Download Digestive System Packet

The Digestive System
Copyright Christopher Lee Publications:
Edited by D. McNeese
II. Students understand structures and functions of body systems. (2.2.1)
>Identify and describe how body systems work together.
Study Sheet A
Name:______________________________
The Digestive System-Food
Man needs food for several reasons including the following: to supply energy to the
body, to store energy for future emergencies, and to build new protoplasm. Protoplasm is a semifluid, which is the essential living matter of all body cells. There are six groups of food. They
are water, vitamins, minerals, carbohydrates, fats, and proteins.
Water is necessary for all living things. It carries all materials in the body and regulates
body temperature through evaporation. Vitamins are needed in small amounts to carry on vital
functions and to maintain normal conditions within the body. Minerals such as salt are needed
for cells to function properly and to build new living tissue. Carbohydrates and fats are used as
sources of energy by the body. Bread, potatoes, and corn are examples of carbohydrates. Fats
include oils, butter, and the fat part of meats. Proteins are needed by the body to replace worn out
and damaged tissue or to build new living tissue. Meats, cheese and milk are in part proteins.
Some of the above foods need little or no digestion. They could be placed directly into
the blood stream just as people are sometimes fed intravenously. Water, vitamins, and minerals
are foods of this type.
However; fats, proteins, and some carbohydrates such as starches, are not ready to go into
the blood stream because they are too complex. Complex foods pose two problems in reaching
and being utilized by body cells. First, most of them are not soluble in water. Because they can’t
be dissolved in water, they would plug up the capillaries. Capillaries are tiny blood vessels that
transport food. Therefore, the complex foods must be broken down into simpler forms that are
water soluble. Second, besides not being water soluble, fats, proteins, and some carbohydrates
are too complex chemically for body cells to use. In fact, many complex foods would act as
poisons or toxins to body cells. Therefore, it is an important function of the digestive system to
break down complex foods into simple foods that the body can use.
The digestive system breaks down carbohydrates into simple sugars, fats into fatty acids
and glycerol, and proteins into amino acids. The simple sugars, fatty acids, glycerol, and amino
acids are all water soluble and non-toxic. They can be dissolved in the blood transportation
system and carried to the cells of the body to be used for energy or to build new tissue or repair
worn out tissue.
To help Bring about the breakdown of food in the digestive process, the digestive system
uses chemicals called enzymes. Enzymes are not used up in the digestive process and therefore
are digestive catalysts.
Questions
1. Two main sources of food energy are _____________ and _____________.
2. Proteins are used mainly to build new ______________________.
3. Chemical catalysts found in the digestive process are called _____________.
4. The six food groups are water, carbohydrates, fats, proteins, _____________ and
________________.
5. Digested food must be soluble in _________________.
Activity
Glue activity sheets 1 and 2 together to make your display sheet for the front view of the digestive
system.
Study Sheet B
Name:______________________________
The Digestive System- The mouth and throat
Permanent teeth begin to appear at about age six and may not be completed until
age twenty-five. A complete set of thirty-two permanent teeth includes eight incisors for
biting and cutting, four sharp canines for tearing, eight premolars and twelve molars for
grinding.
The fragmenting of food in the mouth by the teeth begins the digestive process.
This fragmenting of food is known as mastication. Mastication is important because it
increases the surface area of the food and as a result, digestion can occur more effectively
and rapidly.
The process of mastication is aided by the addition of saliva, a liquid produced by
three pairs of salivary glands which empty into the mouth through short tubes or ducts.
The salivary glands include the parotid glands in the front of the ears, the sublingual
glands below the tongue, and the submaxillary glands near the corner of the jawbone.
Saliva aids the digestive process by softening to food we eat, making it easier to chew
and swallow. At the same time, it washes the teeth and moistens the mouth and lips.
Saliva contains one enzyme, amylase. Amylase begins the digestion of starches. The
flow of saliva is controlled by the nervous system through sight, smell, touch, and
thought. As much as one to two quarts of saliva is produced each day.
The mouth opens into an enlarged area called the throat or pharynx. The pharynx
serves both the respiratory and digestive systems, or in other words, is used for breathing
as well as swallowing. When a person swallows, the uvula, a flap-like projection which
hangs in the back of the mouth, closes off the opening to the nose. In a similar manner, a
valve called the epiglottis closes off the opening to the lungs. In this way, the food you
eat is directed into the esophagus or food tube and not into your nose or lungs.
