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BS453: Physiology > Chapter 8: Gastrointestinal Physiology > Flashcards

Chapter 8: Gastrointestinal Physiology Flashcards

1
Q

summarize the path of the digestive tract

A

mouth -> esophagus -> stomach -> small intestine -> large intestine -> rectum -> anus

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2
Q

the surface of the GI tract is considered to face the (1. inside/outside) of the body; thus, it is lined with (2)

A
  1. outside
  2. epithelium
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3
Q

summarize the layers of the gut (from lumen)

A

lumen -> mucosal layer -> submucosa -> muscle layer -> serosa

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4
Q

in the gut, the (1) faces the lumen, while the (2) layer faces blood

A
  1. mucosal
  2. serosal
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5
Q

mucosal layer in the gut consists of:

A
  1. epithelial lining (contains mucosal glands)
  2. mucosa
  3. mucosal muscle
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6
Q

found beneath the mucosal layer in the gut, and consists of elastin, collagen, glands, and blood vessels

A

submucosa

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7
Q

the submucosal nerve plexus is also called the ()

A

Meissner’s nerve plexus

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8
Q

the muscle layers of the gut consist of:

A
  1. longitudinal muscle (thin)
  2. circular muscle (thick)
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9
Q

the () nerve plexus is found between the longitudinal and circular muscle layers of the gut

A

myenteric

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10
Q

the GI tract is regulated in part by the ()

A

autonomic NS

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11
Q

regulation of the GI tract has intrinsic and extrinsic components:

A
  1. intrinsic: enteric NS
  2. extrinsic: sympathetic and parasympathetic innervation
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12
Q

parasympathetic innervation of the GI tract is supplied by the ff nerves:

A
  1. vagus nerve (CN X) - cranial PNS; upper GI tract
  2. pelvic nerve - sacral PNS; lower GI tract
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13
Q

the upper GI tract consists of (1), while the lower GI tract consists of (2)

A
  1. esophagus to first half of transverse colon
  2. second half of transverse colon to anus
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14
Q

neurons in the vagus and pelvic nerve serve as (pre/postganglionic neurons) in parasympathetic innervation

A

preganglionic

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15
Q

parasympathetic ganglia in the GI tract are located at (1), thus they have (short/long) preganglionic fibers

A
  1. organ walls
  2. long
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16
Q

parasympathetic postganglionic neurons in the GI tract are either (1) or (2), and are located w/in (3)

A
  1. cholinergic (release ACh -> muscle contraction)
  2. peptidergic (release peptides -> muscle relaxation)
  3. myenteric and submucosal plexuses
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17
Q

stimulation of parasympathetic nerves in GI tract result in (1), which in turn results in (2)

A
  1. increased activity of entire enteric NS
  2. enhanced activity of GI functions
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18
Q

sympathetic innervation of the GI tract originate from the (1), between (2) and (3)

A
  1. spinal cord
  2. lower thoracic (T5) segment
  3. upper lumbar (L2) segment
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19
Q

sympathetic preganglionic fibers of the GI tract enter (1), which are (near/far from) target organs

A
  1. sympathetic chains
  2. far from
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20
Q

sympathetic postganglionic neurons are found within the ()

A

sympathetic ganglia: celiac, superior/inferior mesenteric, hypogastric

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21
Q

stimulation of sympathetic nerves in the GI tract result in (); sympathetic action can be broken down into a minor and major effect

A

inhibition of GI activity

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22
Q

minor effect of sympathetic stimulation in GI tract

A

secreted NE inhibits smooth muscle contraction

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23
Q

major effect of sympathetic stimulation in GI tract

A

secreted NE inhibits enteric NS neurons

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24
Q

recall that all preganglionic neurons of the sympathetic NS are ()

A

cholinergic

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25
Q

recall that all postganglionic neurons of the sympathetic NS are ()

A

adrenergic (in GI tract, release NE)

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26
Q

the enteric NS is innervated by ()

A

sympathetic and parasympathetic NS

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27
Q

effect of enteric NS is mostly targeted to () GI tract functions

A

contractile, secretory, and endocrine

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28
Q

note that both the parasympathetic and sympathetic NS can directly innervate () in the GI tract

