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GI Final > 3 Secretions Of The GI Tract And Pancreas > Flashcards

3 Secretions Of The GI Tract And Pancreas Flashcards

1
Q

Parotid glands are what type of glands?

Submaxillary/submandibular glands?

Sublingual glands?

A

Serous

Serous and mucous cells; fluid and mucin glycoprotein

Serous and mucous cells; fluid and mucin glycoprotein

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2
Q

Structure of salivary glands:

_____ produces initial saliva.

____modifies saliva.

_____ contracts to eject saliva as stimulated by neuron I put

A

Acinus

Striated duct

Contractile (myoepithelial cells)

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3
Q

Initial digestion of starches, lipids, and dilution of food, lubrication with mucus for swallowing

A

Saliva

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4
Q

Kallikrein secreted in saliva used to make _____.

A

Bradykinin for vasodilation

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5
Q

Composition of saliva

A

Water, electrolytes, alpha amylase (ptyalin), lingual lipase, kallikrein, mucus

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6
Q

Saliva is ______ compared to plasma.

Higher levels of _____.

Lower levels of _____.

A

Hypotonic

K, HCO3

Na, Cl

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7
Q

What cells modify the saliva?

How?

A

Ductal cells

Saliva was isotonic and plasma like; ductal cells modified the plasma solution to make it hypotonic (saliva)

There is a net absorption of solutes because ductal cells are impermeable to water and not absorbed with the solute->solution becomes hypotonic

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8
Q

What pumps are on the luminal membrane (apical) of a ductal cell?

Basolateral membrane (blood)?

A

IN/OUT

Na/H
Cl/HCO3
H/K

K/Na
——/CL
HCO3,Na/——

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9
Q

Why are there multiple channels moving H and HCO3?

A

Allow the enzymes to work because they work optimally at different pH levels

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10
Q

Parasympathetic innervation of salivary glands

Sympathetic innervation

Fx?

A

Facial and glossopharyngeal N

Originate from T1-T3 and superior cervical ganglion

Increase salivary secretions

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11
Q

Sympathetic postsynaptic nerve fibers extend to glands by _____.

A

Periarterial spaces

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12
Q

Salivary gland parasympathetics stimulated by _____.

Inhibited by ______.

A

Conditioning, food, nausea, smell

Dehydration, fear, sleep

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13
Q

Stimuli->parasympathetic response though _____ nerves-> release ______ binding to ______ receptors in the tissue->secrete _____ in the acinar/ductal cell.

A

CNVII, CNIX (facial and glossopharyngeal)

ACh

Muscarinic

Ca, IP3

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14
Q

Stimuli->sympathetic response through _____ nerves->release _____ binding to _____ receptors in the tissue -> secrete ______ in the acinar/ductal cell

A

T1-T3

NE

Beta

cAMP

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15
Q

Main components of gastric juice and fx

A

HCl: initiates protein digestion; converts pepsinogen to pepsin; kills bacteria

Pepsinogen: inactive precursor to pepsin

Intrinsic factor: secretes vitamin B12

Mucus: lines the stomach and protects, lubricates, neutralize acids

Water

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16
Q

Cells and location of the oxyntic gland

A

In gastric mucosa of proximal stomach, little in body and fundus

Parietal cells
D cells
Mucous cells
ECF cells
Chief cells
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17
Q

Cells and location of pyloric gland

A

Distal stomach (antrum)

G cells
D cells
Mucous cells
ECF cells

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18
Q

Location and fx of parietal cells

A

Body (oxyntic glands)

Secrete HCl (pepsinogen->pepsin)
Increase secretion of H ions (HCl) so more acidic->increase absorption of HCO3

Intrinsic factor

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19
Q

Alkaline tide

A

Venous blood has a higher pH than arterial blood

Because net secretion of HCl and absorption of HCO3 in parietal cells

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20
Q

Location and fx of G cells

A

Antrum (pyloric gland)

Secrete gastrin

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21
Q

Parasympathetic stimulation of G cells by _____ nerve-> release ______-> directly stimulate release of gastrin

A

Vagus N

GRP

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22
Q

Parasympathetic stimulation of _____ nerve -> releases ______ binding to muscarinic receptors on D cells -> stimulating D cells to secrete somatostatin-> indirectly _____ gastrin release.

