Download Mouth - Net Start Class

The Journey
of a Cracker
Amalyse
Mouth
Digestion of the cracker begins here. Teeth physically
(mechanically) crush and chop the food while the
tongue mashes the food around. Saliva which is
excreted by salivary glands, contains water, mucus, and
the enzyme amalyse which chemically breaks large
starch molecules, also called polysaccarides, into smaller
sugar molecules called monosaccarides. (glucose) Only
starches (carbohydrates) are digested here. Enzymes are
proteins that speed or assist chemical reactions. Starch
and sugar are called organic molecules because they
contain carbon as part of their chemical structure.
Esophagus
Wavelike muscle action called peristalsis moves the bolus
(chewed food) from the mouth to the stomach. (no digestion
takes place, though physical changes in shape and texture
occur).
Epiglottis
The epiglottis is a small flap of tissue that closes over the
opening of the trachea, or wind pipe (breathing tube) when
you swallow, keeping food out of your lungs.
Pepsin
Stomach
Food enters the stomach through a valve. The
stomach is a “j” shaped muscular organ that
churns and mixes food mechanically like a
blender. Gastric juices (Hydrochloric acid,
enzymes such as pepsin and mucus) break it
down chemically and change it into chyme
(malt-like liquid). The cracker is now a thin
liquid and leaves the stomach after about 4
hours by way of another sphincter valve.
Small Intestine
The thin liquid enters the first curve of the
small intestine called the duodenum. Most
chemical digestion and absorption of nutrients
into the blood stream takes place here (first 10
inches). After digestion, absorption of the
nutrients through the intestinal wall (the villi)
takes place. The cracker is now glucose
molecules which leave the villi and enter the
blood stream, which carries them to cells for
energy production.
Liver
Manufactures bile – an enzyme that
mechanically breaks down lipids (fat) into
smaller pieces called fatty acids. Food does
not enter the liver. Bile is secreted into the
small intestine through a tiny tube.
Gall Bladder
Small sac under the liver that stores the bile
until needed. The bile is released into the
duodenum of the small intestine. Food
does not enter the gall bladder.
Pancreas
Gland which produces enzymes such as insulin which break
down proteins, starches, and fats chemically. These
enzymes are secreted into the duodenum also. Food does
not enter the pancreas. If the pancreas fails to produce the
right amount of insulin, diabetes or hypoglycemia can result.
The pancreas also produces trypsin which breaks down
proteins into amino acids and lipase, which breaks down fats
into fatty acids and monoglycerides.
Glucose
Insulin
Large Intestine
Water, salt and minerals are absorbed from
the undigested material forming solid waste
called feces. Bacteria break down some
fiber. Vitamins B and K are also produced
here by bacteria and absorbed into the blood.
Cellulose from the cracker provides fiber for
peristalsis to work. The large intestine is
often called the colon.
Rectum
The last vertical section of the large
intestine through which solid waste
(feces) travels.
Anus
Muscular opening where solid waste
is released (excreted) from the body.
Organic Molecules
• Fats chemically break down into fatty acids.
• Proteins chemically break down into amino acids.
• Carbohydrates(starches) chemically break down
into simple sugars.
• They all have Carbon as an element in their
chemical structure, which makes them organic
molecules.
The Path of Food
Main Organs/Structures of
Digestion the Food Passes
Through (all lined with
epithelial tissue).
Organs/Structures of
Digestion that Food Does
NOT Enter (Accessory
Organs)