GI physiology Flashcards
(167 cards)
1
Q
GI tract Layers (4)
relatively uniform throughout
A
- mucosa
- submucosa (blood, nerves, connective tissue)
- Muscularis (longitudinal, circular)
- serosa
2
Q
oblique muscles in
A
stomach only–responsible for enhanced churning
3
Q
nerves in SUBMUCOSA. func.
A
meissner’s plexus:
–senses environment w/in lumen–regulating BLOOD FLOW, directiong epithelial cell function
4
Q
neves in muscle layers: func.
A
Myenteric (Auerback Plexus)
–digestive tract motility
5
Q
nerves embedded in walls of GI tract
A
PNS–enteric enervation–
6
Q
most common nT of:
symp:
parasymp:
A
- norepi & some ACh (mainly inhibitory of motility and veins))
- ACh (excitatory)
7
Q
Myenteric responsible for:
both function under PNS control and independently
A
GI movement:
- ^ tonicity, intensity, rate, velocity of conduction
- v schincter tone
8
Q
Meissner (submucosal) responsible for
A
GI secretion and local blood flow
1. –> unfolding of walls
9
Q
Electrical System of GI:
Smooth muscle is ______ unit–when AP received, ______ travels in all direction.
A
single,
contraction
10
Q
resting membrane potential exhibits ______ ______ ______. Do not cause contractions.
A
rhythmic slow waves–in response to food in instestines
11
Q
Increasing positive charge of SLOW WAVES excite appearcance of ______ _______, exciting ______ ______
A
SPIKE POTENTIALS,
muscle contraction
12
Q
AP caused by rapid ____ ______, only _____ so no contraction
A
Na+ entry,
sodium
13
Q
much _____ enters leading to long duration of AP
A
Ca++ – much like heart
14
Q
blood flow w/ nutrients from gut, spleen and panc travel to the ___ wia the ____ ____
A
SPLANCHNIC FLOW,
liver,
portal vein
15
Q
____ do not go through the portal vein–instead travel through the ____ _____ bypassing liver
A
fats,
lymphatic system
16
Q
reticuloendothelial cells of liver in ____ _____ remove ______
A
Liver sinusoids,
bacteria
17
Q
Salivary glands and products–
A
- Parotid (serous–ptyalin–amylase)
- sublingual (serous and mucus)
- submandibular (serous and mucus
18
Q
Saliva constituents (9): Hypotonic 6-7 pH
stimulated by PNS and SNS
A
- water,
- mucus
- bicarbonate
- K+
- salivary amylase
- lingual lipase
- Cl-
- Na+
- IgA
19
Q
lingual lipase pH– digests?
A
4.5-5.4
digest fats
20
Q
stimulates gastic and salivary response
cephalic phase
A
- sour, smooth
- aggression
- insulin secretion
- irritation/ nausea
21
Q
Inhibition of salivary response
A
- anxiety, fear, dehydration, rage
2. ROUGH testure
22
Q
2 phases of swallow
A
- voluntary component
2. involuntary comp
23
Q
swallow reflex and respiration inhibited by _____ ______ _______
A
medulla swallowing center (involuntary component)
24
Q
pathophys of disruption to mucosal surface as from (3).
