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Term 2: Gastro-Intestinal > GI Phys: Secretions > Flashcards

GI Phys: Secretions Flashcards

1
Q

What are the three peptide hormones that the duodenum secretes?

A
  • Secretin
  • CCK
  • Incretins (GLP=GIP)
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2
Q

What does secretin do?

A
  • increases HCO3 secretion from pancreas
  • inhibits gastric emptying
  • increases insulin and glucagon release
  • decreases gastrin release
  • increases water reabsorption in kidneys (independent of ADH)
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3
Q

What does CCK do?

A
  • stimulates enzymatic secretion from the pancreas
  • gallbladder contraction to secrete bile for emulsifying fats
  • decreases gastric motility and emptying
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4
Q

What does GIP/GLP do?

A
  • inhibits gastric emptying and acid secretion

- increase insulin release

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5
Q

What cells secrete secretin?

A

-S Cells

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6
Q

What cells secrete CCK?

A

-I cells

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7
Q

What stimulates the secretion of CCK?

A

-fats and proteins in the lumen of the duodenum

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8
Q

What does motilin do and what cell secretes it? From which part of the intestine is it secreted?

A

-Secreted by M cells

  • causes the MMC which sweeps bacteria back to the colon
  • also participates in controlling the pattern of smooth muscle contractions in upper GI tract

-secreted in duodenum and jejunum every 90 min

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9
Q

Which of the following is NOT true of CCK?

A. CCK increases acid secretion by parietal cells
B. CCK is a peptide hormone made by I cells of duodenum
C. CCK contracts gall bladder
D. CCK relaxes sphincter of Oddi
E. CCK stimulates release of pancreatic enzymes

A

A. CCK does not increases acid secretion, it decreases it

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10
Q

What are the two types of signaling performed by the pancreas?

A
  • Endocrine

- Exocrine

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11
Q

What are the endocrine hormones secreted by the pancreas?

A
  • insulin (Beta Cells)

- glucagon (alpha cells)

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12
Q

What are the Exocrine secretions of the pancreas?

A
  • bicarbonate

- zymogens

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13
Q

What cells of the pancreas releases bicarb?

A

-intercalated duct cells

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14
Q

What cells of the pancreas release zymogens? What factors stimulate these cells?

A
  • pancreatic acinus cells

- stimulated by CCK and Ach

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15
Q

What are the three sources of bicarb used to neutralize acidic chyme in the small intestine?

A
  • Ductal cells (pancreas)
  • Ductal cells (liver)
  • Brunner’s Cells (duodenum)
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16
Q

Why are cystic fibrosis patients at risk for pancreatic and hepatic insufficiency?

A
  • The pancreatic lumen contents are viscous due to lack of Cl transporter to let Cl into lumen
  • ducts get clogged up
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17
Q

What can trigger pancreatits?

A
  • alcohol

- fatty meals

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18
Q

Why is the pancreas not autodigested by the enzymes that it produces?

A
  • Enzymes are secreted as inactive zymogens
  • there is a pressure gradient in the duct lumen favoring unidirectional flow out of the gland into the lumen
  • the presence of trypsin inhibitors in pancreatic tissue and secretions
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19
Q

What are the four regulators of pancreas function?

A
  • CCK
  • Vagovagal reflex
  • Secretin
  • GIP/GLP (incretins)
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20
Q

Which of the following is NOT true of secretin?

A. It decreases gastrin: result is less acid secretion by parietal cells

B. It is a peptide hormone made by S cells of duodenum

C. It increases bicarbonate secretions

D. It decreases insulin release

E. It increases release of many pancreatic hormones

A

D. It decreases insulin release

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21
Q

Which organs are affected by cystic fibrosis?

A
  • Airways
  • Liver
  • Pancreas
  • small intestine
  • reproductive tract
  • skin
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22
Q

How does cystic fibrosis affect the liver?

A
  • Chloride stays inside cells

- plugging of small bile ducts impedes digestion and liver function

23
Q

How does cystic fibrosis affect the small intestine?

A

-Chloride stays inside cells

  • obstruction of the gut by thick stools
  • requires surgeries in 10% of neonates
24
Q

Why is cystic fibrosis heavily tested on USMLE?

A

-it is the most common genetic disorder in whites

25
Q 
Cystic Fibrosis (D Phenylalanine) Heterozygotes 
may have resistance against what disease?
A.  Malaria
B.  Diarrhea
C.  Infection by Hepatitis C
D.  Tuberculosis
E.  Sepsis
A

B. Diarrhea

26
Q

Cystic fibrosis is the most common genetic disease among Caucasians. Absence or defective Chloride channels lead to problems in many organs.

Out of the following, in which organs does the Chloride
remain outside the cells?

A.  Lungs (Airway)
B.  Pancreas
C.  Liver (Biliary ducts)
D.  Small Intestine
E.  Skin (Sweat glands)
A

E. Skin (sweat Glands)

27
Q

What cells are pancreatic islet cells? What do they each secrete?

A
  • Alpha cells (glucagon)
  • Beta cells (insulin)
  • Delta cells (somatostatin)
  • F cells (pancreatic polypeptide)
28
Q

What does somatostatin do?

A

-regulates the release of glucagon and insulin

29
Q

What does pancreatic polypeptide do?

A

-opposes the actions of CCK and secretin

  • stimulates activity of parietal and chief cells
  • thus more acid secretion by stomach

-inhibits intestinal motility and pancreatic and bile secretions

30
Q

What type of diet do CF patients need?

