Digestive System Flashcards
1
Q
What is the alimentary canal organs?
A
- continuous long tube
- open to external environment on both ends
- everything in canal is technically outside of the body
- absorb through walls of alimentary canal and leave waste to be secreted
- mouth, pharynx, esophagus, stomach, small intestine, large intestine
2
Q
Accessory Digestive Organs
A
tongue, teeth, salivary glands, liver, gallbladder, and pancreas
3
Q
Major functions of digestive processes
A
Ingestion Propulsion Mechanical digestion Chemical digestion Absorption Defecation
4
Q
What does ingestion do?
A
bring food into system
5
Q
Propulsion?
A
movement of material through digestive tract
6
Q
Types of propulsion?
A
-deglutition; swallowing:partial voluntary and involuntary process
-peristalsis;
wave like smooth muscle contraction: begins in esophagus, involuntary
7
Q
Mechanical Digestion
A
- physical breakdown of food
- mastication
- mixing
- segmentation
8
Q
Chemical digestion
A
- use of enzymes to break down food into its building blocks
- proteins into amino acids
- carbs into glucose
- fats into fatty acids
- begins in mouth, continues in stomach, finishes in small intestine
9
Q
Absorption
A
movement of digested products from lumen of alimentary canal to blood or lymphatic system
10
Q
Defecation
A
elimination of waste
11
Q
Sensors
A
sensory receptors
- activation of receptor can increase and decrease the activity of the digestive system
- secretion patterns
- smooth muscle contraction
12
Q
Stretch Receptor
A
when stretches it sends signals to begin stomach action
13
Q
Other types of receptors
A
Osmolarity receptors
pH receptors
Receptors for certain molecules
14
Q
types of Nerve plexuses
A
Short/intrinsic
Long/extrinsic
15
Q
Short/intrinsic:Nerve plexuses
A
localized effects
- utilizes enteric nervous system
- nervous tracts do not leave digestive system
- doesn’t use CNS
16
Q
long/extrinsic:Nerve plexuses
A
utilizes the CNS
17
Q
Hormones
A
glandular secretion of hormones can affect digestive tract elsewhere in the body
18
Q
Mesentery? What is its relationship to the peritoneum?
A
- double layered peritoneum
- anchors the abdominal organs to abdominal wall
19
Q
Four tunics in the digestive tract
A
mucosa
submucosa
muscularis externa
20
Q
Mucosa layer (tunic of digestive system)
A
- composed of epithelial tissue -functions in protection
- absorption
- secretes mucus, enzymes, hormones
21
Q
Submucosa layer (tunic of digestive system)
A
contains dense, irregular connective tissue
-blood vessels, lymphatic vessels, glands, nerves
22
Q
muscularis layer (tunic of digestive system)
A
smooth, involuntary muscle
- movement, mixing, mechanical digestion
- two layers
23
Q
Describe the enteric nervous system.
A
Both of these nerve plexus are types of intrinsic nerve plexus
-Do not need the central nervous system in order to function.
