Digestive System 1 Flashcards
1
Q
main functions of digestive system
A
- take materials into body
- tube mouth to anus
- take stuff from tubes, bring into body, break down
2
Q
alimentary canal
A
continuous, muscular tube of digestive system
3
Q
organs (in order) of alimentary canal
A
mouth pharynx esophagus stomach small intestine large intestine anus
4
Q
accessory organs of digestive system
A
teeth, tongue, salivary glands
5
Q
6 actions of digestive system
A
ingestion propulsion chemical digestion absorption mechanical digestion defecation
6
Q
ingestion
A
bringing food into system
7
Q
propulsion
A
moving food through system
2 types: deglutition and peristalsis
8
Q
deglutition
A
swallowing
a voluntary, initial process
9
Q
peristalsis
A
wave-like smooth muscle contractions
involuntary
10
Q
chemical digestion
A
enzymatic breakdown of stuff brought into digestive system
begins in mouth, ends in small intestine
11
Q
absorption
A
absorbing building blocks (monomers) of foods we eat
occurs in distal parts of small intestine out of lumen
reclaim H2O in large intestine
12
Q
from what do we reclaim water in the large intestine?
A
mucus, gastric juice, and enzymes
13
Q
mechanical digestion
A
physical breakdown; making food smaller increases its surface area
includes mastication, mixing, and segmentation
14
Q
mastication
A
chewing
15
Q
mixing
A
mixing bolus/chyme with saliva
like when stomach is churning
16
Q
segmentation
A
kneading tube of alimentary canal
mixing and propulsion
back and forth movement
17
Q
defecation
A
elimination of wastes from large intestine
wastes formed in large intestine exit body through anus
18
Q
3 ways we control digestive system
A
sensors
nerve plexuses
hormones
19
Q
how do hormones control digestive system
A
whatever sensors were stimulated can cause release/inhibition of certain hormones
20
Q
how do sensors control digestive system
A
sensory receptors are deigned to detect stimuli
stimuli include osmolarity, pH, specific nutrients, and stretch
sensory receptors then send nervous impulses through nerve plexuses
21
Q
stimuli for sensory receptors of digestive system
A
osmolarity
pH
specific nutrients (carbs, proteins, lipids)
stretch (can be on or off switch)
22
Q
short/intrinsic nerve plexus
A
nervous impulse exchange that occurs entirely within GI tract
23
Q
long/extrinsic nerve plexus
A
nervous impulse exchange that involves CNS
24
Q
sensors in GI tract sending signal to brain to activate something other than GI tract is which type of nerve plexus?
A
long/extrinsic
25
stimulus in part of body other than GI tract that changes activity of GI tract is which type of nerve plexus?
long/extrinsic
26
mesentary
specialized peritoneal component in digestive tract
| 2 sided serous membrane that anchors abdominopelvic organs to back wall of abdominopelvic cavity
27
peritoneum
abdominopelvic serous membrane
28
"retroperitoneal" means
this organ is not anchored by mesentery
| because its behind peritoneum
29
tunics of alimentary canal
mucosa
submucosa
muscular externa
serosa
30
mucosa
superficial layer
| epithelial tissue
31
submucosa
deep to mucosa
dense irregular connective tissue
where all blood vessels and nerves go
where we get nutrients into circulatory system
32
muscular externa
```
deep to submucosa
muscular layer (smooth muscle; involuntary)
2 layers: circular layer, longitudinal layer
^ their combined interaction moves things through digestive system
```
33
circular layer of muscular externa
fibers run sideways in a ring around lumen
more superficial than longitudinal layer
when it contracts, it changes the diameter (constricts) of lumen
34
longitudinal layer of muscularis externa
fibers run vertically in tube
| when it contracts, the tube shortens
35
serosa
deepest layer of alimentary canal
| visceral peritoneum
36
what type of tissue is pharynx made of
squamous epithelium
37
what type of tissue is the organs at esophagus and beyond made of?
