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Physiology Block III > GI Endocrinology > Flashcards

GI Endocrinology Flashcards

1
Q

Which types of cells SECRETE into the LUMEN?

A

Mucus

Exocrine

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2
Q

Which cells SECRETE into the BLOOD?

A

Endocrine

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3
Q

Which kind of cells SECRETE into the INTERSTITIAL SPACE to affect cells WITHIN the SAME CRYPT?

A

Paracrine

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4
Q

Which kind of cells SECRETE into SYNAPTIC CLEFT?

A

Neuroendocrine

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5
Q

What are the major roles of SALIVARY secretions?

A
  1. moistens and lubricates to facilitate initial breakdown

2. small amt. of digestion with AMYLASE

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6
Q

What part of the Acinar cells are largely enzymatic?

A

Inclusion Bodies

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7
Q

Which cell type modifies ionic concentrations and pH (via HCO3)?

A

Duct Cells

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8
Q

Which branch of the ANS drives increased salivary secretion?

A

PARASYMPATHETIC

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9
Q

How do parasympathetics increase salivary secretion?

A

By increasing flow of blood vessels that supply the salivary gland via DILATION of mAChR.

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10
Q

What effects do sympathetics have on salivary secretion?

A

DECREASE via CONSTRICTION of alpha-1 receptor

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11
Q

What is the optimal pH for salivary amylase?

A

6.8

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12
Q

As saliva flow increases how does its concentration change?

A

Higher tonicity

More alkaline

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13
Q

Where is the location of first SIGNIFICANT digestion?

A

STOMACH

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14
Q

How is PEPSIN activated from PEPSINOGEN?

A

the ACIDIC environment in the stomach (no enzyme needed)

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15
Q

How do gastric cells protect themselves against their own acidic environment?

A

Secrete Mucus which contains bicarb

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16
Q

How does the gastric contents become STERILE?

A

Gastric secretions kill microbes

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17
Q

T/F. No absorption is done in the stomach

A

FALSE - a very SMALL amount

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18
Q

Which area of the stomach is mostly a RESERVOIR, and does NO ABSORPTION, but secretes some MUCUS.

A

Cardiac (fundus)

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19
Q

Which are of the stomach is mostly in charge of developing the ACIDIC ENVIRONMENT?

A

Oxyntic (body)

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20
Q

Which part of the stomach contains PARIETAL cells?

A

Oxyntic

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21
Q

Which part of the stomach contains G & D cells?

A

Pyloric

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22
Q

Which part of the stomach contains CHIEF cells?

A

Oxyntic

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23
Q

Which part of the stomach contains ECL CELLS?

A

Oxyntic

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24
Q

Which parts of the stomach contain MUCUS cells?

A

ALL!

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25
Q

Where does PEPSINOGEN come from?

A

Inclusion bodies of CHIEF cells!

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26
Q

Which cells RELEASE THE ACID (HCl), which controls pH in the stomach?

A

Parietal cells!

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27
Q

G cells secrete what?

A

Gastrin! This drives GASTRIC SECRETIONS and enhances digestive capabilities

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28
Q

What do D cells secrete?

A

SOMATOSTATIN - which slow digestion DOWN

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29
Q

Which stomach cells secrete INTRINSIC FACTOR?

A

Parietal

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30
Q

Which cell is abundant, chief or parietal cells?

A

PARIETAL is 1 in 3

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31
Q

What is the name of the progenitor cells of the gastric mucosa?

A

Neck cells

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32
Q

What do ECL cells secrete?

A

HISTAMINE

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33
Q

How do we increase secretion rate of gastric juices?

A

BY increasing the PROTONS! Add to a very high concentration so is a very ACTIVE PROCESS and requires 2 pumps! (K exchanger and H pump)

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34
Q

Active pumps require lots of energy, there for there is a high concentration of what energy-producer in Parietal cells?

A

MICTOCHONDRIA

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35
Q

The morphology of the PAREITAL CELLS change when they are secreting, how so?

A

Canaliculi fuse to create large H+ chambers (increase SA)

36
Q

What exchanges with bicarb to maintain charge in the cell?

A

Chloride

37
Q

Then when we pump H+ into the stomach lumen its’s followed by Cl to make what?

A

HCl

38
Q

What is the effect of Carbonic Anhydrase INHIBITORS?

A

Blocks source of protons –> DECREASE ACIDITY

39
Q

What effect do we see in the BLOOD as we increase the acidity in the stomach?

A

more BICARB gets set to blood and creates ALKALINE TIDE

40
Q

What organ neutralizes the ALKALINE TIDE?

A

Pancreas

41
Q

What controls the number of channels and pumps in apical membrane?

A

cAMP + Ca

42
Q

What messengers activate the second messenger systems of cAMP + Ca on parietal cells to increase secretion?

A

ACh (NBT) onto M3 –> Ca+
Histamine (from ECL) onto H2 –> cAMP
Gastrin (from G cells) onto CCK-B –> Ca+

43
Q

What has the opposite effect of Gastrin? (Inhibits acid secretion?)

A

CCK

44
Q

What chemical messenger decreases effect (INHIBITS) of Parietal cells?

A

Somatostatin

45
Q

What neural, local and paracrine messengers effects proton secretion?

A

Neural (Vagus) –> ACh
Local –> Gastrin
Paracrine –> ECL & D

46
Q

How does a D cell known when to release somatostatin?

A

takes a pH sampling at pylorus and when acidic enough starts producing

47
Q

What protein is the target of somatostatin to decrease acid secretion?

A

Gi Protein –> will turn of adenyl cyclase and BLOCK cAMP

48
Q

What else targets the Gi protein beside somatostatin?

