Digestive (GI) System
(Gastrointestinal System)
Gastro = stomach
1
2
Functions
–
–
INGESTION Taking food in by mouth
DIGESTION to break food down into simple
molecules
Mechanical: churning of food in the stomach,
manipulation of food with tongue, tearing and
grinding with teeth.
Chemical: breakdown of food with hydrochloric
acid or enzymes
–
–
ABSORPTION nutrients enter capillaries
DEFECATION to eliminate solid waste
products
3
Digestive
Organs
4
Quiz
http://www.purposegames.com/game/dige
stive-system-labeling-interactive-game
5
Regional Terms
Upper GI
– Stomach and areas superior
Lower GI
– Areas inferior to the stomach
6
Abdominal
Quadrants
7
Mesenteries
8
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Digestion Overview
Digestion Overview Video
http://www.youtube.com/watch?v=Z7xKYNz9AS0
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Mouth
Oral Cavity
Tongue
Salivary Glands
Teeth
11
ORAL CAVITY
Lined by non-keratinized stratified
squamous epithelium. The transition
between the skin of your face
(keratinized) and the non-keratinized
area inside the mouth, is the LIPS. You
can see what happens when they dry
out; becomes cracked.
–
PALATE (ROOF of mouth)
HARD PALATE: bone
SOFT PALATE: soft tissue (can feel with tongue
on roof)
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Mouth
13
Figure 22.8a
TONGUE
Your tongue is the only muscle in your body that is
attached at only one end (at the hyoid bone).
The tongue is all muscle, but it is different than all
other muscles of the body, where the fascicles
are arranged in a particular order.
The fibers of the tongue go in all directions, and
have no fascicles  good ROM.
Some people can curl tongue, others can’t.
The LINGUAL FRENULUM is the flap of skin
under the tongue at the midline. If it is too
short, it limits mobility, called tongue-tied.
Treatment is to cut it.
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Figure 22.8b
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SALIVARY GLANDS
Produce saliva
–
Names of some salivary glands:
Parotid (largest). Mumps is a virus that attacks here.
Submandibular
Sublingual
–
Functions of salivary glands
To moisten food so you can swallow, especially crackers.
The mucus in the saliva is what moistens the food.
To inhibit growth of bacteria (which like dark, warm, moist
areas). What does this are the antibodies, enzymes, and
macrophages in the saliva. These are watery secretions.
16
Saliva
Saliva is not used for digestion of food. There is
a bacteriocidal enzyme (amylase) in saliva that
breaks down starch, but it takes hours. It is
used to break down food stuck between the
teeth so the bacteria can’t eat it and cause
cavities.
Saliva also contains bicarbonate buffer.
However, it does not contain enzymes that begin
the digestion of proteins; chemical digestion
begins in the stomach.
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TEETH
The average adult has 32 teeth.
There are 20 DECIDUOUS TEETH (baby teeth
that fall out)
There are 8 INCISORS (most anterior) for
cutting like scissors
There are 4 CANINES for tearing
There are 8 PRE-MOLARS(called BICUSPIDS
= 2 roots) for chewing, some tearing
There are 12 MOLARS (called TRICUSPIDS =
3 roots) for chewing, some tearing. The 4 most
posterior ones are called WISDOM TEETH,
which sometimes grow crooked, called being
“impacted”
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X-ray of Teeth
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STRUCTURE OF TOOTH
GINGIVA are the
gums
CROWN is the area
above the gingiva
ROOT is embedded in
a socket in the bone.
In the maxilla, the root
can extend into the
maxillary sinus.
Damage to the sinus
can be a lot of
problems.
20
STRUCTURE OF TOOTH
ENAMEL is the external layer of
the tooth. It is stronger than
bone, but does wear out. It is
suppose to be ivory color, not
white. Whitening procedures
scrape away outer oxidized
layer, to expose the layer
underneath, which is white, but it
will oxidize, too.
DENTIN is deep to the enamel.
It is like bone, with living tissues
and cells.
PULP CAVITY with PULP is
deep to the dentin. It has blood
vessels and nerves.
PERIODONTAL LIGAMENT
attaches the tooth to the bone.
21
Tooth Problems
When bacteria eat away at the enamel, it is called a
CARY (CAVITY)
The dentist removes a larger area than where the
bacteria destroyed, and fills it in.
If the cavity extends into the pulp cavity, there is no way
to clean it up. The treatment is to make a big hole,
scrape out the pulp, and fill up the whole thing = ROOT
CANAL. This is a dead tooth, but still there.
Bacteria between the gingiva and tooth causes
inflammation of the gingiva = GINGIVITIS.
When it gets worse, the gingiva pulls away from the
tooth and the bacteria extends down to the periodontal
ligament = PERIODONTITIS. This is the major cause of
tooth loss. The tooth loosens and falls out. That’s why
you need to floss.
22
Cary (called a “cavity”)
23
X-ray of Teeth
24
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25
Plaque on Tooth
26
Pay close attention to each of the following
three pictures and tell me what is wrong
with each picture.
27
28
29
30
What was wrong with each photo?
31
What was wrong with each photo?
This is a campaign ad by Colgate
toothpaste. It proved that food debris on
your teeth draws more attention than any
physical defect does.
In the first picture, the woman has six
fingers.
In the second photo, there is an extra hand
on the man’s shoulder.
In the third photo, the man has no ear.
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VIDEOS
• Dental Implants VIDEO
• How Dentures are made VIDEO
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Fun Facts
The enamel in your teeth is the hardest
substance in your body.
Your teeth start growing 6 months
before you are born.
If you are right handed, you will tend to
chew your food on the right side of your
mouth. If you are left handed, you will tend
to chew your food on the left side of your
mouth.
34
Quiz
http://www.purposegames.com/game/dige
stive-organs-in-the-median-section-of-thehead-quiz
35
GI Tract
This is a tube through the body, forming
the esophagus, stomach, small and large
intestine. The GI tract functions to digest
and absorb.
– Esophagus
– Stomach
– Small Intestine
– Large Intestine
36
NOTE
When you are referring to a structure that
has a cavity (stomach, esophagus, uterus,
eye, etc), the layer that touches the lumen
is considered the superficial layer, even
though from the outside of the body it
would be considered deeper.
