Transcript Digestion

Digestion Part 2
Begins
Thanks Mr. Tooth. Now to continue our journey
out of the mouth. This is a detailed diagram of
the next passage, the PHARYNX.
BOLUS mixture of food
and saliva ball that slides
down the pharynx
3 REGIONS OF THE
PHARYNX
1.Nasopharynx :above soft
palate
2.Oropharynx
from uvula
down throat to hyoid bone. This is
seen by the doctor with the tongue
depressor
3.Laryngoppharynx:
hyoid bone down to esophagus.
EPIGLOTTIS: shuts the entrance to glottis
- trachea (windpipe) Prevents choking
It contains cartilage and
is considered part of the
voice-box — larynx.
Choking occurs when the larynx is open when it should be closed
and allows food or liquid into the windpipe. The larynx muscle
relaxes when laughing – be careful when eating and joking around.
Most people choke at the dinner table. Use the Heimlich
manoeuvre if you have a choking victim.
The food slides down the esophagus
See if you can name the structures.
1 = esophagus
3. = stomach
2 = diaphragm
4.=liver
Esophageal
Hiatus
Esophagus structure:
Slippery mucus lining
25-30 cm length
Smooth muscle
Voluntary muscle
5.=gall bladder
8.= spleen
6.= duodenum
7.=pancreas
PERISTALSIS ; wave like contraction of smooth
muscle layers that pushes food through
digestive tube -- esophagus to colon.
Esophagus function:
Conducts food into abdominal
cavity PERISTALSIS
Passes directly behind the
heart
Passes through the diaphragm
via the esophageal hiatus and
then into the stomach
Next it enters me, the stomach. I produce gastric juice to
digest the food. I hold the food in me for 2 to 6 hours and
expand to about 2 L of food space. Food is trapped in me
by the closed pyloric and cardiac sphincters
Lower esophageal
sphincter = cardiac
sphincter
Cardiac
sphincter
3 muscle layers of stomach churn every 20s mixing the contents
My gastric juice contains powerful digestive
agents The following 3 come from my
gastric pits
I’m here to save the
stomach lining
Mucus cells- lubricate and protect the stomach lining
cells from the powerful Acid - Enzyme combination.
Making
acid!
HCl
HCl – hydrochloric acid secreted by
parietal cell
Pepsinogen – inactive enzyme unless HCl is
present turning it into Pepsin. Secreted by the
Chief cells
Make um
good Pepsi
(pepsin)
You know, even with Captain Mucus, I have to
completely replace the stomach lining every three
days.
Sometimes I don’t feel so good. You get an upset stomach
because of too much acid. This acid activates pepin and the
stomach starts to digest its inner membrane.
esophagus
This leads to ulcers –
bleeding crater- like
depressions
Common in the
stomach and
duodenum
Bleeding
ulcer
stiomach
Small
intestine
Duodenal ulcer
Stomach
(peptic)
ulcer
You know, even with Captain Mucus, I have to completely
replace the stomach lining every three days.
That’s right and alcohol and aspirin tear
my mucus protection away. So be careful
how much you put in your stomach when
acid is present without food.
Hi there. I’m Mr Gall Bladder. Sometimes I
release bile and it backflows into the
stomach. Bile tears the mucus lining away as
well and irritates the stomach lining. The
stomach can start to bleed as a result. Sorry
Hi there. Meet Helicobacter pylori, a member of my evil gang
People underestimate me you know. Doctors now
say that most stomach and duodenal ulcers are
because of ME!! Helicobacter pylori
That bacteria infection is the cause of most
(80%) stomach and duodenal ulcers , Mr.
Stomach. Take a look at an endoscope view of
the inside of the stomach showing an
ulceration. Ugly close up huh?
Well I will
prescribe you an
antibiotic to kill
off those
Helicobacter
pylori. That in
combination with
you watching
your diet should
fix your ulcer
problem
That looks
terrible!
Help me doc!
Ha Ha I did that you
know. I love acid! I
grow well with more
acid! Give me more
acid all the time!
GASTRIN makes
more acid so make
more Gastrin, dude.