The central nervous system can have effects to the same areas innervated by these two plexus
24
Q
Submucosal Nerve Plexus
A
Located in the submucosa
Involves the muscles and glands just outside the submucosa
-Acts on glands to secrete things and muscles to contract
25
Myenteric Nerve Plexus
- Between two different layers of muscle
| - Linked to motility or movement
26
Oral/buccal cavity (alimentary and accessory organ)
Only side of ingestion
- Also includes propulsion, mechanical digestion, and chemical digestion
- Chemical digestion of carbohydrates (starch) begins but does not finish here
Lips and cheeks prevent food from escaping
27
Palate
| alimentary and accessory organ
-Roof of the mouth
-Hard palate
Front part
Bony
Tongue can push food against the hard palate for compaction or compression of food
-Soft palate
Back part
Fleshy
-Changes from bony to soft portions allows you to breathe while eating
Some animals have to stop breathing while eating
-The uvula moves to block the nasal cavity when food passes by
28
Tongue (alimentary and accessory organ)
-Muscular organs
-Moves and mixes food
-Food clumps into a bolus
Ball-shaped mixture of food and saliva
-Tongue plays an important role in deglutition
```
--Papillae
Bumps on the tongue
Filiform papillae
Give grip to move food around
Most abundant
Fungiform papillae
Taste buds
```
29
Salivary glands (alimentary and accessory organ)
-Cleans our mouth even when not eating
-Washes away residual food so there is no food for bacteria to live off of
-Fluid dissolves food; moistens it
Makes the food biologically active
-Contains enzymes
Salivary amylase breaks down starch
-Salivary glands contain mucous cells, serous cells, or a mixture of the two cells
Mucous cell makes mucus
Serous cells make enzymes
30
Sublingual salivary glands (alimentary and accessory organ)
Located underneath the tongue
Made of mucous cells
Activity increases when eating or thinking of eating
31
Parotid salivary glands (alimentary and accessory organ)
Located in the back of the oral cavity
| Made of serous cells
32
Submandibular glands (alimentary and accessory organ)
Made of both serous and mucous cells
33
Teeth (alimentary and accessory organ)
Involved in mastication
34
Two sets of teeth (alimentary and accessory organ)
1. Primary/deciduous/baby teeth
20 total
Should all be in place by 2 years old; breastfeeding should end then
2. Permanent
35
Permanent set of teeth physiology (alimentary and accessory organ)
```
32 permanent teeth
Arrive at different times
4 incisors
2 cuspids
4 bicuspids (premolars)
Sheering edge
6 molars
Relatively flat
Used to break up seeds etc.
```
Around 18 years old, the third molar (wisdom) tooth may come in
o Our mouths are getting smaller, so these teeth may become impacted
36
Tooth structure
```
Crown
Root
Neck
Enamel
Dentine
Pulp
Cementum
Root canal
```
37
Where is the crown? (Tooth structure)
above the gum line
38
Where is the ROOT? (Tooth structure)
below the gum line
39
Where is the neck? (Tooth structure)
right above the gum line
40
Where is the ENAMEL? (Tooth structure)
Hard covering that surrounds the tooth to protect it
| The hardest man-made thing in the body
41
DENTINE? (Tooth structure)
Hard structure deep to the enamel
| Not as hard as enamel
42
PULP? (Tooth structure)
Contains the nerves and blood vessels
| Deep to dentine
43
Cementum (Tooth structure)
Holds the tooth in the socket
The tooth is a peg in a peg and socket joint
44
Root canal (Tooth structure)
Extension of the pulp through the root
| -This is where the nerves and blood vessels pass into the tooth
45
Pharynx (alimentary and accessory organ)
- Functions in propulsion
- Only use oropharynx and laryngopharynx for digestion
- The epiglottis make sure food only goes to the esophagus and not the trachea
46
Esophagus (alimentary and accessory organ)
-Functions in propulsion
-Normally collapsed to keep the airway open
Stays collapsed until we swallow
-Contains two physiological sphincters
Upper esophageal sphincter
Makes sure food goes in one direction
Gastroesophageal sphincter
Keeps things in the stomach from going back into the esophagus
-The esophagus is the propulsion tube to the stomach
47
Stomach (alimentary and accessory organ)
A big and muscular storage tank
| The volume of the stomach can range from 50 mL - 4L
48
What takes place in the Stomach? (alimentary and accessory organ)
Propulsion, mechanical digestion, and chemical digestion
49
Chemical digestion; stomach (alimentary and accessory organ)
-Starch digestion stops due to the acidic pH of the stomach
Amylase is denatured due to the acidic pH
-Protein digestion begins in the stomach
Pepsin (protein enzyme) is activated by the acidic pH
50
What is pepsin (protein enzyme) activated by in the stomach?
activated by the acidic pH
51
When food leaves the esophagus where does it enter in the stomach?
enters the cardiac portion of the stomach
52
Fundus (stomach)
is the higher/bulging portion of the stomach
53
Where does food exit through in the stomach?
