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GI-week 1 > GI phys overview > Flashcards

GI phys overview Flashcards

1
Q

define Bolus

A

rounded mass of food ready to swallow

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2
Q

define Borborygmi-

A

abdominal rumbling sounds.

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3
Q

define Chyme

A

semifluid mass of partly digested food passed from the stomach to the duodenum

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4
Q

Define Diverticulum

A

outpouching of GI wall

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5
Q

define Eructation

A

belching

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6
Q

Define Peristalses

A

propulsion of food through the esophagus and intestines

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7
Q

Define Postprandial

A

after feeding

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8
Q

Define Sitophobia

A

fear of eating

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9
Q

DEfine Steatorrhea-

A

fatty stools

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10
Q

small intestine prefix

A

ileo

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11
Q

large intestine prefix

A

colo

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12
Q

rectum prefix

A

proct

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13
Q

Upper GI structures

A

Oral Cavity, Pharynx, Esophagus, Stomach, Small intestine

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14
Q

Lower GI structures

A

large intestine

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15
Q

what are the parts of the small intestine

A

duodenum,jejunum, ileum

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16
Q

what are the parts of the large intestine

A

cecum,colon,rectum,anus

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17
Q

What are the accessory organs of GI tract?

A

Salivary glands (parotid, submandibular, sublingual)
Exocrine Pancreas
Liver- Hepatic system
Gallbladder- Biliary system

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18
Q

What spincters are voluntary control?

A

external anal and upper esphageal

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19
Q

pylorus sphincter connects what?

A

stomach to the small intestine

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20
Q

what does the sphincter of oddi connect?

A

the galbladder to the small intestine

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21
Q

what does the small intestine have to increase surface area?

A

villus and crypts

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22
Q

what does the colon have to increase surface area?

A

just crypts

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23
Q

what are special about the GI epithelial cells?

A

constant renewal, stem cells at the base of the crypts divide, differentiate and migrate to the tips of the villi

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24
Q

Why is it important that GI epithelial cells renew every 3-6 days?

A

Prevent the accumulation of mutations due to toxin exposure

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25
Q

What are the 4 major GI wall types?

A

Mucosa, submucosa, muscularis externa, serosa

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26
Q

What does the muscularis externa contain in its layer

A

circular muscle (mechanical digestion), myenteric nerve plexus, longitudinal muscle for propulsion

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27
Q

what is a diverticulum?

A

single pouch protruding from alimentary tract. Usually false not true. inflammation due to lack of fiber, can progress to diverticulitis

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28
Q

What are some characteristics of mucus? Secreted by?

A

viscous, hydroscopic gel, goblet cells

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29
Q

How are mucin monomers combined into plexes?

A

by disulfide links,

2 layers in the stomach and colon, 1 layer in small intestine

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30
Q

What protects the protein core of the mucus?

A
  • Glycosylation protects the protein core from proteases (pepsin) in the stomach
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31
Q

What are enterocytes coated with

A

transmembrane mucins

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32
Q

what are the 4 basic processes faciliation caloric uptake?

A

Digestion, Absorption – excess capacity (95% of diet lipids)

Secretion, Motility – under neural and hormonal control

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33
Q

What does the teeth do for digestion?

A

mastication

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34
Q

What does the salvia do?

A

lubricates and breaks down, with chewing creates the bolus

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35
Q

What does the stomach do for digestion?

A

movements and pepsin digests food into chyme

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36
Q

what does the duodenum do for digestion?

A

brush border enzymes from pancrease and bile salts from liver

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37
Q

Where are amino acids, monosaccharides, and

lipids absorbed

A

small intestine-duodenum and jejunum

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38
Q

where are cobalamine (B12) and bile salts/acids absorbed?

A

small intestine-ileum

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39
Q

What absorbs water and electrolytes

A

small and large intestines

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40
Q

What does absorption depend on?

A

Splanchnic Circulation, 1-5 litersAt depending on vasomotor tone

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41
Q

At rest, how much CO goes to the gut?

A

21%

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42
Q

what is the blood flow from the intestine?

A

portal vein to the liver allowing for detoxification.

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43
Q

Where does the liver get its blood from?