No not the antibiotics! I’m
being destroyed. All my
evilness, lost because the
doctors found me out.
AHHHHHHHH
Sometimes, I need the acid reduced because it
hurts when I eat spicy food. I usually take an
antacid (Rolaids, Tums) or an acid blocker like
Pepsid AC. These are good for temporary relief
for occasional problems.
Endoscope
of a
damaged
esophageal
lining
I sometimes also have a problem with heartburn. It is caused
when the acidic contents of the stomach gurgle up through the
cardiac(lower esophageal) sphincter and contact the esophageal
lining. This causes a burning sensation right behind my heart.
The esophageal lining is damaged as a result of this happening
often (chronic) This is ACID REFLUX DISEASE.
Did you know?
Some animals like the lamprey
have no stomach at all. The
esophagus feeds directly into
the intestine.
They are jawless fish and feed by attaching themselves
to another fish with this sucker like mouth. Then they
use their tongue like a rasp to scrape off tissue from the
victim. Lampreys are related to some of the most
primitive fish on the planet. (Makes sense – first fish
were also jawless)
Lamprey are an INVASIVE SPECIES from the ocean
who are now infesting all the great lakes. They
slipped into our system along with the locks that
ocean freighters use to access the waterway. They
are destroying large game-fish.
The food remains in me until it liquefies and forms CHYME. It is
then released through the pyloric sphincter into the duodenum.
This is the first segment of the small intestine. The chyme is
initially acidic, but it is neutralized by secretions by the pancreas
in the duodenum.
Hello there. I’m Mr. Pancreas and I produce a
bicarbonate alkaline solution to neutralize the
stomach acid. The small intestine cannot
withstand acid like the stomach so this is
priority #1.
I also produce over 20 different digestive enzymes. Many such as
trypsin and proteases are not activated until they contact another
enzyme I produce called enterokinase or enteropeptidase
NOTE: The pancreas performs double duty. It is both an exocrine gland
secreting digestive chemicals into a duct, and an endocrine gland
secreting hormones directly into the blood. (Glucagon and Insulin)
Hi there Mr. Liver. What do you do here in the duodenum?
I constantly release bile and store it in Mr. Gall
Bladder. Bile is the waste product of red blood
cell breakdown.
That’s right. I store the bile. When you eat a fat containing meal, I
squeeze the bile out to bile duct and into the duodenum. Bile is an
emulsifier (detergent) that breaks fats into smaller droplets for
easier digestion.
I am the duodenum and when fats come through
I release hormone CCR to cause Mr Gall Bladder is
to release the bile. I also release hormone
ENTEROGASTRONE to slow digestion to allow for
the greater time needed to digest fats.
CCR=cholecystokinin
That ENTEROGASTRONE
stuff makes me produce
less acid and slows
down peristalsis. That
means you start to feel
more full. Eat fat
(cheese) slow digestionfeel full.
I also produce the hormone SECRETIN
that causes the pancreas to add its
alkaline mixture.
Right on!! I can’t do no secreting until I get the
SECRETIN from you Mr. Duodenum
Moving into the SMALL
INTESTINE.
MESENTARY
is like
cellophane,
covering and
preventing
the intestine
from kinks
The purpose of the small
intestine is primarily
absorption , although
some digestion will occur
here. It is long and small
in diameter in order to
facilitate the movement
of nutrients into the
bloodstream . SURFACE
AREA (100m2+) is
ENHANCED with small
finger like projections
called VILLI and even
smaller projections called
MICROVILLI on the villi.
Amino acids and sugars are absorbed and enter
the blood vessel of the villus. Glycerol and fattl
acids pass through the intestine wall and enter
the LACTEAL. These fats are mixed with
CHOLESTEROL and coated with PROTEINS to
form GLOBS called CHYLOMICRONS
Blood from the stomach small and
large intestines that now contain lots
of nutrients from the digested meal
move into the hepatic vein. This vein
goes to the LIVER.
I always wondered what the
HEPATIC PORTAL SYSTEM was about.