pylorus
54
Pylorus (STOMACH)
-The stomach constricts at the pylorus
-Contains an anatomical sphincter called the pyloric sphincter
Manages the release of contents from the stomach into the duodenum
The duodenum is the first portion of the small intestine
55
What does food enter as and leave as in the stomach?
bolus; liquid chyme
56
Rugae (stomach)
irregular folds in the stomach lining
| Play a role in changing the volume of the stomach
57
Third layer of muscle in stomach
Called oblique/transverse layer
| Changes diameter diagonally
58
Anatomical and physiological parts of the stomach
cardiac sphincter (physiologically) and pyloric sphincter (anatomical)
59
Components of saliva
```
water
electrolytes
amylase
musin
lysosomes
IgA
metabolic wastes
```
60
Saliva
-Regulated by the autonomic nervous system
-Parasympathetic system activates salivary gland
Activation of chemoreceptors and pressure receptors stimulate the parasympathetic nervous system to become active
-Sympathetic system inhibits salivary glands
61
Water percentage of saliva
97-99%
62
Electrolytes in saliva have what?
ions
63
Amylase in saliva
Salivary amylase
| This is the enzyme responsible for the breakdown of starch in the mouth
64
Mucin in saliva
Protein made by mucous cells
| Makes up mucus secretions
65
Function of lysosomes in saliva
immune function
66
Function of IgA in saliva
Antibodies
| Have an immune function
67
Deglutition
Food compacted into a bolus
68
Deglutition; Buccal phase (voluntary phase)
-Tip of tongue is placed against the hard palate
-The tongue contracts to force the bolus into the oropharynx
Food moves from the oral cavity into the oropharynx
-The bolus stimulates tactile receptors
69
Deglutition; Pharyngeal-esophageal phase
- Tactile receptors stimulate the medulla oblongata and the pons
- Motor impulses are sent to the smooth muscles of oropharynx and esophagus
- Peristalsis moves bolus towards the stomach
70
Cells found in the stomach
```
goblet
gastric gland
mucous neck cells
parietal cells
chief cells
enteroendocrine cells
```
71
Goblet cells (in stomach)
- Offer protection
| - Secrete mucus
72
Where are goblet cells specifically?
-Located at surface of stomach and on the walls of the gastric pits
Gastric pits are indentations or depressions in the rugae folds
-Generally associated with columnar epithelium
73
Location of gastric gland
| what does it release?
At the end of gastric pit
| Releases digestive enzymes
74
location of mucous neck cells (stomach)
Upper region of gastric gland
75
What do mucous neck cells produce?
a little more acidic pH mucous secretions
76
Location of parietal cells?
Located in the middle region of the gastric gland
77
What do parietal cells secrete?
Secrete hydrochloric acid (HCl)
| Also called gastric acid
78
What do parietal cels produce (factor)?
-Produces intrinsic factor
Intrinsic factor is a glycoprotein that is required to absorb Vitamin B12 in the small intestine
Vitamin B12 is required for red blood cell production
Therefore, intrinsic factor is required to live
79
Location of chief cells
Located at the bottom region of the gastric gland
80
What do chief cells produce?
pepsinogen and small amount of lipase
81
Which cell in the stomach produces pesinogen?