columnar epithelium
| this includes goblet cells
38
tunics for organs above diaphragm
mucosa
submucosa
adventitia (replaces muscular and serosa)
39
tunics for below diaphragm
mucosa
submucosa
muscularis
serosa
40
goblet cells secrete ____
mucus
41
functions of mucus
secretes enzymes
secretes hormones
protects alimentary canal and its blood vessels from abrasive food
42
where are enzymes usually produced in alimentary canal?
produced by glands in submucosa
| needs to get into lumen to digest, so it passes through mucosa
43
where are hormones produced in alimentary canal?
produced in submucosal layers
44
enteric neurons
intrinsic nerve plexus nerves found in wall of alimentary canal
submucosal or myenteric
45
submucosal nerve plexuses
sensory receptors in submucosa that detect stretch, chemical composition, or pH
once activated, they send signals to whatever part of digestive system to make that work
function in secretion
46
why do submucosal nerve plexuses exist
because theres no nerve fibers in mucosa
47
myenteric nerve plexuses
```
enteric neurons located between 2 layers of muscle in muscular externa
function in motility
```
48
motility action of enteric neurons
activation of myenteric nerve plexus causes muscle contraction
49
secretion action of enteric neurons
activation of submucosal nerve plexus causes things like secretions of enzymes/hormones (glandular action)
50
t/f motility and secretion actions of enteric neurons cannot happen at the same time
false
| they can both happen at same time
51
oral/buccal cavity
entry to alimentary canal
connected to pharynx so we can breathe and eat
involved with ingestion, propulsion, mechanical, and chemical digestion
52
only part of digestive system involved with ingestion
oral/buccal cavity
53
components (accessory organs) of oral/buccal cavity
palate
tongue (papillae)
salivary glands
teeth
54
palate
roof of buccal cavity and floor of nasal cavity
| includes uvula
55
uvula
extension off back of soft palate
| blocks nasopharynx when swallowing
56
tongue
functions in swallowing (deglutition)
moves food around oral cavity- causes mixing
creates bolus
includes diff types of papillae
57
bolus
foodstuff ball that we swallow
58
types papillae
fungiform
circumvallate
filiform
59
fungiform papillae
contain taste buds
| sensory component
60
circumvallate papillae
make V in back of tongue
| have some taste buds and chemoceptors
61
filiform papillae
bumps on top
| give tongue grip
62
salivary glands
parotid
sublingual
submandibular
63
parotid salivary gland
far back in oral cavity
| made of serous cells, which produce enzymes
64
enzyme-producing salivary gland
parotid
65
sublingual salivary gland
under tongue
made of mucous cells (make mucus)
help lubricate
66
submandibular salivary glands
somewhere between parotid and sublingual glands
| made of both mucus and serous cells- produces both secretions
67
how much saliva do we produce per day
1-1.5L
68
actions of saliva
cleans mouth
dissolves food to make it biologically active
moistens food- helps form bolus
enzyme in saliva (amylase) starts starch digestion in mouth
69
pH of saliva
slightly acidic (6.75-7)
70
components of saliva
```
water
electrolytes
amylase
mucin
lysosome
IgA
metabolic wastes
```
71
salivary amylase
enzyme that starts starch breakdown in mouth
72
mucin
protein that gives mucus its slipperiness to help move food
73
immune components of saliva
IgA and lysosome
74
metabolic wastes in saliva
we produce things like urea/uric acid when breaking down proteins
get rid of these wastes through defacation
75
control of salivation
parasympathetic nervous stimulation controls saliva production
chemoreceptors and pressure receptors send signal to ANS to produce saliva
76
why do we get cottonmouth when nervous
sympathetic nervous system shuts off saliva production
77
teeth are involved in which digestion process?
mastication
78
2 sets of teeth in humans
primary teeth
| permanent teeth
79
primary teeth
aka vesiduous/baby teeth
20 total- don't all appear at same time
we have all by 2 years old
they will fall out
80
we have all primary teeth by how old?
