Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

N935 Advanced Pathophysiology > Week 4a Gastrointestinal Physiology > Flashcards

Week 4a Gastrointestinal Physiology Flashcards

1
Q

How much body mass is the GI system?

A

5%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the functions of the GI system?

A
  1. motility
  2. digestion
  3. absorption
  4. excretion
  5. circulation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

All regions of the GI system work together to:

A

regulate the intake, processing & absorption of ingested nutrients & the disposal of waste products

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What does the intestines interface with?

A

the immune system, with a diverse array of antigens present in food and gut microbes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are the two primary movements of the GI system?

A
  1. mixing

2. propulsive (peristalsis)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are the layers of the GI wall?

A 
Serosa
Longitudinal muscle layer
Circular muscle layer
Submucosa
Mucosa
Epithelium
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Define the serosa

A

smooth membrane of thin connective tissue

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What does the longitudinal muscle layer do?

A

contracts in order to shorten the length

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What does the circular muscle layer do?

A

contracts to decrease the diameter

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What does the submucosa do?

A

contains the submucosal (Meissner) plexus, which
transmits information from the epithelium to the enteric
and central nervous systems (CNS)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is the mucosa layer?

A

functions to move the villi and contains blood vessels,

nerve endings, and immune and inflammatory cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What layer of the GI system contains the immune and inflammatory cells?

A

mucosa

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the GI system epithelium layer?

A

contents are sensed and where secretion of enzymes, absorption of nutrients, and excretion of waste products
occur

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

How is the GI system innervated?

A
  • Extrinsic
    SNS (primarily inhibitory)
    PSNS (primarily excitatory)
  • Enteric (controls motility, secretion, & blood flow)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What does the SNS do in the GI system?

A

primarily inhibitory as stimulation can decrease or cease GI motility

primary neurotransmitter is norepinephrine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What does the PSNS do in the GI system?

A
  • primarily excitatory as it activates GI motility and function
    • primary neurotransmitter is acetylcholine
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What does the enteric nervous system do in the GI system?

A

independent nervous system of the GI tract, which controls motility, secretions, and blood flow

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What do vagus nerve fibers innervate in the GI system? (5)

[celiac plexus]

A
  • esophagus
  • stomach
  • pancreas
  • small intestine
  • first half of large intestine
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What do pelvic nerve fibers innervate in the GI system? (3)

[inferior hypogastric plexus]

A
  • second half of the large intestine
  • sigmoid
  • rectal/anal regions
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is myenteric (Auerbach’s) plexus?

A

Linear chain of many interconnecting neurons that
extends the entire length of the gastrointestinal tract

→ Lies between the longitudinal and circular layers of the
intestinal smooth muscle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What does stimulation of myenteric plexus result in?

A
  • Tonic contraction
  • Increased intensity of rhythmic contractions
  • Slight increase in rate of rhythmic contractions
  • Increased velocity of peristaltic waves
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What is the submucosal (Meissner’s) plexus?

A

• Controls inner wall of each minute segment of the intestine
• Originates in the epithelium
• Helps control local secretions, absorption, and contraction of the
submucosal muscle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is Meissner’s plexus also called?

A

submucosal plexus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is Auerbach’s plexus called?

A

myenteric plexus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What is another name for the submucosal plexus of the GI system?

A

Meissner’s plexus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What is another name for the myenteric plexus?

A

Auerbach’s plexus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What does the submucosal plexus control?

A

inner wall of each minute segment of the intestine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

Where does the submucosal plexus originate?

A

in the epithelium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What is the excitatory neuron secreted by enteric neurons?

A
  • acetylcholine
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

What are the two inhibitory neurons secreted by enteric neurons?

A
  • norepinephrine

- epinephrine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

Where do peristalsis contractions occur?

A

esophagus
stomach
small intestine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

Where do segmentation contractions occur?

A

small & large intestine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

What type of GI contraction is a mixing movement?

A

segmentation contractions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

Where is the esophagus located?

A

C6-T11

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

What is the job of the esophagus?

A

propels food from the pharynx to the stomach

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

What is the upper 1/3 of the esophagus composed of?

A

striated muscle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

What is the lower 2/3 of the esophagus composed of?

A

smooth muscle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

What prevents aspiration?

A

the epiglottis moves upward in a protective mechanism over the larynx and trachea to prevent aspiration during swallowing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

What is the level of the upper esophageal sphincter? & what is the resting tone?

A

at the level of the cricoid cartilage; C6

resting tone ranges 30-200mmHg

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

What innervates the lower esophageal sphincter?