Chief cells;
82
Pepsinogen (made by chief cells)
Inactive enzyme
Becomes active by HCl
HCl activates pepsinogen -> pepsin
Pepsin breaks down proteins
83
Lipase
small amount produced by chief cells; fat digestive enzyme
84
Enteroendocrine/ G-cells
-Produce a hormone called gastrin
Gastrin affects digestive tract activity
=Affects the motion and secretion of the stomach
=Activates stomach to produce gastric acid
85
Cephalic (reflex) phase; gastric secretion
-Conditioned, learned response
Occurs prior to the arrival of food in the stomach
-When thinking of eating, the stomach becomes active in anticipation of the arrival of food
86
Cephalic (reflex) phase; gastric secretion pt2
-The stomach can be activated neurally or hormonally (gastrin)
-
Gastrin can work directly on stomach/parietal cells or can activate ECL (enterochromaffin-like) cells
ECL cells release histamine
Histamine activates parietal cells (stomach cells)
-
Neural and hormonal pathways work synergistically; combined effects produce a greater effect
87
Gastric phase; gastric secretion
-Starts when food arrives in the stomach
-Causes an increase of neural/hormonal stomach activity
-Biggest activator is the stretch of the stomach
Sends signal to the brain and parasympathetic response increases stomach activity to produce HCl
-pH of food arriving at the stomach has an effect on stomach activity
Arrival of food with high pH is a stimulus for gastric phase
Low pH food inhibits gastrin
-Composition of food can cause release of gastrin and activate the digestive tract
If food is high in protein, gastric phase is activated
88
Gastric phase; as HCL IS MADE...
the pH changes and shuts off the neural and endocrine controls
89
iNTESTINAL phase
-Stomach activity is affected by movement of food into the small intestine
-Excitatory component
As chyme leaks out of the stomach into the duodenum (small intestine), gastric activity increases
As the small intestine begins to stretch, stomach activity increases
-Inhibitory component
The stretch of the small intestine from continuous arrival of chyme causes a switch from parasympathetic stimulus to sympathetic stimulation of the stomach
Sympathetic impulses inhibit stomach activity and constrict the pyloric sphincter
Called the enterogastric reflex
90
Enterogastrone: intestinal phase
-hormone secreted by the small intestine
Inhibitory hormone that shuts off stomach activity
-Hormonal control of stomach instead of neural excitatory/inhibitory component
-Shuts off stomach to save energy for elsewhere
-Protects the stomach from digesting itself
91
Receptive relaxation; gastric filling
- Occurs before food arrives
- Stomach enlarges volume to prepare to accept food
- Rugae flatten, stomach DOES NOT stretch in this phase
92
Adaptive relaxation; gastric filling
- As food arrives, the rugae continue to relax in proportion to the amount of food coming in
- Continues to enlarge after food arrives
93
Gastric Filling
The stomach can go from 50 mL - 1 L without stretch
| When the stomach begins to stretch, the stomach is stimulated to contract
94
Gastric contraction
-Basic electrical rhythm
-Interstitial cells of Cajal
Autorhythmic cells of the stomach
Pacemaker cells
Located in longitudinal layer of smooth muscle in muscularis
Depolarize by themselves
Action potential causes peristalsis
Contracts 3x/min at rest
Any factor to increase stomach activity will cause increasing contraction
Stretch, higher pH, high protein composition
-The stomach contracts from the cardiac portion towards the pylorus
The pressure is highest by the sphincter between the stomach and small intestine
Fluid (chyme) moves from high pressure in the stomach through the pyloric sphincter into the small intestine
-The sphincter opens about 2 mm.
This allows chyme to pass through into the small intestine while leaving solid and semisolids in the stomach to continue to be digested.
-30 mL of chyme passes from the stomach to small intestine, but 27 mL returns to the stomach
-In total, 3 mL of chyme enters the small intestine per contraction
This allows for much greater efficiency in digesting acidic chyme.
95
Gastric emptying
-Chyme enters the duodenum
-Stretch and chemoreceptors in the small intestine are activated
-The enterogastric and enterogastrone reflexes are initiated
This inhibits the activity of the stomach
- Gastric activity is reduced
- Pyloric contractions stop
- Duodenal filling stops
96
Bicarbonate-rich mucus (protective barrier that prevents the stomach from digesting itself)
-Acts as a pH buffer in the stomach
The stomach acid gets into the mucus and the bicarbonate buffers it
-Does not provide complete protection for the stomach by itself
97
Tight junctions in mucosal epithelium (protective barrier that prevents the stomach from digesting itself)
If acid gets through the mucus, the acid can’t slip between cells due to the tight junctions
98
HCL impermeable plasma membranes in gastric gland cells (protective barrier that prevents the stomach from digesting itself)
As gastric gland cells produce HCl, the HCl goes into the duct, but does not digest the cells in the duct
99
Undifferentiated stem cells at junction of gastric pits of gastric glands (protective barrier that prevents the stomach from digesting itself)
- Can become columnar epithelium, goblet, chief, or parietal cells
- Replace cells in stomach every 3-7 days
100
Small intestine
major chemical digestive organ of the body
101
What is digested in the small intestine?
