GI system Flashcards

1
Q

functions

A

ingestion
motility
digestion
absorption
secretion

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2
Q

ingestion

A

food and liquid intake into oral cavity

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3
Q

motility

A

mechanical processing: swirling, mixing, churning, propulsive motions in tract along entire tube
compaction: dehydration of undigestable material + waste into feces (colon to anus)

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4
Q

digestion

A

chemical + enzymatic breakdown of sugars, lipids, + proteins into small molecules

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5
Q

secretion

A

acids, enzymes, + buffers are secreted by accessory organs (liver + pancreas)
help digestion

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6
Q

absorption

A

movement of molecules, electrolytes, vitamins, + water into ISF → blood vessels
carried from GI tract to liver = distributed to rest of body

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7
Q

excretion

A

elimination of undigested residue + waste products

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8
Q

GI tract

A

oral cavity (salivary glands) → pharynx → esophagus → stomach → small intestine (duodenum + jejunum + ileum) → large intestine → anus
accessory organs: liver, gallbladder, pancreas

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9
Q

exocrine tissue

A

secretions into GI tube (lumen)

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10
Q

endocrine tissue

A

secretions into surrounding connective tissue → circulation

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11
Q

histology of GI tube

A

4 layers found along entirety
- mucosa
- submucosa
- muscularis externa
- serosa

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12
Q

mucosa

A

epithelium (stratified at beginning + end; simple in middle for absorption
lamina propria
muscularis mucosa

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13
Q

lamina propria

A

connective tissue
has innervation + vasculature to support epithelium
glands + immune cells

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14
Q

muscularis mucosa

A

propels content of glands (in submucosa) into lumen

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15
Q

submucosa

A

connective tissue layer
conduit for vasculature, nerves, and lymphatics
immune cells, some exocrine glands, submucosal nerve plexus

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16
Q

muscularis externis

A

external muscle layer: (skeletal at ends, smooth in the middle)
- inner circular muscle = constriction
- myenteric plexus
- outer longitudinal muscle = propulsion

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17
Q

myenteric plexus

A

autonomic parasympathetic
innervates both smooth muscle layers
controls GI motility

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18
Q

serosa

A

simple squamous epithelium + connective tissue
serous membrane = produces watery fluid to lubricate peritoneal surfaces

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19
Q

abdominal quadrants

A

direct pain
vert + horiz planes intersect at umbilicus
RUQ + RLQ + LUQ + LLQ

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20
Q

RUQ

A

liver
gall bladder
duodenum
head of pancreas
transverse colon
right kidney

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21
Q

LUQ

A

stomach
spleen
pancreas (body + tail)
jejunum
transverse colon
left kidney

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22
Q

RLQ

A

ileum
cecum
appendix
ascending colon

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23
Q

LLQ

A

ileum
descending + sigmoid colon

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24
Q

abdominal regions

A

referred pain
two vertical midclavicular planes
horiz. subcostal plane (below ribs, along L1)
horiz. intertubercular plane (tubercles of iliac crests, along L5)

epigastric, umbilical, hypogastric

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25
Q

peritoneum

A

serous membrane lining peritoneal body wall + organs
parietal (line body wall) + visceral (line organs) layers

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26
Q

mesentery

A

2 layers of serosa around vasculature
allows vasculature to reach organs for absorption

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27
Q

omentum

A

layer of peritoneum folded on itself that contains more than vasculature + innervation

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28
Q

greater omentum

A

mesentery from greater curvature of stomach to transverse colon
large pouch in front of most organs below stomach
contains fat and immune cells in addition to blood, nerves, and lymphoid tissue
lipid deposition = temp control
immunological function → cells migrate to region of infection = first immune response in abdomen

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29
Q

lesser omentum

A

mesentery from lesser curvature of stomach to liver

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30
Q

intraperitoneal

A

organs that are within peritoneum = covered by visceral peritoneum
most of GI tube, liver

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31
Q

retroperitoneal

A

organs or structures found behind peritoneum
- in abdomen but not associated with GI = kidneys, ureters
- large vessels = aorta, inf vena cava
- anchoring organs = duodenum, pancreas, asc + desc colon
- pelvic organs below peritoneum

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32
Q

anchoring organs

A
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33
Q

abdominal aorta

A

supplies organs with vasculature
branches into:
- celiac trunk = foregut
- sup. mesenteric artery = midgut
- inf. mesenteric artery = hindgut

also branches to supply retroperitoneal organs

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34
Q

foregut

A

epigastric region: abd. esophagus to desc. duodenum
- vasc = celiac trunk
- innervation = celiac ganglia (T7-T9)