A

SNS and PSNS

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

What is the resting tone of the lower esophageal sphincter?

A

10-45mmHg

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

What controls the lower esophageal sphincter?

A

it responds to esophageal distention via myogenic & neurohormonal mechanisms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

How much does the stomach store?

A

1.5-2L

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

What does the stomach do?

A

Breaks down food into chyme through physical/chemical mechanisms
- Solids must be broken into 1-2mm particles to enter the duodenum

  • mixes food with gastric secretions
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

What are the 3 types of cells in the stomach?

A
  1. G cells - secrete gastrin (stimulate parietal cells)
  2. Parietal cells – secrete hydrochloric acid (lowers pH)
  3. Chief cells – secrete pepsin (enzyme to digest PRO, needs acidic pH 1.5-2 to secrete)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

What is the innervation of the stomach?

A

intrinsic & extrinsic

Parasympathetic stimulation to the vagus nerve increases the number and force of contractions
• Sympathetic stimulation inhibits these contractions via the splanchnic nerve

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

PSNS signal is sent to the stomach via ___

A

the vagus nerve

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

SNS signal is sent to the stomach via ___-

A

the splanchnic nerve

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

What 2 hormones increase the strength and frequency of stomach contractions?

A
  1. gastrin

2. motilin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
50
Q

What does gastric inhibitory peptide do?

A

inhibits contractions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
51
Q

What hormone inhibits stomach contractions?

A

gastric inhibitory peptide

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
52
Q

What prompts emptying of the stomach? (3)

A

gastric distention, gastrin, nitric oxide

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
53
Q

What inhibits emptying of the stomach?

A

duodenal distention, increased fat content via release of cholecystokinin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
54
Q

What does cholecystokinin do?

A

inhibits stomach emptying

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
55
Q

What volume of gastric secretions are secreted per day?

A

~2L

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
56
Q

What are 2 types of tubular glands in the stomach?

A
  1. oxyntic glands; aka gastric glands

2. pyloric glands

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
57
Q

What do the oxyntic glands secrete?

A

[acid forming glands]

hydrochloric acid,
pepsinogen, intrinsic factor, mucus

58
Q

Where does hydrochloric acid come from?

A

oxyntic glands

59
Q

What do the pyloric glands secrete?

A

mainly mucous for protection from stomach acid,

gastrin

60
Q

What does hydrochloric acid do in the stomach?

A

kills bacteria
aids in protein digestion
releases pepsin from pepsinogen

61
Q

When parietal cells are stimulated, they secrete ____. At the same time, ___ is secreted

A

parietal cells secrete an acid solution of hydrochloric acid,

at the same time, HCO3 diffuses into the blood so that gastric venous blood has a higher pH than arterial blood when the stomach is secreting acid

62
Q

How does H+ occur?

A

hydrogen-potassium pump

63
Q

What is the pH of the acid secreted by parietal cells?

A

0.8

H+ concentration is about 3 million x that of arterial blood

64
Q

What is the function of the small intestine?

A

to circulate the contents and expose them to the mucosal wall in order to maximize absorption of water, nutrients, and vitamins before entering the large intestine

65
Q

How many liters of secretions are released per day?

A

7L

66
Q

How much fluid enters the small intestine each day?

A

9L

67
Q

How many liters of fluid make it to the colon from the small intestine?

A

1-2L

68
Q

What are the 3 portions of the small intestine?

A
  1. duodenum
  2. jejunum
  3. ileum
69
Q

Where is the duodenum and how long is it?

A

inferior to stomach, 25-30cm long

70
Q

Where does the small intestine start?

A

begins at the pyloric sphincter, ligament of Treitz

71
Q

What happens in the duodenum?

A

chemically digests chyme for absorption

72
Q

What part of the small intestine is the jejunum?

A

the proximal 2/5

73
Q

What happens in the jejunum?

A

absorption of nutrients

74
Q

By the time chyme enters the ileum (from the jejunum), how much of the nutrients have been absorbed?

A

almost 90%

75
Q

What is the ileum?

A

the final section (distal 2/5) of the small intestine

76
Q

What vitamin is absorbed in the ileum?

A

Vitamin B12

77
Q

Where does the ileum end?

A

the ileoceal valve

78
Q

What is the ileocecal valve?

A

a circular muscle that serves to prevent reflux of colonic contents into the small intestine

79
Q

What is the function of the large intentine?

A

reservoir for waste and indigestible material before elimination and extracts any remaining electrolytes and water

80
Q

Where is the highest concentration of organisms in any ecosystem located?