A

-low in fats and proteins

31
Q 
Main regulator (stimulator) of bicarbonate secretion 
into the duodenum is:
A.  Incretins (like GLP = GIP)
B.  CCK
C.  Somatostatin
D.  Secretin
E.  Gastrin
A

-D. Secretin

32
Q

During gastric phase (about one hour after a nice meal),
If you analyze venous blood,
levels of which of the following will increase?

A.  GRP (Gastrin Releasing Peptide)
B.  Gastrin
C.  Acetylcholine
D.  Histamine
E.  Prostaglandin
A

-B. Gastrin, it is hormone so it will be found in venous blood

33
Q

CCK is a hormone release by I cells in the duodenum.
Which of the following is true of CCK?

A. Relaxes gall bladder
B. Constricts sphincter of Oddi
C. Decreases release of pancreatic enzymes
D. Decreases release of acid by parietal cells
E. Decreases synthesis / release of bile by liver

A

-D. Decreases Release of Acid by parietal cells

34
Q

What are the functions of the liver?

A

Metabolic function:

Storage function

Detoxification

Synthesis of important components

Excretion

35
Q

What are the two inflows of the liver?

A
  • Hepatic portal vein

- Hepatic artery

36
Q

What are the two outflows of the liver?

A
  • Bile

- Hepatic vein

37
Q

Describe the contributions to bile synthesis

A
  • Hepatocytes secrete bile into canaliculi

- Bile ducts secrete a watery bicarb rich fluid into bile

38
Q

What kind of bile is in the gallbladder?

A

-concentrated gallbladder bile

39
Q

What is the main component of bile salts?

A

-cholesterol

40
Q

What differentiates bile acids and bile salts?

A
  • Bile salts are made of cholesterol conjugated to a glycine or taurine
  • bile acids are unconjugated
41
Q

How does conjugation affect the pKa of bile salts?

A

-it decreases the pKa and thus bile salts are more effective in emulsification

42
Q

What are the functions of bile acids?

A
  • Emulsification
  • Help in absorption of fat soluble vitamins
  • Increase the solubility of cholesterol in the gallbladder
  • Excreting cholesterol
  • Acts as a hormone to modulate the expression of proteins involved in cholesterol homeostasis
43
Q

Identify the INCORRECT statement below.

A. An alkaline tide is formed in the blood capillaries in the basolateral surfaces of parietal cells

B. Detoxification of drugs mediated by cytochrome p450
take place in smooth endoplasmic reticulum

C. ~ 70% of the blood to the liver comes from the portal vein

D. In humans, Chief cells secrete intrinsic factor

E. The migrating motor complex (MMC) occurs about
every 90 min. in the fasted state

A

-D. In humans, Chief cells secrete intrinsic factor.

False, Parietal cells secrete intrinsic factor.

44
Q

What are Cholangiocytes and what do they secrete?

A
  • Epithelial cells that line the intrahepatic biliary tree

- secrete bicarbonate

45
Q

Why can’t cystic fibrosis patients handle high fat food?

A

-Their bile ducts get clogged because of the lack of CFTR channels on the cholangiocytes

46
Q

How does CCK control bile secretion?

A
  • It causes contraction of the gallbladder and relaxation of the choledochal sphincter
  • allows bile to be secreted into the duodenum
47
Q

What factors control bile secretion? List in order of decreasing importance.

A
  • CCK
  • Secretin
  • Motilin
  • Parasypmathetic stimulation
  • Sympathetic stimulation
48
Q

What are gall stones made of?

A
  • Cholesterol and Bilirubin

- a little bit of bile and calcium salts

49
Q

What is the difference between primary, secondary, and tertiary bile salts/acids?

A
  • Primary bile salts are made in the liver from cholesterol, and are reabsorbed via ATP active transport
  • Secondary bile salts are 1’ bile salts modified by bacteria. They are reabsorbed via 2ndary transport with Na gradient
  • Tertiary bile salts are 2’ salts modified even more by bacteria. They are reabsorbed via OH or HCO3 dependent anion exchange
50
Q

Tell me about portal hypertension.

A
  • When liver blocked, blood in portal circulation cannot get back to heart, leading to portal hypertension
  • caused by cirrhosis, hepatitis, drugs/chemicals, liver cancer
51
Q

Tell me about cirrhosis of the liver.

A
  • means you have fewer hepatocytes and lots of fibrous tissue
  • caused by sustained injury to hepatocytes
  • progressive and irreversible
  • alcohol, drugs, hepatitis, autoimmune
52
Q

Where in the liver cell, bile salts are made?

A.  Mitochondria
B.  Rough endoplasmic reticulum
C.  Smooth endoplasmic reticulum
D.  Soluble cytoplasm
E.  Lysosomes
F.  Proteasomes
A

C. Smooth ER

53
Q

Prolonged and profuse diarrhea will result in
which of the following?

A. Hypokalemic, hypochloremic, metabolic alkalosis
B. Hypokalemic, hypochloremic, metabolic acidosis
C. Hyperkalemic, hyperchloremic, metabolic alkalosis
D. Hyperkalemic, hypochloremic, metabolic acidosis
E. None of the above

A

B. Hypokalemic, hypochloremic, metabolic acidosis

Term 2: Gastro-Intestinal (5 decks)

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