A
Apthous Ulcers (mouth/ oropharynx): -trauma, infection, or inflammation
25
Esophagus from--how long
C6-T10/11
| 25 cm
26
______ _______ _______must relax from ______ ____ ____ innervation for food to pass into esophagus
upper esophageal sphincter,
| medulla swallowing center
27
____ _____ rises to close off nasopharynx
soft palate
28
GI muscle contraction takes ____ and ____ activity
Na+ and Ca++
29
esophageal mucosa layers (3)
1. epithelium w/ mucus secreting cells
2. lamina propria
3. muscularis mucosa
30
UES
LES
Characteristics
Upper esophageal sphincter (both functional not anatomic)
Lower esophageal sphincter
--normally HIGHER tonicity so air won't descend and acid won't ascend
31
esophageal submucosa components: (5)
| "out from mucosa"
1. loose connective tissue
2. blood vessels
3. lymphatic and lymphoid follicels
4. MEISSNER plexus
5. mucus secreting glands
32
esophageal muscularis propria characteristic:
- Inner: circular layer for ring contractions
- AUERBACH plexus
- outer layer logitudinal--shortening contractions
- - muscularis propria muscle
a. top 1/3 skeletal muscle
b. middle 1/3 smooth/skeletal
c. bottom 1/3 smooth
33
Stimulation of esophagus (3)
1. meissner plexus
2. auerbach plexus
3. vagus nerve (along adventitia)
34
LES tone relaxes w/ (3)
- non-adrenergic, non-cholinergic vagal impulses
| - progesterone and glucagon
35
coordinated contractions to propel bolus down esophagus--gravity assisted
PRIMARY peristalsis--from mouth --> anus
36
If bolus gets stuck, stretch receptora signal swallowing center for
secondary waves of peristalsis until clear
37
Pathophys of esophagus--greater stretch leads to ^ ________
Esophageal spasm,
| contraction
38
narrowing of esophagus from scar tissue
Esophageal stricture--as from GERD (irritation)
39
LES fails to relax--food backs up
Achalasia
40
Thick bands of muscle form in lower esophagus
Esophageal rings--as from GERD (irritation)
41
space btwn peritoneal membranes
peritoneal cavity
42
Stomach functions: (4)
1. stores food
2. digestive juices secreted
3. mixes food via peristalsis
4. proples chyme into duodenum
43
proximal boundary of stomach:
| distal boundary of stomach:
- LES
| - pyloric sphincter
44
serous membrane with visceral and parietal surfaces
peritoneum
45
inner surface of stomach--increase volume w/out increasing pressure--^area utilized for digestion
rugae
46
oxyntic glands in ______ and _______
fundus and body
47
parietal cells secrete (2) (in OXYNTIC glands)
```
HCl,
intrinsic factor (imp for Vit B12 absorption)
```
48
Chief cells secrete (in OXYNTIC glands)
(aka peptic cells),
| pepsinogen (HCl splits into pepsin)
49
Enterochromiffin cells secrete
ECL cells,
| histamines (encourages acid secretion)
50
Goblet (aka) secrete (in OXYNTIC and PYLORIC glands)
(mucous neck cells),
| mucus
51
G cells secrete--stimulates? (in Pyloric glands)
gastrin (stimulates gastric acid secretion)
52
churning of stomach imp for (2)
1. breakdown of macromolecules
| 2. introduce molecules to mucosa throughout stomach
53
point at which esophagus enters stomach
cardia (just area no function)
54
lateral boundaries of stomach
greater and lesser curbatures
55
D cells secrete--function? (in Pyloric glands and OXYNTIC)
somatostatin--inhibits HCl secretion
56
abundance of very ALKALINE viscid mucus for stomach protection secreted by
surface mucous cells
57
somatostatin _________ ECF, Parietal, and G cells
inhibits
58
pyloric glands in
antrum
59
Histamine binds to ____ _______ on ______ ______ -->
H2 receptors (as in H2 channel blocker)
parietal cells,
^ HCl production
60
stimulation of gastric phase of digestion (4)
1. ^est in afternoon/evening vest in morning
2. ^w/ aggression
3. cephalic phase stimulates before food arrives
4. ParaNS
61
Inhibition of gastric phase of digestion (2)
1. SNS (inhibs GI secretns, sphincter and vessel contractions)
2. bad tastes, rage, fear, pain
62
PNS' role in gastric phase
1. stimulates release of HCl, hist, intrinsic factor, mucus)
2. contractions of GI tract
3. relaxation of sphincters
63
Swallowing causes ____ to relax