2
81
permanent teeth
32 total
replace primary teeth
dont necessarily last whole life- but will not be replaced
82
types of teeth
incisors
cuspid
bicuspid
molars (incl 18 yr molar)
83
incisors
front 4 teeth
| "shearing teeth"- allow us to cut/pull things
84
cuspid
one on each side of incisors
| "canine/fang tooth"- for piercing/grabbing hold of things
85
bicuspids/premolars
2 on each side of cuspids
| for shearing/cutting
86
molars
last 3 teeth on each side
flat teeth
for grinding and breaking up seeds/plants
87
3rd molar/wisdom tooth/18 yr molar
last tooth to come in
in evolution, human jaw has shrunk
often doesn't emerge at all or emerges not in line with other teeth
often removed
88
"carnivorous teeth"
cuspids and bicuspids
89
components of tooth structure
```
crown
root
neck
enamel
dentine
pulp
root canal
cementum
```
90
crown of tooth
part of tooth above gumline
91
gingiva
gumline
92
root of tooth
part of tooth below gumline
| embedded in bone in jaw
93
neck of tooth
transition part between crown and root
94
enamel
hard substance covering crown of tooth
| strengthens tooth; only on crown
95
pulp of tooth
soft tissue deep to dentine
| contains blood vessels and nerves
96
root canal
pulp that extends into root
97
dentine
substance deep to enamel
| in root and crown
98
cementum
connective tissue
| glues tooth into socket
99
digestive function of pharynx
propulsion
100
which parts of pharynx are pathways for food?
oropharynx and laryngopharynx
101
when swallowing, epiglottis is _____
down!
| covers trachea so food only goes through esophagus
102
esophagus
muscular tube involved in propulsion; sits just behind trachea
includes upper esophageal sphincter and gastroesophageal sphincter
103
upper esophageal sphincter and gastroesophageal sphincter
prevent food from going wrong way
| not true sphincters
104
main steps of deglutition
1. food compacted into bolus
2. buccal phase (voluntary)
3. pharyngeal-esophageal phase (involuntary)
105
buccal phase of deglutition
voluntary part
1. tip of tongue placed against hard palate
2. tongue contracts to force bolus into oropharynx
3. bolus stimulates tactile receptors
106
t/f you cannot swallow with your tongue against roof of mouth, you need something in between
true
| that is usually bolus
107
pharyngeal-esophageal phase of deglutition
involuntary part
1. tactile receptors stimulate medulla and pons
2. motor impulses (parasympathetic) sent to muscles in pharynx and esophagus
3. peristalsis moves bolus to stomach
(in stomach, bolus is liquified and turned into chyme)
108
digestion events that occur in stomach
propulsion
mechanical digestion
chemical digestion of proteins
109
2 types of action that stomach can engage in
secreting gastric juice
| muscular contraction
110
cardia
part of stomach that's connected to esophagus
111
fundus
part of stomach above direct path from esophagus to body
112
pylorus
portion where stomach constricts again
113
cardiac sphincter
kink in cardia created from distention/bending of stomach when it fills
prevents stuff from going back up
not true valve
114
pyloric sphincter
regulates emptying of stomach
true valve
connects to duodenum
115
muscular layers of stomach
circular
longitudinal
oblique
116
rugae
folds all over lining of stomach to increase surface area
| flatten to increase volume of stomach
117
volume of empty/relaxed stomach
50 mL
118
volume of stretched stomach
~4L
119
stomach cells
```
goblet cells
mucous neck cells
parietal cells
chief cells
enteroendocrine cells
```
120
gastric glands are located __
at base of gastric pits of stomach
121
goblet cells
found in mucosa, which lines gastric pits and stomach wall
| produce mucus
122
mucous neck cells
first cells of gastric glands
| produce slightly acidic mucus
123
parietal cells
embedded within mucus neck cells
| produce HCl and Intrinsic factor
124
HCl
digestive component secretion of parietal cells
pH= 2
activates pepsinogen to become pepsin
125
intrinsic factor
glycoprotein required by small intestine to absorb B12
| B12 needed to make RBCs and carry O2
126
chief cells
cells in stomach that produce pepsinogen (inactive form of pepsin)
127
enteroendocrine cells
cells in stomach that release gastrin