A

smooth muscle

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29
Q

the enteric NS consists of:

A
  1. myenteric nerve plexus
  2. submucosal nerve plexus
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30
Q

the myenteric nerve plexus mainly controls ()

A

GI movements

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31
Q

the submucosal plexus main controls ()

A

Gi secretion and local blood flow

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32
Q

3 types of reflexes in the GI tract

A
  1. integrated entirely within gut wall enteric NS
  2. from gut to prevertebral sympathetic ganglia
  3. from gut to CNS then back to GI tract
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33
Q

reflexes () control Gi secretion, peristalsis, mixing contractions, local inhibitory effects, etc.

A

that are integrated entirely within gut wall enteric NS

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34
Q

example of a GI reflex from gut to prevertebral sympathetic ganglia

A

gastrocolic reflex (stomach -> colon)

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35
Q

the gastrocolic reflex is triggered by (1), and causes (2)

A
  1. distention of the stomach
  2. evacuation of the colon
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36
Q

example of reflexes from gut to CNS then back to GI tract

A

vagovagal reflex

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37
Q

neurotransmitters and neuromodulators of the enteric NS

A
  1. ACH
  2. NE
  3. vasoactive intestinal petide (VIP)
  4. nitric oxide (NO)
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38
Q

neurotransmitters and neuromodulators of the enteric NS; released by enteric NS neurons

A

VIP and NO

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39
Q

neurotransmitter/neuromodulator of the enteric NS that causes:
1. smooth muscle contraction of wall
2. relaxation of sphincters
3. stimulates gastric, pancreatic, and salivary secretion

A

ACh

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40
Q

neurotransmitter/neuromodulator of the enteric NS that causes:
1. smooth muscle relaxation of wall
2. contraction of sphincters
3. stimulates salivary secretion

A

NE

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41
Q

neurotransmitter/neuromodulator of the enteric NS that causes:
1. smooth muscle contraction of wall
2. stimulates intestinal, pancreatic secretion

A

vasoactive intestinal peptide (VIP)

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42
Q

neurotransmitter/neuromodulator of the enteric NS that causes:
1. smooth muscle relaxation of wall

A

nitric oxide

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43
Q

3 classes of GI peptides

A
  1. hormones
  2. paracrines
  3. neurocrines
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44
Q

GI peptide that is released from endocrine cells and enters systemic circulation

A

hormones

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45
Q

GI peptide that is released from endocrine cells and acts locally (within same tissue from which it was released)

A

paracrines

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46
Q

GI peptide that is synthesized by enteric NS neurons; released following an action potential

A

neurocrines

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47
Q

main GI hormones

A
  1. gastrin
  2. cholecystokinin (CCK)
  3. secretin
  4. gastric inhibitory peptide (GIP)
  5. glucagon-like peptide-1 (GLP-1)
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48
Q

gastrin is secreted by ()

A

G cells of antrum (stomach), duodenum, jejunum

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49
Q

CCK (GI hormone) facilitates digestion of ()

A

fat and protein

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50
Q

CCK is released by ()

A

I cells of small intestine

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51
Q

CCK release inhibits ()

A

gastric emptying

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52
Q

secretin is secreted by ()

A

S cells of small intestine

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53
Q

secretin release inhibits ()

A

gastric acid secretion

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54
Q

GIP is also called ()

A

glucose-dependent insulinotropic peptide

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55
Q

GIP is secreted by ()

A

K cells of duodenum, jejunum

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56
Q

GIP release inhibits ()

A
  1. gastric acid secretion
  2. gastric emptying
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57
Q

GLP-1 is a GI tract hormone synthesized from ()

A

incretin

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58
Q

GLP-1 is released by ()

A

L cells of small intestine

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59
Q

hormones involved in insulin secretion

A

GIP and GLP-1

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60
Q

liraglutide drugs target () receptors to target diabetes and chronic obesity

A

GLP-1

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61
Q

why are liraglutides safer than directly injecting insulin

A

they only indirectly affect glucose levels; insulin injections result in abrupt drop in blood sugar

