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Physiology Exam 3 > Lecture 49- Gastric, Pancreatic And Bile Secretions > Flashcards

Lecture 49- Gastric, Pancreatic And Bile Secretions Flashcards

1
Q

How do most bile salts return to the liver?

A

Via enterohepatic circulation

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2
Q

How are bile salts transported from SI lumen into portal blood?

A

Na/bile salt co-transporter

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3
Q

What does the liver extract? What does it add to?

A

Extracts bile salts

Adds to hepatic bile salt/bile acid pool

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4
Q

When does the ejection of bile occur?

A

30 minutes after meal is ingested

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5
Q

What contracts the gallbladder and relaxes the sphincter?

A

CCK

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6
Q

What cells in the gallbladder absorb ions and water?

A

Epithelial cells

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7
Q

Bile is provided _________ and stored.

A

Continuously

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8
Q

What are the functions of gallbladder?

A

Stores, concentration and ejects of bile

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9
Q

What is bilirubin?

A

Product of hemoglobin degradation

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10
Q

What are the products of lipid digestion?

A

Bile salts bind products to form micelles and assist in absorption of lipid products

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11
Q

How are the two primary bile acids made?

A

Made by hepatocytes

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12
Q

What are the two primary bile acids

A

Colic acid, chenodeoxycholic acids

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13
Q

What properties do bile salts have?

A

Amphipathic

Emulsify lipids so digestion can occur

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14
Q

What is the composition of bile?

A

50% are bile salts, 40% phospholipids, 2% bile pigments, 4% cholesterol

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15
Q

What charge do bile salts have?

A

Negative

Causes charges to repel each other

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16
Q

Liver conjugates ______ ______ with _______ to form bile salts

A

Bile acids
AA

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17
Q

Why is bile secretion needed?

A

Digestion
Absorption of lipids

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18
Q

What is the binary system made of?

A

Liver, gallbladder, bile duct, duodenum, ileum, portal circulation

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19
Q

What synthesize components of bile, flow out of bile ducts into gallbladder?

A

Hepatocytes

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20
Q

What stimulates contraction of gallbladder and relaxes sphincter of Oddi?

A

CCK

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21
Q

After lipid absorption, bile salts recirculated to the _______ via reabsoprtion in the ______.

A

Liver
Ileum

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22
Q

What is aqueous stimulated by?

A

Hydrogen in duodenum

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23
Q

What is the cephalic phase initiated by? Which nerve?

A

Initiated by smell, taste, conditioning -> vagus nerve

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24
Q

What is the gastric phase initiated by? The nerve?

A

Gastric phase-initiated by distinction of stomach->vagus nerve

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25
Q

What is the most important phase in the regulation of pancreatic secretion?

A

Intestinal phase

(80% of secretions)

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26
Q

Which cells are receptors for CCK and Ach?

A

Acinar cells

27
Q

What does CCK stimulus?

A

AA, peptides, FA

28
Q

What potentialem the action of CCK?

A

Ach

29
Q

What are receptors for CCK, Ach, secretin?

A

Ductal cells

30
Q

Aqueous and enzymatic portions are regulated ________.

A

Separately

31
Q

Which two flow rates remain consistent?

A

Na
K

32
Q

Which concentration rate increases and which decreases at high flow rates

A

HCO3- concentration increases

Cl- concentration decreases

33
Q

At low flow rates, what does the solution mainly contain?

A

Na Cl and water

34
Q

At high flow rates, what does the solution mainly contain?

A

Na
HCO3-
Water

35
Q

What are the two components of pancreatic secretions?

A
  1. Enzymatic component
  2. Aqueous component
36
Q

What does the aqueous component of pancreatic secretions contain?

A

Na Cl K HCO3
Juice is isotonic

37
Q

Aqueous component

What makes initial secretion? And what is it modified by?

A

Centroacinar and ductal cells make initial secretion, then modified by transport process in ductal cells

38
Q

Aqueous component

What does the luminal membrane contain?
What does the basolateral membrane contain

A

Luminal membrane: HCO3-/Cl- exchanger

Basolateral membrane: Na/K ATPAse & Na/H exchanger

39
Q

Enzymatic component of pancreatic secretion

What are secreted as active enzymes?

A

Amylase and lipases

40
Q

Enzymatic component of pancreatic secretion

What are proteases secreted in?

A

Inactive forms

41
Q

Enzymatic component of pancreatic secretion

Where are enzymes synthesized on?

A

Rough ER of acinar cells

42
Q

What comprises 90% of the pancreas?

A

Pancreatic secretions

Aqueous + enzymatic components

43
Q

What is the structure of exocrine glands?

A

Acinus lined with acinar cells
Ducts lined with ductal cells
Centroacinar cells

44
Q

In the exocrine glands, what secretes aqueous portions?

A

Ducts lined with ductal cells
Centroacinar cells

45
Q

What is the inner action of exocrine pancreas?

A

SNS -> celiac and superior mesenteric plexuses (inhibit)

PNS -> vagus nerve (stimulate

46
Q

When do duodenal ulcers occur?

A

H+ secretory rate higher than normal

Overhwelming buffering capacity of pancreas

47
Q

What is Zollinger-Ellison syndrome (Gastrinoma)?

A

High rates of H secretion due to high gastrin
Delivery of high H to dudeonum
Causes steatorrhea

48
Q

What happens if there is low pH in SI?

A

Inactivates lipases

So no fat digestion

49
Q

What form gastric ulcers?

A

Form because mucosal barrier is defective

50
Q

What is the one cause of gastric ulcers?

A

H. Pylori

51
Q

What is peptic ulcer disease?

A

Ulcerative lesion of gastric or duodenal mucosa
Caused by loss of mucus, have excessive H+ and pepsin secretion or combination of both factors

52
Q

What are the barriers to acid and pepsin damage to gastric mucosa?

A

Bicarbonate
Mucus

53
Q

When is HCl secretion inhibited?

A

When no longer needed for conservation of Pepsinogen to pepsin

**need pH for conversion

54
Q

What are three things that inhibit HCl secretion?

A
  1. Decreased pH of gastric contents
  2. Somatostatin
  3. Prostaglandins antagonize histamine by reducing cAMP
55
Q

How does somatostatin inhibit HCl secretion?

A

Binds parietal cells and antagonizes histamine pathway by decreasing cAMP

Inhibits both histamine and gastrin release

56
Q

During the cephalopods phase what % is HCl secretion

A

30

57
Q

During the gastric phase what % is HCl secretion?

A

60

58
Q

What are the stimuli of cephalic phase?

A

Smelling, tasing, chewing, swallowing, conditioned reflexes

59
Q

What are the stimuli of gastric phase?

A

Distension of stomach and presence of AA and peptides

60
Q

What are the stimuli of intestinal phase?

A

Products of protein digestion

61
Q

What are the four mechanisms to promote HCl secretion during gastric phase?

A

Distension -> vagal stimulation
-indirect via gastrin
-distension of Antron -> local reflexes -> gastrin
-AA + peptides -> Gastrin

62
Q

What is the direct path of vagal stimulation?

A

Vagus nerve -> Ach -> parietal cells -> HCl

Vagus nerve -> GRP -> G cells

63
Q

What is the indirect path of vagal stimulation (rest of G cell path)

A

Gastrin from G cells -> systemic circulation -> HCL from parietal cells

64
Q

Why will atropine not block HCl secretion completely?

A

Using GRP in G cell pathway

Physiology Exam 3 (17 decks)

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