37
Layers of GI Tube
There are four layers:
1. MUCOSA (inner layer). The lining varies from region
to region.
– Epithelium
– Lamina Propria: Loose connective tissue
– Muscularis mucosae: very thin smooth muscle, causes little
twitches within the mucosa.
2. SUBMUCOSA (moderate dense connective tissue).
Lots of elastic fibers, blood vessels, and lymphatic
vessels.
3. MUSCULARIS EXTERNA: smooth muscle layer with
two parts:
– Circular Layer (inner)
– Longitudinal layer (outer)
4. Serosa
38
Serosa
Mucosa
Muscularis Externa
Submucosa
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3. Muscularis Externa
Muscularis Externa is extremely important for
digestion.
It allows for 2 types of actions:
a. PERISTALSIS: a rhythmic contraction to push
something along. This pushes food down by smooth
muscle contraction of the inner circular layer.
b. SEGMENTATION: A back-and-forth squeezing
of the outer longitudinal layer of muscle to grind up food.
Food moves forward then backward a little, then forward
again. Function is to churn up the food inside, not really
move it forward.
Some areas have thicker smooth muscle = SPHINCTER.
Circular muscles open and closes an oriface.
– Controls the flow of food from one region to another.
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Layers of GI Tube
4. SEROSA is not in all regions (none in
esophagus).
– Simple squamous epithelium
– Loose connective tissue
– From internal to external, the layers of
this tube are the mucosa, submucosa,
muscularis externa, serosa.
41
Esophagus
Extends from the oropharynx to the stomach,
about 25 cm long. The things that are
specialized in the esophagus are:
1. MUCOSAL EPITHELIUM (non-keratinized
stratified squamous epithelium).
Why? It protects against things you swallow;
pointy potato chips, etc. Cuboidal would slough.
2. MUSCULARIS EXTERNUM in upper half =
skeletal muscle. Lower half = smooth muscle.
Why? The upper half, skeletal muscle, is under
voluntary control. Smooth muscle is not
voluntary. Food gets caught in the lower half
because it hasn’t started peristalsis.
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Cardiac Sphincter
The esophagus goes through the thoracic
cavity and has to enter the abdominal
cavity.
It needs to go through the diaphragm’s
opening (esophageal hiatus).
It empties to the stomach through a
CARDIAC SPHINCTER = a thickening of
the muscularis externa. This is NOT A
TRUE SPHINCTER. A true sphincter will
not let anything go back the other way.
43
Stomach Anatomy
44
Stomach: Functions
Store Food
Mechanically churns food into a paste called
CHYME
Kill bacteria
Begins chemical digestion: of proteins only
Mechanical digestion of all solid food
Some absorption: of water, alcohol
Gastric emptying is the release of food from the
stomach into the duodenum; the process is tightly
controlled with liquids being emptied much more
quickly than solids.
45
STOMACH FUNCTIONS
1. Store Food, so it can be slowly released into the
small intestine. Your whole Thanksgiving dinner can
take your stomach from 2” to 8” in diameter.
2. Mechanically Churns food. Secretions from the
stomach are added, turns everything into a gooey paste.
When you throw up, you can see the enzyme secretions
= CHYME.
3. Kill bacteria. The stomach is very acidic (pH 1) like
battery acid. Chyme will even eat through clothing.
4. Some chemical digestion: of proteins only.
5. Some absorption: of water, alcohol (alcohol is
absorbed in the mouth, too!)
Food takes four hours to completely leave the stomach.
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FUN FACTS
Body measurements
for food portions
1 oz = a handful
3 oz = palm size (meat)
cup = fist
teaspoon = tip of thumb
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FUN FACTS
The stomach is about the size of your two fists.
It can hold about one gallon.
When you blush (when your face turns red), the
lining of your stomach ALSO turns red!
Animals with stomachs can move around more
than animals without (roundworms don't have
stomachs), and animals with stomachs can also
run larger brains with all the extra energy,
making them smarter.
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REGIONS OF THE STOMACH
1.
2.
3.
4.
5.
Cardiac region (near heart)
Fundus (above the cardiac sphincter)
Body
Pyloric region
PYLORIC SPHINCTER (a true sphincter)
The lining of the stomach is folded over into
RUGAE, to allow for expansion of the stomach.
When the stomach is full, the rugae flatten out.
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The Stomach
Figure 22.14a
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The Stomach
Figure 22.14b
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HISTOLOGY OF THE STOMACH
Epithelium: simple columnar epithelium.
– Its function is for secretion and absorption.
Lamina Propria: contains gastric pits.
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The Stomach
Figure 22.15a-c
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Stomach Cells
CHIEF CELLS secrete an enzyme called
pepsinogen. “ogen” means that substance is
inactive. It needs to be cut by an enzyme or
other substance. When pepsinogen is exposed
to hydrochloric acid (HCl), it is cleaved into
pepsin, its active form. Pepsin digests proteins.
PARIETAL CELLS in the stomach secrete
hydrochloric acid.
They also secrete intrinsic factor, which is
needed to absorb vitamin B12, which is
needed to make red blood cells.
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Intrinsic Factor
A person who lacks intrinsic factor (such
as those who have a stomach stapling
procedure or gastric bypass) will not be
able to absorb vitamin B12 and they will
get a type of anemia called pernicious
anemia.
Treatment is injectable B12 shots monthly
for the rest of their lives. They also have a
new dissolvable sublingual (under the
tongue) form of vitamin B12
57
Gastric
gland
Stomach
Digestion
Video
Figure 22.15a-c
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PARTICULARS OF STOMACH
Has a third layer of the muscularis
externum: an OBLIQUE LAYER to churn
food in all three planes.
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The Stomach
Figure 22.14b
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Problems with the stomach
There are lots of goblet cells in the stomach which make mucus to
prevent the stomach from digesting itself. Bacterial infection can
erode this area = GASTRIC (or Peptic) ULCER.
Acid Reflux
– The acid in your stomach is strong enough to dissolve razor
blades. The acid can creep up the esophagus and erode the
lining there, causing heartburn.
– The acid can stay in the stomach and cause an ulcer. In severe
cases, the ulcers are so deep, they bleed, and the person might
even vomit blood.