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62
Q

new GLP-1 receptor agonists; administered weekly

A

semaglutides

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63
Q

examples of liraglutides

A

victoza, saxenda

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64
Q

examples of semaglutides

A

ozempic, wegovy

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65
Q

new GIP and GLP-1 dual agonist

A

tirzepatide

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66
Q

() are slow, undulating waves in smooth muscle RMP

A

slow waves

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67
Q

slow waves appear to be caused by complex interactions between smooth muscle cells and (1), which act as (2)

A
  1. interstitial cells of Cajal
  2. electrical pacemakers
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68
Q

true action potentials of GI tract smooth muscles

A

spike potentials

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69
Q

spike potentials are caused by opening of (), which open and close more slowly compared to rapid Na+ channels

A

calcium-sodium channels

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70
Q

slow waves (do/do not) cause Ca2+ entry

A

do not

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71
Q

spike potentials are generated at () of slow waves; cause significant quantities of Ca2+ to enter smooth muscle cell

A

peaks

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72
Q

muscle layers of the GI tract act as (1) due to being electrically coupled via large numbers of (2)

A
  1. syncytium
  2. gap junctions
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73
Q

technical term for swallowing

A

deglutition

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74
Q

swallowing is controlled by the ff nerves

A
  1. vagus nerve - esophagus
  2. glossopharyngeal nerve - tongue and pharynx
  3. trigeminal nerve - soft palate
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75
Q

3 phases of swallowing

A
  1. buccal (oral) phase
  2. pharyngeal phase
  3. esophageal phase
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76
Q

the pharyngeal and esophageal phases of swallowing are (voluntary/involuntary)

A

involuntary

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77
Q

characteristics of pharyngeal phase of swallowing

A
  1. closed trachea
  2. open esophagus
  3. fast peristaltic wave triggers by pharynx NS
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78
Q

whole pharyngeal phase of swallowing lasts ()

A

less than 2 seconds

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79
Q

2 movements of esophageal phase of swallowing

A

primary and secondary peristalsis

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80
Q

continuation of peristaltic wave from pharynx in esophageal phase

A

primary peristalsis

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81
Q

secondary peristalsis in the esophageal phase occurs if ()

A

primary peristalsis fails to move all bolus into stomach

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82
Q

secondary peristalsis is triggered by (1); continues until (2)

A
  1. distension of esophagus
  2. all bolus enters stomach
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83
Q

the lower esophageal sphincter (LES) is also called the ()

A

gastroesophageal sphincter

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84
Q

normally, the LES remains ()

A

tonically constricted

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85
Q

receptive relaxation in the LES occurs () to facilitates easy propulsion of food into stomach

A

ahead of peristalsis

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86
Q

the esophagus is lined with (), which is resistant to abrasion and similar to skin

A

squamous epithelium

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87
Q

where 2 different types of epithelium meet at the gastroesophageal junction

A

squamocolumnar junction

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88
Q

mucosa consists of () epithelium, specialized for absorption

A

gastric and intestinal

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89
Q

2 mechanisms that prevent esophageal reflux

A
  1. tonic constriction of LES
  2. valve-like mechanism of a short portion of the esophagus that slightly extends into stomach
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90
Q

increased () seals the valve-like section of the esophagus closed to prevent esophageal reflux

A

intra-abdominal pressure

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91
Q

gastroesophageal reflux disease (GERD) is caused by (1) LES, causing (2)

A
  1. weak, incompetent open
  2. reflux
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92
Q

frequent presence of (1) in esophagus due to GERD turns squamous epithelium into (2), thus increasing risk of (3)

A
  1. stomach acid
  2. mucosa
  3. cancer
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93
Q

condition that results from failure of LES to relax during swallowing

A

achalasia (megaesophagus)

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94
Q

achalasia is characterized by ()

A
  1. dilation of esophageal body
  2. bird’s beak
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95
Q

why does LES remain contracted in achalasia

A

damage to neural network in lower 2/3 of esophagus prevents myenteric plexus from sending signal for receptive relaxation

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96
Q

treatment options for achalasia

A
  1. balloon angioplasty to stretch bird’s beak
  2. antipasmodic drugs
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97
Q