A

in the large intestine

81
Q

What are the 7 portions of the large intestine?

A 
cecum
appendix
ascending colon
transverse colon
descending colon 
sigmoid colon
rectum
82
Q

Where is water absorbed in the large intestine?

A

throughout the ascending, transverse, and descending portions

83
Q

What promotes relaxation of the internal anal sphincter to allow for defecation?

A

rectal distention & nitric oxide release

84
Q

What does poor motility through the large intestine cause?

A

greater absorption of water and hard feces in the transverse colon → constipation

85
Q

The pancreas is a part of what organ systems? (2)

A

digestive

endocrine

86
Q

How much of the pancreas is endocrine?

A

1%

87
Q

What is the endocrine function of the pancreas?

A

regulates blood sugar by secreting insulin, glucagon, & somatostatin

88
Q

What percent of pancreas function is exocrine?

A

99%

89
Q

What is the exocrine function of the pancreas?

A

secretes digestive enzymes

90
Q

Where is the pancreas located? and how does it function?

A

behind the stomach & functions as a gland

91
Q

How does the pancreas perform the exocrine function?

A

glands lined with epithelial (pancreatic acini) cells, secrete digestive
enzymes and sodium bicarbonate into ducts that drain via the
pancreatic duct and the common bile duct into the duodenum

92
Q

What are the epithelial cells of the pancreas that line the gland?

A

pancreatic acini

93
Q

What are pancreatic acini?

A

epithelial cells that line the gland

94
Q

What does the pancreas secrete?

A

digestive enzymes and bicarbonate

95
Q

Where does the pancreas secrete enzymes to?

A

into ducts that drain via the pancreatic duct and common bile duct into the duodenum

96
Q

What portion of the small intestine does the pancreas secrete into?

A

the duodenum

97
Q

What ducts does the pancreas use to secrete enzymes?

A

the pancreatic duct & the common bile duct

98
Q

In what form are the enzymes produced by the pancreas?

A

inactive precursors (zymogens) that are converted into active forms once in the duodenum

99
Q

What are zymogens?

A

inactive precursor enzymes secreted by the pancreas

100
Q

Where are pancreatic enzymes converted into their active form?

A

in the duodenum

101
Q

What stimulates the pancreas to secrete?

A

Pancreatic juice is secreted in response to the type of chyme in the upper portions of the small intestine

102
Q

What is the pathway of secretion of pancreatic juice?

A

Flow is through a long pancreatic duct that normally joins the common
bile duct immediately before it empties into the duodenum through the papilla of Vater, surrounded by the sphincter of Oddi

103
Q

Where does pancreatic juice empty into the duodenum (name)?

A

papilla of Vater

104
Q

What surrounds the papilla of vater?

A

the sphincter of Oddi

105
Q

Where does the pancreas secrete insulin?

A

into the bloodstream via the islets of Langerhans

106
Q

Where are the islets of Langerhans located?

A

in islet patches throughout the pancreas

107
Q

What hormones/neurotransmitters stimulate exocrine secretion by the pancreas?

A

Acetylcholine

Cholecystokinin (CCK)

Secretin

108
Q

How is acetylcholine involved in the exocrine stimulation of the pancreas?

A

released from the parasympathetic vagus nerve endings and from other cholinergic nerves in the enteric nervous system

109
Q

How is cholecystokinin (CCK) involved in exocrine stimulation of the pancreas?

A
  • secreted by the duodenal and upper jejunal mucosa when food
    enters the small intestine
110
Q

How is secretin involved in the exocrine stimulation of the pancreas?

A
  • secreted by the duodenal and jejunal mucosa when highly acidic food enters the
    small intestine
111
Q

What enzyme is secreted/works in the esophagus?

A

salivary amylase

starch → maltose

112
Q

What does salivary amylase do?

A

starch → maltose

113
Q

What are the 2 categories of enzymes secreted by the stomach?

A
  1. proteases; protein → polypeptides

2. stomach acid; chemical digestion

114
Q

What enzymes are released from the liver/gallbladder?

A

bile salts; emulsification of lipids

115
Q

What is the function of bile salts?

A

emulsification of lipids

116
Q

What do proteases do?

A

protein → polypeptides

117
Q

The pancreas secretes these 5:

A
  1. amylase; starch → maltose
  2. lipase; triglycerides → fatty acids
  3. endopeptidase; peptides → amino acids
  4. nuclease; DNA/RNA → nucleosides
  5. bicarbonate ions; neutralize stomach acid
118
Q

What enzymes are found in the small intestine?