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35
Q

midgut

A

umbilical region: desc. duodenum to L colic flexure of transverse colon
- vasc = sup. mesenteric artery
- innervation = sup. mesenteric ganglia (T9-T11)

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36
Q

hindgut

A

hypogastric region: transverse colon to rectum
- vasc = inf. mesenteric artery
- innervation = inf. mesenteric ganglia (T11-L1)

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37
Q

celiac trunk

A

abd esophagus
stomach
spleen
liver
gallbladder
pancreas
duodenum

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38
Q

superior mesenteric artery

A

pancreas
duodenum
jejunum
ileum
cecum + appendix
asc + transverse colon

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39
Q

inferior mesenteric artery

A

desc + sigmoid colon
rectum

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40
Q

renal artery

A

kidneys
adrenal glands

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41
Q

gonadal artery

A

ovaries/testes

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42
Q

venous vasculature

A

similar to arterial but splenic vein instead of celiac
portal vein carries blood from GI tract to liver
veins from body wall organs drain into inf. vena cava

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43
Q

portal vein

A

receives blood from splenic vein + sup+inf mesenteric veins

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44
Q

oral cavity

A

stratified squamous epithelium = protection from stress
innervation = sensory analysis
mechanical digestion (teeth, tongue, palatal surfaces, cheeks)
saliva = mixed to lubricate + start enzymatic digestion

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45
Q

oral vestibule

A

space between lips, cheeks, + teeth
“entrance” to cavity

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46
Q

tonsils

A

lymph
- pharyngeal
- palatine
- lingual

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47
Q

tooth - crown

A

above gum line
- enamel
- dentin
- pulp cavity

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48
Q

tooth - neck

A

mucosa layer
gingiva

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49
Q

tooth - root

A

bone
periodontal ligament
cement
dentin
root canals = neurovascular bundle

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50
Q

periodontal ligament

A

fibrous tissue between bone + mucosa
gomphosis = articulation between maxilla/mandible + tooth

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51
Q

incisors

A

blade-like teeth
front of mouth
clip/cut food

52
Q

canines

A

pointed teeth
side of mouth
tears/slash food

53
Q

premolars

A

bicuspid
back of mouth
crush/mash/grind food
large surface area

54
Q

molars

A

multi-cuspid
back of mouth
crush/grind food
large surface area

55
Q

trigeminal nerve

A

sensory innervation of dentition
V2 → superior alveolar nerve = maxilla (upper)
V3 → inferior alveolar nerve = mandible (lower)

56
Q

deciduous teeth

A

baby teeth = 20
no premolars
eruption 6-24 months
shed 6-12 years

57
Q

permanent teeth

A

32 teeth
eruption 6-18 years (fully formed before)

58
Q

skeletal muscles of tongue

A

innervated by CN XII
intrinsic + extrinsic

59
Q

intrinsic tongue mm

A

shape of tongue
speech
3 orientations: sup/inf longitudinal, vertical, transverse

60
Q

extrinsic tongue mm

A

swallowing + movement of tongue
4 mm: palatoglossus, styloglossus, hyoglossus, genioglossus

61
Q

tongue surface

A

stratified epithelium covered by papillae → taste buds found throughout
taste: CNs VII (chorda tympani) + IX
general sensation: CNs V3 + IX

anterior 2/3 and posterior 1/3 are divided by terminal sulcus (associated with oropharynx)

62
Q

salivary glands

A

exocrine glands with ducts into oral cavity
- serous = moistens food + contains enzymes
- mucous = lubricates passage of food

parotid
sublingual
submandibular

63
Q

saliva

A

produced even without food = control bacteria population
contains
- amylase = initiation of CHO digestion
- buffers regulate oral pH
- antibodies for immune surveillance
dissolves chemicals = stimulate taste buds

64
Q

stimulation of saliva

A

ANS
- parasymp. = stimulates secretion
- symp = inhibits secretion
presence of food + taste, sight, smell, thought

65
Q

pharynx

A

stratified squamous epithelium
common passageway for food, liquid, + air
naso, oro, + laryngopharynx
ends at location of prox. esophagus + trachea
glands throughout = secretion of serous + mucous
innervated by CN X

66
Q

pharynx muscles

A

palatal: (tensor + levator veli palatini) elevate soft palate during swallowing
pharyngeal constrictors (superior, middle, inferior → sequential contraction) + suprahyoid mm help elevate larynx + push bolus to esophagus