fundus (distends and pH lowers)
64
_____ _____ inactive in mouth--needs low ____ to break down ____
lingual lipase,
pH,
fats
65
pace of stomach peristalsis mediated by ____ of _____
cells of cajal (pacemakers for slow waves)
66
protein digestion (in stomach) products ____ the acid
buffer--increasing the pH
67
stomach contractions stimulated by (3)
1. Auerbach plexus (from distension)
2. chemicals or irritants
3. strong paraNS signal
68
pepsin digests--so problem with this cell will cause problems in meat breakdown
cholagen,
| chief cells
69
Protein breakdown particularly in S.I. by _______ and _____ from________
trypsin and chymotrypsin,
| pancreas
70
reflex leading to ^ ilial emptying triggered by distention of stomach
gastroileal reflex increases ileal motility
71
distention of stomach triggers peristalsis
gastroenteric reflex
72
Pathophys of stomach:
| mucosa attack due to permiability of mucus layer
gastritis / gastric ulcer (may be caused by helicobacter Pylori, smoking, alcohol)
73
Small Intestine:
| epithelium makeup
1. circular folds
2. valves of kerckring
3. plicae circulares
74
GI reflex word breakdown
- first part where stimulus coming from
| - second part location of response
75
villi (slow food movement ) secrete ______ _______ and _____ _______
1. digestive enzymes
| 2. absorb nutrients
76
microvilli create a _______ ______ which ^ _______ ______. It has thick _______ layer of fluid for absorption
brush border,
absorptive surface,
"unstirred"
77
duodenum beginning and end
pylorus --> treitz ligament
| retroperitoneal
78
Jejunum is __________
intraperitoneal
79
ileum ends at
ileocecal valve (sphincter) intraperitoneal
80
outer layer of esophagus
adventitia
81
LACTEALS in SI w/ ______ _______ to absorb and transport _____ molecules and drain into _______ ______
lymphatic channel,
fats,
thoracic duct
82
rugae called ______ in SI
plica near valves of kirkring
83
mucous glands at top of duodenum secrete BICARB
Brunner's gland
84
secrete digestive juices in duodenum
Crypts of Leiberkuhn (undifferentiated cells in crypt base)
85
secrete cholecystokinin slowing gastric emptying and ^ bile ejection in duodenum and jejunum
I-cells
86
Peyer's patch/ lamina propria only in
Ileum
87
Submucosa has ______ _______ (only in duodenum) and _____ ______
Brunner's glands,
| Meissner's plexus
88
Willi have absorptive columnar cells w/ ______ _____ to absorb ____ and ______
tight junctions,
| water and electrolytes
89
Muscularis Propria in SI components (3)
1. inner circular layer
2. Auerbach plexus (Myenteric)
3. outer longitudinal layer
90
outermost layer of SI / GI in general
serosa/adventitia
91
ILEOCECAL valve protrudes into _____ of ______ _________; lips reverse into ileum preventing ______
cecum,
large intestine,
backflow
92
each villi has good ______ _______ for ^ absorption
blood supply,
93
When cecum is distended, both cecum ______ and ileal _____ ^
contraction,
| peristalsis
94
intrinsic factor binds to
Vitamin B12
95
Improper nourishment to small intestine villi as from malnourishment--villi will get ______ and ______ will decrease leading to ______
smaller,
absorption,
diarrhea
96
stimulation of SI (intestinal phase) (6)
1. peristalsis triggered by stretch of duodenum
2. gastrin
3. CCK
4. insulin
5. motilin
6. serotonin ^ peristalsis
97
__________ stimulates the digestion of fat and protein--through release of bile from the ________ and enzymes from the _________ (INHIBITS Chief/Parietal/Peristalsis)
Cholecystokinin CCK (stimulatory and inhibitory),
gallbladder,
pancreas
98
Inhibition of SI intestinal phase
1. distention
2. irritant
3. acidity
4. CCK/ GIP
5. Secretin
99
Further inhibition of SI intestinal phase
1. Presence of fat, protein breakdown products, hyperosmotic or hypo-osmotic fluids, or irritants in duodenum
100
Irritants in duodenum stim relase of ____ and ___ into circulation
CCK and GIP
101
DECREASE in pH stimulate release of _____ into circ, it inhibits _____ _____ ______
secretin,
| Chief, Parietal/ Peristalsis
102
GIP--stimulates RELEASE of _____ inhibiting ______ _____ and ________
