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Physiology II - HLSC 128 > Chapter 16- The Digestive System > Flashcards

Chapter 16- The Digestive System Flashcards

1
Q

What is the primary function of the digestive system?

A

-Transfer nutrients, water and electrolytes from ingested food into body’s internal environment

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2
Q

What are the four general functions of the digestive system?

A
  1. Motility
  2. Secretion
    3.Digestion
    4.Absorption
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3
Q

What is motility?

A

Muscular activity to mix and move contents

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4
Q

What are the two types of digestive motility?

A
  1. Propulsive movements
  2. Mixing movements
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5
Q

What are propulsive movements?

A

Push contents forward through the digestive tract

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6
Q

What are mixing movements?

A

Have two functions:
1. Mixing food with digestive juices promotes digestion of foods
2. Absorption

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7
Q

What do exocrine glands (neural and hormonal stimulation) secrete into the digestive tract lumen?

A

Digestive secretions

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8
Q

What are digestive secretions?

A

-Water
-electrolytes
-specific organic constituents

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9
Q

What happens to digestive secretions once they have participated in digestion?

A

Reabsorbed in one form or another back into blood

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10
Q

What is digestion?

A

Biochemical breakdown of structurally complex foodstuffs into smaller, absorbable units

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11
Q

What allows digestion to be accomplished?

A

Digestive enzymes

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12
Q

What are carbohydrates absorbable unit?

A

Monosachharides

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13
Q

What are proteins absorbable units?

A

Amino acids

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14
Q

What are fats absorbable units?

A

Glycerol and fatty acids

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15
Q

How are most carbohydrates consumed in one’s diet?

A

As disaccharides or polysaccharides

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16
Q

What are examples of disaccharides or polysaccharides?

A

Sucrose
Lactose
Maltose
Starch
Glycogen
Cellulose (not digested –
“fibre”)

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17
Q

What kind of carbohydrates are absorbed by the intestinal cells for use in the body?

A

Monosaccharides

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18
Q

What must Disaccharides and polysaccharides be digested into before they can be absorbed?

A

Must be digested into monosaccharides

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19
Q

What are carbohydrates?

A

Simple sugars
C6H12O6

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20
Q

What is the chemical structure of a disaccharide/double sugar?

A

2 monosaccharides linked together

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21
Q

What is the chemical structure of a polysaccharide?

A

Many sugar molecules linked together

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22
Q

What are proteins first broken down into?

A

peptide fragments

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23
Q

What are peptide fragments further digested into?

A

Free amino acids

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24
Q

What happens to free amino acids during protein digestion?

A

The free amino acids enter epethial cells to be absorbed along with shorts chains of 2-3 a.a are also absorbed

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25
Q

What are most dietary fats?

A

Triglycerides
Glycerol + 3 fatty acids

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26
Q

What does the digestion of triglycerides produce?

A

2 free fatty acids and a monoglyceride

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27
Q

What is absorption?

A

Occurs in small intestine, small absorbable units along with water, vitamins and electrolytes from digestive tract are transferred into lumen then into blood or lymph.

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28
Q

What are the parts of the digestive tract?

A

Mouth
Pharynx
Esophagus
Stomach
Small intestine
Duodenum
Jejunum
Ileum
Large intestine
Cecum
Appendix
Colon
Rectum
Anus

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29
Q

What are the accessory digestive organs?

A

Salivary glands
Exocrine: pancreas
Bilary system: Liver and gallbladder

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30
Q

What are the four major tissue layers of the digestive tract wall? (innermost to outermost)

A
  1. Mucosa
  2. Submucosa
  3. Muscularis externa
  4. Serosa
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31
Q

What is the mucosa?

A

Layer that line the luminal surface
has 3 layers

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32
Q

How does the mucosa increase surface area?

A

It has a highly folded surface

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33
Q

What are the 3 layers of the mucosa?

A
  1. Mucous membrane
  2. Lamina propria
  3. Muscularis mucosa
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34
Q

What is the mucosa’s mucous membrane function?

A

-Protection
-Modified for secretion and absorption

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35
Q

What does the mucosa’s mucous membrane contain?

A

a. Exocrine gland cells
b. Endocrine gland cells
c. Epithelial cells

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36
Q

What is the function of exocrine gland cells (mucous membrane)?

A

Secrete digestive juices

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37
Q

What is the function of endocrine gland cells (mucous membrane)?

A

Secrete blood-borne gastrointestinal hormones

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38
Q

What is the functions of epethielial cells (mucous membrane)?

