GI Endocrinology Flashcards
(85 cards)
1
Q
Which types of cells SECRETE into the LUMEN?
A
Mucus
Exocrine
2
Q
Which cells SECRETE into the BLOOD?
A
Endocrine
3
Q
Which kind of cells SECRETE into the INTERSTITIAL SPACE to affect cells WITHIN the SAME CRYPT?
A
Paracrine
4
Q
Which kind of cells SECRETE into SYNAPTIC CLEFT?
A
Neuroendocrine
5
Q
What are the major roles of SALIVARY secretions?
A
- moistens and lubricates to facilitate initial breakdown
2. small amt. of digestion with AMYLASE
6
Q
What part of the Acinar cells are largely enzymatic?
A
Inclusion Bodies
7
Q
Which cell type modifies ionic concentrations and pH (via HCO3)?
A
Duct Cells
8
Q
Which branch of the ANS drives increased salivary secretion?
A
PARASYMPATHETIC
9
Q
How do parasympathetics increase salivary secretion?
A
By increasing flow of blood vessels that supply the salivary gland via DILATION of mAChR.
10
Q
What effects do sympathetics have on salivary secretion?
A
DECREASE via CONSTRICTION of alpha-1 receptor
11
Q
What is the optimal pH for salivary amylase?
A
6.8
12
Q
As saliva flow increases how does its concentration change?
A
Higher tonicity
More alkaline
13
Q
Where is the location of first SIGNIFICANT digestion?
A
STOMACH
14
Q
How is PEPSIN activated from PEPSINOGEN?
A
the ACIDIC environment in the stomach (no enzyme needed)
15
Q
How do gastric cells protect themselves against their own acidic environment?
A
Secrete Mucus which contains bicarb
16
Q
How does the gastric contents become STERILE?
A
Gastric secretions kill microbes
17
Q
T/F. No absorption is done in the stomach
A
FALSE - a very SMALL amount
18
Q
Which area of the stomach is mostly a RESERVOIR, and does NO ABSORPTION, but secretes some MUCUS.
A
Cardiac (fundus)
19
Q
Which are of the stomach is mostly in charge of developing the ACIDIC ENVIRONMENT?
A
Oxyntic (body)
20
Q
Which part of the stomach contains PARIETAL cells?
A
Oxyntic
21
Q
Which part of the stomach contains G & D cells?
A
Pyloric
22
Q
Which part of the stomach contains CHIEF cells?
A
Oxyntic
23
Q
Which part of the stomach contains ECL CELLS?
A
Oxyntic
24
Q
Which parts of the stomach contain MUCUS cells?
A
ALL!
25
Where does PEPSINOGEN come from?
Inclusion bodies of CHIEF cells!
26
Which cells RELEASE THE ACID (HCl), which controls pH in the stomach?
Parietal cells!
27
G cells secrete what?
Gastrin! This drives GASTRIC SECRETIONS and enhances digestive capabilities
28
What do D cells secrete?
SOMATOSTATIN - which slow digestion DOWN
29
Which stomach cells secrete INTRINSIC FACTOR?
Parietal
30
Which cell is abundant, chief or parietal cells?
PARIETAL is 1 in 3
31
What is the name of the progenitor cells of the gastric mucosa?
Neck cells
32
What do ECL cells secrete?
HISTAMINE
33
How do we increase secretion rate of gastric juices?
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)
34
Active pumps require lots of energy, there for there is a high concentration of what energy-producer in Parietal cells?
MICTOCHONDRIA
35
The morphology of the PAREITAL CELLS change when they are secreting, how so?
Canaliculi fuse to create large H+ chambers (increase SA)
36
What exchanges with bicarb to maintain charge in the cell?
Chloride
37
Then when we pump H+ into the stomach lumen its’s followed by Cl to make what?
HCl
38
What is the effect of Carbonic Anhydrase INHIBITORS?
Blocks source of protons --> DECREASE ACIDITY
39
What effect do we see in the BLOOD as we increase the acidity in the stomach?
more BICARB gets set to blood and creates ALKALINE TIDE
40
What organ neutralizes the ALKALINE TIDE?
Pancreas
41
What controls the number of channels and pumps in apical membrane?
cAMP + Ca
42
What messengers activate the second messenger systems of cAMP + Ca on parietal cells to increase secretion?
ACh (NBT) onto M3 --> Ca+
Histamine (from ECL) onto H2 --> cAMP
Gastrin (from G cells) onto CCK-B --> Ca+
43
What has the opposite effect of Gastrin? (Inhibits acid secretion?)
CCK
44
What chemical messenger decreases effect (INHIBITS) of Parietal cells?
Somatostatin
45
What neural, local and paracrine messengers effects proton secretion?