3 anatomic division of the stomach

A
  1. fundus
  2. body
  3. antrum
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98
Q

thin-walled stomach division consisting of fundus and proximal portion of body

A

orad region

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99
Q

thick-walled stomach division consisting of distal portion of body and antrum

A

caudad region

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100
Q

caudad stomach region generates stronger contractions for ()

A

mixing stomach contents

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101
Q

receptive relaxation in the stomach results in ()

A
  1. reduced pressure
  2. increased orad stomach volume
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102
Q

receptive relaxation in the stomach is caused by ()

A

vagovagal reflex

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103
Q

neurotransmitter released in vagovagal reflex

A

vasoactive intestinal peptide (VIP)

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104
Q

() completely eliminates motor and sensory components of receptive relaxation

A

vagotomy

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105
Q

3 parts of the small intestine

A
  1. duodenum
  2. jejunum
  3. ileum
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106
Q

the jejunum contains ()

A

plicae circulares

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107
Q

movement in small intestine that causes food to move forward along GI tract

A

propulsive movement (peristalsis)

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108
Q

movement in small intestine that keeps intestinal contents thoroughly mixed at all times

A

mixing movements (segmentation)

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109
Q

parts of the large intestine

A
  1. ascending colon
  2. transverse colon
  3. descending colon
  4. sigmoid colon
110
Q

the rectum constitutes the lase () of the GI tract

A

15 cm (6 in)

111
Q

expandable organ for temporary storage of feces

A

rectum

112
Q

last portion of the rectum

A

anal canal

113
Q

the anal canal contains small longitudinal folds called ()

A

anal columns

114
Q

the anus is also called the ()

A

anal orifice

115
Q

exit of anal canal; has keratinized, epidermis-like skin

A

anus

116
Q

circular muscle layers of muscularis externa in anus; made up of smooth muscle -> involuntary

A

internal anal sphincter

117
Q

encircles distal portion of anal canal; made up of a ring of voluntary skeletal muscle

A

external anal sphincter

118
Q

the weak intrinsic reflex in defecation is triggered by ()

A

rectal wall distension due to entry of fecal matter

119
Q

in the intrinsic reflex of defecation, signals from myenteric plexus result in ()

A
  1. peristaltic waves that force feces into anus
  2. relaxation of internal anal sphincter
120
Q

converts weak intrinsic reflex to powerful process of defecation

A

parasympathetic defecation reflex

121
Q

purposely activates defecation reflexes by increasing intra-abdominal pressure and forcing fecal matter into rectum

A

valsalva maneuver

122
Q

reflexes initiated by the Valsalva maneuver are (more/less) effective that reflexes that arise naturally

A

less

123
Q

type of epithelium found in stomach, intestine, and gallbladder lining

A

simple columnar epithelium

124
Q

main function of simple columnar epithelium

A

absorption, secretion, protection

125
Q

type of epithelium found in glands, ducts, portion of kidney tubules, and thyroid gland

A

simple cuboidal epithelium

126
Q

type of epithelium found on skin surface, lining of mouth, throat, esophagus, anus, and vagina

A

stratified squamous epithelium

127
Q

main function of stratified squamous epithelium

A

provides physical protection against abrasion, pathogens, and chemical attack

128
Q

most important organ for digestion of proteins

A

pancreas

129
Q

interface between stomach antrum and duodenum

A

pylorus

130
Q

Histamine, released by (1) is a strong stimulator for (2)

A
  1. enterochromaffin-like (ECL) cells
  2. acid secretion
131
Q

to increase acid secretion, histamine stimulates (1), which release HCl and (2)

A
  1. parietal cells
  2. intrinsic factor
132
Q

oxyntic means ()

A

acid-forming

133
Q

() cells are found all over the stomach (both in oxyntic and pyloric gland)

A

mucus

134
Q

the oxyntic gland consists of:

A
  1. mucus neck cells -> mucus
  2. chief cells -> pepsinogen
  3. parietal cells -> HCl and intrinsic factor
135
Q

chief cells are innermost cells; secreted pepsinogen passes by parietal cells, allowing pepsinogen to be ()