gastrin regulates activity of others parts of digestive tract
at way bottom of gastric gland
aka G cells
128
G cells are also known as
enteroendocrine cells
129
phases of gastric secretion
cephalic (reflex) phase
gastric phase
intestinal phase
130
cephalic (reflex) phase of gastric secretion
first thing that can cause stomach to activate
acquired/learned
if we THINK about eating foods we like, stomach starts to activate and secrete
before food arrives to stomach
long reflex arc
131
t/f cephalic reflex phase occurs for any foods, whether we like them or not
false
| it only happens with foods we like
132
gastric phase of gastric secretion
begins once food starts arriving in stomach
several different stimuli occur once food is in stomach
these stimuli stimulate enteroendocrine cells to start producing gastrin
gastrin activates cells in gastric gland to start secreting things
133
stimuli in stomach during gastric phase of secretion
stretch, change (elevation) in pH, or presence of proteins
134
stretch stimulus in gastric phase of secretion
1. food causes stretch in wall of stomach
2. sends signal to ANS
3. ANS sends parasympathetic impulses back
4. causes release of acetylcholine
5. acetylcholine stimulates gastric gland to start secreting
135
pH stimulus in gastric phase of secretion
stomach pH is very low (2), saliva pH is closer to 7
| body senses this change once saliva reaches stomach
136
feedback loop of gastric phase of gastric secretion
```
increased pH activates gastrin secretion
gastrin activates gastric gland cells (like parietal cells)
parietal cells produce HCl
HCl makes pH go down
low pH shuts off gastrin secretion
```
137
intestinal phase of gastric secretion
stomach is still active as food leaves stomach entering small intestine
2 parts: excitatory then inhibitory
138
excitatory intestinal phase
arrival of some material in small intestine continues to activate stomach
basically stomach "finishing up" its job
139
inhibitory intestinal phase
after excitatory part has gone for a while, small intestine says it is time to start slowing down
bc stomach is probably getting pretty empty, so we don't want to digest the stomach itself
140
contents from stomach trickle into small intestine _____ (vol) at a time
3 mL
141
enterogastric reflex
small intestine shutting off stomach by inhibiting nervous stimulation
continued stretch on small intestine inhibits parasympathetic activity and activated sympathetic activity
causes pyloric sphincter to squeeze shut
142
what prevents us from digesting our own stomach by HCl and pepsinogen?
mucosal barrier
143
mucosal barrier components
bicarbonate-rich mucus
tight junctions in mucosal epithelium
HCl-impermeable plasma membranes in gastric gland cells
undifferentiated stem cells at junction of gastric pits and gastric glands
144
bicarbonate-rich mucus of mucosal barrier
produced by goblet cells
| buffers pH at lining of stomach (not secreting into stomach)
145
how do tight junctions in mucosal epithelium contribute to mucosal barrier
impermeable junctions mean no acid can slip in between cells to get into underlying tissue
146
how do HCl-impermeable plasma membranes in gastric gland cells contribute to mucosal barrier
so that the acid that gastric gland cells are producing can only go into gastric pit; cannot go to other side
147
how do undifferentiated stem cells at junction of gastric pits/glands contribute to mucosal barrier
gastric pits and glands in lining of stomach need to constantly replace cells
entire wall of stomach is replaced every 3-6 days
148
2 types of gastric filling
receptive relaxation
| adaptive relaxation
149
t/f stomach has ability to change shape when it's filling
true
150
receptive relaxation
thinking about food can make stomach start secreting and make it change shape even before food has gotten there
no stretch has occurred yet! increased size is due to rug flattening out
151
adaptive relaxation
after food has started arriving in stomach
rug continue to flatten out
stretch starts to occur only after we have ~ 1 L of food in stomach
^ this stretch causes signals to brain to stomach to start secreting
152
gastric contractions are mostly what kind?