67
Q

peristalsis

A

propulsion of bolus along tube
coordination of circular + longitudinal mm (opposite contraction)

circ = prevent movement in other direction

68
Q

segmentation

A

churn + mix contents to breakdown
no directional movement
mechanical digestion

mainly circular muscle layer

69
Q

esophagus

A

stratified squamous epithelium
passage to stomach
C6 - T7
~25 cm long
skeletal muscle at beginning, smooth muscle after
peristalsis carries bolus to cardiac sphincter
extra glands in submucosal layer = mucous secretion
innervated by CN X

70
Q

prevention of reflux

A

lower esophageal sphincter
peristaltic clearance (prevent mvt back)
stratified squamous epithelium
submucosal glands
mucous from stomach

71
Q

stomach

A

muscular sac that stores food temporarily
intraperitoneal in LUQ
supplied by celiac trunk = foregut
simple columnar epithelium
has extra layer of smooth muscle

72
Q

chyme

A

viscous, acidic, soupy mixture
mixture of bolus and gastric juices formed in stomach
formed through mechanical breakdown (contractions of muscular wall = segmentation) + chemical digestion (actions of secreted acid and enzymes)

73
Q

cardia

A

entrance of stomach from esophagus
proximal to heart

74
Q

fundus

A

found in all muscular structures
dome-like superior portion of stomach
has cells that will stimulate others for contraction
usually empty

75
Q

stomach curvatures

A

greater = outside → forms greater omentum
lesser = inside → forms lesser omentum

76
Q

pyloric canal

A

tube shape
controls what enters small intestine

77
Q

stomach wall

A

3 layers of smooth muscle = inner oblique, middle circular, outer longitudinal
simple columnar epithelium
gastric glands within mucosa
rugae in mucosa

78
Q

surface mucus cells

A

produce thick mucus to protect from acid

79
Q

mucus neck cells

A

produce more serous mucus
role in digestion → activation of acid and enzymes once mixed

80
Q

parietal cells

A

secrete H+ and Cl- = HCl acid
digestion of tougher structures

81
Q

chief cells

A

secrete digestive enzymes: pepsin + lipase
do not activate until mixed with mucus

82
Q

G cells

A

enteroendocrine cells in fundus of stomach
release gastrin when food first enters stomach = stimulates other secretory cells
role in GI tract regulation

83
Q

small intestine

A

longest part of GI tract (6-7m long)
found in all quadrants
specialized for absorption → circular folds, villi, + microvilli = ↑ SA

84
Q

duodenum

A

25 cm; c-shaped; mainly in RUQ
beginning + end = intraperitoneal; middle = retroperitoneal
receives chyme from stomach; secretions of pancreas + liver
digestion of fat, proteins, + sugars
dual vasculature: anastomosis of celiac + SMA branches

85
Q

Brunner’s glands

A

in submucosa of duodenum
provide abundant alkaline mucus to neutralize the acid contents entering from the stomach

86
Q

hepatopancreatic ampulla

A

entrance of common duct from liver + pancreas into duodenum

87
Q

pancreas

A

posterior to stomach, between duodenum + spleen
retroperitoneal
vasc: anastomosis of celiac + SMA branches (celiac → splenic artery) = foregut + midgut
endocrine + exocrine gland
secretes digestive enzymes + bicarbonate buffer

88
Q

bicarbonate buffer

A

neutralizes acidic chyme from stomach
establishes alkaline pH for pancreatic digestive enzymes

89
Q

venous drainage of pancreas

A

splenic vein to hepatic portal vein

90
Q

islets of langerhans

A

endocrine secretions
closely associated with vasculature
alpha cells → glucagon
beta cells → insulin
delta cells → somatostatin

91
Q

pancreatic acinus

A

acinar + centroacinar cells
exocrine secretion = pancreatic juice
neutralize acidic chyme, break down ingested material

92
Q

acinar cells

A

secrete digestive enzymes (amylase, lipase, proteinase)

93
Q

centroacinar (duct) cells

A

secrete bicarbonate buffer + regulate pre-enzyme release from acinar cells

94
Q

pancreatic duct

A

carries exocrine secretions to duodenum
main duct merges with bile duct → enters duodenum at hepatopancreatic ampulla

95
Q

liver

A

largest gland in the body
intraperitoneal
metabolic + secretory functions (endocrine + exocrine)
vasc: celiac trunk = foregut + hepatic portal vein

