GI Secretions Flashcards

1
Q

What are the sources of gut secretions?

A

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

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2
Q

What are the epithelial secretions?

A

Water and electrolytes
Mucus
Special molecules

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3
Q

Water and electrolytes secretion

A

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

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4
Q

Mucus secretion for epithelial cells

A

For lubrication and protection

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5
Q

What are the special molecules for epithelial secretion?

A

Digestive enzymes like lipase and amylase
Used for digestion and absorption

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6
Q

How much does ruminants secrete a day?

A

80 L

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7
Q

What are the 2 types of salivary secretions?

A
  1. Organic
  2. Inorganic (ions)
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8
Q

Digestive enzymes of organic salivary secretions

A
  1. Amylase (carbs)- neutral pH, pa1,4 glycoside bond
  2. Lipases (fats)- Triglycerides, acidic pH
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9
Q

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

A

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

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10
Q

Why is mucus important for salivary glands?

A

Because it has lactoferase used to kill bacteria (bactericidal)

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11
Q

How is saliva regulated?

A

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

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12
Q

What are the organic salivary secretions?

A

Digestive enzymes
Mucus/ glycoproteins
Lysozymes/ Lactoferrin
Kallikrein

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13
Q

Kallikren

A

Converts plasma protein to bradykinin (vasodilator)

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14
Q

Bradykinin

A

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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15
Q

Inorganic Salivary Secretions

A

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

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16
Q

Gastric secretions

A

HCl
Pepsinogen
Mucus
Intrinsic Factor

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16
Q

What of the function of HCI

A

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

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17
Q

Pepsin

A

Protein digestion
Secreted as inactive pepsinogen
Stimulated by vagus and secretin

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18
Q

What is the function of gastric mucus?

A

Protection, lubrication and barrier

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19
Q

Intrinsic factor

A

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

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20
Q

2 Component Theory

A

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

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21
Q

Where is the 2 component theory used?

A

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

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22
Q

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

A

Vagotomy
Antrectomy
H2 Antagonists

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23
Q

How is gastric acid secretion controlled?

A

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

24
Q

Cephalic Phase of the stomach

A

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

25
Q

Gastric Phase of the stomach

A

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

26
Q

Intestinal Phase of the stomach

A

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

27
Q

What are the 2 types of gastric mucus?

A

Soluble mucus
Insoluble mucus

28
Q

Soluble mucus of gastric secretions

A

Source: mucous neck cells
Lubrication
Stimulated vagally

29
Q

Insoluble mucus of gastric secretions

A

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

30
Q

Pancreatic Secretions

A

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

31
Q

Endocrine secretions

A

Islands of Landerhans
Hormones
4% total secretion

32
Q

Exocrine secretions

A

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

33
Q

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

A
  1. Secretes glycogen
  2. Order liver to convert glycogen into glucose
  3. Release into the blood
34
Q

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

A
  1. Insulin secreted
  2. Liver concerts it to glycogen
  3. Glycogen held in liver until body needs it
35
Q

Ionic secretions in the pancreas

A

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

36
Q

Enzymatic secretions of the pancreas

A

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

37
Q

Control of pancreatic secretions

A

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

38
Q

What are the phases of pancreatic secretions?

A

Cephalic
Gastric
Intestinal

39
Q

Cephalic (pancreas) phase

A

20%
Vagally mediated
Low vol/ high concentration

40
Q

Gastric (pancreas) phase

A

5-10%
Vagally mediated

41
Q

Intestinal (pancreas) phase

A

70%
Hormonal control (CCK)

42
Q

Secretion clinical considerations

A

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

43
Q

Secretion tumors

A

Decrease trypsin, chymotrypsin and lipase but NOT Amylase

44
Q

Chronic pancreatitis

A

Active proteases
Low bicarbonate
Obstructions
Trypsin

45
Q

Gall Bladder

A

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

46
Q

What are the functions of the bile?

A

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

47
Q

Components of bile

A

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

48
Q

Bile Acids function

A

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

49
Q

Phospholipds function

A

Prevents aggregation of fat droplets
Increase surface area for fat

50
Q

Characteristics of bile acids

A

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

51
Q

Absorption of bile acids

A

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

52
Q

Characteristics of Phospholipids

A

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

53
Q

Characteristics of cholesterol

A

4%
Excess served as Gallstone Nidus (center)

54
Q

Characteristics of bile pigment

A

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

55
Q

When is bile pigment soluble?

A

When conjugated with glucuronic acid in the liver

56
Q

Cholecyectomy

A

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

57
Q

What are the 2 types of gallstones?

A

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