A

specialized for absorbing digestive nutrients

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39
Q

What is the function of the mucosa’s lamina propria?

A

Houses GALT

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40
Q

What is GALT?

A

Gut-Associated Lymphoid Tissue
-Defend against disease-causing intestinal bacteria

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41
Q

What is the mucosa’s muscularis mucosa?

A

Sparse layer of smooth muscle

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42
Q

What is the anatomy of the Submucosa?

A

Thick layer of connective tissue

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43
Q

What is the function of the submucosa?

A

Provides digestive tract with distensibility and elasticity

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44
Q

What does the submucosa contain?

A

-Larger blood and lymph vessels
-Nerve network: Submucosal plexus

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45
Q

What is the Muscularis Externa?

A

Major smooth muscle coat of digestive tube

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46
Q

What are the 2 layers of the Muscularis externa?

A
  1. Circular layer
  2. Longitudinal layer
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47
Q

What is the circular layer of the muscularis externa?

A

-Inner layer
-Contraction —> decrease diameter of lumen

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48
Q

What is the longitudinal layer of the muscularis externa?

A

-Outer layer
-Contraction —> shorten the tube

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49
Q

Contractile activity of the muscularis externa produces what?

A

propulsive and mixing movements

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50
Q

What cells are found between the two muscle layers of the muscularis externa?

A

Pacemaker cells called Interstitial cells of Cajal

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51
Q

What are Interstitial cells of Cajal?

A

Origin of rhythmic electrical activity (BER)
-Basic Electrical Rhythm

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52
Q

What nerve network lies between the two muscle layers of the muscularis externa?

A

Myenteric plexus

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53
Q

What is the function of the serosa?

A

Secrete serous fluid

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54
Q

What does serous fluid do?

A

Lubricates and prevents friction between digestive organs and surrounding viscera

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55
Q

What is the serosa continuous with throughout most of the tract?

A

Continous with the mesentery

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56
Q

What does the attachment of the serosa and mesentery do?

A

Provides relative fixation
Supports digestive organs (during mixing/propulsive movements)

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57
Q

What is digestive motility and secretion regulated by?

A

-Autonomous smooth muscle functions
-Intrinsic nerve plexuses
-Extrinsic nerves
-Gastrointestinal hormones

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58
Q

What autonomous smooth muscle functions help regulate digestive system functions?

A

Interstitial cells of Cajal (BER)

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59
Q

What are the intrinsic nerve plexuses that help regulate digestive system functions?

A

Enteric NS= Myenteric + submucosal plexuses
Other sensory and motor functions

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60
Q

What extrinsic nerves help regulate digestive system functions?

A

Nerves from the ANS

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61
Q

What gastrointestinal hormones help regulate digestive system functions?

A

a. Gastrin
b. Other hormones from the brain

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62
Q

What parts of the digestive tract do the things regulating digestive system functions act on?

A
  1. Smooth muscle
  2. Exocrine gland cells
  3. Endocrine gland cells
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63
Q

What are the parts of the oral cavity?

A

-Lips
-Palate
-Tongue
-Pharynx
-Teeth

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64
Q

What is the function of the lips?

A

-Forms an opening
-Helps procure, guide and contains food in the mouth
-Important for speech
-Tactile sensation

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65
Q

What is the function of the tongue?

A

-Forms floor of oral cavity
-Movements of skeletal muscle aid in chewing and swallowing
-Important for speech
-Taste buds

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66
Q

What is the function of the palate?

A

-Forms the roof of the oral cavity
-Contains uvula: seals off nasal passages during swallowing

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67
Q

What is the function of the pharynx?

A

-Passageway for digestive and respiratory systems
-Contains tonsils (lymphoid tissue)

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68
Q

What is the function of teeth?

A

CHEWING:
-Grind, break food into small pieces
-Mix food with saliva
-Stimulate taste buds

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69
Q

Why is it important that teeth break food into smaller pieces?

A
  1. Make swallowing easier
  2. Increase surface area for salivary enzymes to act on
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70
Q

What are the 3 pairs of salivary glands?

A
  1. Parotid
  2. Sublingual
  3. Submandibualr
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71
Q

How do the salivary glands secrete?

A

Secretion occurs when there’s a large increase in blood flow
-Per gram, have the largest secretion of any exocrine gland

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72
Q

What is Saliva composed of?

A

99.5% H2O
0.5% electrolytes and protein

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73
Q

What is the 0.5% of saliva composed of specifically?