insulin,
| chief, parietal, peristalsis
103
Addition of (4) facilitate digestion of carbs --> absorption --> liver
SI: sucrase, maltase, lactase
Panc: amylase
104
Organization of SI allowing to "mix and cut"
segmentation-- this along with peristalsis allow INTESTINAL MOTILITY (2 separate actions)
105
Most proteins absorbed in ____, pancreas adds _____ and _____ for their digestion
SI,
| trypsinogen (1st) and chymotrypsinogen (must be converted to trypsin by peptides--> breakdown proteins into aa's)
106
Digestion of fats by ______ ____ from ______ & _____ from _______
- bile salts from liver
| - lipase from pancreas
107
prevent fat reformation in SI
partially digested fats bathed w/ bile salts and lecithin
108
If ileum is distended the ______ _______ inhibits ______ _____ into the SI
ILEOGASTRIC REFLEX,
| gastric motility
109
________ _______ initiates propulsion through the colon to the ____ and ____
gastrocolic reflex,
| sigmoid and rectum
110
The ________ ______ INHIBITS intestinal motility if any segment is ______-_______
intestinointestinal reflex,
| over-distended
111
Ca++ absorbed in SI via _____, _____, and ______ -______
passive,
active,
carrier proteins
112
Ca++ and Vit D absorption facilitated by ____ ______. Increased _____ leads to ______ uptake.
bile salts,
demand,
increased
113
Vitamin B12 released from ___ ____. Binds to ______ _____, making it resistant to ________.
animal proteins,
intrinsic factor,
digestion
114
Vitamin B12 aborbed in _____. Necessary for _______ _______
ileum,
| erythrocyte maturation
115
*Recycling of bile for reuse in liver
enterohepatic circulation
116
___-___% of fluids and electrolytes absorbed in SI--rest in _____
80-95%,
| colon
117
____ is released from heme (hemoglobin/ myoglobin) in meat. Amount absorbed = _____ ______. Absorption facilitated by ________ _
iron,
amount required (if low in blood dif. from Ca++ absorption)
Vitamin C
118
Most aborption of (8) in SI
carbs, proteins, lipids, Ca++, Vit B12, Iron, Fluids, Electrolytes
119
In SI:
1. Na+ enters in exchange for____
2. Cl- enters in exchange for ______
3. K+ moves _______
1. H+
2. bicarb. HCO3-
3. passively
120
Inside paritenium is (3)
| Pathophys:
1. liver
2. stomach
3. some of SI
Pathophys--hardening-->paritenitis (adhesions from scar tissue btwn loops of S/L intestine)
121
Prolonged diarrhea may lead to (2)
1. hypokalemia
| 2. metabolic acidosis
122
Function of LI
1. absorb H2O and electolytes (some left)
| 2. store feces
123
draped over front of LI
mesentery
124
____ ______ present in cecum
tenaie coli
125
2 sections of LI
1. absorbing section
| 2. storing section
126
Mucosa of LI (2) and function
1. Rugae
| 2. ^ crypts of Leiberkuhn (secrete bicarb & mucus --absorbe Cl-)
127
sigmoid colon contains only
waste/feces
128
controls movement of waste from sigmoid colon to rectum
O'Beirne sphincter
129
Stimulation of LI ()
1. ParaNS ^ peristalsis
2. irritant --> ^ H2O and electrolyte secretion (for dilution of irritant ) --> diarrhea
3. intrinsic (myenteric plexus) and extrinsic (vagus) innervate
130
external anal sphincter control
skeletal muscle--voluntary
| Ex-Ske
131
Internal anal sphincter control
smooth muscle--involuntary
| Inter-invol
132
defecation reflex stimulated by
rectal wall stretching from movement into rectum
133
Rectal reflex inhibited by
pain or fear of pain
134
defecation starts when _____ ______ relaxes, causing urge to defecate
sphincter relaxes
135
defecation facilitated by ______, ____ or ______--increase ____-_____ pressure
squatting, sitting, or valsalva,
| intra-abdominal
136
Bacteria in LI
1. increase as tract descends
2. colonized few hours after birth
3. doesn't help in digestion or absorption
4. does metabolize molecules
137
inflammatory disease particularly in apenix
Crohn's disease
138
2 bands that run in colon
| Allow giant mass movements--move much fast thru colon
1. circular--
2. tenai coli--longitudinal bands to shorten colon
(form pockets (haustra)--motility like SI)
139
In L/S I outpouches? If they get inflammed?