longitudinal contractions for propulsion
153
interstitial cells of Cajal
autorhythmic cells of stomach (pacemaker of stomach)
| within longitudinal layer
154
t/f anything that increases production of HCl also increases rate of muscular contractions in stomach
true
| includes stretch, proteins, and increased pH
155
basic electrical rhythm of gastric contraction
longitudinal cells of stomach contain some autorhythmic cells (interstitial cells of Cajal)
creates basic rhythm of contraction, which happens about 3x per minute
156
autorhythmic cells
cells that can depolarize because of leaky membranes
157
reasons for slow release of chyme from stomach
increases efficiency of digestion
| prevents giant wave of low pH from getting into stomach
158
stomach starts to empty about ___ after you've had your meal
4 hours
159
process of gastric emptying
1. chyme enters duodenum
2. stretch and chemoreceptors of small intestine activated
3. enterogastric or enterogastrone reflexes initiated
4. gastric activity reduced
5. pyloric contractions reduced
6. duodenal filling stopped
160
enterogastrone
hormone of small intestine that inhibits gastric secretion
161
what happens during gastric emptying? like how is this chyme actually leaving stomach?
every time we get contraction, pressure pushing against pyloric sphincter increases
with each contraction, 30 mL of chyme leaves stomach and goes to duodenum
BUT as "squeeze" relaxes, 27 mL goes back into stomach
only 3 mL escape stomach with each muscular contraction
162
t/f vomiting/emesis is reverse peristalsis
false!
| peristalsis only moves in one direction (down)
163
vomiting/regurgitation/emesis
something enters stomach that causes too much stretch or irritation
excessive stress/irritation stimulates abdominal muscles and diaphragm to contract
this contraction puts lots of pressure on stomach- contents are forced up through esophagus
continues as long as there is stretch/irritation
164
projectile vomiting
when the pressure on stomach from contraction of abdominal muscles and diaphragm is very intense
165
why do we have dry heaving
emesis continues as long as there is stretch/irritation
even with no food left, there may still be irritation
as this continues, contractions can be so hard you pull up bile from small intestine
166
major digestive organ of body
small intestine
167
functions of small intestine
chemical digestion of every class of macromolecule
absorption once everything is digested
propulsion through alimentary canal
168
length of small intestine
8-13 ft
| runs from pyloric sphincter to ileocecal valve
169
when we die how long is out small intestine
like 20 ft
170
how much intestinal juice does small intestine produce per day
1 to 2 liters
171
production of intestinal juice in small intestine stimulated by _______
arrival of acidic chyme
172
function of intestinal juice
slightly alkaline, so it neutralizes pH and shuts off/denatures pepsin
173
digestion occurs mostly in _____
duodenum
174
absorption of nutrients happens mostly in _____
jejunum
175
subdivisions of small intestine
duodenum
jejunum
ileum
176
duodenum
first 10 inches of small intestine
| contains hepatopancreatic ampulla
177
jejunum
middle 8 ft of small intestine
178
ileum
last part of small intestine
| ends with ileocecal valve
179
structural modifications of small intestine
length
plicae circulares
villi
microvilli
180
structural modification of small intestine: length
long length gives small intestine increased surface area
| surface area ~ 200 m^2
181
plicae circulares
aka spiral valve
folds in mucosa and submucosa of lining of small intestine
make incoming chyme spiral while going through small intestine
--slows liquid down
--increases contact of liquid with wall to increase efficiency
182
villi of small intestine
fingerlike projections of mucosa that increase surface area
| help increase contact with chyme to break down its contents
183
microvilli of small intestine
within modified plasma membrane of epithelial cells of villi
increases surface area further
why lining of small intestine is called brush border
184
brush border
lining of small intestine
| because of the villi and microvilli
185
chyme leaving small intestine to go into large intestine is ______; what would happen if we let it all go at once?