A

membrane-bound enzymes (eg. maltase)

119
Q

What are 4 digestive secretions of the stomach?

A
  1. hydrochloric acid
  2. pepsin
  3. mucous
  4. intrinsic factor
120
Q

What is secreted by gastric glands?

A
  1. HCl
  2. Pepsin
  3. intrinsic factor
121
Q

What is secreted by the mucus glands of the stomach?

A

mucus

122
Q

What is the acinus?

A

the functional unit of the exocrine pancreas. it is composed of acinar cells, centroacinar cells, and duct cells.

  • a connective tissue matrix (including basal lamina) surrounds the acinus but does not insert itself between individual acinar cells
123
Q

Where is the spleen located?

A

Located in the left upper abdominal quadrant, posterior/lateral to the
stomach, and along the tail of the pancreas

124
Q

What is the blood supply to the spleen?

A
  1. splenic artery (branching off of the celiac trunk)

2. splenic vein (uniting with the superior mesenteric vein to form the hepatic portal vein)

125
Q

What are the 2 major units of the spleen?

A

White pulp; lymphatic tissue/WBCs

Red pulp: venous sinuses, reservoir for monocytes to aid in wound healing, macrophages for digestion of abnormal or aging RBCs

126
Q

When does splenic vasculature begin to develop?

A

in the 5th week of gestation

127
Q

Where is the primary site of fetal erythropoiesis (until 28 weeks gestation)?

A

the spleen

128
Q

What are 4 functions of the spleen?

A
  1. filtration
  2. iron metabolism
  3. prevention of infection
  4. red blood cell and platelet storage
129
Q

How is the spleen connected to the GI tract?

A

vascular connections between the spleen, pancreas, stomach

130
Q

the spleen is not ___

A

directly involved in digestion

131
Q

What is splanchnic circulation?

A

blood flow through the gut, spleen, pancreas

that immediately flows to the liver via the portal vein

132
Q

What cells are responsible for removing bacteria and other particulate matter from the blood? where are these cells?

A

the reticuloendothelial cells that line the liver sinusoids

133
Q

How does surgery affect bowel function?

A

stress = ↑ SNS = ↓ GI moility

*directly proportional to the amount

134
Q

What pre-op medication has benefits for the GI tract? Why?

A

midazolam,

will help ↓ the SNS response of the body.
less SNS = less GI inhibition

135
Q

How do volatile anesthetics affect the GI tract?

A

Depression of spontaneous activity and changes in intestinal tissue
oxygenation

Small intestine is the first part to recover, followed by the stomach in approximately 24
hours and then the colon 30 to 40 hours postoperatively

136
Q

What is the first part of the GI tract to recover from volatile anesthetic administration?

A

the small intestine

137
Q

How does the administration of propofol affect the GI tract?

A

no difference in overall recovery and bowel function when
comparing isoflurane/nitrous oxide, propofol/air, and
propofol/nitrous oxide

138
Q

How does Nitrous Oxide administration affect the GI tract?

A

30 x’s more soluble than nitrogen in the blood and as such will diffuse into gas-containing cavities from the blood faster than the nitrogen already present in those cavities can diffuse out

AKA…. don’t use!

139
Q

How do NDMR affect the GI tract?

A

only affect skeletal

muscle, so GI motility remains intact

140
Q

How does succinylcholine affect the GI tract?

A

mimics acetylcholine

  • Produces an initial muscle contraction
  • Increases intra-gastric pressure, which may be so strong as to overcome the tone of the LES and allow reflux
141
Q

How does neostigmine administration affect the GI tract?

A

increases
parasympathetic activity and bowel peristalsis

  • partially offset by simultaneous administration of the anticholinergic medications, glycopyrrolate
  • Not seen with sugammadex – prudent choice for reversal in tenuous bowel anastomoses
142
Q

How do opioids affect the GI tract?

A

reduced GI motility & constipation

 central and peripheral receptors, namely mu, delta, and kappa
       • Central = analgesia
       • Peripheral = adverse effects (mu-opioid receptors in the myenteric and submucosal plexuses)

 Depresses peristaltic contraction

 Increases GI muscular activity and resting tone

 Reduced motility the stool will remain in the gut for a longer period of time à more water is absorbed, and the stool becomes hard and dry leading to constipation
      • Use of laxatives, stool softeners, and prokinetic agents, such as metoclopramide and neostigmine, have shown some success in alleviating opioid-induced constipation

N935 Advanced Pathophysiology (9 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions