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GI Final > Secretions of the GI Tract and Panceas > Flashcards

Secretions of the GI Tract and Panceas Flashcards

1
Q

functions of saliva

A

initial digestion of starches and lipids
dilution and buffering of ingested food
lubrication of ingested food with mucus

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2
Q

parotid glands

A

largest of the salivary structure
located near the angle of the jaw and the ear
composed of serous cells
secrete fluids composed of water, ions, and enzymes (rich in amylase)
secrete 25% of the daily output of saliva

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3
Q

submaxillary glands and sublingual glands

A

composed of serous and mucous cells
secrete aqueous fluid and mucin glycoprotein for lubrication
secrete most of the rest of 75% of daily output saliva

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4
Q

salivary galnd

A

ectodermal in origin
has the appearance of a bunch of grapes
similar features as the exocrine pancreas
the blood supplied to the salivary glands is distributed by carotid artery

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5
Q

acinus - blind end

A

acinar cells secrete initial saliva

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6
Q

myoepithelial cells

A

rest on the basement membrane of acinar cells
contain an actinomycin
have motile extensions
when stimulated by neural input, contract to eject saliva into the mouth

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7
Q

intercalated duct

A

contains myoepithelial cells

saliva in the intercalated duct is similar in ionic composition to plasma

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8
Q

striated duct

A

lined by columnar epithelial cells (ductal cells)
ductal cells modify the initial saliva to produce the final saliva (hypotonic)
ductal cells alter the concentration of various electrolytes

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9
Q

composition of saliva

A

water, electrolytes, alpha amylase, lingual lipase, killikrein, and mucose
increased K and HCO3
decreased N and Cl

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10
Q

alpha amylase

A

begins initial digestion of carbohydrates

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11
Q

lingual lipase

A

beings initial digestion of lipids

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12
Q

killikrein

A

protease involved in the production of bradykinin (vasodilator)

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13
Q

mechanism of salivary secretion

A

formation of isotonic plasma like solution by acinar cells

modification of the isotonic solution by the ductal cells

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14
Q

cystic fibrosis

A

pt. lack the Cl transporter

salivary Ca Na and protein are elevated

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15
Q

flow rate and ion composition of saliva

A

increased - saliva resembles plasma and initial saliva

decreased - saliva has lower concentrations of Na and Cl and higher K

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16
Q

parasympathetic inn of salivary glands

A

presynaptic n originate at facial and glossopharyngeal n

postsynaptic fibers in autonomic ganglia innervate individual glands

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17
Q

sympathetic inn of salivary glands

A

preganglionic n originate at the cervical ganglion

postganglionic fibers extend to the glands in the periarterial spaces

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18
Q

HCl

A

with peptin will initiate the process of protein digestion
needed for the conversion of pepsinogen to the enxyme pepsin
kills a large number of bacteria that enter the stomach

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19
Q

pepsinogen

A

inactive precursor to peptin

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20
Q

mucus

A

lines the wall of the stomach and protects it from damage
acts as lubricant
together with HCO neutralized acid and maintains the surface of the mucosa at a neural pH

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21
Q

intrinsic factor

A

required for the absorption of vit B12 in the ileum

indispensable component

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22
Q

water

A

medium for the action of HCl and enzymes

solubilizes much of the ingested material

23
Q

ocyntic gland

A

located in the proximal 80% of the stomach (body and fundus)
secretes acid

24
Q

pyloric gland

A

located in the distal 20% of the stomach (antrum)

synthesizes and release gastrin

25
Q

parietal cells

A

intrinsic factor and HCl

26
Q

chief cells

A

pepsinogen

27
Q

G cells

A

gastrin

28
Q

mucus cells

A

mucus, HCO3, and pepsinogen

29
Q

histamine regulation of HCl

A

stimulation of HCl secretion
released form ECL cells
binds to H2 R on parietal cells leads to cAMP which will activate H/K ATPase

30
Q

Ach regulation of HCl

A

stimulation of HCl secretion
released from vagus n
binds to M3 mAChR on parietal cells leads to IP3 and Ca2 release which stimulates H/K ATPase
stimulation of ECL cells