– Tends to occur more when a person is under a lot of stress
because more acid is produced.
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Two major causes
of Peptic (stomach and
duodenum) Ulcers:
1) 60% of gastric and up to 90% of duodenal ulcers are
due to a bacterium called Helicobacter pylori.
– The body responds by increasing HCl secretion,
which erodes the stomach lining. 50% of the world’s
population has this bacterial infection, especially in
underdeveloped countries.
2) NSAIDs (non-steroidal anti-inflammatory drugs, such
as aspirin) block prostaglandin synthesis.
– Prostaglandins promote the inflammatory reaction.
They also are found in the stomach, protecting it from
erosion.
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63
Stomach (gastric) ulcer
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Does stress cause ulcers?
There is debate as to whether
psychological stress can influence the
development of peptic ulcers.
Helicobacter pylori thrives in an acidic
environment, and stress has been
demonstrated to cause the production of
excess stomach acid.
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Risk and Transmission
The lifetime risk for developing a peptic ulcer is
approximately 10%.
In Western countries the prevalence of Helicobacter
pylori infections roughly matches age (i.e., 20% at age
20, 30% at age 30, 80% at age 80 etc.).
Prevalence is higher in third world countries.
Transmission is by food, contaminated groundwater, and
through human saliva (such as from kissing or sharing
toothbrushes or food utensils)
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Treatment
Younger patients with ulcer-like symptoms are often
treated with antacids or H2 antagonists (blocks the acid
secretion of parietal cells).
Patients who are taking NSAIDs may also be prescribed
a prostaglandin analogue (Misoprostol) to help prevent
peptic ulcers.
When H. pylori infection is present, the most effective
treatments are combinations of 2 antibiotics (e.g.
Clarithromycin, Amoxicillin, Tetracycline, Metronidazole)
and 1 proton pump inhibitor (PPI), sometimes together
with a bismuth compound. An example of a PPI is
Omeparazole (Prilosec).
68
GERD or NERD? New type of heartburn
doesn't respond to drugs
http://www.foxnews.com/health/2012/11/1
3/gerd-or-nerd-new-type-acid-refluxdoesnt-respond-to-drugs/
69
Problems With the Stomach
The cardiac sphincter doesn’t close well, since it
is not a true sphincter; consequences:
– You can throw up (reverse peristalsis). Rats do have
a true cardiac sphincter, and can’t vomit!
– That’s why rat poison won’t kill people or dogs; they
can throw it up.
Another consequence: hiatal hernia.
70
HIATAL HERNIA
Part of the stomach, protrudes through
esophageal hiatus, causing pain and
difficulty swallowing.
It is the most common of all hernias.
There is a great amount of acid reflux;
erodes walls of esophagus, causing
ulcerations of esophagus.
Treatment is surgical; pull down the
stomach, and tighten the hiatus in a
laparoscopic procedure.
71
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Fun Facts
Astronauts can't belch - there is no gravity to separate
liquid from gas in their stomachs.
The Tasmanian Devil can swallow 40 percent of its body
weight in a half-hour. That's like eating 216 hamburgers
for lunch!
If you ate like a vulture, you could eat 108 hamburgers
in one meal. They eat 20% of their body weight. Their
stomach acid is so strong they can dissolve botulism and
cholera.
Frogs can't vomit, and whenever they need to, they end
up vomiting their entire stomach.
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SMALL INTESTINE (Small bowels)
These are the longest part of the GI tract
(9-15 feet long, 1” diameter)
In a cadaver, they are even longer,
because the muscles relax.
The small intestine is the most important
region of the GI tract because almost all of
the digestion and absorption takes place
here.
77
Small Intestine Structure
The small intestine needs a lot of surface area:
200 square meters, which is the floor space of a
typical house.
How do you get such a lot of surface area?
There are lots of folds called PLICAE
CIRCULARIS.
Each of these folds also has folds, called VILLI
(“finger-like projection”). If you take velvet and
fold it, the fold is the plicae, and the velvet hairs
are villi.
Each of the villi has epithelial cells with
MICROVILLI, which make a BRUSH BORDER. 78
The Small Intestine
Crypt of Lieberkuhn
Figure 22.17a-c
79
Small Intestine Regions
Duodenum “12 finger widths long”
Jejunum “hungry when empty”
Ileum “twisted”
80
DUODENUM
This is the shortest region, only one foot
long.
It receives chyme from the stomach. This
is where the vast majority of digestion
begins.
There are two ducts at the beginning of
the duodenum from the pancreas and
gallbladder.
It is the site of action of liver and pancreas
secretions.
81
The Duodenum
Figure 22.16
82
Pancreas
PANCREAS is an exocrine AND an endocrine
gland. Endocrine because it makes hormones,
and exocrine because it makes most of the
digestive enzymes which exit through a duct.
They go out the PANCREATIC DUCT to enter
the small intestine.
It also produces BICARBONATE (from a
hormone called SECRETIN) to increase the pH
(decrease the acidity) of the chyme coming from
the stomach. If there is too much acid there, get
a DUODENAL ULCER.
83
PANCREAS
ACINAR CELLS: secretes digestive
enzymes. That’s what makes the pancreas
an exocrine gland.
ISLETS OF LANGERHANS: secretes
insulin and glucagon. Those are
hormones, so that’s what makes the
pancreas an endocrine gland.
84
Pancreas Histology
Figure 22.25a
85
Pancreas
Acinar cells
(secrete
enzymes)
Islet of
Langerhans
(secretes
insulin and
glucagon)
86
Pancreatic cancer diagnosis by 15 year
old
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87
Gall Bladder
GALL BLADDER stores and concentrates bile,
which emulsifies fat: It breaks down the fat into
microscopic droplets which can be broken down
by pancreatic enzymes. Bile is a soap, not an
enzyme. It does not digest, it emulsifies. Think of
the gall bladder as a soap dispenser.
Fat doesn’t dissolve in water, so when you go to
McDonalds and order the Big Mac, fries, and
shake, you get 200 grams of fat (one week
supply), which globs together in the intestine,
and that much more bile is needed to break it
down.
88
GALL BLADDER
This is located inferior to the liver, and its
function is to store and concentrate bile.
