Download Digestive System

Parts of the
digestive system
(draw the missing
pictures)
HBS pgs. 30 - 31
Esophagus
HBS pgs. 30 - 31
Stomach
In Joann’s mouth, her teeth begin to mechanically digest the slice of pizza.
(Mechanical digestion increases the surface area of the food thus allowing the
digestive enzymes/juices greater access to the food pieces in order to more efficiently
do their job.) At the same time, her tongue is mixing the food with her saliva which
is produced by her three pairs of salivary glands. In her saliva there is an enzyme
called amylase that begins the chemical digestion of starches (complex
carbohydrates). The starches are broken down into simple sugars. Digestive
enzymes help the body chemically break down nutrients into forms that the body can
use. The ball of soggy food is now called a bolus as it travels down the food tube,
the esophagus.
To make sure that the bolus only travels down the esophagus and not the windpipe
(which leads to the lungs), the epiglottis (flap of skin) will shut off the entrance to
the windpipe making sure food does not end up in your lungs. The food moves down
our esophagus as a result of regular wave-like muscular contractions called
peristalsis which moves food through the entire digestive tract. At the end of the
esophagus is the lower esophageal sphincter, a tight ring of muscles that make sure
the food stays in the stomach and moves in a one-way direction.
Peppi and Bollo find themselves in the J-shaped organ known as the stomach. The
stomach has folds of pink velvet and a lot of gastric juice which is a digestive juice
made up of hydrochloric acid and an enzyme called pepsin. Here begins the
chemical digestion of proteins. The churning of the stomach helps the gastric juices
do their job even better. The churning is caused by the 3 layers of muscles that
make up the stomach wall. This churning is an example of mechanical digestion. The
thick, creamy contents of the food in the stomach is called chyme. The stomach is
coated with a thick layer of mucus to protect it from the gastric juice, but if the juice
finds a spot without mucus, it can penetrate the stomach and make a small hole
known as an ulcer. And when the gastric juice backs up into the lower esophagus
from the stomach, you get a burning sensation which is called heartburn but it has
nothing to do with your heart.
Vomiting can be triggered by bad food, by some medications, or by poisons.
Teeth / Tongue
Bolus / Saliva
Amylase / Enzyme
Mechanical Digestion
Chemical Digestion
Sugar/Starch
Sphincter / Peristalsis
Salivary Glands
Esophagus / Windpipe
Epiglottis
Gastric Juices
Hydrochloric Acid
Enzyme / Pepsin
Protein
Stomach Muscles
Chyme
Mucus / Ulcer
Heartburn
Mechanical (muscles churning) &
Chemical (gastric juice)
HBS pgs. 38 -39
What does it do?
Mechanical (teeth and tongue) Nothing
significant.
& Chemical (amylase)
Mouth
Words to include in
your description.
Type of
digestion:
mechanical
or chemical
Digestive System Grid – Teacher Version
Pancreas
Liver
Gall Bladder
Large intestine
Duodenum
Pancreatic Juices
Bile
Protein / Amino Acids
Carbohydrates
Fats
Surface Area
Bloodstream
Villi / Microvilli
Colon
Appendix
Appendicitis
Water / Minerals
Bloodstream
Waste / Feces / Gas
Diarrhea / Constipation
(peristalsis)
HBS pg. 56 – 59
Peppi and Bollo enter the large intestine which is also called the colon. Just off to the
right is the entrance to the appendix which scientists believe has no known function
but can get infected and cause appendicitis. As they move through the large
intestine, more and more of the water is being absorbed out of the waste. No food is
digested here, it’s just waste (feces). Both minerals and water are absorbed out
into the bloodstream to help keep the body in balance. (There are also some
vitamins which are made in the large intestine!)
Two things can go wrong in the large intestine: if the waste moves too quickly, and
not enough water is absorbed out…diarrhea. If the waste moves too slowly and a lot
of water is absorbed out…constipation. To prevent constipation, eat more fiber or
take a laxative. Bacteria in the large intestine start to fed on undigested food and can
release gas.
Pyloric Sphincter
Mechanical
(peristalsis)
HBS pgs. 48 – 49,
54 – 55
Leaving the stomach, Peppi and Bollo pass through the pyloric sphincter which
leads them to the first 25 cm of the small intestine, better known as the duodenum.
Into the duodenum the pancreas squirts pancreatic juice which is packed with
enzymes that help chemically digest carbs, proteins and fats. The gall bladder also
squirts in the greenish-yellow liquid called bile that the liver produced. (The bile
mechanically digests the fats, turning it into smaller fat droplets. This is similar to
what dish detergent does!) The pancreatic juice is alkaline, or basic, to neutralize the
stomach acids. At this point, proteins chemically break down further into amino
acids, complex carbs into simple sugars, and fats into fatty acids and glycerol. The
chemical digestion is now complete and the particles are now simple enough to be
absorbed through the lining of the small intestine.
Your digestive system has ways of making sure the surface area of the food you eat
is as large as possible. Chewing begins to increase the surface area of food, allowing
digestive enzymes greater access to them. As the chyme moves through the small
intestine, the nutrients are absorbed through the intestinal wall into your
bloodstream. The intestinal wall is packed with wrinkles and folds which are
covered with tiny projections called villi and the villi are covered with even small
microvilli. The folds, villi and microvilli are yet another way that the digestive system
increases the surface area to maximize nutrient absorption!
Chemical (bile &
pancreatic juice)
Small intestine