The act of swallowing is usually begun voluntarily. When a person wants to
swallow, the food is moved by the tongue to the top of the mouth at the back. The tongue
then presses up against the roof of the mouth and flips the food backwards into the
pharynx where the swallowing becomes involuntary. Contractions of the muscles of the
pharynx move the food to the esophagus where wave-like muscle movements or
peristalsis, push the food on to the stomach.
Questions
1. What enzyme is found in saliva? _______________
2. What word describes the fragmenting of food by the teeth? _______________
3. How many teeth are found in a complete permanent set? ________
4. What is another name for the throat? ______________
5. What valve keeps food from going into the lungs? _________________
6. What system controls the flow of saliva? __________________
Activity
Locate diagram 5 on activity sheet 4. Color the tongue red, the teeth yellow, and the
salivary glands blue. Next, cut out diagram 5 and glue it to your display sheet. Then,
label the tongue, teeth, and salivary glands.
Study Sheet C
Name:______________________________
The Digestive System-The esophagus and stomach
The esophagus is a muscular tube about ten inches long that conveys food from
the throat or pharynx to the stomach. It lies behind the trachea or windpipe and the heart.
As you swallow, two sets of muscles act together to force the food and water through the
esophagus and into the stomach. One set is circular and presses inward. The other set
runs up and down and also contracts inward forcing the food downward. This wave-like
motion is called peristalsis. Since the ring of muscle contracts behind the food, you can
swallow upside down. In the esophagus there is no chemical digestion since the
esophagus does not produce any enzymes; however, it does secrete mucus. This mucus
acts as a lubricant permitting the food to slide through the esophagus more easily.
The stomach is a J-shaped sac lying in the abdomen just under the diaphragm.
The diaphragm is a muscle that forms the floor of the chest cavity. The stomach is made
of three layers of smooth muscle tissue, each running in a different direction. The
stomach is mainly a storehouse for food. It can hold as much as two quarts of food.
Peristaltic waves, moving across the stomach, break the food up into small pieces. It may
continue to churn the food for up to five hours before passing it on to the small intestine.
The stomach aids the process of chemical digestion by mixing the food with
gastric juices produced by the lining of its walls. Gastric juices are made up of water,
mucus, hydrochloric acid, and the enzyme pepsin. The water softens the food. The
mucus protects the stomach from digesting itself. The hydrochloric acid creates a
favorable environment for the pepsin enzyme to work. Pepsin begins the digestion of
proteins. By the time the food leaves the stomach to enter the small intestine, it is a semiliquid called chyme.
Questions
1. What is the name of the wave-like process that moves food down the esophagus?
_____________
2. Does any chemical digestion occur in the esophagus? ________________
3. What acid is present in the stomach? _____________
4. What enzyme to gastric juices contain? ________________and what food type
does it work on? ____________________
5. What is the semi-liquid food that leaves the stomach? _______________
6. What word best describes the function of the stomach? ______________
Activity
Locate diagram 6 on Activity sheet 4 and diagram 3 on Activity sheet 3. Color the
esophagus orange and the stomach purple. Next, cut out diagram 6 and diagram 3
and glue them to your display sheet. Then, label the esophagus and stomach.
Study Sheet D
Name:______________________________
The Digestive System-The liver and pancreas
When food passes out of the stomach in enters the small intestine. The upper ten
inches of the small intestine is called the duodenum. It is in the area of the duodenum
that liquids from the liver and pancreas enter the small intestine to aid in the process of
digestion.
The liver is the largest gland in the body. The liver produces a liquid called bile.
The bile is produced continuously by the liver but it is only needed after meals. Bile is
stored until needed in a sac under the liver called the gall bladder. The gall bladder
connects to the small intestine through a tube called the bile duct. Bile contains no
enzymes. It is more like a soap or detergent in that it separates fats and oils into tiny
droplets. This makes it easier for enzymes that are present in the small intestine to
effectively digest the fats you eat into fatty acids and glycerol.
The pancreas, a fish-shaped gland, is located in the back of the stomach. The
large or head end, lies next to the duodenum. The duodenum loops around the pancreas
like a huge letter C. The pancreas is really two glands in one. First, it produces the
hormone insulin which it secretes directly into the blood stream. Insulin is necessary for
the proper usage of sugar. Second it produces a digestive fluid called pancreatic juice
which enters the small intestine through the pancreatic duct. Pancreatic juice contains
three very important enzymes: trypsin, which breaks down protein into smaller
molecules; pancreatic amylase, which changes starch into sugar; and lipase, which
converts fats to fatty acids and glycerol.