A

activated by HCl (from parietal cells)

136
Q

pepsinogen is activated by contact with HCl to form ()

A

active pepsin

137
Q

pepsin has no proteolytic activity above a pH of about ()

A

5

138
Q

optimum pH range for pepsin activity

A

1.8 to 3.5

139
Q

intrinsic factor is essential for the () in the ileum

A

absorption of vitamin B12

140
Q

in patients with (), acid-producing parietal cells of the stomach are frequently destroyed

A

chronic gastritis

141
Q

lack of stomach acid secretion

A

achlorhydria

142
Q

results from the failure if red blood cell maturation due to the absence of vitamin B12 stimulation in the bone marrow

A

pernicious anemia

143
Q

phases of gastric secretion

A
  1. cephalic
  2. gastric
  3. intestinal
144
Q

gastric secretion phase that occurs even before food enters the stomach, especially while it is being eaten

A

cephalic phase

145
Q

during the cephalic phase of gastric secretion, neurogenic signals from the cerebral cortex and appetite centers (amygdala and hypothalamus) are transmitted through the () to the stomach

A

vagus nerves

146
Q

the cephalic phase of gastric secretion normally accounts for about ()% of gastric secretion associated with eating a meal

A

30

147
Q

gastric secretion phase in which multiple mechanisms cause secretion of gastric juice for several hours while food remains in the stomach

A

gastric phase

148
Q

the gastric phase of secretion accounts for about ()% of the total gastric secretion associated with eating a meal

A

60

149
Q

gastric secretion phase wherein presence of food in the upper portion of the small intestine (esp in duodenum) will continue to cause stomach secretion of small amounts of gastric juice

A

intestinal phase

150
Q

continued secretion of gastric juice during the intestinal phase is partly due to ()

A

small amounts of gastrin released by the duodenal mucosa

151
Q

the intestinal phase of secretion accounts for about ()% of the total gastric secretion associated with eating a meal

A

10

152
Q

to neutralize gastric juice, presence of acid in the small intestine liberates (1) from the intestinal mucosa, which promotes rapid secretion of pancreatic juice containing a high concentration of (2)

A
  1. secretin
  2. sodium bicarbonate
153
Q

an excoriated area of stomach or intestinal mucosa caused principally by the digestive action of gastric juice or upper small intestinal secretions

A

peptic ulcer (disease)

154
Q

peptic ulcers are most frequent along the (1); aka (2)

A
  1. lesser curvature of the antral end of the stomach
  2. duodenal ulcer
155
Q

gastric ulcers can be classified into:

A
  1. ulcers in the cardia
  2. marginal ulcers
156
Q

ulcers in the cardia are due to ()

A

reflux of gastric juice

157
Q

marginal ulcers are due to ()

A

surgical openings (e.g. gastrojejunostomy)

158
Q

usual cause of peptic ulceration is an imbalance between

A
  1. gastric juice secretion rate (H+, pepsin) -> destructive
  2. degree of protection offered by gastroduodenal mucosal barrier and neutralization of gastric acid (by HCO3- in duodenal juice) -> protective
159
Q

NSAIDs (non-steroidal anti-inflammatory drugs) work by inhibiting (1); decrease in 1 results in less inhibition of acid secretion in stomach, so NSAIDs should be taken (before/after) eating a meal

A
  1. prostaglandins
  2. after
160
Q

common damaging factors involved in development of peptic ulcer disease

A
  1. smoking
  2. alcohol
  3. consumption of aspirin and other NSAIDs
161
Q

at least 75% of people with peptic ulcers have chronic infection of the terminal portions of the gastric mucosa and initial portions of the duodenal mucosa, most often caused by the bacterium ()

A

Heliobacter pylori

162
Q

action of H. pylori infection

A
  1. physically burrows through mucosal barrier
  2. releases ammonium that liquifies the barrier and stimulates the secretion of HCl
163
Q

treatment options for peptic ulcer disease

A
  1. antibiotics
  2. acid-suppressant drugs
  3. surgery
164
Q

acid-suppressant drug that works as an antagonist at histamine H2 receptors

A

cimetidine

165
Q

acid-suppressant drug that works as a blocker of H+-K+ ATPase (proton inhibitor, PPI)