hypertonic; significant water loss
186
factors of small intestine emptying
gastroileal reflex
gastrin
pressure
187
gastroileal reflex
linkage between activity (action/motility) of stomach and ileocecal valve
signal from stomach tells small intestine to start releasing contents
causes segmentation-like contractions within small intestine
188
contractions caused by gastroileal reflex trigger ____ in small intestine
segmentation
189
how does gastrin affect small intestine emptying
activates stomach and small intestine
| relaxes (opens) ileocecal valve
190
how does pressure affect emptying of small intestine
as chyme from small intestine is released into cecum, it starts to accumulate
this causes stretch and back pressure on ileocecal valve to close it
191
largest internal organ in body
liver
192
major function of liver
process blood (recycle RBCs and turn hemoglobin into bilirubin and amino acids)
193
byproduct of major function of liver
bile production!
194
functions of bile
acts as emulsifier
breaks big fat globs into smaller fat globs --> increases surface area
basically causes mechanical digestion of fats to occur
195
t/f bile is an enzyme
false!
| it does not chemically break anything down
196
bile composition
```
water
bile salts
bile pigments- bilirubin, urobilinogen
cholesterol
neutral fats
phospholipids
electrolytes
```
197
lobes of liver
4: right, left, caudate, quadrate
198
falciform ligament
attaches liver to muscular diaphragm and separates R/L lobes
199
bile salts
made of salts from breakdown of blood cells and bilirubin/biliverdin
what's actually doing the emulsifying
200
urobilinogen
when bile is secreted into digestive tract, bilirubin is converted into urobilinogen
brown color
201
common hepatic duct
from liver to bile duct
| right and left hepatic ducts merge to form common hepatic duct
202
cystic duct
brings bile from gallbladder to common hepatic duct
203
bile duct
from common hepatic duct to hepatopancreatic ampulla
| takes bile from liver and gallbladder to small intestine
204
hepatopancreatic ampulla is also known as
ampulla of vater
205
pancreatic duct
connects to bile duct
| brings secretions from pancreas
206
hepatopancreatic duct is only open when?
at mealtime
207
functions of gallbladder
store bile
| concentrate bile
208
how does the gallbladder concentrate bile?
bile is mostly water, gallbladder reclaims some of the water
209
gallstones
when gallbladder concentrates bile so much that it crystallizes
get stuck in ducts, cause pain and pressure
210
bile storage
1. hepatopancreatic sphincter closed when not digesting
2. liver continually produces bile
3. bile backs up cystic duct into gallbladder
211
bile release
1. fatty chyme entering duodenum stimulates intestine to produce cholescystokinin (CCK)
2. CCK causes parasympathetic nervous impulses to promote gallbladder contraction to squeeze out bile
3. CCK also relaxes hepatopancreatic sphincter
212
endocrine function of pancreas
insulin and glucagon
213
exocrine function of pancreas
produce pancreatic juice
| goes into pancreatic duct, connects to bile duct, and released at hepatopancreatic ampulla
214
pancreatic juice components
water
enzymes
bicarbonate
215
bicarbonate component of pancreatic juice
secreted by cells of pancreatic duct
pH > 8
helps neutralize chyme so enzymes can function
216
enzyme component of pancreatic juice
```
from exocrine cells of pancreas
enzymes for every class of macromolecule
```
217
protease enzymes of pancreatic juice
break down proteins
secreted into duct in inactive form; activated in duodenum
trypsin, carboxypeptidase, and chymotrypsin
218
other enzymes (not proteases) of pancreatic juice
secreted in active form
| amylase (starches), lipase (lipids), nuclease (nucleic acids)
219
trypsin
protease enzyme in pancreatic juice
| inactive form trypsinogen is activated by enterokinase (enteropeptase)
220
where is enterokinase produced