96
Q

liver functions

A

metabolic regulation:
- carb, protein, + fat metabolism
- regulates circulating levels of everything absorbed by intestine
hematological regulation:
- destroys aged/damaged RBCs, cellular debris, + pathodens
- secretes plasma proteins into blood (osmotic concentration, nutrient transport, clotting system)

97
Q

bile

A

water, ions, bilirubin, bile salts
required for digestion of lipids
synthesized + secreted by liver
stored in gallbladder

98
Q

anatomy of liver

A

2 lobes
inf. vena cava passes posteriorly → L+R hepatic veins drain into
portal triad underneath R lobe → gallbladder

99
Q

portal triad

A

hepatic artery + hepatic vein flow in
bile duct flows out

100
Q

hepatic portal vein

A

carries deoxygenated nutrient-rich blood from GIT to liver
= all blood from intestines passes through liver before returning to heart

101
Q

hepatic veins

A

carry metabolites from liver to inferior vena cava

102
Q

lymphatic system

A

delivers large lipids directly to general circulation (drains into thoracic duct)

103
Q

liver lobule

A

made up of hepatocytes = epithelial liver cells
surrounded by connective tissue (interlobular septum)
portal triad:
- bile canaliculi drain into bile duct
- central vein drains into hepatic veins

104
Q

Kupffer cells

A

liver macrophages
line sinusoids

105
Q

liver endocrine function

A

endocrine surface with fenestrated endothelium
takes substances from blood + secrete into blood

106
Q

liver exocrine function

A

exocrine surfaces = epithelial tight junctions
face each hepatocyte
form small channels called canaliculi → bile is secreted into

107
Q

gallbladder

A

storage of concentrated bile

108
Q

cystic duct

A

bile enters gallbladder from common hepatic duct when ampulla is closed

109
Q

bile duct

A

bile exits gallbladder to duodenum when ampulla is open

110
Q

CCK

A

cholecystokinin
released by presence of chyme in duodenum
induces relaxation of sphincter + contraction of gallbladder → movement of bile into small intestine

111
Q

jejunum

A

intraperitoneal (upper quadrants)
vasc = SMA + vein (midgut)
begins at duodenojejunal flexure
majority of nutrient absorption
thicker walls, larger diameter, + redder in colour than ileum (++ vasc)
larger + more plicae circulares

112
Q

ileum

A

intraperitoneal (lower quadrants)
vasc: SMA + vein (midgut)
ileocecal valve = empties into large intestine

113
Q

Peyer’s patches

A

aggregated lymphoid nodules in ileum
protection from colonic bacteria

114
Q

SA of small intestine

A

↑ 600x by plicae circulares → villi → microvilli
= 2 million cm2 + absorptive area

115
Q

absorptive cells

A

main epithelial cell
lots of microvilli

116
Q

goblet cell

A

secrete mucus
promote movement along intestine

117
Q

I + S cells

A

enteroendocrine cells in small intestine
release hormones to regulate other intestinal cells

118
Q

paneth cells

A

variable secretions
determines gut flora
immunity = secretions kill some bacteria

119
Q

absorption in small intestine

A

sugars → monosaccharides
proteins → amino acids
= absorbed into hepatic portal circulation

fats → fatty acids → chylomicrons → chyle
= absorbed into lacteals → lymphatic vessels → thoracic ducts

120
Q

large intestine

A

1.5 m long; 7.5 cm in diameter
intraperitoneal: cecum, transverse, sigmoid
retroperitoneal: asc + desc, rectum
vasc: SMA + IMA = midgut + hindgut
reabsorbs water + electrolytes
absorbs vitamins produced by bacteria
compacts + stores feces

121
Q

midgut

A

parts of small intestine
cecum → left colic flexure of transverse colon

122
Q

hindgut

A

descending colon → rectum

123
Q

teniae coli

A

longitudinal smooth muscle layer
merges together to form 3 stripes to assist propulsion along colon

124
Q

haustra

A

pouches along large intestine that can expand
= contraction → segmentation (packaging of waste)

125
Q

colon wall

A

simple columnar epithelium → no villi
mucosa = mucus glands (goblet cells)
lymphoid nodules in submucosa

126
Q

rectum

A

simple columnar epithelium
15 cm
temporary storage of feces
entry into rectum triggers urge to defecate

127
Q

anal canal

A

non-keratinized → keratinized stratified squamous epithelium (hard protein = protection)
internal sphincter = smooth muscle
external sphincter = skeletal muscle (levator ani: iliococcygeus + puborectalis)