31
Q

gastrin regulation of HCl

A

stimulates HCl secretion
secreted by G cells
binds to CCKB R on parietal cells leads to IP3 and Ca2 leading to stimulation of H/K ATPase
stimulation of ECL cells

32
Q

somatostatin regulation of HCl

A

inhibits HCL secretion
secreted by detla cells
binds to SSTR2 R on parietal cells which inhibits adenylate cyclase
inhibits histamine and gastrin

33
Q

vagus n and HCl secretion

A

direct pathway - stimulation of parietal cells

indirect pathway - stimulation of G cells

34
Q

cephalic phase

A

30% of HCl secreted in response to meal
brain tells stomach to prepare for receipt of meal
vagus n. - fxn through direct and indirect pathways to lead to release of HCl

35
Q

gastric phase

A

60% of the total HCl secreted in response to meal
distention of the stomach and presence of breakdown of proteins, amino acids, and small peptides
activation of mechanoR leads to stimulation of the vagus n, local stimulation of G cells

36
Q

intestine phase

A

less than 10% of the total HCl secreted in response to meal
distention of SI stimulates acid secretion
digested protein stimulate acid secretion via direct effect on parietal cells through gastrin relase

37
Q

gastric juice secretion rate

A

low - solution of NaCl
high - more H than Na
more H, K , and Cl and less Na than plasma

38
Q

non parietal gastric secretion

A

basal alkaline secretion of constant and low volume
make of Na, Cl, and K at same concentration as K
HCO3is secreted at a concentration of 30 mEq/L

39
Q

parietal gastric secretion

A

hyperosmotic
150-160 mEq H/L and 10-20 mEq/L
Cl is the only anion present
as secretion rate increases the concentration of electrolytes begin to approach those of pure parietal cell secretion

40
Q

regulation of gastrin release

A

stimulated by GRP which is released though stimulation of vagus n
inhibited by somatostatin
works through negative feedback

41
Q

pepsinogen secretion

A

secreted by chief cells and mucus cells in the oxyntic glands
needs to be converted into pepsin by H
vagus n stimulation is the most important stimulus for pepsinogen secretion
H will trigger the release of pepsinogen

42
Q

function of pepsin

A 
converts more pepsinogen to pepsin 
splits interior peptide linkages 
pH 1.8 to 3.5 
reversible inactivated at pH greater than 5 
irreversible inactivated at pH 7-8
43
Q

intrinsic factor

A

secreted by parietal cells
combines with B12 to make a complex which allows the absorption of B12
no secretion leads to pernicious anemia

44
Q

growth of gastic mucosa

A

epithelium secretes HCO3 and mucus to form gel like mucosal barrier (neck cells - mucus and epithelial cells - HCO3)
protects the gastric mucosal epithelium against HCl and pepsin

45
Q

factors that protect gastric mucosa

A

HCO3, mucus, prostaglandins, mucosal blood flow and GF

46
Q

factors that damage gastric mucosa

A

acid, pepsin, NSAIDs, H pylori, aspirin, bile and stress

47
Q

peptic ulcer diseases

A

H. pylori infections and NSAID use

loss of protective mucosal barrier, excessive H and pepsin secretion

48
Q

gastric ulcers

A

because of mucosal barrier defect
caused by H. pylori
urease converts urea to NH3 which alkalinizes the local environment which lets the bacteria live

49
Q

duodenal ulcers

A

H secretory rates are higher than normal

H. pylori inhibits somatostatin

50
Q

zollinger-ellison syndrome

A

duodenal ulcers

tumor in the panceas secretes large quantities of gastrin

51
Q

exocrine panceas

A

secretes aqueous solution containing HCO3 and enzymatic secretion
acinus - secrete enzymatic portion
ducts - secrete HCO3

52
Q

inn of exocrine pancreas

A

sympathetic- celiac and superior mesenteric plexuses (inhibit)
parasympathetic - vagus n (activates)

53
Q

secretion rate of pancreatic juices

A

increased - high HCO3 and Cl lowest

decreased - high Cl and HCO3 lowest

GI Final (8 decks)

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