A

Amylase
Mucous
Lysozyme

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74
Q

What does amylase do?

A

Begins digestion of carbs
Polysaccharides —> Disaccharides

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75
Q

What does mucus (in saliva) do?

A

Provides lubrication

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76
Q

What does lysozyme do?

A

-Antibacterial action by destroying bacteria

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77
Q

What antibacterial action does saliva have other than lysozyme?

A

Saliva rinses away material that could be a food source for bacteria

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78
Q

How does saliva stimulate taste buds?

A

Is a solvent for molecules that stimulate taste buds

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79
Q

What other functions does saliva have?

A

-Moistens food making it easier to swallow
-Makes movements of lips/tongue easier for speech
-helps keep mouth and teeth clean
-Rich in bicarbonate buffers

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80
Q

What stimulates saliva secretion?

A
  1. Presssure receptors and chemoreceptors in the mouth
  2. Thinking, seeing and smelling food signals the cerebral cortex
    -triggers salivary centre in medulla
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81
Q

What is swallowing?

A

Motility associated with pharynx and esophagus

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82
Q

What kind of reflex is swallowing?

A

Sequentially programmed all-or-none reflex
-Most complex reflex

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83
Q

How is swallowing initiated?

A

When bolus is voluntarily forced by tongue to rear of mouth into pharynx
-Once initiated cannot be stopped

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84
Q

What is the esophagus?

A

Fairly straight muscular tube extending between the pharynx and stomach

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85
Q

What does the esophagus have at each end?

A

Sphincters

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86
Q

What are the two sphincters of the esophagus?

A
  1. Pharyngoesophageal sphincter
  2. Gastroesophageal sphincter
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87
Q

What is the function of the Pharyngoesophageal sphincter?

A

Prevents large volumes of air from entering esophagus and stomach during breathing

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88
Q

What is the Gastroesophageal sphincter?

A

Prevents reflux of gastric contents

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89
Q

What pushes food through the esophagus?

A

Peristaltic waves

90
Q

How is the esophagus protected?

A

Mucus secretions

91
Q

What is the stomach?

A

J-shaped sac-like chamber lying between esophagus and small intestine

92
Q

What are the 3 sections the stomach is divided into?

A
  1. Fundus
  2. Body
  3. Antrum
93
Q

What are the two areas of the mucosa of the stomach?

A
  1. Oxyntic
  2. Pyloric gland area
94
Q

What re the 3 main functions of the stomach?

A
  1. Store food before it goes into S.I
    2.Secrete HCl and enzymes to digest proteins
  2. Mixing movements to make chyme
95
Q

What are the four aspects of gastric motility?

A
  1. Filling
  2. Storage
  3. Mixing
  4. Emptying
96
Q

What volume can the stomach fill up to?

A

50ml- 1L

97
Q

How does the stomach accommodate extra volume of food without rising stomach pressure?

A

Receptive relaxation

98
Q

What part of the stomach is responsible for storage?

A

Body

99
Q

What part of the stomach is responsible for mixing?

A

Antrum
-Because its a thicker muscle

100
Q

How is emptying of the stomach controlled?

A
  1. Largely by factors in duodenum
  2. Stomach peristalsis
101
Q

What are the factors in the duodenum?

A
  1. Acid
  2. Hypertonicity
  3. Distention
102
Q

How is acid a factor in the duodenum?

A

acid in duodenum inhibits further emptying of acidic gastric contents

103
Q

How is hypertonicity a factor in the duodenum?

A

Gastric emptying is reflexly inhibited when osmolarity of duodenal contents starts to rise

104
Q

How is distention a factor in the duodenum?

A

Too much chyme in duodenum inhibits emptying of even more gastric contents

105
Q

What can the factors in the duodenum trigger?

A
  1. Neural response
  2. Hormonal response
106
Q

What is the neural response triggered by factors in the duodenum?

A

Enterogastric reflex

107
Q

What collectively mediates the enterogastric reflex?

A

Mediated through both:
1. intrinsic nerve plexuses (short
reflex)
2. autonomic nerves (long reflex)

108
Q

What is the hormonal response triggered by factors in the duodenum?

A

Enterogastrones hormones released from duodenal mucosa

109
Q

What are enterogastrones?

A

Secretin
Cholecystokinin (CCK)

110
Q

What additional factors can influence gastric motility?

A

a. Emotions
b.Intense pain

111
Q

How do emotions influence gastric motility?