brush border of SI
221
carboxypeptidase
protease enzyme in pancreatic juice
| inactive form procarboxypeptidase is activated by trypsin
222
chymotrypsin
protease enzyme in pancreatic juice
| inactive form chymotrypsinogen is activated by trypsin
223
components of pancreatic secretion control
secretin
CCK
parasympathetic impulses
224
how does secretin help control pancreatic secretion
stimulates cells of pancreatic duct to start producing bicarbonate
225
how does CCK help control pancreatic secretion
opens hepatopancreatic ampulla
stimulates production of enzymes
activates some exocrine cells to start producing/secreting enzymes
226
how do parasympathetic impulses help control pancreatic secretion
stimulates exocrine cells or duct cells to start producing/secreting
227
acidic chyme stimulates intestine to produce _____, which stimulates production of bicarbonate and lowers acidity of chyme
secretin
228
presence of fats/proteins stimulates wall of intestine to produce ___, which stimulates production of enzymes to break down proteins and fats
CCK
229
digestive actions of large intestine
absorption (mostly water)
propulsion
elimination
230
length of large intestine
9 feet
231
segments of large intestine in order
```
cecum
ascending colon
transverse colon
descending colon
sigmoid colon
rectum/rectal canal
anus
```
232
rectal valve
"bends" in large intestine
separates solids and gases
allow gases to pass at higher rate than solids
233
internal anal sphincter
closest to rectum
| smooth muscle; involuntary
234
external anal sphincter
outside of internal sphincter
skeletal muscle
voluntary
235
vermiform appendix
appendage that hangs off cecum
no longer any function (possibly used to function in cellulose digestion)
harbors microbiota from digestive tract
becomes trap- things we ate plug opening and cause appendicitis
236
appendicitis
something plugs opening of appendix
appendix becomes inflamed/swollen and loses blood supply
caused by tiny seeds, or (most common) gum, or (2nd most common) opiates
237
haustra
saclike puckering that divide large intestine
238
taenia coli
bands of smooth muscle from muscular that wrap around large intestine and create haustra
239
epiploic appendages
deposits of adipose tissue accumulated along large intestine
| no known function
240
intestinal bacteria functions
ferment indigestible carbs
synthesize B vitamins
synthesize K vitamins
241
intestinal bacteria fermentation of indigestible carbs
produces gas rich in dimethylsulfide (smelly)
242
intestinal bacteria synthesis of B vitamins
we get all the B vitamins we need in diet, bacteria just add a little more
absorbed with water thats being reclaimed
243
intestinal bacteria synthesis of K vitamins
we get enough K vitamins from healthy diet, this just adds more
vitamin K used by liver to make clotting protein
244
motility of large intestine
haustral contractions
| mass movements
245
haustral contractions
activated by stretch caused by arrival of chyme in large intestine
one haustra contracts and slowly moves contents to next haustra, etc
every 30 minutes all day
basically a form of segmentation
246
mass movements
arrival of food in stomach causes us to push previous meal from large intestine
happens 3-4 times per day; usually triggered by meal
247
defecation reflex
1. mass movements cause stretch on large intestine wall
2. stretch triggers parasympathetic stimulation of sigmoid colon and rectum, and inhibits anal sphincters
3. external anal sphincter under voluntary control still (can 'hold it')
4. valsalva's maneuver assists emptying
248
valsalva's maneuver
"pushing"
| contracting diaphragm and intercostal muscles to help poop
249
what makes up feces
undigested food residue
sloughed off epithelial cells from ileum and large intestine
bacteria from digestive tract
tiny bit of water
250
constipation
if too much water is reclaimed
251
diarrhea
if not enough water is reclaimed
