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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
**The sphincter of Oddi is __________ by the hormone___________ via ____________** ## Footnote HIGH yield
The sphincter of Oddi is **relaxed** by the hormone **cholecystokinin (CCK)** via **vasoactive intestinal peptide (VIP)**
26
What materials is the Large Intenstine (Colon) an entry for? ## Footnote HIGH yield
* **Entry of undigestible/unabsorbed material** through the **ileocecal sphincter** ## Footnote Unabsorbed material= soluble (ex. pectin)/unsoluble (ex.cellulose) fibers
27
What the the Colon (LI) a final site for? ## Footnote HIGH yield
* **FInal site for absorption of water and ions** (many under hormonal control)
28
What happens to undigested nutrients (fibers) in the colon? ## Footnote HIGH yield
**Are metabolized by intestinal flora(bacteria)** and converted to **short chain fatty acids (SCFAs)**, neurotransmitters (ex. 5HT-3, dopamine) and vitamins ## Footnote **Fiver→colonic bacteria→SCFAs→feed colonocytes**
29
What triggers Peptide YY production and release in the Colon? | Also in Ileum ## Footnote YY=tyrosine-tyrosine
Protein and Fat
30
What does the release of PYY cause in the Colon?
**Inhibits meal-stimulated GI functions** * ↓ Gastric acid secretion * ↓ Gastric emptying * ↓ Pancreatic secretion * ↓ decreased transit rate * ↓ Colonic motility ## Footnote PYY has very strong anti appetite effet
31
List the parts of the Colon
* Terminal Ileum * **Ileocecal valve** * Cecum * **Ascending colon** (site of most colon cancers) * **Transverse colon** * **Descending colon** (↑ [microbome]) * Sigmoid colon * Rectum
32
What is the main difference in the right and left colon and why?
**Function and Slow Wave Propagation differ to help ↑ H2O reabsorption**
33
What is the function of the right and left colon?
* **Right colon**: Absorption of water and electrolytes * **Left colon**: Formation and storage of feces
34
What are the three contraction pattern displayed by the colon?
1. Mixing Movements 2. Haustral Migration 3. Mass Movement
35
Explain the three contraction patterns * Mixing Movements * Haustral Migration * Mass Movements
* 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
What occurs with sympathetic nerve stimulation in the colon?
Sympathetic nerve stimulation decreases spike frequency and inhibits colonic contractions ## Footnote Mainly a parasympathetic process
37
What are Interstital Cells of Cajal (ICC)?
* **"Pacemakers" and generate slow waves** * aka: BER; basal electrical rhythm
38
How is the colonic response to a meal initated?
**By signals from the stomach, intestines** and brain ## Footnote **Gastrocolonic Reflex**: neural and hormonal controlled
39
What role does Aldosterone play in the colon? ## Footnote HIGH yield
* Promotes expression of transporters required for sodium absorption * Water follows sodium concentration
40
List the main functions of SCFAs from gut microbiome (5) | SCFAs= Short Chain Fatty Acids ## Footnote HIGH yield
* **Main fuel for coloncytes** * Tumor supressor effect * Crosesses Blood Brain Barrier (BBB) * HDAC activity * Downregulates VEGF and has other epigentic effects
41
What enhances the production of SCFAs?
Prebiotics and Probiotics that influence colonic bacteria
42
What mediates the transport of SCFA in the gut? ## Footnote HIGH yield
**Sodium coupled monocarboxylate transporters (SMCT1)**
43
What are the different causes of constipation?
* Usually d/t diet * Drugs * Diseases
44
List the dietary aspects that cause constipation (3) ## Footnote HIGH yield
* **Not enough dietary fiber** * **High Calcium + Diary** * **Dehydration**
45
List the drugs the cause constipation (2)
* Opiates * Calcium antacids
46
List the diseases that cause constipation (5)
* **Irritable Bowel Disease** * **Hirchsprung's Disease**: lack of ENS in distal colon * **Physiological Stress** * Hypothyroid * GI cancers
47
List the causes of Diarrhea (5)
* **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 ## Footnote NOTE: Diarrhea kills more children than malaria, measles, and AIDs combined
48
List the four types of Diarrhea (4) ## Footnote HIGH yield
* **Secretory diarrhea**: e.g. Cholera toxin * **Osmotic diarrhea: maldigestion**, hyperosomtic * **Motilty-related diarrhea**: vagotomy, neuropathy * **Inflammatory: Brush border damage from infection**
49
What are treatments for Diarrhea?
* **Antimotility agents** (Immodium=**Loperamide**) * **Nonspecific agents (Pepto-Bismol**=bismuth subsalicylate) buffer and anti-inflammatory effects ## Footnote Loperamide=opioid receptor agonist that remains in stomach
50
How do you treat Traveler's Diarrhea?
CDC recommends **antibiotics** (3 day regimen) or **Pepto Bismol** (8 doses over 4 hours)
51
What is Gastritis (inflammatory) and how do you treat? ## Footnote HIGH yield
* **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** ## Footnote Anti-emetic: anti-vomiting
52
What is Irritable Bowel Disease (IBD) | NOT IBS and Celiac ## Footnote HIGH yield
* **Chronic inflammation of bowel**; unkown reasons * **Include Crohn's Disease and Ulcerative Colitis**
53
List the abnormalities found in IBD (4) | Irritable Bowel Disease (IBD) ## Footnote HIGH yield
* **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
List the abnormalities reported in Irritable Bowel Syndrome (IBS) (6)
* ↑ 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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