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Physiology: Exam 3 > Lecture 9: GI (Exocrine Pancreas, Liver/Gallbladder, LI) > Flashcards

Lecture 9: GI (Exocrine Pancreas, Liver/Gallbladder, LI) Flashcards

1
Q

Which peptide enhances insulin secretion?

A

Oral Glucose-stimulates Insulinotrophic Peptide

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2
Q

What stimulates GIP release at a larger magnitude? Intravenous glucose or oral glucose

GIP (gastrin inhibitor of peptide) aka K cells

A

Oral glucose

Intravenously not as stimulatory to GIP b/c not directly in the duodenum but in blood vessels

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3
Q

How much enzymes are produced and secreted by the exocrine pancreas?

A

Excess, altough prodcution decreases progressively as we age (~30-50 decrease @ ge 75 years)

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4
Q

When do nutrition problems arise?

A
  • If production of pancreatic enzyme falls by as little as 10%
  • Outflow of pancreatic juice is obstructed (ex. sphincter of oddi obstructed)
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5
Q

Review: List the sphincters that are present in the Gastrointenstinal Tract

A
  • Upper and lower esophageal sphincters
  • Pylorus
  • Sphincter of Oddi
  • Internal and external anal sphincter
  • Illeocecal valve

Know location and function

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6
Q

Which ducts drain to the Duodenum (in duodenal papilla)?

A

Common bile duct and Pancreatic Duct

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7
Q

What are the major pancreatic enzymes? (8)

A
  • Trypsin
  • Chymotrypsin
  • Elastase
  • Carboxypeptidase
  • Lipase
  • Amylase
  • Ribonuclease
  • Deoxyribonuclease
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8
Q

For the Enzyme(s): Trypsin, Chymotrypsin, & Elastase, what is the

  • Substrate
  • Action
A
  • Substrate: Proteins
  • Action: Breaks peptide bonds in proteins to form peptide fragments
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9
Q

For the Enzyme(s): Carboxypeptide, what is the

  • Substrate
  • Action
A
  • Substrate: Proteins
  • Action: Splits off terminal amino acid from carboxyl end of protein
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10
Q

For the Enzyme(s): Lipase, what is the

  • Substrate
  • Action
A
  • Substrate: Fats
  • Action: Splits off two fatty acids from triacylgcerols, forming free fatty acids and monoglycerides
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11
Q

For the Enzyme(s): Amylase, what is the

  • Substrate
  • Action
A
  • Substrate: Polysaccharides
  • Splits polysaccharieds into glucose and maltose
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12
Q

For the Enzyme(s): Ribonuclease, Deoxyribonuclease, what is the

  • Substrate
  • Action
A
  • Substrate: Nucleic Acids
  • Action: Splits muclei acids into free mononucleotides
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13
Q

The Exocrine Pancreas is a two-stage model utilizing _________ and ________.

A

Acinar cells; Ductal cells

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14
Q

List the cell types that play a part in pancreatic acinar cell regualtion and explain their functions

A
  1. Vasointestinal peptide (VIP) and secretin
  • Both regulate the activation of cAMP
  1. GRP, ACh, CCK
  • All regulate the presence of intracelluar [Ca2+]

Both cAMP & Ca2+ play a role in the phosphorylation of structural and regulatory proteins→Fusion of granules w/ apical membrane and discharge of contents

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15
Q

What cell dectects low pH in the duodenum?

HIGH yield

A

Acid sensing S-cells (aka ductal cells)

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16
Q

What hormone acts in the pancreatic duct when S-cells detect low pH?Explain it’s function

S-cells: Ductal cells

HIGH yield

A

Secretin stimulatese HCO3- secretion to raise duodenum pH

Overall goal: ↑ pH of environment so that enzymes can fucntion properly

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17
Q

How are secretin receptors expressed?

HIGH yield

A

Densely expressed on Pancreatic Ductular Cells in Humans

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18
Q

What action(s) liberate free fatty acids?

A

Gastric mixing and triglyceride digestion

Gastric lipase ↑ liberation of TAG

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19
Q

What are fatty acids a potent stimulate for?