A

omeprazole

166
Q

2 major kinds of cells in pancreas

A
  1. endocrine cells (of pancreatic islets
  2. exocrine cells
167
Q

endocrine cells of the pancreatic islets secrete () into the bloodstream

A

insulin and glucagon

168
Q

2 major kinds of exocrine cells

A
  1. acinar cells
  2. ductal cells
169
Q

pancreatic exocrine cells secrete ()

A

pancreatic juice

170
Q

() stimulate pancreatic acinar cells

A

ACh and CCK

171
Q

(1) stimulates secretion of large quantities of water solution of NaCO3- by (2)

A
  1. secretin
  2. ductal cells
172
Q

main function of small intestine is:

A

completed digestion of food

173
Q

main function of large intestines

A

only absorbtion

174
Q

salivary or pancreatic enzyme involved in initial digestion of starch

A

alpha-amylase

175
Q

after initial digestion by alpha-amylase, other enzymes, found at the (), further digest alpha-amylase products into glucose/galactose

A

intestinal brush-border

176
Q

lactose intolerance is caused by (1), and results in (2)

A
  1. lactase deficiency
  2. osmotic diarrhea
177
Q

osmotic diarrhea is caused by the presence of an () -> attracts increased amount of water

A

inabsorbable osmole

178
Q

carbohydrates are absorbed in the form of ()

A

monosaccharides

179
Q

3 monosaccharides absorbed by the gastrointestinal tract

A

glucose, galactose, fructose

180
Q

glucose and galactose are transported into the small intestine epithelial cells by ()

A

Na+ co-transport mechanism

181
Q

fructose is absorbed into small intestine epithelial cells by ()

A

facilitated diffusion

182
Q

blood (containing monosaccharides) from the digestive system must first pass through the () before returning to the heart

A

liver

183
Q

summary of portal circulation

A

artery -> capillary -> portal vein -> capillary -> vein

184
Q

protein digestion first starts is (1), but majorly occurs in (2)

A
  1. stomach
  2. small intestine (via pancreatic enzymes)
185
Q

gastrointestinal protease that hydrolyzes interior peptide bonds

A

endopeptidase

186
Q

types of endopeptidases

A
  1. pepsin
  2. trypsin
  3. chymotrypsin
  4. elastase
187
Q

gastrointestinal protease that hydrolyzes from the C-terminal ends

A

exopeptidases

188
Q

examples of exopeptidases

A

carboxypeptidase A and B

189
Q

activator for all other proenzymes (including itself) in the small enzyme

A

trypsin

190
Q

activator of trypsinogen to produce trypsin; located in the brush border

A

enterokinase

191
Q

“absorbable” forms of proteins

A
  1. amino acids
  2. dipeptides
  3. tripeptides
192
Q

products of protein digestion by pepsin in stomach lumen

A

amino acids, oligopeptides

193
Q

L-amino acids are absorbed into small intestine epithelial cells via ()

A

Na+ - amino acid transporter

194
Q

dipeptides and tripeptides are commonly absorbed through (1); afterward they are hydrolyzed to amino acids by (2)

A
  1. H+ dependent cotransporters
  2. cytosolic peptidases
195
Q

3 types of dietary lipids absorbed by GI tract

A

triglycerides, cholesterol, phospholipids

196
Q

first step of lipid digestion; physically breaking fat globules into small sizes so that water-soluble digestive enzymes can act on the globule surfaces

A

emulsification

197
Q

emulsification in the duodenum occurs due to the influence of (1), which contains (2)

A
  1. bile juice
  2. bile salts, lecithin
198
Q

bile acids conjugated with amino acids (glycine or taurine); amphiphatic

A

bile salts

199
Q

triglycerides are broken down into () by the action of lingual, gastric, and pancreatic lipases

A

monoglyceride, 2 fatty acids

200
Q

cholesterol ester is broken down into (1), by the action of (2)

A
  1. cholesterol, fatty acid
  2. cholesterol ester hydrolase
201
Q

phospholipids are broken down into (1) by the action of (2)