A

Sadness and fear – tend to decrease motility
Anger and aggression – tend to increase motility

112
Q

How does intense pain influence gastric motility?

A

Inhibits motility via the SNS

113
Q

What do the two area of gastric mucosa secrete?

A

Gastric juice

114
Q

What does the Oxyntic mucosa of the stomach line?

A

Lines the body and fundus

115
Q

What does the pyloric gland area of the stomach mucosa line?

A

Line the antrum

116
Q

What are at the bases of gastric glands?

A

Gastric pits

117
Q

What 3 gastric exocrine secretory cells does the Oxyntic mucosa have?

A
  1. Parietal oxyntic cells
  2. Chief cells
  3. Mucous cells
118
Q

What do parietal oxyntic cells secrete?

A
  1. HCl
  2. Intrinsic factor (B12 absorption)
119
Q

What do Chief cells (oxyntic) secrete?

A

Enzyme precursor: Pepsinogen

120
Q

What do mucous cells (oxyntic) secrete?

A

Thin, watery mucous

121
Q

What do mucous cells line?

A

Gastric pits and entrance of glands

122
Q

What is the purpose of the mucous cells secretion?

A

-Covers gastric mucosal barrier
-Lubricant
-Prevents mechanical injury
-Protects against self-digestion via HCl and pepsin

123
Q

What are the functions of Hydrochloric acid?

A
  1. Pepsinogen—>Pepsin
  2. Breakdown connective tissues+muscle fibres
    3.Denatures proteins via pepsin
  3. Antibacterial properties
124
Q

What does Pepsin do?

A

Splits certain amino acid linkages in proteins into small a.a chains

125
Q

What does the Pyloric gland area secrete?

A

Hormones/paracrine substances
1. Gastrin
2. Somatostatin

126
Q

What can gastrin stimulate to release from ECL cells?

A

Histamine

127
Q

What are the 3 phases of Gastric secretion?

A
  1. Cephalic phase
  2. Gastric phase
  3. Intestinal phase
128
Q

What is the Cephalic phase of gastric secretion?

A

Increased secretion of HCl and pepsinogen that occurs in response to stimuli acting in the head before food reaches stomach

129
Q

What is the Gastric phase of gastric secretion?

A

Begins when food reaches stomach
-Presence of protein increases gastric secretion

130
Q

What is the Intestinal phase of gastric secretion?

A

aka Inhibitory phase
Shuts off flow of gastric juices as chyme begins to empty into small intestine

131
Q

What is the pancreas?

A

Elongated gland begins and below stomach containing exocrine and endocrine tissue

132
Q

What is the endocrine function of the pancreas?

A

Islets of Langerhans

133
Q

What is the exocrine function of the pancreas?

A

Secrete pancreatic juice

134
Q

What does pancreatic juice consist of?

A

3 different types of enzymes
Aqueous alkaline solution
(NaHCO3 + HCl → CO2 + NaCl + H2O)

135
Q

What cells secrete enzymes in the exocrine pancreas?

A

Acinar cells

136
Q

What cells secrete an aqueous alkaline solution in the pancreas?

A

Duct cells
(line pancreatic ducts)

137
Q

What are the 3 enzymes acinar cells secrete?

A
  1. proteolytic
  2. Pancreatic amylase
  3. Pancreatic lipase
138
Q

What are proteolytic enzymes?

A

Digest protein

139
Q

What are 3 proteolytic enzymes (inactive forms)?

A

Trypsinogen
Chymotrypsinogen
Procarboxypeptidase

140
Q

What are the 3 proteolytic enzymes called when converted to their active form?

A

Trypsinogen —-> Tripsin
Chymotrypsinogen —-> Chymotripsin
Procarboxypeptidase —-> Carboxypeptidase

141
Q

What is the function of pancreatic amylase?

A

Converts polysaccharides —> Disaccharide maltose

142
Q

What is the function of pancreatic lipase?

A

Only enzyme in digestive system that can digest fat

143
Q

What is the function of the Aqueous NaHCO3 solution secreted by pancreatic duct cells?

A

Secretes into the duodenal lumen to neutralise acid

144
Q

What is the liver?

A

Largest and most important metabolic organ in the body
-Body’s major biochemical factory

145
Q

How is the liver important to the digestive system?

A

Secretes bile salts via gallbladder and ducts

146
Q

What is bile?

A

Stubstance secreted by liver, diverted to gallbladder between meals

147
Q

What does the gallbladder do?

A

Stores and concentrates bile
50mL capacity

148
Q

What are bile salts?