Every type of macromolecule is digested here
| Carbohydrates, proteins, nucleic acids and lipids
102
Name of the lining of the small intestine
brush border;
| Secrete enzymes to digest carbohydrates and proteins
103
What does the small intestine make?
-makes intestinal juice
-The stomach makes a very acidic gastric juice
Arrival of acidic chyme promotes the production of intestinal juice
-Intestinal juice is alkaline
This helps neutralize the acidic chyme
-All digestion is finished by the end of the small intestin
104
More stuff about small intestine
- 8-13 ft long when alive, 20 ft when dead (due to relaxation of muscles)
- involved in propulsion
- site of absorption of nutrients
105
Regions of the small intestine
DUODENUM
JEJUNUM
ILEUM
106
Duodenum; regions of the small intestine
-First 10 inches of the small intestine
-Hepatopancreatic ampulla is located here
This is where the ducts from the liver, gallbladder and pancreas meet
107
Jejenum; region of the small intestine
Middle of the small intestine
| Roughly 8 ft long
108
Ileum; regions of the small intestine
- Last part of the small intestine
| - Where the ileum meets cecum is called the ileocecal valve
109
Structural modifications on the wall of the small intestine
length
plicae circulares
villi
microvilli
110
Length; Structural modifications on the wall of the small intestine
gives over 200m of surface area to work with
| -allows for the most efficient extraction of nutrients from the 3 mL of chyme each time
111
Plicae circulares; Structural modifications on the wall of the small intestine
-circular folds of the mucosa and submucosa that further increase the surface area
- helps increase the surface area
- chyme is slowed down by the folds
- causes chyme to corkscrew through the small intestine
- some textbooks call it the spiral gland
112
Villi; Structural modifications on the wall of the small intestine
- fingerlike extensions of the plasma membrane of the mucosal layer
- increases surface area
113
Microvilli; structural modifications on the wall of the small intestine
- irregular surface of the villi
| - extensions of the plasma membrane
114
Liver
- main role is nondigestive
- recycling of red blood cells
- its digestive role is to produce bile
- bile is an emulsifier
- emulsifiers turn large fat molecules into smaller areas of fat molecules
- not digestion of fats, only make fat molecules easier to digest
- largest internal organ
115
Liver Lobes
- right lobe
- left lobe
- caudate lobe
- quadrate lobe
- falciform ligament
- what holds the liver in place
- piece of mesentery that anchors the liver in place off the diaphragm
- also separates the left and right lobes of the liver
116
Falciform ligament; liVER LOBE
- what holds the liver in place -piece of mesentery that anchors the liver in place off the diaphragm
- also separates the left and right lobes of the liver
117
Gall ladder
stores bile;
-when bile is not released, the bile backs up into the cystic duct and is stored in the gallbladder until it is needed
concentrates bile;
- reclaims some of the water
- sometimes bile is so concentrated that the bile crystalizes and forms gallstones
- when removing gallbladder, people must watch the far content in their diet
118
Ducts
common hepatic duct;
-goes into the liver
cystic duct;
-just goes into gallbladder
bile duct;
-merging of the common hepatic duct and the cystic duct
119
Bile
```
H20
BILE salts
bile pigments
cholesterol
neural fats
phospholipids
electrolytes
```
120
Bile salts; bile
- acts in emulsification
| - increases the surface area of fats for greater digestion efficienc
121
Bile pigments; bile
-bilirubin to urobilinogen
-bilirubin is a product from the breakdown of hemoglobin
urobilinogen causes feces to be brown
122
Bile storage
- hepatopancreatic sphincter is closed when not digesting
- liver is continually producing bile
- bile backs up into the cystic duct and enters the gallbladde
123
Bile release
- fatty chyme entering the duodenum stimulates the production of cholecystokinin