Now I know. It’s just Mr Liver filtering
through all the digested blood
nutrients.
HEPATIC=LIVER
I will store much of the
sugar and release it later.
I will keep blood glucose
relatively constant at
about 90mg/100mL
Everything you absorb
from food must pass first
through me!
Ascending colon
like ascending
into heaven.
Remember
Jacob’s ladder?
Undigested matter passes
into the colon (large
intestine) which is short but
has a large diameter. It
primarily absorbs the water
back into the blood.
Descending colon
like descending
into hell. Heard of
Dante’s inferno?
Abandon all hope
all who enter.
Transverse
colon
Ascending
colon
Descending
colon
caecum
Sigmoid colon
Appendix
Rectum
We are almost at the end of our journey. In the
large intestine, large numbers of bacteria (E coli)
are normal and they produce some vitamin K ,
biotin, folic acid and several B vitamins. These are
absorbed and are useful for the body.
Mr Badbacter. Get out of here. The
colon is already full of us E coli
I know I can’t get a foothold in this guy’s colon
because of you. Why aren’t you bad like me? How
come you’re helpin the guy like makin him vitamins?
You know he’s just gonna flush you down the toilet
He gives
us food
and a
good
home.
That’s all
we want.
The remaining waste is stored in the rectum until
eliminated from the body as feces. The bulk of the feces is
actually bacteria.
Why are feces(stools) always
brown Mr. Genius?
Remember the bile. Well the brown is from a
combination of bile and bilirubin from the break
down of red blood cell. The brown colour is
normal. If you see black stools, however, that
indicates that blood is being digested. You are
probably leaking blood into the intestines,
perhaps from an ulcer.
Finally somthin’ evil is
happenin’
Hey something serious is rumbling. I better get topside to see what is going on!
What’s the problem here?
Not me. It must be that enterkin-ASS duodenum
producing too much- maybe ulcerating.
I’m not producing to much enterokinase. Besides
I’d just hurt myself as trypsin would tear away at
my membrane. There is no ulcer you hepatic
hypocrit.
It’s not me either. Duodenum is
making the secretin so I am adding
enough base to the acid coming out
of the stomach. Check out Mr Duo
again. Maybe the problem is
Enterogastrone
Stop arguing guys. I’m the problem.
When Mr. Duo sent the CCR I was blocked
from releasing the bile. Sorry but I hurt.
I feel OK . I’m
was producing
gastrin and
making more
acid but the
guy is eating.
That’s normal
So I just added a little
enterogastrone now . There
was fat in the meal. It needs to
slow down and I need the bile
so I released CCR
If you are blocked, that means we have a
gall stone problem.
I can feel the solidified cholesterol crystals at the entrance
to the bile duct. They are causing a blockage every time I
try to release bile.
Gall stones will require surgery in your case. I will
have to remove the stone and also Mr. Gall Bladder
completely because he looks infected. It’s too bad
they aren’t small stones because if they were we
could smash them up with powerful ultrasonic waves
in a non surgical setting.
Those gall stones are
very ugly inside you
Mr. Gall Bladder. We
have to stop
releasing bile. That
means no fats in
meals right now!
Remove me. I thought the
body needed me.
We are having gall stone attacks. The
pain is really bad. You have to go.
The body can get along without you. The liver will just
drain the bile directly into the duodenum and bypass your
storage system.
You are lucky that the stones did not block the pancreatic
duct as well. If this happens, pancreatitis develops.
Jaundice( yellowing of skin or eyes) is also a serious
affecting the liver. Call me right away if this or a fever
develops.
I’m essential.
I’m also essential to survival.
It’s better you go Mr.Gall
Bladder than we all get
destroyed resulting in death.
Well that solves that problem. Wait a
minute. What now? We have excruciating
pain in our lower right abdomen. What is
going on?
You are experiencing an appendix attack. I will i I I
I will remove it before it bursts. If it does, it will
leak bacteria into the surrounding abdominal
cavity leading to PERITONITIS a massive bacterial
infection
Well that’s all for today. Keep yourself
healthy and eat properly.
Digestion
Ends