A

Derivatives of cholesterol that play a role in digestion and absorption of fats

149
Q

What does bile consist of?

A
  1. Bile salts
  2. Cholesterol
  3. Lecithin (phospholipid)
  4. Bilirubin
150
Q

After a meal where does bile go?

A

It enters the duodenum

151
Q

What do bile salts convert?

A

Convert large fat globules into a liquid emulsion

152
Q

What are the functions of bile salts?

A
  1. Break up large fat droplets with intestinal mixing
  2. Increase surface area for lipase
153
Q

What is a Micelle?

A

Water soluble structure that is a loosely bound aggregation of several tens or hundreds of atoms

154
Q

What happens to bile salts and lecithin in micelle formation?

A

Aggregate into small clusters where the fat soluble part shuttle together to form a hydrophobic core

155
Q

What is the function of micelles?

A

-Fat absorption
-Transport digested fats

156
Q

What digested fats do Micelle’s transport?

A

-Monoglycerides
-Free fatty acids
-Also fat soluble vitamins e.g; Vitamin K

157
Q

Where are monoglycerides + fatty acids located in a micelle?

A

At the centre

158
Q

How does the gallbladder concentrate bile?

A

Salt is actively transported out, and water follows osmotically

159
Q

What is the small intestine?

A

Site where most digestion and absorption take place

160
Q

What are the 3 segments of the small intestine?

A
  1. Duodenum
  2. Jejunum
  3. Ileum
161
Q

What does small intestine motility include?

A

-Segmentation
-Migrating motility complex

162
Q

What is segmentation?

A

Primary method of motility
-Consists of ring-like contractions along length of small intestine

163
Q

What is the action of segmentation?

A

Within seconds, contracted segments relax and previously relaxed areas contract to mix chyme throughout small intestine

164
Q

What cells initiate segmentation in the small intestine?

A

Pacemaker cells that produce basic electrical rhythm (BER)

165
Q

What are the frequencies of BER in the duodenum and ileum?

A

Duodenum ~12/min
Ileum ~9/min

166
Q

What is the function of segmentation?

A
  1. Mix chyme with small intestine digestive juices
  2. Expose chyme to absorptive surfaces of mucosa
  3. Slowly move chyme through digestive tract
167
Q

What happens to S.I motility when most of a meal has been absorped?

A

Segmentation contractions stop and migrating motility complex starts

168
Q

What is migrating motility complex (MMC)?

A

Peristaltic wave sweeps intestines clean between meals

169
Q

What does the small intestine secrete?

A

A juice without digestive enzymes

170
Q

What is the purpose of small intestine secretion?

A
  1. Lubrication
  2. Salt solution
171
Q

What synthesised enzymes act within brush-border membrane of epithelial cells of the small intestine?

A
  1. Enterokinase
  2. Disaccharidases
  3. Aminopeptidases
172
Q

What does enterokinase do?

A

converts trypsinogen to trypsin

173
Q

What does disaccharidase do?

A

converts disaccharides to monosaccharides

174
Q

What are some examples of disaccharidases?

A

maltase, sucrase, lactase

175
Q

What does aminopeptidase do?

A

converts peptide fragments to amino acids

176
Q

What is the function of brush-border enzymes?

A

Complete digestion of carbohydrates and protein after pancreatic enzymes

177
Q

Where is fat entirely digested by pancreatic lipase?

A

Within the small intestine lumen

178
Q

What does the small intestine absorb?

A

Almost everything (in the ingested liquids and solids) presented to it

179
Q

Where in the small intestine does most absorption occur?

A

Duodenum and jejunum

180
Q

Where is Vit B12 and bile salts absorbed in the small intestine?

A

ileum

181
Q

How does the small intestine adapt to increase surface area?

A

a. Inner surface has circular folds
b. Villi
c. Brush border microvilli

182
Q

What are found at the base of villi that play a role in absorption? (small intestine)

A

Crypt

183
Q

What do crypt secrete?

A

Water solution and new epithelial cells

184
Q

How often is the lining of the S.I replaced?

A

Every 3 days

185
Q

What molecules are reabsorbed in the S.I that is similar to a nephron?

A

Na+ and H2O

186
Q

How is fat able to passively absorbed in the S.I?

A

undergo transformations

187
Q

How are carbohydrates digested?

A

Broken down into monosaccharides via brush-border enzymes

188
Q

How is glucose and galactose transported into epithelial cells?

A

Via Na-dependent transporters

189
Q

How is fructose transported into epithelial cells?