- CCK causes parasympathetic impulses to promote gallbladder contraction
- CCK relaxes the hepatopancreatic sphincte
- CCK affects pancreatic activity as well
124
Pancreas
produces pancreatic juice;
- exocrine glands empty into the pancreatic duct
- pancreatic duct fuses with bile duct just before the hepatopancreatic ampulla
- CCK opens ampulla and activates pancreas to release pancreatic juice to flow with bile into the small intestine
125
Pancreatic juice
H20
ENZYMES
BICARBONATE
126
Enzymes in pancreatic juice
- there are enzymes for all classes of macromolecules
| - made by acinar cells
127
Bicarbonate in pancreatic juice
- produced by epithelial cells of pancreatic duct
- pH of approx. 8
- helps to buffer the acidic chyme coming into the small intestine from the stomach
128
Controls of pancreatic secretion
secretin
CCK
Parasympathetic impulses
129
Secretin; control of pancreatic secretion
- produced when chyme is high in HCl
| - activates duct cells to produce bicarbonat
130
CCK; control of pancreatic secretion
- increase of fat and protein in chyme increases release of CCK
- causes activation of acinar cells and secretion of pancreatic juice
131
Parasympathetic impulses; control of pancreatic secretion
-increases the activity of both duct cells and acinar cells
132
Gastroileal reflex (regulation of pancreatic juice and bile into the small intestine)
-As the stomach becomes activated by the arrival of food, the small intestine becomes
activated
- Segmentation
activity increases, and food moves slowly through the small intestine into the
large intestine
- Caused by
the stomach
133
Gastrin hormone (regulation of pancreatic juice and bile into the small intestine)
Gastrin;
causes relaxation of the ileocecal valve (between the secum
- This valve is normally in the closed position
Again, the
activity of the stomach is regulating the emptying of the small intestine
-Gastrin
is produced by enteroendocrine cells (G cells)
134
Pressure (regulation of pancreatic juice and bile into the small intestine)
As material
accumulates in the large intestine, a back pressure is created that pushes
against the ileocecal valve
---This forces the ileocecal valve to close
135
Trypsin (pancreatic enzymes)
breaks down large proteins
- Trypsinogen
-Made by
the pancreas; released into the small intestine
```
Enterokinase
-Brush
boarder enzyme; made in the small intestine
-Activates
trypsinogen -> trypsin
-Also called enteropeptidase
```
136
Carboxypeptidase (pancreatic enzymes)
Procarboxypeptidase;
-Produced in the pancreas
Trypsin
-Activates procarboxypeptidase -> carboxypeptidase
·
137
Chymotrypsin (pancreatic enzymes)
Chymotrypsinogen
-Produced in the pancreas
Trypsin
-Activates
chymotrypsinogen -> chymotrypsin
-Activates chymotrypsinogen -> chymotrypsin
138
Trypsin
Carboxypeptidase
Chymotrypsin
all enzymes are activated in the duodenum
-Enzymes produced in the pancreas are inactive to prevent the digestion of the pancreas itself
139
Other Pancreatic Enzymes (produced in their active form)
pancreatic amylase
lipase
nucleases
140
pancreatic amylase (Other Pancreatic Enzymes (produced in their active form))
breaks down starches
141
Lipase (Other Pancreatic Enzymes (produced in their active form))
breaks down fats/lipds
142
Nucleases Other Pancreatic Enzymes (produced in their active form))
breaks down nucleic acids
143
Large intestine
- Also called the colon
- Continues propulsion of digested materials
- Main function is in the reabsorption of water
- ----As water is reabsorbed, chyme turns into feces
144
Feces components (large intestine)
- Undigested food residue
- sloughed off epithelial cells of the alimentary canal
- bacteria
- small amount of h20
145
undigested food residue; components of feces, large intestine
Undigested food because we could not digest it or we just did not digest it
146
Sloughed off epithelial cells of the alimentary canal; feces components in large intst
Some from the esophagus, small intestine, and large intestine
147
Bacteria; feces components in large intest.