divertiula,
| diverticulitis
140
Accessory GI organs:
The liver produces ____ for ______ & _____ of fats. Metabolizes nutrietns from ____ _____ --nutrients released into blood stream or stored
bile,
digestion & absorption,
small intestine
141
Stores and _________ bile btwn meals--ejects bile into ducts for release into ________
CONCENTRATES,
| duodenum
142
EXOCRINE pancreas produces enzymes for digestion of ________, ______, and ______.
carbs, proteins, and fats,
143
pancreas produces _____ ______ (bicarb) to neutralize ______. Makes Duodenal pH supportive of ______ ______
alkaline fluid,
chyme,
enzymatic action
144
vein from inferior/superior mesenteric and splenic veins through liver
hepatic portal vein--70% of venous supply
145
_____ _____ divides liver L from R. Superrior to liver.
falciform ligament,
| diaphragm
146
capsule around liver
Glisson gibroelastic capsule--stretch = pain
147
_________ form bile from conjugation of bile acid-bile salts
hepatocytes (functional cell of liver--grouped make up lobule)
148
Liver stores (8)
1. fat
2. glycogen
3. iron
4. copper
5. Vit B12, A, D, and E
149
small capillaries next to hepatocytes
sinusoids
150
carries bile from hepatocytes to bile ducts
bile canaliculi
151
Mucosa of gallbladder absorbes ______ & ________, ________ bile
water & electrolytes,
| concentrating
152
Gallbladder ejects bile ____ min after eating. Bile ejections mediated by _____ _____ & ____ from _ _____
30,
vagus nerve,
CCK,
I cells
153
Bile from Gallbladder:
| cystic duct-->common bile duct-->sphincter of Oddi at...
Ampula of Vater-->duodenum
154
Pancreas secretes aqueous: (4)
1. K+
2. Na+
3. HCO3-
4. Cl-
155
inactive pancreatic enzymes (trypsinogen, chymotrypsinogen, procarboxypeptidase) activated by _____ in ______
```
enterokinase in duodenum--
active forms (trypsin, chymotripsin, carboxypeptidase)
```
156
pancrease releases _____ _____ for carb digestion
Alpha Amylase
157
when bile comes back to liver, synthesis of ______ happens
lipids, triglicerides
158
slow waves do not cause _______
contractions
159
liver synthesizes ______ from simple lipids
cholesterol
160
Pain after eating:
Gastric ulcer:
duodenal ulcer:
- abdominal pain worsens w/ food intake
| - pain occurs 2 hrs after food intake
161
CCK stimulated by + stimulates digestion of: cause
protein and fats,
| release of enzymes and bile from pan and liver
162
Pyloric glands in...
Antrum of stomach
163
In stomach propulsion back from sphincter resulting in ^ mixing
Retropulsion
164
Trypsin oven converted by
Enterokinase-- secreted by SI
165
Secretory cells in duodenum and products (3)
Brunners --> bicarb mucus
Crypts of Leiberkuhn --> digestive juices (hold undif cells)
I-cells --> CCK (slows stomach emptying, ^ bile ejection)
166
compounds released by duodenum in response to chyme arrival/ drop in pH (3)
All inhibit Chief/ parietal/peristalsis
1. CCK
2. GIP (gastric inhibaroty polypeptide)
3. Secretin
167
Crypts of Leiberkuhn in L/S I
SI: digestive juice--undifferentiated cells
LI: bicarb & mucus secretion, Cl- absorption