A

CCK release

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20
Q

Which cells in the duodenum releases CCK and how is it activated?

A
  • I-cells
  • Free fatty acids(high protein or high carb meal)
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21
Q

What are the roles of CCK?

A
  • Relaxes Stomach
  • Can influence eating behavior (satiating effect)

Satiation: Process that causes on to stop eating

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22
Q

How much of TAGs are digested in the stomach?

TAG: Triglycerides

A

Approx. 10%

23
Q

Which enzymes are required for the activation of some pancreatic digestive enzymes?

HIGH yield

A
  • Brush Border Entrokinase (aka. Entropeptidase)
  • Luminal Tyrsin
24
Q

What does CCK stimulate and by which methods?

A
  • Stimulates Gallbladder contraction & Sphincter of Oddi Relaxation
  • Neural and Humoral Pathways
25
Q

The sphincter of Oddi is __________ by the hormone___________ via ____________

HIGH yield

A

The sphincter of Oddi is relaxed by the hormone cholecystokinin (CCK) via vasoactive intestinal peptide (VIP)

26
Q

What materials is the Large Intenstine (Colon) an entry for?

HIGH yield

A
  • Entry of undigestible/unabsorbed material through the ileocecal sphincter

Unabsorbed material= soluble (ex. pectin)/unsoluble (ex.cellulose) fibers

27
Q

What the the Colon (LI) a final site for?

HIGH yield

A
  • FInal site for absorption of water and ions (many under hormonal control)
28
Q

What happens to undigested nutrients (fibers) in the colon?

HIGH yield

A

Are metabolized by intestinal flora(bacteria) and converted to short chain fatty acids (SCFAs), neurotransmitters (ex. 5HT-3, dopamine) and vitamins

Fiver→colonic bacteria→SCFAs→feed colonocytes

29
Q

What triggers Peptide YY production and release in the Colon?

Also in Ileum

YY=tyrosine-tyrosine

A

Protein and Fat

30
Q

What does the release of PYY cause in the Colon?

A

Inhibits meal-stimulated GI functions

  • ↓ Gastric acid secretion
  • ↓ Gastric emptying
  • ↓ Pancreatic secretion
  • ↓ decreased transit rate
  • ↓ Colonic motility

PYY has very strong anti appetite effet

31
Q

List the parts of the Colon

A
  • Terminal Ileum
  • Ileocecal valve
  • Cecum
  • Ascending colon (site of most colon cancers)
  • Transverse colon
  • Descending colon (↑ [microbome])
  • Sigmoid colon
  • Rectum
32
Q

What is the main difference in the right and left colon and why?

A

Function and Slow Wave Propagation differ to help ↑ H2O reabsorption

33
Q

What is the function of the right and left colon?

A
  • Right colon: Absorption of water and electrolytes
  • Left colon: Formation and storage of feces
34
Q

What are the three contraction pattern displayed by the colon?

A
  1. Mixing Movements
  2. Haustral Migration
  3. Mass Movement
35
Q

Explain the three contraction patterns

  • Mixing Movements
  • Haustral Migration
  • Mass Movements
A
  • Mixing Movements: Strong contraction of circular muscles to ↑ SA→to help main absorption
  • Haustral Migration: Back and forth contraction to ↑ H2O extraction
  • Mass Movements: Stimulated by eating, laxatives, exercise by enteric NS to ↑ contraction
36
Q

What occurs with sympathetic nerve stimulation in the colon?

A

Sympathetic nerve stimulation decreases spike frequency and inhibits colonic contractions

Mainly a parasympathetic process

37
Q

What are Interstital Cells of Cajal (ICC)?

A
  • “Pacemakers” and generate slow waves
  • aka: BER; basal electrical rhythm
38
Q

How is the colonic response to a meal initated?

A

By signals from the stomach, intestines and brain

Gastrocolonic Reflex: neural and hormonal controlled

39
Q

What role does Aldosterone play in the colon?