A
  1. lysolecithin, fatty acid
  2. phospholipase A2
202
Q

major site of intestinal Na+ absorption

A

jejunum

203
Q

secretion of HCO3 neutralizes the acidity generated by ()

A

bacteria in the gut

204
Q

absorbed fluid in small intestine epithelial cell is always ()

A

isosmotic

205
Q

Na+ absorption through Na+ channels in colon epithelial cells can be facilitated by ()

A

aldosterone

206
Q

aldosterone is secreted from adrenal gland in response to ()

A

blood volume deficiency

207
Q

absorbed Na+ can help with blood volume deficiency because

A

Na+ (extruded by NaK ATPase) in blood holds onto water and prevents it from entering cell; water stays in blood and increases blood volume

208
Q

tight junctions between epithelial cells of the colon are much tighter than those of the jejunum and ileum, which prevents ()

A

significant amounts of back-diffusion of Na+ ions

209
Q

bacteria in the colon is capable of digesting small amounts of () -> provides a few extra calories of extra nutrition for the body

A

cellulose

210
Q

essential substance for blood clotting

A

vitamin K

211
Q

substance required for maturation of red blood cells

A

vitamin B12

212
Q

intestinal Cl- channels are usually (open/closed), but can be opened by (2)

A
  1. closed
  2. cAMP-dependent signalling pathway
213
Q

cholera toxin enters epithelial cells to cause () of G_alpha_S protein -> results in loss of GTPase activity -> adenylyl cyclase is constantly active

A

ADP ribosylation

214
Q

due to action of cholera toxin, (1) builds up in GI tract lumen -> attracts a lot of water via osmosis -> form of (2)

A
  1. Cl-
  2. secretory diarrhea
215
Q

common causes of diarrhea

A
  1. enteritis
  2. psychogenic
  3. lactose intolerance
216
Q

inflammation in intestinal tract, usually caused by bacteria or virus -> causes secretory diarrhea

A

enteritis

217
Q

only problem of diarrhea

A

dehydration

218
Q

cause of diarrhea that accompanies periods of nervous tension -> caused by excessive stimulation of parasympathetic NS (increases motility and secretion)

A

psychogenic

219
Q

gross anatomy of the liver: (1) lobes separated along the line of the (2)

A
  1. left and right
  2. falciform ligament
220
Q

functional anatomy of the liver: (1) sectors and (2) segments; separated by (3)

A
  1. 4
  2. 8
  3. blood supply or biliary drainage
221
Q

the liver has dual blood supply: (1)% of blood supply is arterial blood from the hepatic artery, while (2)% is venous blood from hepatic portal vein

A
  1. 30
  2. 70
222
Q

arterial blood supply from hepatic artery provides (1)% of liver’s oxygen supply; venous blood from portal vein delivers remaining (2)%

A
  1. 60
  2. 40
223
Q

delivers blood from GI tract and spleen to liver; not a true vein and is rich in nutrients

A

portal vein

224
Q

why is the portal vein not a true vein

A

it doesn’t deliver blood back to heart

225
Q

hepatocellular carcinoma (HCC) takes is blood supply almost completely from the ()

A

hepatic artery

226
Q

the portal triad runs along the ()

A

porta hepatis

227
Q

the portal triad consists of ()

A
  1. portal vein
  2. hepatic artery
  3. bile duct
228
Q

basic fundamental units of the liver

A

liver lobules

229
Q

each liver lobe is divided by () into about 100k liver lobules about 1mm diameter each

A

connective tissue

230
Q

liver lobules are () in cross section

A

hexagonal

231
Q

blood from portal vein and hepatic artery flows to central vein through ()

A

sinusoid

232
Q

() in the liver (histology) absorb many substances from from plasma

A

hepatocytes

233
Q

bile flows into the (), which opposes the flow in the sinusoid

A

bile canaliculi

234
Q

the space in which fibers (collagen) accumulate as a consequence of liver cirrhosis

A

space of Disse

235
Q

final outcome of almost all liver diseases

A

liver cirrhosis

236
Q

like macrophages -> immune cells in the liver

A

Kupffer cells

237
Q

physiologic functional unit of the liver

A

liver acini

238
Q

liver acini are divided into 3 zones according to distance from blood supply:

