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PHGY-210 > GIT - Lecture 6 > Flashcards

GIT - Lecture 6 Flashcards

1
Q

How is the GI motility organized in the interdigestive period?

A

into an intense pattern of cyclic myoelectric (motor) activity

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2
Q

How often does the intense pattern of cyclic myoelectric activity recur in the GIT in the absence of a meal?

A

every 90 minutes

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3
Q

Where does the cyclic motor activity of the GIT move during the interdigestive period?

A

over the distal stomach and small intestine

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4
Q

What is the rate of GI motility during the interdigestive period?

A

moves over portions of the GIT at 2-10 cm/minute

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5
Q

How many phases are in the migrating myoelectric complex?

A

3

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6
Q

What happens to spike potentials and contractions during phase I of the MMC?

A

no spike potentials, no contractions

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7
Q

What happens to spike potentials and contractions during phase II of the MMC?

A

irregular spike potentials and contractions

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8
Q

What happens to spike potentials and contractions during phase III of the MMC?

A

regular spike potentials and contractions

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9
Q

Why is it called the “migrating” myoelectric complex

A

because it moves down the length of the GIT

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10
Q

How long does phase I of the MMC last?

A

60 min

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11
Q

How long does phase II of the MMC last?

A

20 min

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12
Q

How long does phase III of the MMC last?

A

10 min

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13
Q

When is the MMC interrupted?

A

when we consume a meal

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14
Q

Why is the MMC important?

A

because it allows us to move food in the interdigestional period that haven’t moved at other times

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15
Q

What is the function of the MMC?

A

gastric emptying of large, nondigestible particles even in the absence of a meal

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16
Q

Which nervous system does the MMC need in order to be initiated?

A

the enteric nervous system

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17
Q

Which nervous system does the MMC need in order to be propagated?

A

the enteric nervous system

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18
Q

What helps the ENS propagate MMC?

A

ANS and gut peptides

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19
Q

What is the function of the exocrine secretions?

A

chemical breakdown of food

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20
Q

What are the 2 kinds of gland secretion?

A

endocrine and exocrine

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21
Q

Are gland secretions that move into GIT external environment considered exocrine or endocrine?

A

exocrine

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22
Q

Are gland secretions that move into the blood stream and internal environment considered exocrine or endocrine?

A

endocrine

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23
Q

What is important to consider about the enzymes involved in digestion?

A

their medium requirements: pH, ions

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24
Q

Digestion results from the secretory activity of a large number of ___ glands found within and in association with the GIT.

A

exocrine

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25
Q

Where are exocrine secretions released in the digestive tract?

A

the lumen

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26
Q

What kind of process is secretion?

A

active, energy and blood flow dependent

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27
Q

What does secretion result in the release of?

A

fluids containing ions and enzymes

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28
Q

What are the 3 types of digestive enzymes?

A
  • amylases
  • proteases
  • lipases
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29
Q

What is the pattern of nervous system regulation of secretion?

A

decreases from proximal -> distal

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30
Q

What is the pattern of hormonal regulation of secretion?

A

increases from proximal -> distal

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31
Q

Which nervous system regulates secretion?

A

ANS

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32
Q

Which hormones regulate secretion?

A

gut peptides

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33
Q

What are the 3 salivary glands?

A
  • parotid
  • submandibular
  • sublingual
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34
Q

Which secretion of the mouth protects and lubricates?

A

mucin

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35
Q

What does mucin lubricate?

A

the bolus

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36
Q

Which 2 secretions in the mouth allow for chemical digestion?

A
  • salivary amylase
  • lingual lipase
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37
Q

What does salivary amylase begin?

A

carbohydrate digestion

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38
Q

What does lingual lipase begin?

A

lipid digestion

39
Q

What fluid does the parotid gland release?

A

serous fluid

40
Q

What fluid does the sublingual gland release?

A

mucin-rich fluid

41
Q

What fluid does the submandibular gland release?

A

mixed fluid (serous + mucin-rich)

42
Q

Which is the only secretion in the GIT that is hypotonic?

A

saliva

43
Q

What is the volume of saliva produced every day?

A

0.5-1.5 liters/day

44
Q

What are the 4 ions present in saliva?

A

Na+, K+, Cl-, HCO3-

45
Q

What is the pH of saliva? Why?

A

6.5-7.0 because of the bicarbonate secreted into it

46
Q

What can starch (polysaccharide) be broken down into by saliva? With which enzyme?

A

maltose by the enzyme ptylin

47
Q

Where does lipase break down fats?