HIGH yield

A
  • Promotes expression of transporters required for sodium absorption
  • Water follows sodium concentration
40
Q

List the main functions of SCFAs from gut microbiome (5)

SCFAs= Short Chain Fatty Acids

HIGH yield

A
  • Main fuel for coloncytes
  • Tumor supressor effect
  • Crosesses Blood Brain Barrier (BBB)
  • HDAC activity
  • Downregulates VEGF and has other epigentic effects
41
Q

What enhances the production of SCFAs?

A

Prebiotics and Probiotics that influence colonic bacteria

42
Q

What mediates the transport of SCFA in the gut?

HIGH yield

A

Sodium coupled monocarboxylate transporters (SMCT1)

43
Q

What are the different causes of constipation?

A
  • Usually d/t diet
  • Drugs
  • Diseases
44
Q

List the dietary aspects that cause constipation (3)

HIGH yield

A
  • Not enough dietary fiber
  • High Calcium + Diary
  • Dehydration
45
Q

List the drugs the cause constipation (2)

A
  • Opiates
  • Calcium antacids
46
Q

List the diseases that cause constipation (5)

A
  • Irritable Bowel Disease
  • Hirchsprung’s Disease: lack of ENS in distal colon
  • Physiological Stress
  • Hypothyroid
  • GI cancers
47
Q

List the causes of Diarrhea (5)

A
  • Viral, bacterial, or parasitic infection in the colon (most common). Drugs too (Antibiotics, PPIs, Chemo, etc)
  • Inflammatory bowel syndrome/Crohn’s disease
  • Food intolerances: Wheat and diary products, sugar
  • Ischemic bowel disease (older individuals)
  • Colon

NOTE: Diarrhea kills more children than malaria, measles, and AIDs combined

48
Q

List the four types of Diarrhea (4)

HIGH yield

A
  • Secretory diarrhea: e.g. Cholera toxin
  • Osmotic diarrhea: maldigestion, hyperosomtic
  • Motilty-related diarrhea: vagotomy, neuropathy
  • Inflammatory: Brush border damage from infection
49
Q

What are treatments for Diarrhea?

A
  • Antimotility agents (Immodium=Loperamide)
  • Nonspecific agents (Pepto-Bismol=bismuth subsalicylate) buffer and anti-inflammatory effects

Loperamide=opioid receptor agonist that remains in stomach

50
Q

How do you treat Traveler’s Diarrhea?

A

CDC recommends antibiotics (3 day regimen) or Pepto Bismol (8 doses over 4 hours)

51
Q

What is Gastritis (inflammatory) and how do you treat?

HIGH yield

A
  • Serious diarrhea combined with vomiting and retching over several hours
  • The fluid loss from the colon will cause metabolic acidosis
  • Treatment: Go to ER for anti-emetic, IV fluids, and anti-diarrheal

Anti-emetic: anti-vomiting

52
Q

What is Irritable Bowel Disease (IBD)

NOT IBS and Celiac

HIGH yield

A
  • Chronic inflammation of bowel; unkown reasons
  • Include Crohn’s Disease and Ulcerative Colitis
53
Q

List the abnormalities found in IBD (4)

Irritable Bowel Disease (IBD)

HIGH yield

A
  • Inapproriate immune response to normally innocuous gut flora
  • Damage to intestinal: maldigestion/malabsorption; defects in barrier function
  • Malabsorption of bile acids in terminal ileum impacts colonic electrolyte transport, leading to diarrhea
54
Q

List the abnormalities reported in Irritable Bowel Syndrome (IBS) (6)

A
  • ↑ incidence of 3/min slow waves (↑ motility=diarrhea)
  • ↓ myoelectric response to feeding (↓ motility=constipation)
  • ↑ response to CCK and cholinergic agents (↑ pancreatic secretions)
  • ↓ stressed-related small bowel dysmotility (slowed digestion)
  • ↓ threshold for pain caused by distension (hypersensitve b/c cytokine & chemokine receptors increase)
  • ↑ psychophsiologic scores

Physiology: Exam 3 (10 decks)

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