A

1/4 blood from hepatic artery, 3/4 blood form portal vein

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44
Q

by how much can flow increase during increased gut activity?

A

4-5 Liters

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45
Q

What happens to blood flow to the GI tract during exercise and emergencies

A

massive vasoconstriction shunts blood away from the gut.

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46
Q

what does the enterohepatic circulation do

A

Recycling of bile salts/acids from the ileum, can alter drugs (what body goes to Rx), some metals get secreted into feces

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47
Q

What are the metabolic vasodilatiors that increase blood flow?

A

CO2, H+, K+, adenosine, etc

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48
Q

Chylomicrons are too large to pass through the capillary cells, so what happens to them?

A

they get absorbed through lacteals which empty into blood stream via thoracic duct

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49
Q

what is mesenteric ischemia due to?

A

occlusive mechanisms like thombi, or
non-occlusive mechanisms including prolonged reflex vasoconstriction (due to hypovolemia, heart failure) or abnormal levels of circulating vasoconstrictors (e.g, epinephrine, angiotensin II)

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50
Q

what are the effects of mesenteric ischemia?

A

Postprandial Pain, Sitophobia (fear of eating)
Necrosis of the tips of the villi
Loss of barrier function of the wall of the gut and uptake of vasodilator toxins (endotoxin) from the gut resulting in Septic Shock

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51
Q

The fluid environment of the GI tract is supplied by what

A

organs that drain into the GI tract and GI epiethlial

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52
Q

What does the fluid in the GI tract contain

A

ions, digestive enzymes, mucins, and bile

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53
Q

Where are majority of the fluids reabsorbed

A

reabsorbed in the small intestine with nutrients

54
Q

What regulares secretion of the GI system?

A

Parasympathetic, hormonal, and enteric nerves

55
Q

What is transmural water movement driven by?

A

osmotic gradients

56
Q

How does water move across the epithelium?

A

through the cells (transcellular route) perhaps with the help of specific water channels (aquaporins) and between cells (paracellular route) according to osmotic gradients driven by active electrolyte transport.

57
Q

What is conductivity defined by in regards to the epithelia

A

leakiness, depends on the variable presence of absense of tight junction

58
Q

What coupled activity mediates fluid uptake?

A

electroneutral NACL absoprotion with NA/H exhanged on the apical side, CL/HCO3- exchange in apical membrane

59
Q

what is secretory diarrhea

A

infection-increases CL secretion drwaring water into lumen

60
Q

what is osmotic diarrhea

A

small bowel overgrowth leads to production of organic acids suffiencet enough to pull water from blood stream via osmosis

61
Q

What does fluid flux depend on?

A

surface area available for ion transport and residence time in the lumen

62
Q

What is the action of some antidiarrheal in regards to fluid flux

A

slows transit to increase fluid absorption

63
Q

What controls the length of time food takes for digestion and absoprotion?

A

motility

64
Q

Time spent in the Esophagus

A

10 seconds

65
Q

time spent in the stomach

A

4-5 hours

66
Q

time spent in the SI

A

2.5-3 hours

67
Q

time spent in the LI

A

30-40 hours

68
Q

total time it takes food to digest?

A

36-48 hiours

69
Q

What is most of the GI tract made up of?

A

SMOOTH MUSCLE

70
Q

What are the exceptions to most of the GI tract being made of muscle

A

striated muscle in upper third of esophagus, pharynx, external anal sphincter

71
Q

GI smooth muscle contractile characteristics- describe the rhythmic

A

Rhythmic “phasic” (seconds) contractions and long “tonic” contractions (minutes to hours)

72
Q

How is basal tone maintained in regards to Gi smooth muscle?

A

bassal resting tone is maintained w/o elevation in intraceullar CA2+ and without energy expenditure. (sphincters)

73
Q

What can GI smooth muscle do in response to stretching?

A

DEPOLARIZE! leading to contraction

74
Q

Proximal pressure on a sphincter causes the sphincter to do what?

A

relax

75
Q

distal pressure a sphincter causes the sphincter to do what?

A

contract

76
Q

The slow waves electrical activity is initiated by

A

interstitial cells of Cajal are phasic and propagated over a few centimeters

77
Q

What are the slow waves due to?