A

Vagus N

ACh

Inhibits

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23
Q

Somatostatin is secreted from _____. Act on G cells by _____ gastrin release.

Negative feedback: gastrin ____ somatostatin secretion

H in lumen stimulates _____ secretion.

A

D cells

Inhibiting

Increases

Somatostatin

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24
Q

Location and fx of chief cells

What stimulates chief cells?

A

Body of stomach in oxyntic glands

Secrete pepsinogen

Vagus N

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25
Q

Pepsinogen needs a ____ pH.

Why?

inactivated at a _____ pH.

A

Low

Pepsinogen is converted to pepsin (breaks down peptides/proteolytic enzyme) at the optimal pH of 1.8-3.5 (LOW)

Therefore needs parietal cells to secrete HCl (H+) and decrease pH

High

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26
Q

Vagus N -> releases ACh -> binds to M3 receptors on parietal cells-> stimulate H+ secretion-> triggers _____ reflexes-> stimulates chief cells to secrete _____.

A

Cholinergic

Pepsinogen

27
Q

Secretion and CCK come from ______ and affect what contents of stomach

A

Duodenum

28
Q

Location and fx of gastric mucous cells

A

Antrum of stomach

Mucus and pepsinogen

29
Q

K/H pump on the _____ membrane of parietal cells.

Cl/HCO3 pump on the _____ membrane of parietal cells.

Fx?

Powered by _____.

A

Apical/lumen
Basolateral/blood

How H+ is secreted because Cl follows into lumen

HCO3 absorbed into blood
ALKALINE TIDE

Na/K ATPase pump

30
Q

K/H pump on parietal cells is inhibited by what?

How?

A

Omeprazole (prilosec, zegerid)

Reduces HCl secretion

31
Q

Inhibitors of ECL

Activators of ECL

ECL secretes _____ that binds to a _____ receptor.

A

Prostaglandins and Somatostatin

ACh and gastrin

Histamine which binds to an H2 receptor -> G protein -> cAMP -> K/H pump -> H+ secretion

32
Q

Inhibitor of prostaglandin

What effect does it cause?

A

NSAIDS—allow gastric secretions

Inhibit prostaglandins therefore preventing the inhibition of H+ secretion from parietal cells

33
Q

What inhibits the ACh M3 (muscarinic) receptors on parietal cells?

A

Atropine

34
Q

Combined response of two stimulants that exceeds their summed response

Require a separate receptor for each stimulant

A

Potentiation

35
Q

Histamine potentiates ____ and _____.

ACh potentiates _______ and ______.

Effects of Cimetidine and Atropine??

A

ACh and gastrin

Histamine and gastrin

Cimetidine blocks direct action of histamine, therefore blocks potentiated effects of ACh and gastrin

Atropine blocks direct action of ACh, therefore blocks potentiated effects of histamine and gastrin

36
Q

Three phases of gastric HCl secretion

A

Cephalic, gastric, intestinal

37
Q

Stimuli of cephalic phase of gastric secretion

A

Smell, taste, chewing, swallowing, conditioned reflexes

38
Q

Mechanism of cephalic phase of gastric secretion

A

Vagus N DIRECTLY stimulates parietal cells by releasing ACh

Vagus N INDIRECTLY stimulates G cells to release gastrin

Vagus N releases GRP-> activates G cells -> release gastrin-> stimulates parietal cells to secrete HCl

39
Q

Stimuli of gastric phase of gastric secretion

A

Distention of stomach, amino acids, small peptides

All stimulate gastrin release leading to HCl release from parietal cells

40
Q

Activates direct and indirect vagus N stimulation of parietal cells

A

Distention of stomach

41
Q

Pyloropyloric reflex

A

Local reflex in the antrum of stomach that stimulates gastrin release—> H+ release from parietal cells

42
Q

Stimuli of intestinal phase of gastric secretion

A

Distention of SI, and presence of digested protein

43
Q

Gastric juice is a mixture of what two secretions?

A

Non parietal and parietal

44
Q

______ secrete intrinsic factor which is required for vitamin _____ absorption in the _____.

Lack of intrinsic factor will cause what?

A

Parietal cells

B12

Ileum ***

Pernicious anemia

45
Q

Gastric mucosal defense includes ____.

