GI Secretions Flashcards by Trenni Jefferson

What are the sources of gut secretions?

Epithelial cells
Salivary glands
Stomach
Pancreas and liver (gall bladder)

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What are the epithelial secretions?

Water and electrolytes
Mucus
Special molecules

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Water and electrolytes secretion

Reaction medium
Used to liquify, lubricate and dissolve
Moves ingesta from the mouth to the anus
H+ and Bicarbonate

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Mucus secretion for epithelial cells

For lubrication and protection

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What are the special molecules for epithelial secretion?

Digestive enzymes like lipase and amylase
Used for digestion and absorption

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How much does ruminants secrete a day?

80 L

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What are the 2 types of salivary secretions?

Organic
Inorganic (ions)

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Digestive enzymes of organic salivary secretions

Amylase (carbs)- neutral pH, pa1,4 glycoside bond
Lipases (fats)- Triglycerides, acidic pH

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What is the difference between lipase and amylase in pancreas vs. saliva?

Pancreatic lipases/ amylases are 10x more effective/ potent in digesting lipids and carbs compared to saliva

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Why is mucus important for salivary glands?

Because it has lactoferase used to kill bacteria (bactericidal)

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How is saliva regulated?

Salivary nuclei is either stimulated (neuronal) or inhibited (hormonal) by certain factors, it will activate the hindbrain that regulates salivation

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What are the organic salivary secretions?

Digestive enzymes
Mucus/ glycoproteins
Lysozymes/ Lactoferrin
Kallikrein

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Kallikren

Converts plasma protein to bradykinin (vasodilator)

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Bradykinin

Opens up blood vessels (easy blood flow)
Decrease in bradykinin leads to the constriction of blood vessels and high blood pressure

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Inorganic Salivary Secretions

Ions (Cl-, Na+, K+ and HCO3-)
Increase during meals

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Gastric secretions

HCl
Pepsinogen
Mucus
Intrinsic Factor

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What of the function of HCI

Converts pepsinogen into active pepsin
Bacteriostatic (bacteria won’t grow)
When you have a max need for digestion

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Pepsin

Protein digestion
Secreted as inactive pepsinogen
Stimulated by vagus and secretin

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What is the function of gastric mucus?

Protection, lubrication and barrier

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Intrinsic factor

Binds B12 to facilitate absorption
Secreted by parietal cells
Absent in pernicious anemia

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2 Component Theory

When the same cell secretes both secretions depending on the state of the gut

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Where is the 2 component theory used?

The parietal cell secretes HCl in the digestive state is replaced with salt in the interdigestive state

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What is interdigestive state of the gastric acid secretion inhibited by?

Vagotomy
Antrectomy
H2 Antagonists

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How is gastric acid secretion controlled?

Study These Flashcards

Digestive phase
1. Cephalic phase
2. Gastric phase
3. Intestinal phase

Cephalic Phase of the stomach

Vagally mediated Treatment for hyperactivity 30% of secretion Increased by hypoglycemia, insulin and glucose analogues

Gastric Phase of the stomach

Major player (70%) Inhibit with H2 blocker Increased by alcohol, Ca and caffeine

Intestinal Phase of the stomach

Vagally mediated 10% (not gastrin related) Stimulated by duodenal amino acids

What are the 2 types of gastric mucus?

Soluble mucus Insoluble mucus

Soluble mucus of gastric secretions

Source: mucous neck cells Lubrication Stimulated vagally

Insoluble mucus of gastric secretions

Source surface mucous cells Barrier between gastric mucosa and food (broken= ulcers) Stimulated mechanically or chemically (food)

Pancreatic Secretions

Islands of Landerhans - insulin/ glucagon Ductal cells- ions Acinar cells- digestive enzymes

Endocrine secretions

Islands of Landerhans Hormones 4% total secretion

Exocrine secretions

Ions (6%)- ductal cells Enzymatic (90%)- acinar cells

What happens when there's low blood pressure (needs to increase)?

1. Secretes glycogen 2. Order liver to convert glycogen into glucose 3. Release into the blood

What happens when there's high blood pressure (needs to decrease)?

1. Insulin secreted 2. Liver concerts it to glycogen 3. Glycogen held in liver until body needs it

Ionic secretions in the pancreas

Ductal cells will secrete salt from pancreas @ low rate Then will secrete bicarbonate @ high rate 2 component theory

Enzymatic secretions of the pancreas

Active enzymes: lipase and amylase Inactive enzymes: trypsinogen activated by enterokinase

Control of pancreatic secretions

Secretes and stops pancreas from eating itself 1. Synthesized inactive 2. Trypsin inhibitors 3. membrane bound 4. Autodigestion by trypsin

What are the phases of pancreatic secretions?

Cephalic Gastric Intestinal

Cephalic (pancreas) phase

20% Vagally mediated Low vol/ high concentration

Gastric (pancreas) phase

5-10% Vagally mediated

Intestinal (pancreas) phase

70% Hormonal control (CCK)

Secretion clinical considerations

Chronic Pancreatitis Tumors Cystic Fibrosis (low chloride) 80% damage to produce steatorrhea

Secretion tumors

Decrease trypsin, chymotrypsin and lipase but NOT Amylase

Chronic pancreatitis

Active proteases Low bicarbonate Obstructions Trypsin

Gall Bladder

Sac/ container of bile Function: digest and absorb fat Hormonal (CCK) and vagal control

What are the functions of the bile?

Fat digestion (emulsification) Fat absorption (micelle formation) Elimination of cholesterol, heavy metals, bile pigments, drugs

Components of bile

Organic (bile acids, phospholipids, cholesterol, bile pigment) Inorganic (water, bicarbonate and ions)

Bile Acids function

Binds to fat droplets --> allow lipase to work on fatty droplets by adding an electrical charge--> digest Synthesized and recycled daily

Phospholipds function

Prevents aggregation of fat droplets Increase surface area for fat

Characteristics of bile acids

From hepatocytes Continuous production 30 min after a meal Hormonal/ Vagal control

Absorption of bile acids

50% passive re-absorption (upper intestine, unconjugated) 50% active re-absorption (low intestine, conjugated)

Characteristics of Phospholipids

Lecitin is amphipathic (has electrical charge and affinity to water) 30-40% Micelle formation to solubilize cholesterol

Characteristics of cholesterol

4% Excess served as Gallstone Nidus (center)

Characteristics of bile pigment

2% Bilirubin- RBC- liver damage Damage causes jaundice Secreted as glucuronic salt Not found in micelle

When is bile pigment soluble?

When conjugated with glucuronic acid in the liver

Cholecyectomy

Removing gall bladder Secretions will be coming directly from liver and not gall bladder

What are the 2 types of gallstones?

Cholesterol (50-75% cholesterol) Pigment (unconjugated bilirubin with Ca++)

GI Secretions Flashcards

(58 cards)