Bile is a detergent/soap (not an enzyme) which
emulsifies fat: It breaks down the fat into
microscopic droplets which can be broken down
by pancreatic enzymes.
It does NOT make or secrete bile; that is done
by the liver.
Bile is made in the liver from Hemoglobin (Hgb),
and also contains cholesterol and other things.
The function of bile is to break down lipids (fats)
so they can be digested.
89
Gall Bladder
Two HEPATIC
DUCTS join the
cystic duct to form
the COMMON BILE
DUCT, which enters
the small intestine
along with the
PANCREATIC
DUCT. At the
entrance is a
SPHINCTER.
90
Gallbladder and Pancreas
Figure 22.16
91
Gall Bladder
As the liver produces bile, if there is no
food in the duodenum, the sphincter
closes and bile backs up into the gall
bladder. When there is food, the sphincter
releases the bile.
The gall bladder is similar to the stomach.
It is lined with RUGAE (allows organ
expansion). Has muscles around it to
push bile out.
92
Gall Stones
One function of the gall bladder is to
concentrate the BILE, but if the bile salts
crystallize, GALL STONES can form.
The stones block the cystic duct, and
causes a lot of pain as the bile backs up.
Treatment is to cut the cystic duct and
remove the gall bladder.
Now that person can only eat small
amounts of fats at a time.
93
What Ronald McDonald is doing
to your arteries
94
Types of Gall Stones
Stones are often made out of cholesterol
(most common type). It has nothing to do
with the cholesterol levels in the blood.
Stones can also be made from too much
bilirubin in the bile.
Gallstones are more common in women,
Native Americans and other ethnic groups,
and people over age 40. Gallstones may
also run in families.
95
Cholesterol gallstones
Pigment gallstones
Mixed cholesterol and pigment
gallstones
99
Hepatobiliary scan (liver and bile duct)
Black dots show gallstones
The following also make you more
likely to develop gallstones
Failure of the gallbladder to empty bile properly (this is
more likely to happen during pregnancy)
Medical conditions that cause the liver to make too much
bilirubin, such as chronic hemolytic anemia, including
sickle cell anemia
Liver cirrhosis and biliary tract infections
Diabetes
Bone marrow or solid organ transplant
Rapid weight loss, eating a very low-calorie diet
Receiving nutrition through a vein for a long period of
time (intravenous feedings)
101
Symptoms of Gall Stones
May be asymptomatic or have sudden and
rapidly intensifying pain in the upper right
portion of the abdomen, lasting several
minutes to a few hours.
The doctor may order the following blood tests:
Bilirubin
Liver function tests
Pancreatic enzymes
102
Treatment for Gall Stones
Symptomatic patients usually have
surgery.
Medicines may be given in pill form to
dissolve cholesterol gallstones.
However, they may take 2 years or longer
to work, and the stones may return after
treatment ends.
They usually just take the whole gall
bladder out, since the stones are likely to
return. Now, the person cannot have much
fat at a time, or they get diarrhea.
103
Gallstone Removal VIDEO
Gallbladder Removal VIDEO
104
Jejunum
JEJUNUM (“empty”)
It is 3 feet long.
This is the part of the small intestine where
most digestion occurs and some
absorption.
105
Ileum
ILEUM (“twisted”) is 5-10 feet long. It is
the terminal portion of the small intestine.
Much of the absorption takes place here.
106
Histology of Small Intestine
The intestines are lined with simple columnar
epithelium with lots of goblet cells that make
mucus for protection.
However, the pancreatic enzymes can digest the
mucus and the epithelial cells, so the lining of
the small intestine is replaced every day.
The basic functions of this epithelium are
secretion and absorption.
Absorption is a digestive process in which
nutrients enter the capillaries.
107
Crypt of Lieberkuhn
The INTESTINAL CRYPT (CRYPT OF
LIEBERKUHN) is where the new epithelial
cells come from, and they are pushed
upwards into the villi to replace the
digested cells.
Also in this crypt are cells that produce
enzymes and hormones.
108
Crypt of Lieberkuhn
Lacteal
109
Crypt of Lieberkuhn
Figure 22.17a-c
110
Absorption in Small Intestine
In the villis is a fenestrated capillary bed (the
capillaries have holes in them), which is needed
because they absorb a lot of material.
The small intestine absorbs carbohydrates, fats,
and proteins (although protein enzymes have
already begun working earlier in the digestive
tract in the stomach).
111
Intestinal Villi
112
Lymphatics of Small Intestine
There are also large lymphatic capillaries
in each villis called LACTEALS, whose
function is to absorb breakdown products
of fat. The vessel is large so it won’t get
clogged up.
Under all this are the MUSCULARIS
MUCOSA muscles which can twitch to
move the villa so food does not get stuck.
113
Inguinal Hernia
The inguinal canal is open in the male to allow for passage of the
spermatic cord. In the female, the area is closed, but weak.
When there is abdominal pressure (lifting a weight), a piece of small
intestine can push out of this canal, causing pain.
Symptoms and warning signs:
http://www.symptomfind.com/diseases-conditions/hernia-symptoms-warning-signs/
114
Hernia Repair VIDEO
115
Problem with Small Intestine
Crohn’s Disease
– Autoimmune disease of the GI tract
– Most common area affected is small intestine
– Inflammation causes pain and diarrhea (may
be bloody)
– Genetic cause (high risk if siblings have it)
– Usually occurs in males in their 20’s
– No cure; just treatment of symptoms
116
Celiac disease
(Sprue; gluten intolerance)
Genetic autoimmune disorder of the small intestine,
causing chronic diarrhea. The person is allergic to
gluten. Causes destruction of microvilli and villi.
It is characterized by having pale, loose and greasy
stools (steatorrhoea) which are voluminous and
malodorous.
It often presents with abdominal pain and cramping,
abdominal distension, and sometimes mouth ulcers.
Without adjusting the diet, coeliac disease leads to an
increased risk of adenocarcinoma (small intestine
cancer).
117
Celiac disease
(Sprue; gluten intolerance)
They may develop ulcerative jejunitis and stricturing (narrowing as a result
of scarring with obstruction of the bowel).
The changes in the bowel make it less able to absorb carbohydrates, fats,
minerals (calcium and iron), and the fat-soluble vitamins A, D, E, and K.