A
  • Anti-histamines block histamine initiating cAMP pathway. (H2 receptor blocker drugs)
  • Prostaglandins also block this
49
Q

How do NSAIDs/ASA increase acid secretion?

A

By blocking prostaglandins, it is not able to block H2 blocker from histamine

50
Q

What type of cells secrete mucus to protein epithelial cells?

A

GOBLET cells

51
Q

What are the 3 stages of Gastric Acid Secretion?

A

Cephalic
Gastric
Intestinal

52
Q

What drives the cephalic phase?

A

All NEURAL - vagus gear up secretion of gastrin and HCl (taste, smell, or tactile sensation)

53
Q

What drives the Gastric phase?

A

All SENSORY - mechano and chemo receptors sense when food arrives and enhances acid secretion

54
Q

Both the cephalic and gastric phases influence a parasympathetic reflex via the:

A

Medulla oblongata and vagus nerve

55
Q

In the intestinal phase, chyme enters the duodenum and if it’s ph is below____ then gastric secretion is no longer needed.

A

2 - gets this low with by containing lipids from digestion of fats or has HCl in it

56
Q

What is the NEURAL way that a pH <2 inhibits gastric secretion in the intestinal phase?

A

They cause impulse to go to the MEDULLA OBLONGATA (LONG LOOP) to decrease parasympathetic stimulation of the glands

57
Q

What is a LOCAL way that a pH <2 inhibits gastric secretion in the intestinal phase?

A

Set up local reflexes (SHORT LOOP), via neurons in the wall of the gut, that decreases secretion

58
Q

What is another LOCAL way that pH <2 inhibits gastric secretion in the intestinal phase?

A

They cause release of local hormones that trail to gastric glands and inhibit their secretion

59
Q

What local hormones DECREASE acid secretion?

A

Secretin and CCK

60
Q

What are ENTEROGASTRONES?

A

Secretin, CCK, GIP that are secreted by SI in response to acidity, high fat, high protein, etc as it reaches duodenum. these feeds back to stomach and SLOW GASTRIC EMPTYING.

61
Q

T/F. Control of pepsinogen release parallels agonists for acid secretion.

A

TRUE

62
Q

Which type of nutrient types do pancreatic enzymes help digest?

A

ALL - proteins =protease, CHO = amylase and fat = lipase!

63
Q

Majority of proteases are dominated by:

A

Trypsinogen (most important step)

64
Q

In addition to digestive enzymes, what else does the pancreas secrete?

A

Bicarb to neutralize acid

65
Q

CCK and secretion both decrease acid secretion, but they have different targets in doing so:

A

CCK targets ACINAR cells (enzymes)

Secretin target DUCT cells (bicarb)

66
Q

Which is dominating in the Cephalic phase, CCK or Secretin?

A

CCK

67
Q

Which is dominating the Interstinal phase, CCK or Secretin?

A

Secretin (because worry about neutralizing the acid that just came through)

68
Q

Bicarb secretion is stimulated by:________ , which is potentiated by:_________

A

Secretion, CCK

69
Q

Enzymes secretion is stimulated by:_____, which is potentiated by:_______

A

CCK, Secretin

70
Q

T/F. Presence of both CCK and secreting has more effect on their individual roles than if they were only present alone.

A

True –> They POTENTIATE each other and have more of an effect when both present

71
Q

When the Duct cells are secreting a lot of bicarb into the lumen, where do they get that bicarb from?
What builds up inside the cell as a result

A

created inside by carbonic anhydrase

Chloride

72
Q

What do we do with the excess Cl inside the cell as a result of secreting bicarb?

A

Cystic Fibrosis Transmembrane regulator, is cAMP driven (produced by Secretin binding) and transports Cl out.

73
Q

How does the CHOLERA TOXIN affect the Cl transport out of the cell?

A

INCREASES it by creating a lot of cAMP and increasing the amount of Cl channels. When too much Cl leaves, water follows and get lots of DIARRHEA!!!

74
Q

If a high fat level is sensated in the SI, what does it secrete and how does that help?

A

Will increase CCK secretion, which will stimulate the pancreas to INCREASE ENZYME secretion which will INCREASE DIGESTION of fats and protein in SI

75
Q

Which hormone has a greater effect on the GALLBLADDER?

A

CCK - will contract it

76
Q

CCK stimulates primary secretion of both:

A 
Secretion of bile (GB contraction)
Enzyme release (from pancreas)
77
Q

What is contained in Bile?

A

bile acids –> as glycine and taurine (to be water-soluble)
cholesterol
Phospholipids
lecithin

78
Q

Where is bile secreted into?

A

Canaliculi

79
Q

Where in the SI is bile recycled back to liver?

A

Downstream at the ILEUM

80
Q

CCK causes relaxation of:

A

Sphincter of Oddi, which increase bile flow to duodenum.

81
Q

How does Chrons disease effect the uptake of Bile back to the liver?

A

Effects terminal ileum so interrupts that process and also the B12 binding site is located here

82
Q

In additon to CCK, what else causes contraction of the GB and relaxation of the sphincter of OddI?

A

Neural innvervation via VAGYS and ACh

83
Q

What is the major function of the LI?

A

Reabsorb water

84
Q

What are side effects of Cystic Fibrosis?

A

abnormal function of CFTR chloride channel and exchange of bicarb - so wouldn’t draw water out and mucus is dry and will scar and filled with bacteria.

85
Q

What are the side effects of PANCREATITIS?

A

Retain enzymes and AUTODIGEST

Physiology Block III (8 decks)

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