The Digestive System!
I was wondering if I would ever have the opportunity to
use this "sweets" theme... not bad, huh? I certainly cannot use it in the
next unit on the metabolism of food, because that is very similar to a week on
nutrition... Sweets and nutrition? I don't think so!
The digestive system includes many organs, and each
organ has many names for its various regions. Also, the main tract through the
digestive system (from the mouth, through the stomach and intestines, and then out of the
body), called the alimentary canal, has a certain thickness to its walls,
which can be described by layers of tissues. We have already looked at many of these
gross anatomical and some of the microscopic anatomical regions in lab.
On these pages, I will focus on the portions of the
digestive system that we will cannot cover in lab: secretions of the digestive system,
movements of the digestive system, the control over digestion, and absorption of
nutrients. Here's a slightly more thorough outline:
Regions of the digestive system that need a
bit more attention than we can do in lab... Also, the generalized major functions of these
Mouth-- here our focus will be on the salivary
glands that secrete into the mouth, as well as learning about our teeth
Esophagus-- you need to learn about its
structure to understand its movements
Stomach-- you will investigate the inner
surface of the stomach and the production of chyme... you will need to understand why the
stomach digests only the food that enters it-- not itself!
Small and large intestines-- what do they do?
Digestive System Accessory Organs-- you will
begin to understand some of the digestive functions of the liver, gallbladder, and
Secretions of the digestive system
What chemicals do digestive organs secrete, and
In this section, you will move through a clickable map of the digestive
system. Each time you click on a digestive organ, you will go to a summary of the
chemicals secreted by that organ and why.
Control of secretion
Digestion only occurs because the digestive system secretes digestive
chemicals. By controlling the secretion of these chemicals, we can control much of
Here is another clickable map of the digestive
system, but this time, as you click on each organ you will get information about the
secretion-controlling chemicals that organ produces.
Steps to digestive secretion in the stomach.
The stomach has phases of digestive secretions, which is a way that we
can control when secretion occurs in our stomachs.
Movements of the digestive system--
Much of the alimentary canal is able to undergo peristalsis to move
Absorption of nutrients
It is not enough that we break down the food we eat. We must also
be able to get those nutrients into our blood for use by all the cells of the body.
This is mainly done in the intestines.
Another way to view this outline is with this
Because nutrients are the building blocks of macromolecules and
you need to understand both the nutrients and the macromolecules for this unit, you may
wish to review unit 3 a little bit.
here to go to a very nice (and comprehensive) website about the digestive