Anemia may develop in several ways: iron malabsorption may cause iron
deficiency anemia, and vitamin B12 malabsorption may give rise to
megaloblastic anemia.
Calcium and vitamin D malabsorption may cause osteopenia (decreased
calcium in the blood) or osteoporosis (bone weakening and risk of fragility
fractures).
A small proportion have abnormal coagulation due to vitamin K deficiency
and are slightly at risk for abnormal bleeding.
Gluten intolerance is also associated with bacterial overgrowth of the small
intestine, which can worsen malabsorption or cause malabsorption despite
adherence to treatment.
118
Celiac disease
(Sprue; gluten intolerance)
Celiac disease is caused by an allergy to gluten.
Gluten is present in Wheat subspecies (such as spelt, semolina and
durum) and related species such as barley, rye, triticale and Kamut.
A small minority of celiac patients also react to oats. It is most
probable that oats produce symptoms due to cross contamination
with other grains in the fields or in the distribution channels.
Generally, oats are therefore not recommended.
Other cereals such as maize (corn), millet, sorghum, teff, rice, and
wild rice are safe for patients to consume, as well as non cereals
such as amaranth, quinoa or buckwheat. Non-cereal carbohydraterich foods such as potatoes and bananas do not contain gluten and
do not trigger symptoms.
119
Gluten-free diet
Several grains and starch sources are considered acceptable for a
gluten-free diet. The most frequently used are corn, potatoes, rice,
and tapioca (derived from cassava). Other grains and starch
sources generally considered suitable for gluten-free diets include
amaranth, arrowroot, millet, montina, lupin, quinoa, sorghum(jowar),
taro, teff, chia seed, and yam.
Various types of bean, soybean, and nut flours are sometimes used
in gluten-free products to add protein and dietary fiber. Almond flour
is a low-carbohydrate alternative to flour, with a low glycemic index.
In spite of its name, buckwheat is not related to wheat; pure
buckwheat is considered acceptable for a gluten-free diet, although
many commercial buckwheat products are actually mixtures of
wheat and buckwheat flours, and thus not acceptable.
Gram flour, derived from chickpeas, is also gluten-free (this is not
the same as Graham flour made from wheat).
120
Gluten-free diet
Gluten is used in foods in some unexpected ways, for example as a
stabilizing agent or thickener in products like ice-cream and ketchup.
People wishing to follow a completely gluten free diet must also take
into consideration the ingredients of any over-the-counter or
prescription medications and vitamins. Also, cosmetics such as
lipstick, lip balms, and lip gloss may contain gluten and need to be
investigated before use. Glues used on envelopes may also contain
gluten.
Most products manufactured for Passover are gluten free.
Exceptions are foods that list matzah as an ingredient, usually in the
form of cake meal.
A blood test for IgA antiendomysial antibodies can detect celiac
disease.
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Large Intestine
(Colon, or large bowel)
This is about 5 feet long, diameter of 4”.
Absorbs a LOT of water and salts
Absorbs electrolytes (Na, K, etc)
Stores feces for defecation (terminal portion)
Contains abundant bacteria (E. coli):
–
–
–
–
Make vitamins (B5, K, biotin)
Allow material to move through large intestine easier
Keep out harmful bacteria
They eat things you can’t digest
Fiber (plant cell walls)
Some sugars that we don’t have enzymes for
122
Intestinal Gas
When these bacteria are happy and dividing, they
produce gas. If you are lactose intolerant, your are
missing the enzyme for lactose so the bacteria gets
more sugar and you get more gas! Beans also have
these sugars, so they give you gas.
Mexico has different strains of E. coli in their water; the
two strains battle it out and you get diarrhea.
Diarrhea is when the large intestine does not absorb
water  dehydration and electrolyte imbalance.
Cholera is a disease which attacks the large intestine,
preventing water absorption, and can be fatal in 24-48
hours.
The difference between diarrhea and constipation is the
amount of water absorbed from the large intestine.
123
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124
125
Probiotics: Beneficial or
Marketing Hype?
LOS ANGELES (KABC) -- Go to most grocery stores and you'll see
drinks, snacks and supplements all saying they're loaded with
probiotics. But are they really beneficial and can they help fight
conditions like Irritable bowel syndrome (IBS), or are they simply
marketing hype?
These live bacterial bugs can be found in yogurt, cheese and
fermented milk. In fact more than 150 probiotic products have hit
stores in the U.S. By the year 2014, probiotic food is projected to be
a $32 billion a year business.
"Unfortunately we don't have the long term studies to prove whether
or not there is a definite health benefits" said Dr. Sanni Thomas.
There's also concern about whether the right bacteria is getting into
the right products. "Unfortunately you are at the mercy of the
company that produces that food product," said Dr. Thomas.
126
There's actually a thousand species of bacteria in our GI tract, and
within each species, hundreds of strains. But dietitian Ashley Koff
warns digestive balance is easily disrupted. "Sometimes antibiotics,
different medications, different things throughout our life that we're
doing, etc., may reduce the amount of good bacteria, which can
generate some not-so-healthy results," said Koff.
Bloating, constipation and diarrhea all require different kinds of
bacteria to get you back on track, which you might have to consume in
copious amounts. The product should have over 2 billion colonyforming units (CFUs) per serving for the product to be effective.
Since heat kills this bacteria, there's no guarantee that probiotics live
through the shelf life of products. How they are stored, along with how
you take them, is important. "Avoid hot liquids, you avoid coffee, you
avoid alcohol, because alcohol is obviously a sanitizing agent," said
Trenev.
And these bacteria are only beneficial when they are in the colon. If
we swallow probiotics, how do these bacteria survive the stomach
acid and small intestine enzymes before they reach the colon?
127
Regions of the Large Intestine
Cecum
Ascending colon
Transverse colon
Descending colon
Sigmoid colon
Rectum
Anus
128
Large Intestine
Figure 22.18a
129
Gross Anatomy of the Large
Intestine
The large intestine is divided into regions, but
they function the same.
The ileum enters into the first region of the large
intestine called the CECUM.
The ileo-cecal valve separates these and
controls the amount of chyme that enters into
the large intestine.
It also prevents the E. coli from leaving the large
intestine and getting into the small intestine,
where they would cause disease.