A

Via Facilitated diffusion

190
Q

Once inside epithelial cells, how do monosaccharides and amino acids move out of a cell to be diffused into blood?

A

Via carriers

191
Q

How are amino acids transported into epithelial cells?

A

Via Na-dependent transporters

192
Q

What structures help transport eructs of fat digestion (triglycerides)?

A

Micelles

193
Q

How are fats transported to epithelial cells?

A

Passively

194
Q

Inside epithelial cells what happens to components of triglycerides?

A

They reform to make intact triglycerides

195
Q

What happens to the reformed triglycerides?

A

Packaged into larger particles called Chylomicrons

196
Q

Where do Chylomicrons enter?

A

Centreal lacteal of the lymphatic vessel of villus

197
Q

What is the large intestine?

A

Primarily a drying and storage organ

198
Q

What are the parts of the large intestine?

A

Colon
Cecum
Appendix
Rectum

199
Q

What are the contents that the large intestine receives from the S.I?

A
  1. Indigestible food residues
  2. Unabsorbed binary components
  3. Remaining fluid
200
Q

What is the colon?

A

Extracts more water and salt from contents
Forms feces

201
Q

What 2 structures does the large intestine have?

A

Teniae coli
Haustra

202
Q

What are teniae coli?

A

Longitudinal bands of muscle

203
Q

What are Haustra?

A

Pouches or sacs that actively change location as a result of contraction of circular smooth muscle layer

204
Q

What are haustra contractions?

A

Main motility (slow)
Intimated by autonomous rhythmicity of colonic smooth muscle cells

205
Q

What are mass movements of the large intestine?

A

Massive contractions that move colonic contents into distal part of large intestine
-2 reflexes

206
Q

What are the 2 reflexes contributing to mass movements or the large intestine?

A
  1. Gastrocolic reflex
  2. Defecation reflex
207
Q

What is the Gastrocolic reflex?

A

Stimulate from stomach to colon by gastrin and by autonomic nerves
-most evident after first meal of the day
-often followed by urge to defecate

208
Q

What stimulates the defecation relflex?

A

Stretch receptors in the rectal wall stimulated by distention

209
Q

What does the stimulation of the defecation reflex cause?

A

Causes internal anal (smooth muscle) sphincter to relax and rectum and sigmoid colon to contract more via Parasympathetic NS

210
Q

When does defecation occur?

A

If external anal sphincter is voluntarily also relaxed
(Micturition)

211
Q

What does the large intestine secrete?

A

-Alkaline mucous solution
-Has good bacteria
NO DIGESTIVE ENZYMES

212
Q

What does the Colon normally absorb?

A

Salt and water

213
Q

What are some issues related to the colon?

A

A. Constipation
B. Diarrhea (not always a colon issue)

214
Q

What is constipation?

A

Large amount of dry feces
Blockages causing discomfort
Decreased motility due to age, low-bulk diet

215
Q

What is diarrhoea?

A

Loss of watery material – colon cannot absorb it all
Fluid bulk – not increased motility
Increased secretion
eg cholera: NaCl loss (therefore H2O), K+ and HCO3 - (metabolic acidosis)

216
Q

What is gastrin stimulated by?

A

Presence of protein in stomach

217
Q

What is gastrin secretion inhibited by?

A

When acid in stomach accumulates

218
Q

What are the functions of gastrin?

A
  1. Increase HCl and pepsinogen secretion
  2. Enhances gastric motility
  3. Stimulates ideal motility
  4. Relaxes ileocecal sphincter
  5. Induces mass movements in the colon
  6. Helps maintain viable digestive tract lining
219
Q

What stimulates the secretion of Secretin?

A

Presence of acid in duodenum

220
Q

What are the functions of secretin?

A
  1. Stops gastric emptying from entering duodenum, until acid already in duodenum is neutralised
  2. Inhibits gastric secretion to reduce amount of acid produced
  3. Stimulates duct cells to secrete NaHCO3
  4. Stimulates liver to secrete NaCO3 rich bile for neutralization
    5.Trophic to exocrine pancreas (along with CCK)
221
Q

What are the functions of CCK?

A
  1. Inhibits gastric motility and secretion
  2. Stimulates acinar cells to increase enzyme secretion
  3. Contracts gallbladder
  4. Relaxes sprinter of oddi
    5.Trophic to pancreas
  5. Long-term adaptive changes to prolonged diet changes
  6. Regulator of food intake

Physiology II - HLSC 128 (7 decks)

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