Questions
1. What gland is located in the back of the stomach? ____________________
2. What liquid is produced by the liver? _____________________
3. In what structure is liver bile stored until needed? __________________
4. What is the area of the small intestine called where liquids from the liver and
pancreas enter? _____________________
5. How many enzymes does bile contain? _________ and How many enzymes does
pancreatic juice contain? __________.
Acitivity
Locate diagram 1 on Activity sheet 3. Color the pancreas black, the liver brown, the gall
bladder green, the bile duct yellow, and the pancreatic duct blue. Next, cut out diagram 1
and glue it to your display sheet. Then, label the pancreas, liver, gall bladder, bile duct,
and pancreatic duct.
Study Sheet E
Name:______________________________
The Digestive System- The small intestine
The small intestine is the single most important part of the digestive system. It is
here that the final breakdown or simplification of food takes place. Also, it is in the small
intestine that digested food enters the blood transportation system.
The small intestine is a muscular tube approximately twenty-three feet long and
an inch in diameter. It is located in the abdomen between the stomach and large intestine
and is held in place by a thin membrane called the mesentery. The upper end of the small
intestine is slightly larger in diameter and is called the duodenum. It is in the area of the
duodenum that the digestive juices from the liver and pancreas enter the small intestine.
The small intestine produces digestive juice of its own from special cells in its
walls. The digestive juice is called intestinal juice and it contains several important
enzymes. Three of these, maltase, sucrase, and lactase, finalize the breakdown of
compound sugars, or disaccharides, into simple sugars. Other enzymes, called pepidases,
complete the digestion of proteins into amino acids. The completely digested food is
now water soluble and the food molecules are simple, not complex. In this form it can be
carried by the blood stream and used by all cells of the body.
The digested food passes from the small intestine into the blood stream through
finger-like projections of the wall of the small intestine called villi. The surfaces of villi
are covered with a network of blood capillaries, or tiny blood vessels. All digested food
except fats enter these blood capillaries. The fats pass through the surface of the villi into
a small branch of the lymphatic system. The lymphatic system is a series of vessels
which collect tissue fluid that bathes the body cells. The fats make up part of this tissue
fluid. Any remaining water and undigested food, such as fiber, is passed on into the large
intestine.
Questions
1. The tiny finger-like projections in the small intestine are called______________.
2. Digested proteins are called__________________.
3. Digested food passes through the villi into tiny blood vessels
called_________________.
4. Intestinal juice contains several important _____________________.
5. What membrane holds the small intestine in place? __________________.
Activity
1. Locate diagram 2 on Activity sheet 3. Color the small intestine red. Next, cut out
diagram 2 and glue it to your display sheet. Then, label the small intestine.
2. Locate diagram 7 on your display sheet. Color the artery and capillary network
to the left of the slash marks red and the vein and capillary network to the right of
the slash marks blue. This will indicate the change from oxygen rich red blood to
oxygen poor blue blood. Color the villi yellow.
Study Sheet F
Name:______________________________
The Digestive System- The large intestine
The large intestine is about five feet long. It is located in the abdomen and
encircles the small intestine. The large intestine connects to the small intestine at the
lower right side of the small intestine. From there, the large intestine starts up the right
side, crosses over to the left side, and extends down the left side of the small intestine.
The appendix is attached to the large intestine near the area where the small
intestine is connected to the large intestine. The appendix is a small worm-like projection
about three inches long. The appendix has no known function. It is a hollow sac that
often fills with wastes which remain in it for a long time. In this environment, bacteria
thrive, giving rise to an infected appendix. This condition is known as appendicitis.
Most of the material entering the large intestine is non-digestible food plus
mucus, bacteria, and water. The main function of the large intestine, in addition to
elimination of wastes, is absorption or recovery of water. If the body were to lose this
water for an extended period of time dehydration would result. The waste material that
results when the water reabsorbed into the blood stream is a semi-solid. This semi-solid,
called fecal matter, is moved to an area at the lower end of the large intestine called the
rectum. This movement is caused by a massive peristaltic wave sweeping over the large
intestine. From the rectum, the waste is eliminated from the body through an opening
called the anus.
Questions
1. What is found attached to the large intestine near its connection to the small
intestine? _______________.
2. The material entering the large intestine is mainly non-digestible food, mucus,
bacteria, and ____________________.
3. What is the main function of the large intestine? ________________________.
4. What is the lower end of the large intestine called? _____________________.
5. Waste material leaves the body from the large intestine through an opening called
the _______________.
Activity
Locate diagram 4 on Activity sheet 4. Color the large intestine brown and the appendix
green. Next, cut out diagram 4 and glue it to your display sheet. Then, label the large
intestine and the appendix.