Download Slideshow

The Digestive
System
Part 1
Anatomy of…
Chapter 14
Photo Credit: science.nationalgeographic.com
The Big Picture
• Our digestive system
o Takes in food
o Breaks it down with
mechanical and physical
processes into nutrients
o It then absorbs these nutrients
into the blood stream
o Then rids the body of the
unused remains
The Alimentary Canal
• The alimentary canal is
the “tube” that our
food and ultimately our
food waste travel
through.
• These notes, part 1,
look at the organs that
form the canal.
• Part 2 looks at the
organs that help in the
process of digestion;
the accessory organs.
In the above figure, all the labeled
parts but the liver form the
alimentary canal
Organs of the Alimentary Canal
• When you put something in your mouth, and if it later
pops out your anus, it traveled through your body but
it was never inside your body
• Here’s the list of organs that “something” would come
in contact with
o Mouth
o Pharynx
Putting food in your
o Esophagus
body is like putting
your finger through a
o Stomach
donut; it passes
o Small intestine
through the donut but
never enters the
o Large intestine
donut!
o Anus
Mouth
• The mouth is also
called the oral cavity
• The players here are
the lips, cheeks, hard
palate (anterior roof of
mouth), soft palate
(posterior roof of
mouth), uvula (dangles
from the soft palate),
tongue, and teeth
Uvula
• The uvula seems to
function in aiding
speech, swallowing,
prevent food from
entering nasal cavity,
and in the “gag” reflex
Pharynx
• As food is leaving the
mouth it passes into the
pharynx
• The pharynx is the
common area that
both food and air pass
through
Esophagus
• A 10” long tube from
mouth to stomach
• Below is a an
endoscope view
looking into this tube
Stomach
• A sac with two valves
at both ends. The
cardioesophageal
sphincter at the top
and the pyloric
spincter valve at the
bottom
• It can hold up to 4 L or
a gallon of food and is
used in both digestion
and temporary storage
Small Intestine
• It’s big; the major
player in digestion, and
the longest part at up
to 13’ long in a live
person.
• Has three major parts
o Duodenum
o Jejunum
o ileum
The small intestine is lined with intestinal villi increase surface area to absorb nutrients,
connect to vessels
Large Intestine
• Short (5’) but bigger
diameter than the
small intestines
• It absorbs water and
dries out the waste
• It’s divided into parts:
o
o
o
o
Ascending colon
Transverse colon
Descending colon
Sigmoid colon
• The sigmoid colon
leads to your anus and
the end of the tube…
How to Make Fake Poop...
Photo Credit: http://www.biologycorner.com