A

at the level of the stomach

48
Q

What do lysozymes break down?

A

bacterial cell walls

49
Q

What do lysozymes protect us from?

A

bacteria in food

50
Q

Which branch of the ANS increases secretion?

A

parasympathetic system

51
Q

How can you block secretion?

A

by giving atropine

52
Q

What happens when ACh is released onto a secretory cell?

A

it will depolarize and the depolarization will lead to secretion (exocytosis)

53
Q

What also increases when secretion increases?

A

vasodilation

54
Q

What would happen to secretion if the sympathetic system were activated?

A

it would decrease

55
Q

Does the sympathetic system cause vasoconstriction or vasodilation?

A

vasoconstrction

56
Q

What activates afferents that feed into the salivary centres in the medulla?

A

sensory receptors in the mouth

57
Q

What do the salivary centres in the medulla send out to the salivary glands?

A

efferents via parasympathetic supply

58
Q

What activates higher centres in the cortex and then in turn activates salivary centres in medulla?

A

smelling food or seeing food

59
Q

What is the first phase of secretion?

A

cephalic

60
Q

What is the cephalic phase made of?

A
  • psychic
  • gustatory
61
Q

What are the 3 phases of secretion?

A
  1. cephalic
  2. gastric
  3. intestinal
62
Q

How much mixed gastric juice is produced per day?

A

1.5-2 L/day

63
Q

What are the ions found in mixed gastric juice?

A

Na+, K+, Cl-, H+

64
Q

Which ion is the most important in mixed gastric juice?

A

H+

65
Q

What is the pH of mixed gastric juice?

A

1-2

66
Q

What kind of fluid is mixed gastric juice?

A

isotonic

67
Q

What gives the stomach its low pH?

A

the HCl found within it

68
Q

What are the 4 main components of mixed gastric juice?

A
  • HCl
  • pepsinogen
  • intrinsic factor
  • mucin
69
Q

Which enzymes break down proteins into smaller proteins? (4)

A
  • pepsin
  • trypsin
  • chymotrypsin
  • elastase
70
Q

Which enzymes break down smaller peptides into individual amino acids? (2)

A
  • aminopeptidase
  • carboxypeptidase
71
Q

What do surface epithelial cells throughout the GIT secrete? (2)

A

mucous and alkaline fluid

72
Q

How do we increase the surface area of secretion in the stomach?

A

by tubular glands

73
Q

What kind of fluid do the cardiac and pyloric tubular glands secrete?

A

alkaline, mucin-rich fluid

74
Q

What kind of fluid do the fundus and body tubular glands secrete? (3)

A

acid, enzymes and intrinsic factor

75
Q

What are the 3 important cells found in the fundus and body of the stomach?

A

parietal cells, chief cells, mucus neck cells

76
Q

What do parietal cells release into the lumen of the tubular gland?

A

HCl

77
Q

What do chief cells release?

A

pepsinogen

78
Q

What do mucus neck cells produce?

A

mucus and alkaline fluids

79
Q

What do surface epithelial cells release?

A

HCO3 and mucus

80
Q

What do the canaliculi of the parietal cells do?

A

increase their apical surface area for the secretion of HCl

81
Q

What do parietal cells have a lot of? Why?

A

mitochondria, because producing HCl requires a lot of energy

82
Q

What is the mEq of H+ and Cl- of the HCl produced by the parietal cells?

A

150 mEq H+ and 150 mEq Cl-

83
Q

For every HCl molecule moving into the lumen, 1 molecule of ___ is going to move into the capillary.

A

HCO3- (bicarbonate)

84
Q

As we acidify the lumen, we create an ___ of the blood.

A

alkalization

85
Q

Cl- entering the cell is ___ transported across the canalicular membrane.

A

actively

86
Q

H+ available from the dissociation of intracellular water, is also actively pumped into the canaliculi in exchange for ___.

A

K+

87
Q

What does the secretion of H+ leave an excess of in the cell?

A

OH-

88
Q

What happens to pH when there is an excess of OH- in the cell?

A

it increases

89
Q

When there is an increase in the intracellular pH, what happens to CO2?

A

it diffuses in from the plasma and combines with water to produce H2CO3

90
Q

When does CO2 combine with water in the presence of?

A

carbonic anhydrase

91
Q

What does H2CO3 react with to produce H20 and HCO3?

A

excess OH-

92
Q

What happens to the alkalinity in the venous blood during HCl secretion?

A

it increases

93
Q
A

PHGY-210 (36 decks)

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