130
131
Appendix
Below the cecum is the APPENDIX, which is a
lymph node, but it contains E coli as well.
It might become inflamed, which closes off the
opening: APPENDICITIS
This is dangerous because It can rupture. Need
antibiotics and surgery or can be fatal.
Most common age for this is late teens to early
20’s because a child has a larger opening which
shrinks with age. When you’re done growing,
it’s done shrinking, so if you haven’t had a
problem by then, you might be ok.
Appendectomy VIDEO
132
Flowering Plants Speed Postsurgery Recovery
Studies show that when patients have great stress
associated with surgery, they typically experience more
severe pain and a slower recovery period.
133
Flowering Plants Speed Postsurgery Recovery
Patients with plants in their rooms had
significantly fewer intakes of pain
medication, more positive physiological
responses (lower blood pressure and
heart rate), less pain, anxiety, and fatigue,
and better overall positive and higher
satisfaction with their recovery rooms than
their counterparts in the control group
without plants in their rooms.
134
Large Intestine
Up from the cecum is the ASCENDING
COLON, TRANSVERSE COLON, and
DESCENDING COLON.
Then there is an “S” shaped section called
the SIGMOID COLON, which leads to the
RECTUM, and out the ANUS.
135
136
SIGMOID COLON
This area allows for the passage of gas without passage
of feces. The LEVATOR ANI MUSCLE, when relaxed,
allows only gas to pas. When contracted, the feces can
pass.
Therefore, this muscle controls defecation by lifting
the anal canal superiorly around the feces.
Another thing that controls defecation is the INTERNAL
and EXTERNAL ANAL SPHINCTER. The internal one
is smooth muscle, and the external is skeletal muscle
(voluntary control).
The smooth muscles which line the large intestine work
in coordinated fashion to move the feces out.
It takes about 24 hours for food to be processed through
the entire digestive tract.
137
Sigmoid Colon
138
Fun Facts
A healthy individual releases 3.5 oz. of gas in a single
flatulent emission, or about 17 oz. in a day.
The bombardier beetle combines chemicals in his rear
end and can squirt out boiling hot acidic liquid which
quickly neutralizes any attack.
All land spiders breathe through a hole on the rear part
of their bodies.
The Fitzroy river turtle absorbs two-thirds of the oxygen it
needs through its rectum.
139
Quiz
http://www.purposegames.com/game/drgennero-digestive-2-ah-game
140
Problems with Large Intestine
DIVERTICULITITS
INFLAMMATORY BOWEL DISEASE
– Crohn’s Disease
– Ulcerative colitis
IRRITABLE BOWEL SYNDROME
COLON CANCER
– SIGMOIDOSCOPY or a COLONOSCOPY
POLYPS
HEMORRHOIDS
141
DIVERTICULITITS
DIVERTICULUM (Diverticula is plural) can
form, a small pouch in the large intestine.
They can become inflamed, usually from a
small, hard piece of feces, causes the
condition known as DIVERTICULITITS.
These are painful and often need to be
surgically removed.
May be caused by lack of fiber, causing
increased pressure in the colon.
142
Inflammatory Bowel Disease (IBD)
IBD is a group of inflammatory conditions
of the colon and small intestine.
The major types of IBD are Crohn's
disease and ulcerative colitis
143
Ulcerative Colitis
The main symptom is constant diarrhea mixed with
blood, of gradual onset.
An intermittent disease, with periods of exacerbated
symptoms, and periods that are relatively symptom-free
No known cause, but may be genetic
May be triggered by environmental factors
Dietary modification may reduce the discomfort
It is treated as though it were an autoimmune disease
(anti-inflammatory drugs, immunosuppression)
Colectomy (partial or total removal of the large bowel
through surgery) is occasionally necessary, and is
considered to be a cure for the disease.
144
Ulcerative Colitis
145
IRRITABLE BOWEL SYNDROME (IBS)
IBS is a diagnosis of exclusion.
Symptoms are chronic abdominal pain, bloating,
and alteration of bowel habits in the absence of
any detectable organic cause.
May manifest as diarrhea or constipation or may
alternate between the two.
May be caused by infection, stress, or onset of
maturity
No cure; treatments attempt to relieve
symptoms, including dietary adjustments,
medication and psychological interventions.
146
COLON CANCER
This is the #1 most deadly cancer (kills more
people) because it metastasizes and there are
no symptoms. It can be suspected by seeing
blood in the stool; this is an easy test, but not
very accurate.
A more accurate test is a SIGMOIDOSCOPY. A
tube is inserted into the sigmoid colon, done in
the doctor’s office. The tube has a light, and
they look for growths on the walls of the intestine
= POLYPS, which are pre-cancerous growths.
A colonoscopy is done under general anesthesia
since the tube has to go through the entire
colon, but it’s more effective.
147
Colonoscopy Photos
Ileo-cecal valve
148
Colonoscopy VIDEO
149
HEMORRHOIDS
HEMORRHOIDS are varicose veins in the
rectum.
There are large veins along the rectum,
with nothing constricting them.
They are common in pregnant women and
in fighter pilots from the g-forces they pull.
They can be surgically removed.
150
151
Digestive System
Overview VIDEO
152
Hepatic Portal System
Almost all of the blood coming from the digestive
system drains into a special venous circulation
called the portal circulation.
This is because it contains all the nutrients and
toxins that have been absorbed along the
digestive tract from ingested food.
Before these absorbed substances can go into
the systemic circulation (the main blood
circulation in the body), it must be filtered first to
remove or detoxify toxic substances first.
This filtering and detoxification is one of the 500+
functions of the liver.
153
Hepatic Portal System
Many drugs that are absorbed through the GI
tract are substantially metabolized by the liver
before reaching general circulation. As a
consequence, certain drugs can only be taken
via certain routes.
For example, nitroglycerin cannot be swallowed
because the liver would inactivate the
medication, but it can be taken under the tongue
or transdermal (through the skin) and thus is
absorbed in a way that bypasses the portal
venous system.
154
A portal system is one that has two separate
capillary beds between the arterial supply
and the final venous drainage.
155
Liver
Figure 22.22
156
Hepatic Portal System
The first capillary bed is in the small intestines.