Neural (Vagus) --> ACh
Local --> Gastrin
Paracrine --> ECL & D
46
How does a D cell known when to release somatostatin?
takes a pH sampling at pylorus and when acidic enough starts producing
47
What protein is the target of somatostatin to decrease acid secretion?
Gi Protein --> will turn of adenyl cyclase and BLOCK cAMP
48
What else targets the Gi protein beside somatostatin?
- Anti-histamines block histamine initiating cAMP pathway. (H2 receptor blocker drugs)
- Prostaglandins also block this
49
How do NSAIDs/ASA increase acid secretion?
By blocking prostaglandins, it is not able to block H2 blocker from histamine
50
What type of cells secrete mucus to protein epithelial cells?
GOBLET cells
51
What are the 3 stages of Gastric Acid Secretion?
Cephalic
Gastric
Intestinal
52
What drives the cephalic phase?
All NEURAL - vagus gear up secretion of gastrin and HCl (taste, smell, or tactile sensation)
53
What drives the Gastric phase?
All SENSORY - mechano and chemo receptors sense when food arrives and enhances acid secretion
54
Both the cephalic and gastric phases influence a parasympathetic reflex via the:
Medulla oblongata and vagus nerve
55
In the intestinal phase, chyme enters the duodenum and if it’s ph is below____ then gastric secretion is no longer needed.
2 - gets this low with by containing lipids from digestion of fats or has HCl in it
56
What is the NEURAL way that a pH <2 inhibits gastric secretion in the intestinal phase?
They cause impulse to go to the MEDULLA OBLONGATA (LONG LOOP) to decrease parasympathetic stimulation of the glands
57
What is a LOCAL way that a pH <2 inhibits gastric secretion in the intestinal phase?
Set up local reflexes (SHORT LOOP), via neurons in the wall of the gut, that decreases secretion
58
What is another LOCAL way that pH <2 inhibits gastric secretion in the intestinal phase?
They cause release of local hormones that trail to gastric glands and inhibit their secretion
59
What local hormones DECREASE acid secretion?
Secretin and CCK
60
What are ENTEROGASTRONES?
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
T/F. Control of pepsinogen release parallels agonists for acid secretion.
TRUE
62
Which type of nutrient types do pancreatic enzymes help digest?
ALL - proteins =protease, CHO = amylase and fat = lipase!
63
Majority of proteases are dominated by:
Trypsinogen (most important step)
64
In addition to digestive enzymes, what else does the pancreas secrete?
Bicarb to neutralize acid
65
CCK and secretion both decrease acid secretion, but they have different targets in doing so:
CCK targets ACINAR cells (enzymes)
| Secretin target DUCT cells (bicarb)
66
Which is dominating in the Cephalic phase, CCK or Secretin?
CCK
67
Which is dominating the Interstinal phase, CCK or Secretin?
Secretin (because worry about neutralizing the acid that just came through)
68
Bicarb secretion is stimulated by:________ , which is potentiated by:_________
Secretion, CCK
69
Enzymes secretion is stimulated by:_____, which is potentiated by:_______
CCK, Secretin
70
T/F. Presence of both CCK and secreting has more effect on their individual roles than if they were only present alone.
True --> They POTENTIATE each other and have more of an effect when both present
71
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
created inside by carbonic anhydrase
Chloride
72
What do we do with the excess Cl inside the cell as a result of secreting bicarb?
Cystic Fibrosis Transmembrane regulator, is cAMP driven (produced by Secretin binding) and transports Cl out.
73
How does the CHOLERA TOXIN affect the Cl transport out of the cell?
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
If a high fat level is sensated in the SI, what does it secrete and how does that help?
Will increase CCK secretion, which will stimulate the pancreas to INCREASE ENZYME secretion which will INCREASE DIGESTION of fats and protein in SI
75
Which hormone has a greater effect on the GALLBLADDER?
CCK - will contract it
76
CCK stimulates primary secretion of both:
```
Secretion of bile (GB contraction)
Enzyme release (from pancreas)
```
77
What is contained in Bile?
bile acids --> as glycine and taurine (to be water-soluble)
cholesterol
Phospholipids
lecithin
78
Where is bile secreted into?
Canaliculi
79
Where in the SI is bile recycled back to liver?
Downstream at the ILEUM
80
CCK causes relaxation of:
Sphincter of Oddi, which increase bile flow to duodenum.
81
How does Chrons disease effect the uptake of Bile back to the liver?
Effects terminal ileum so interrupts that process and also the B12 binding site is located here
82
In additon to CCK, what else causes contraction of the GB and relaxation of the sphincter of OddI?
Neural innvervation via VAGYS and ACh
83
What is the major function of the LI?
Reabsorb water
84
What are side effects of Cystic Fibrosis?
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
What are the side effects of PANCREATITIS?
Retain enzymes and AUTODIGEST