We have a lot of bacteria in the digestive system
| -Some of these bacteria are excreted when feces are excreted
148
Small amount of H20; feces comp. (large intest)
- Too much water resorption causes constipation
| - Too little water resorption causes diarrhea
149
Length of large intestine; begins-ends
- Approximately 9 ft in length
| - Begins at the cecum; ends at the anus
150
Large intestine segments
```
Cecum
Ascending colon
Transverse colon
Descending colon
Sigmoid colon
Rectum
Internal anal sphincter
external anal sphincter
rectal valves-bends
```
151
Cecum (large intest. seg)
First part of the large intestine; connected to the small intestine
152
ascending colon (large intest. seg)
goes up towards the diaphragm
153
transverse colon (large intest. seg)
goes from the right side of the body to the left side of the body
154
descending colon (large intest. seg)
where the colon goes down
155
sigmoid colon (large intest. seg)
s-shapes portion of the colon
156
rectum (large intest. seg)
- large part of the large intestine
| - end of the rectum is the anus
157
internal anal sphincter (large intest. seg)
invol. sphincter; made of smooth muscle
158
external anal sphincter (large intest. seg)
voluntary sphincter; made of skeletal muscle
159
rectal valves-bends (large intest. seg)
twists in colon
160
bacteria in the large intestine produces...
produces gas
| -The bends in the colon allow for gas (flattus) to pass through without moving feces
161
Large intestine anatomy
haustra
taenia coli
epiploic appendages
intestinal bacteria
162
Haustra (large intestine anatomy)
-Pouches of the large intestine
Single is haustrum
- Divides the colon into segments
- Sac like Puckerings
163
Taenia coli (large intestine anatomy)
- Band of smooth muscles
| - Causes the pouching/puckering that create the haustra
164
Epiploic appendages (large intestine anatomy)
- Pouches of adipose tissue that accumulate along the large intestine
- Animals that live in the cold build up fat on the large intestine to keep warm and have energy
- We don’t know for certain, but we believe they are a vestigial appendage that kept us warm when our ancestors lived outside
165
Intestinal bacteria (large intestine anatomy)
Ferment indigestible carbohydrates
-We don’t get nutritional value from these carbohydrates because absorption occurs in the small intestine
-These bacteria produce dimethyl sulfate
Gives flattus (gas/farts) odor
Synthesize B vitamins
Synthesize Vitamin K
-Vitamin K is used by the liver to make clotting proteins
166
Bacteria intestinal (large intestine anatomy cont)
Bacteria are there for themselves
| - They are there because we provide them food and a warm place to reproduce
167
Haustral contractions; Motility of Food in the Large Intestine
- Pushes material from one haustra to the next
- Stimulated by the accumulation of material
- Occur roughly every 30 minutes
- Very slow propulsive movements
- Not peristalsis; more similar to segmentation
168
Mass movements; motility of food in the large intestine
- Occurs 3-4x/day
- Directional waves of peristalsis that moves large mass towards the rectum
- Prompted by the arrival of food in our stomach
- “Food in prompts food out.”
169
Vermiform appendix
-Located off the cecum
-Vestigial organ
-Appendix may have been used to digest cellulose in our ancestors
-Houses bacteria that can replenish digestive bacteria
-The appendix can trap foreign things in its lumen (ex: gum, seeds)
This can cause the appendix to become inflamed; appendicitis
170
Defecation Reflex; defecation process
-Mass movements cause stretch
-Stretch triggers parasympathetic stimulation of sigmoid colon and rectum
-Anal sphincters are inhibited and relax
Both internal and external sphincters relax
-External anal sphincter is under voluntary control
Can stop parasympathetic relaxation by consciously contracting the external sphincter
```
-Valsalva’s maneuver assists emptying
Contract diaphragm and abdomen
This increases abdominal pressure
-Close glottis
-Strain
```