The blood enters the liver via the hepatic portal
vein (which drains blood into the liver, not from
the liver). The hepatic portal vein then branches
into many smaller vessels that open into hepatic
sinusoids.
The second capillary bed is the sinusoids.
The blood is then cleaned by the hepatocytes
and macrophages of the liver, before draining
into the hepatic veins, which drains into the
inferior vena cava.
157
Hepatic Portal System
The hepatic portal system has two distinct
capillary beds separated by a portal vein.
The functions of these two capillary
beds are that the first picks up
nutrients and the second delivers these
nutrients to liver cells.
Therefore, this system is a capillary
system within a venous system.
Because one capillary bed empties into
another capillary bed, there is some
oxygen left in the hepatic portal vein.
158
Hepatic Portal System
Hepatic portal vein: oxygen not-poor
and nutrient rich.
Capillary – Portal Vein – Capillary
– the first capillary bed picks up nutrients
– the second capillary bed delivers these
nutrients to liver cells.
159
LIVER
This is the largest internal organ of the
body, located on the right side, below the
diaphragm, and extends below the costal
margin (can palpate).
It has many functions and is the most
complex organ except the brain.
The liver has 500+ known functions.
160
Liver
Makes blood
Makes blood proteins (clotting factors)
Makes bile
Makes cholesterol
Regulates glucose levels
Processes fats
Processes amino acids
Detoxifies chemicals
161
Liver
With only 1/6th of your liver present your
body could continue to function.
As much as 80% of your liver could be cut
away and it would grow back to a full size
in approximately three months.
It is usually hard to determine if the liver is
damaged until the damage is quite
advanced.
162
Liver
It has a right and left lobe, separated by
the FALCIFORM LIGAMENT.
The liver gets blood from 2 sources:
Artery = Hepatic artery
Vein = Hepatic portal system = Blood from
the spleen, stomach, pancreas, small and
large intestines which all go through the
liver. The nutrients that are absorbed by
the GI tract go to the liver first for
processing, then to the rest of the body.
163
Liver
Most systemic venous blood is both oxygen poor
and nutrient poor.
However, systemic venous blood that is oxygen
not poor and nutrient rich occurs in the hepatic
portal vein.
It is nutrient rich because it receives blood from
the small intestine right after it has absorbed the
nutrients.
It is not completely oxygen poor because it has a
capillary  vein  capillary system that has
more oxygen than just one capillary  vein.
164
Liver
Figure 22.22
165
INTERNAL STRUCTURE OF
LIVER
The liver is made of hundreds of
thousands of LIVER LOBULES; each one
is the size of a sesame seed, giving the
liver a grainy texture when you eat it.
Each lobule carries out all of the functions
of the liver. That means the functional unit
of the liver is the lobule.
166
LIVER LOBULE
It has a hexagonal shape, at each corner
are some vessels = HEPATIC TRIAD:
– ARTERIOLE from the hepatic artery
– VENUOLE from the hepatic portal vein
– BILE DUCT, which goes to the gall bladder.
167
(Kupffer cells)
168
Liver
Hepatic
Triad: Vein,
Artery, Bile
Duct
Figure 22.23a,169
c, d
LIVER CIRCULATION
The HEPATIC TRIAD vessels enter the
liver lobule through a capillary, then join to
combine the blood  becomes a
CAPILLARY VEIN, which drains into the
CENTRAL VEIN at the center of the lobule
 HEPATIC VEIN  INF. VENA CAVA.
170
Liver
171
Figure 22.22
Liver Lobules
172
Liver: Central vein and sinusoids
173
Sinusoids
LIVER SINUSOIDS are channels that blood can
flow through. Cells that line the sinusoids are
called HEPATOCYTES, and each one faces the
sinusoid and is in contact with blood.
The hepatocytes are what carry out all of the
functions of the liver.
If you made a machine to do the work of the
liver, it would have to be the size of a large oil
refinery.
174
Liver: sinusoids and hepatocytes
175
Blood Flow in the Liver
Blood flow to the liver is unique in that it receives both
oxygenated and deoxygenated blood.
Nutrient-rich, oxygen-not poor (purple) blood from the
intestine enters the liver by the hepatic portal vein. It
flows through the sinusoids for detoxification.
Oxygen-rich blood enters the liver by the hepatic artery.
It flows through the sinusoids to supply them with
oxygen.
All of the blood mixes together, and when the oxygen
demand of the hepatocytes is satisfied, and the toxins
have been removed, the oxygen-depleted blood collects
in a central vein within each lobule, which drains into the
hepatic vein. The hepatic vein subsequently drains into
the inferior vena cava and back to the heart.
176
Blood Flow in the Liver
Because of the mixture of oxy and deoxy blood in the
liver, the partial pressure of oxygen (pO2) and perfusion
pressure of portal blood are lower than in other organs of
the body.
Partial Pressure of oxygen means the amount of
dissolved oxygen.
Perfusion pressure is the amount of pressure
required to deliver nutrients to cells.
These low pressures in the liver prevent the
nutrients from leaving the circulation so that the
hepatocytes don’t use up all the nutrients.
177
Function of Hepatocytes
Detoxification of poisons
Storage of fat soluble vitamins (A, D, E, K)
Picking up and processing of nutrients
from the portal blood
– This includes picking up glucose from the
nutrient-rich blood coming from the small
intestine and stores it as glycogen (the storage
form of glucose) for when the body needs it later.
178
Kupffer Cells
Within the sinusoids are KUPFFER CELLS,
which are macrophages. As blood flows through
the sinusoids, they phagocytize old erythrocytes.
The released Hgb is given to the hepatocytes,
which convert it to bilirubin, one of the main
components of BILE.
Bile flows through a series of channels called the
BILE CANNICULI to the bile duct.
179
The Liver Destroys
Old Red Blood Cells
By the way, when you have dark circles
under your eyes, it is from hemoglobin and
iron deposits from broken RBC’s that
leaked out of the delicate capillaries under
the thin skin there.
Will skin creams remove this?
180
Problems with the Liver
HEPATITIS
CIRRHOSIS
JAUNDICE
181
Liver Problems
Infection of the liver = HEPATITIS (can be
deadly)
CIRRHOSIS is when the hepatocytes die
and are replaced by connective tissue.