A

increase in calcium followed by repolarization by K+ channels

78
Q

What can change in the slow waves-amplitude or frequency?

A

AMPLITUDE! by signals releasing calcium from internal stores or opening Ca++ channels on plasma membrane

79
Q

Parasympathetics release of AcH binds to what receptor? and causes what?

A

Myscarinic-increase of CA into cell, phophorylation of myosin and increase ATP actvity by increase myosin/actin binding. this leads to contraction

80
Q

What do peristaltic contractions do to the bolus of food?

A

propel intestinal contents forward, longitindal

81
Q

wha do Segmenting contractions do to the bolus of food?

A

contractions of circular muscles in small and

large intestine that locally mix contents (churning), nonpropulsive

82
Q

What controls the migrating motor complex?

A

motiln

83
Q

what is the migrating motor complex?

A

relaxation of sphincters and contractions in stomach and small intestine occurring during fasting

84
Q

what is also know as the mini brain?

A

the enteric nervous system,can operate independently of CNS! but control of secretion and motility may be less than optimal.

85
Q

Where are the submucosal nerve plexus?

A

small and large intestine, sensory and blood flow, Meissner’s

86
Q

Where is the myenteric nervous plexus?

A

between circular and longitudinal muscle layer from esophagus to internal anus
Auerbach’s

87
Q

changes in GI tract are detected by what?

A

intrinsic sensory receptors including: stretch receptors, osmoreceptors, and chemoreceptors

88
Q

Do Chemosensitive taste receptors always evoke taste?

A

NO! they are other places in the body besides the mouth

89
Q

What excites the afferent sensory neurons of the enteric nervous system?

A

distension of the gut wall or chemical signals from the lumen of the gut transmitted to sensory neurons.-like 5HT

90
Q

many of the sensory neurons are stimulated by serotonin (5-HT) released from what kind of cells?

A

mucosal enterochromaffin cells (ECL) - respond with a few action potentials followed by hyperpolarization (adaptation)

91
Q

What transfers the info about the gut environment?

A

the myenteric plexus- relays signals up and down the gut

92
Q

The enteric efferent motorneurons are found where? what kind of neuron are they?

A

myenteric plexus, unipolar

93
Q

What excites the efferent motorneurons?

A

Fast ESPS’s, respond to sustaintined trains of AP

94
Q

What does the efferent motorneurons carry?

A

information to GI smooth muscle, vascular smooth muscle, GI exocrine secretory cells and GI endocrine secretory cells

95
Q

What do the excitatory motorneurons release?

A

release acetylcholine, neurokinin A and substance P

96
Q

what do the inhibitory fibers release

A

vasoactive intestinal peptide (VIP) and nitric oxide (NO) on smooth muscle cells.

97
Q

Long neural reflexes involve?

A

CNS AND ANS

98
Q

short neural reflexes invovle?

A

only nerves of the enteric plexus

99
Q

Nutrients activate what neural reflexes?

A

both autonomic nervous system and enteric nervous system promoting secretion and motility.

100
Q

Afferent information leaving GI tract is carried by ?

A

Extrinsic Autonomic Nervous System-para and sympathetics

101
Q

parasympathetics relsease what in the GI tract?

A

AcH! AGAIN! via vagus nerve

102
Q

parasympathetics activate what in the GI tract?

A

REST AND DIGEST! stimulates activity of the enteric plexuses, increases GI motility and secretory activity.

103
Q

Sympathetics mostly relese in the GI tract

A

andregerics-epi,

104
Q

Sympathetics inhibits what in the GI tract? other actions?

A

DECREASES ACTIVITY! inhibits activity of the enteric plexuses, decreases GI motility, contracts GI sphincters, constricts GI microvasculature

105
Q

What does the vaso-vagal efferent response do?

A

coordinate excitatory and inhibitory activity within the Enteric Nervous System to mediate peristalsis

106
Q

What does the vaso-vagal afferent go?

A

to autonomic centers in the medulla

107
Q

What are the neurotransmitters of the enteric nervous system?

A

AcH, gastrin releasing peptide, substance P, Vasoactive intestinal peptide, NO

108
Q

Who releases AcH? Where does it go?