A
  1. periportal zone (closest)
  2. intermediate zone
  3. perivenular zone (farthest)
239
Q

advantage of viewing the acinus as a functional unit

A

helps to explain the patterns and zonal property of many diseases

240
Q

mesenchymal cell located in the space of Disse; involved in production of collagen and cell matrix when activated

A

hepatic stellate cell

241
Q

other cells in the liver include:

A

endothelial cells, bile ductular cells

242
Q

term for vomiting blood

A

hematemesis

243
Q

abdominal cavity accumulates fluid (water)

A

ascites

244
Q

liver cirrhosis causes portal vein hypertension because ()

A

hardening of liver narrows porta hepatis

245
Q

portal vein hypertension causes (1) to distal vein, leading to (2) formation

A
  1. venous blood reflux
  2. varices
246
Q

liver maintains blood glucose level -> () function

A

glucose buffer

247
Q

fatty acids hydrolyzed from dietary fat are important (1) and (2) of the cell

A
  1. energy sources
  2. structural components
248
Q

() are synthesized by the liver and intestine -> play a key role in transport of liquid

A

apolipoproteins

249
Q

excess glucose in the liver is converted to (1) and stored as (2)

A
  1. fatty acid
  2. adipose tissue
250
Q

lipoprotein that contains high concentrations of triglycerides and moderate concentrations of both cholesterol and phospholipids

A

very low density lipoprotein (VLDL)

251
Q

VLDL from which a share of the triglycerides has been removed -> concentrations of cholesterol and phospholipids are increased

A

intermediate-density lipoprotein (IDL)

252
Q

derived from IDLs by the removal of almost all the triglycerides, leaving an especially high concentration of cholesterol and a moderately high concentration of phospholipids

A

low-density lipoprotein (LDL)

253
Q

contain a high concentration of protein (about 50 percent) but much smaller concentrations of cholesterol and phospholipids.

A

high-density liproprotein (HDL)

254
Q

ultra-low-density lipoprotein formed in intestinal mucosa that goes to the liver

A

chylomicron

255
Q

transported triglycerides and cholesterol are repackaged into () in the liver and delivered to other organs

A

VLDL

256
Q

HDL facilitates a process called () -> cholesterol in plasma membrane of peripheral cells is transported to liver

A

reverse cholesterol transport

257
Q

increased HDL level may reduce the risk of ()

A

atherosclerosis

258
Q

binding protein in the blood -> regulates oncotic pressure of blood; produced from liver

A

albumin

259
Q

(increased/decreased) albumin level is a strong indicator of liver cirrhosis -> new albumin level results in ascites and peripheral edema

A

decreased

260
Q

the phase 1 pathway in the liver for the inactivation of various substances absorbs (1); mediated by (2) -> most reactions are (3)

A
  1. fat-soluble toxins
  2. cytochrome p450
  3. oxidations
261
Q

the phase 2 pathway in the liver for the inactivation of various substances releases (1); reactions involve (2) to result in a (3)

A
  1. water-soluble waste
  2. conjugation of drug metabolites
  3. water-soluble conjugate
262
Q

the biliary system consists of ()

A
  1. bile duct
  2. gallbladder
263
Q

2 components of bile duct

A

intrahepatic, extrahepatic ducts

264
Q

the intrahepatic duct is composed of

A

left and right hepatic ducts

265
Q

the extrahepatic duct consists of

A

common hepatic duct, common bile duct

266
Q

pear-shaped muscular sac that stores and concentrates bile prior to excretion

A

gallbladder

267
Q

contraction of the gallbladder is due to () stimulation

A

cholecystokinin (CCK)

268
Q

functions of bile juice

A
  1. intestinal lipid digestion
  2. maintenance of cholesterol homeostasis
  3. excretion of substances
269
Q

the function of () is to make lipids stable with forming micelle -> lipid becomes soluble in water

A

bile salt

270
Q

results from supersaturation (increased cholesterol, decreased bile salts)

A

cholesterol stone

BS453: Physiology (6 decks)

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