This is often from alcoholism, which kills
the hepatocytes.
182
Jaundice
One of the symptoms from any liver
disorder is a connection of the bile
canaliculi and the sinusoid so some
bilirubin can enter the blood.
Bilirubin is yellow-green (later in its
degradation it will turn brown and that is
what gives the feces its color).
The yellow color of bilirubin in the skin is
known as JAUNDICE.
183
Liver
Hepatic
Triad: Vein,
Artery, Bile
Duct
Figure 22.23a,184
c, d
Jaundice
Jaundice is not a disease; it is a symptom of
liver disorder.
It first shows up in the sclera of the eyes
because it is white there. The skin has other
pigments, so yellow doesn’t show up as well.
Newborns get jaundice from a lot of erythrocytes
being broken down, and the liver gets
overloaded, but it’s harmless.
The treatment is UV light or sunlight, goes away
in a few days.
185
186
Healthy Numbers
TOTAL CHOLESTEROL
– Less than 200 mg/dL
LDL ("BAD") CHOLESTEROL
– Less than 160 mg/dL
HDL ("GOOD") CHOLESTEROL
– Women: 50 mg/dL or higher
– Men: 40 mg/dL or higher
187
188
Healthy Numbers
TRIGLYCERIDES Less than 150 mg/dL
FASTING GLUCOSE Less than 100
mg/dL
BODY MASS INDEX (BMI) Less than 25
kg/m²
WAIST CIRCUMFERENCE
– Women: 35 inches or less
– Men: 40 inches or less
189
190
191
192
193
Blood Tests for Liver Function
Alanine transaminase (ALT): An enzyme that helps metabolize
protein. When the liver is damaged, ALT is released in the
bloodstream.
Alkaline phosphatase (ALP): An enzyme needed in small amounts
to trigger specific chemical reactions. Normally present in the liver,
bone, kidney, and intestine, higher than normal levels may indicate
liver damage or disease.
Aspartate transaminase (AST): This enzyme plays a role in the
metabolism of the amino acid alanine. An increase in AST levels
may indicate liver damage or disease.
Albumin and total protein: Levels of albumin – a protein made by the
liver – and total protein indicate how well the liver is making the
proteins needed to fight infections and perform other functions.
Lower than normal levels may indicate liver damage or disease.
Bilirubin: A bi-product from the breakdown of red blood cells,
bilirubin normally passes through the liver and is excreted in stool.
Elevated levels – manifested as jaundice – may indicate liver
damage or disease.
194
Blood Tests for Liver Function
Gamma-glutamyl transferase (GGT): This
test measures the amount of the enzyme
GGT in the blood. Higher than normal
levels may indicate liver or bile duct injury.
Lactate dehydrogenase (LDH): An enzyme
found in many body tissues, elevated
levels of LDH may indicate liver damage.
Prothrombin time (PT): This test measures
the clotting time of plasma. Increased PT
may indicate liver damage.
195
Liver Transplant
Adult-to-adult liver transplantation has
been done using the donor's right hepatic
lobe which amounts to 60% of the liver.
Due to the ability of the liver to regenerate,
both the donor and recipient end up with
normal liver function if all goes well.
196
Situs Inversus
Congenital condition in which the major visceral organs
in the thorax and abdomen are reversed or mirrored from
their normal positions.
The heart is located on the right side of the thorax, the
stomach and spleen on the right side of the abdomen
and the liver and gall bladder on the left side.
The left lung is trilobed and the right lung bilobed, and
blood vessels, nerves, lymphatics and the intestines are
also transposed.
Situs inversus is generally an autosomal recessive
genetic condition, although it can be X-linked or found in
identical "mirror" twins.
197
198
Situs Inversus
As long as there are no heart defects, the person has no
health issues.
However, donating an organ is more complicated, since
the connecting blood vessels are not in the same place!
People are not aware of their condition until an unrelated
health issue arises, such as appendicitis, presenting on
the left side instead of the right side. The doctor cannot
find the heart sounds in the proper location, either.
199
Peritoneum and Mesenteries
The peritoneum is the lining of the GI tract
and abdominal wall, similar to the pleura
and pericardium.
It is made of simple squamous epithelium
with underlying loose connective tissue.
A mesentery is a double layer of
peritoneum, fused back-to-back, that
extends from the body wall to the digestive
organs.
200
CROSS SECTION OF ABDOMEN
In the center is the GI tract.
The PARIETAL PERITONEUM lines the wall,
the VISCERAL PERITONEUM lines the organs,
and in between is the PARIETAL CAVITY.
But the organ can’t just float in space; it has to
be attached. The MESENTERY is what
attaches the GI organs to the peritoneum (like
hanging a pipe from the ceiling by another pipe).
201
Peritoneum and Mesenteries
202
Peritoneum and Mesenteries
203
Mesenteric Vessels
Blood vessels and nerves go through the
mesentery, that’s why they are called
MESENTERIC VESSELS.
In some regions of the GI tract, there are
accessory organs (liver, kidney, pancreas,
etc).
The peritoneum continues around each
organ.
204
Peritoneum goes around organs
205
OMENTA
The liver is suspended by a mesentery
called the OMENTUM.
There are two omenta: greater and
lesser.
GREATER OMENTUM is flat, and is in
front of the intestines like an apron. Its
function is to store fat, especially in
people with large bellies.
LESSER OMENTUM is smaller.
206
40 lb Abdominal Tumor
207
PERITONEAL CAVITY
Why is this important? The peritoneum
divides the abdominal cavity into three
distinct regions:
PERITONEAL CAVITY (digestive organs)
INFRAPERITONEAL CAVITY (inferior to
peritoneum; urinary bladder)
RETROPERITONEAL CAVITY (posterior
to it; kidneys)
208
PERITONEAL CAVITY
This is clinically important because if you tear
something in the GI tract (ruptured appendix),
bacteria go out into the peritoneal cavity, affects
all the organs there, which is the entire GI tract.
Bleeding in the kidney will accumulate in the
retroperitoneal cavity.
Infection in the urinary bladder doesn’t affect the
peritoneal cavity.
Bleeding and infection are confined to one
compartment.
209
Warning!
The Government has issued a health
warning not to swallow chewing gum. The
following is a photo of what can happen:
210
211