A

primary excitatory transmitter from sensory cells and from motoneurons to muscle, epithelium, secretory cells and at interneuronal junctions. intracellular Ca++

109
Q

Who releases Gastrin releasing peptide? function?

A

released from vagal nerve endings to stimulate G cell secretion of gastrin

110
Q

When is substance P released? and usually with who?

A

an excitatory transmitter generally co-released with acetylcholine

111
Q

Vasoactive Intestinal Peptide (VIP) action is?

A

DILATION! Promotes motility
Relaxes smooth muscle in esophagus and stomach
Stimulates fluid secretion and promotes dilation of the GI vasculature. increases cAMP

112
Q

What kind of neurotransmitter is NO? What is it usually corealsed with?

A

inhibitory transmitter co-release with VIP from inhibitory motoneurons, hydrophobic- intracellular targets.

113
Q

What are the primary Gastro-Intestinal Hormones

A

Gastrin, Cholecystokinin (CCK) , Secretin, Gastric Inhibitory Peptide or Glucose-Dependent Insulinotropic Peptide (GIP), and Motilin

114
Q

Gastrin is released from what cells?

A

G cells in antrum of stomach (vagus_

115
Q

what does gastrin detect?

A

detect amino acids leading to pepsinogen and H+ release.

116
Q

CCK is released from what kind of cells? Due to what? Stimulates what?

A
  • I cells in D/J detectdetect fat and amino acids, secretion of pancreatic enzymes and bile salts involved in fat uptake
117
Q

Secretin is released from what kind of cells? Due to what? Stimulates what?

A

S cells primarily in D/J detect acid stimulates secretion of pancreatic juice including bicarbonate and inhibits gastric motility.

118
Q

GIP s released from what kind of cells? Due to what? Stimulates what?

A

K cells in D/J detect carbohydrates and fat to inhibit gastric acid secretion and stimulate insulin release from pancreas.

119
Q

Motilin is released from what kind of cells? Due to what? Stimulates what?

A

secreted by endocrine cells; released cyclically during fasting state to initiate Migrating Motor Complex

120
Q

Histamine in the GI tract is from what kind of cells and does what?

A

(ECL cells) , endocrine regulartor

121
Q

Somatostatin in the GI tract is from what kind of cells and does what?

A

(D cells)- paracrine regulators

122
Q

Where are digestive enzymes store?

A

specialized cells and and products are packaged into zymogen granules and stored.

123
Q

How do digestive enzymes get released

A

Secretion usually involves a stimulus-induced increase in either cAMP or [Ca+2]i (or both) … which then leads to zymogen granule docking and dumping.

124
Q

T/F because of all the bacteria we have in our guy, its equivalent to being outside of our body

A

TRUE

125
Q

How is gas produced?

A

some of it is swallowed when eating, neutralization of gastic acid by bicarbonate generates CO2, Gas byproducts of fermentation of fiber in colon can be used by other bacteria, excreted by lungs, and evacuated

126
Q

Borborygmi, “stomach rumble” is actually?

A

CREATED BY GAS IN THE BOWELS!

127
Q

Why do people have flammable gas?

A

because of methenobrevibacter smithii

128
Q

bacterial overgrowth syndrome occurs because of

A

delayed small intestine transit and diverticulum

129
Q

what are side effects of bacterial overgrowth syndrome

A

Gas and bloating fromfermentation, Compete for B12 uptakeleading to anemia, Deconjugate bile acids leading to steatorrhea, Produce toxins altering epithelium

130
Q

How do you diagnose bacterial overgrowth syndrome

A

Diagnose with hydrogen breath test

131
Q

What are properties of the GI tract that limit growth of bad bugs

A

Saliva contains lactoferrin, lysozyme, and secretory IgA
Acidic environment in stomach
More lymphocytes in GI than the circulating immune system
Mucus- IgA, lysozyme, lactoferrin
Paneth cells secrete antimicrobial peptides
Digestive enzymes cleave bacteria
Diarrhea
Vomiting
Microflora prevent colonization of pathogenic microorganisms (probiotics and prebiotics, <pH)
Peristalsis, Ileoceccal valve

GI-week 1 (11 decks)

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