinar cells in structure and function than to other duct cells
44
what type of model is saliva production?
two stage
45
describe the two stage model of saliva production? | ***very important
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
why are tear and sweat glands so salty?
they DO NOT have duct cell reclaim of Na+ like salivary glands do
47
what cells make primary and secondary saliva?
* primary= acinar and intercalated duct cells | * secondary= striated duct and excretory duct cells
48
difference in pH of primary and secondary saliva?
* primary= isotonic | * secondary= hypotonic
49
what is Heidenhain's Law?
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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