Types of cells

A

Mucous neck cells (mucous)
Gastric epithelial cells (HCO3)

Protects against HCl and pepsin

46
Q

Protective factors of gastric mucosa

A 
HCO3
Mucus
Prostaglandins
Blood flow
Gastrin
Growth factors
47
Q

Damaging factors of gastric mucosa

A 
Acid
Pepsin
NSAID/aspirin
H. Pylori
Alcohol
Bile
Stress
48
Q

_____ is used in the diagnosing of gastrin-secreting tumors (gastrinoma).

Why?

A

In gastrinomas, injection of secretion causes a paradoxical increase in gastrin release

Normally secretin inhibits gastrin release

49
Q

Peptic ulcer disease caused by what?

A

Loss of protective mucosal barrier

Excessive secretion of H and pepsin

H. Pylori infection and use of NSAIDS

50
Q

Gastric ulcers caused by _____ bacteria that secretes _____.

A

H. Pylori

Urease: allows the bacteria to colonize

Converts urea to NH3 (decrease H+) therefore increase in gastrin

Releases cytotoxins that breakdown the mucosal barrier

51
Q

Duodenal ulcers ____ secretion higher.

H. Pylori inhibits _____ from D cells.

A

H+ secretion

Inhibits somatostatin (nothing to control gastrin)

Increase gastrin levels

52
Q

Gastric H. Pylori infection can spread to the _____ and inhibit HCO3 secretion

A

Duodenum

53
Q

H+ secretion is the highest

Pancreatic tumor secretes LARGE amounts of gastrin

Trophic effect on parietal cell (mass increases)

A

Zollinger-Ellison Syndrome

54
Q

Effect of trophic parietal cell from Zollinger-Ellison Syndrome

Treatment

A

Excessive delivery of H+ to duodenum

Inactivated pancreatic lipases therefore fat in stool (steatorrhea)

Treat with cimetidine, omeprazole, surgery

55
Q

Two main components of pancreatic secretions

A

Aqueous solution (ISOTONIC) with HCO3, Na, K, and Cl (to neutralize H+ from stomach)

Enzymatic secretion of pancreatic amylase and lipase, and pancreatic proteases (to digest CHO, protein, lipids)

56
Q

What secretes HCO3 from pancreas?

What secretes enzymes?

A

Ductal epithelial cells secrete aqueous solution with HCO3

Acinar cells secrete pancreatic enzymes

57
Q

Ductal cells of the pancreas cause a net reaction

A

Secrete HCO3 and absorb H+ in the blood

Modify initial isotonic solution

58
Q

Three phases of pancreatic secretions

A

Cephalic, gastrin, and intestinal

59
Q

Pancreas sympathetic innervation (INHIBITORY) includes _____ nerves from _____ and ______ plexuses.

Pancreas parasympathetic innervation (STIMULATORY) includes the _____ nerve; preganglionic fibers synapse in _____ and postganglionic fibers synapse on _____.

A

Postganglionic

Celiac and superior mesenteric plexues

Vagus

ENS

Exocrine pancreas

60
Q

Pancreatic phases:

Cephalic is initiated by ______ nerve by _____ and produces _____.

Gastric is initiated by ____ nerve by _____ and produces _____.

Intestinal phase contains _____ of pancreatic secretions and stimulates _____.

A

Vagus N
Smell, taste, and conditioning
Enzymatic secretions

Vagus N
Distention of the stomach
Enzymatic secretions

80%
Enzymatic and aqueous secretions

61
Q

Duodenal i cells secrete ___ and S cells secrete ____ that help regulate pancreatic secretions during the intestinal phase.

A

CCK and secretin

62
Q

Regulated Cl channel on the apical surface of ductal cells in pancreas

A

Cystic fibrosis transmembrane conductance regulator (CFTR)

63
Q

In a CFTR mutation, the Cl channel does not work -> can’t regulate/secrete HCO3–> build up of H+

Pancreas will fail early in this disease t

A

Cystic fibrosis

64
Q

A carbonic anhydrase inhibitor causes what?

A

Decrease formation of HCO3 therefore decrease secretion of HCO3 secretion into salivary ducts

GI Final (11 decks)

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