Download Study Sheet A

Study Sheet A
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 via 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 to ready to go into the
bloodstream 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 the body cells to use. In fact, many complex foods would act as
poisons or toxins to body cells. It is, therefore, 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 there are
digestive catalysts.
Questions
1. The 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 _______________.
Activities
Glue Activity Sheets 1 and 2 together to make your display sheet for the digestive system.
Copr. Christopher Lee Pub!., 1978, Route 1, Box 582A, Houghton Lake, Mich. 48629
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Study S h eet B
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, and 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 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 the food we eat, making it easier to chew and swallow. At the same time,
it washed the teeth and moistens the mouth and lips. Saliva contains one enzyme, amylase.
Amylase begins the digestion of starches. The flow of saliva is contr olled 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 t o
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 to the lungs?
6. What system controls the flow of saliva?
Activities
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.
Copr. Christopher Lee Publ., 1978, Route 1, Box 582A, Houghton Lake, Mich. 48629
Study Sheet C
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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. It does secrete mucus, however.
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 enzyme pepsin to work. Pepsin begins the digestion of
proteins. By the time the food leaves the stomach to enter the small intestine, it is a
semi-liquid called chyme.
Questions
1.
2.
3.
4.
5.
6.
What is the name of the wave-like process that moves food down the esophagus?
Does a ny che mical digestion occur in the e sopha gus ?
What acid is present in the stomach?
What enzyme does gastric juices contain? What food type does it work on?
What is the semi-liquid food that leaves the stomach?
What word best describes the function of the stomach?
Activities
1. 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.
Copr. Christopher Lee Publ., 1978, Route 1, Box 582A, Houghton Lake, Mich. 48629
Study Sheet D
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THE DIGESTIVE SYSTEM – THE LIVER AND PANCREAS
When food passed out of the stomach, it 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 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 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. Pancreatic juice contains three very important enzymes:
trypsin, which breaks down protein into smaller molecules; pancreatic amylase, which changes starch
to sugar; and lipase, which converts fats into fatty acids and glycerol.
Questions
1. What gland is located in 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?
6. How many enzymes does pancreatic juice contain?
Activities
Locate Diagram 1 on Activity Sheet 3. Color the pancreas black, the liver brown, the gallbladder
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, gallbladder, bile duct, and pancreatic duct.
Copr. Christopher Lee Publ., 1978, Route 1, Box 582A, Houghton Lake, Mich. 48629
Study Sheet E
THE DIGESTIVE SYSTEM – THE SMALL INTESTINE
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The small intestine is the single most important part of the digestive system. It is here that the
final breakdown of 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 juices 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
peptidases, complete the digestion of proteins into amino acids. The completely
digested food in now water soluble and the food molecules are simple, not complex. In
this form it can be carried by the bloodstream and used by all cells of the body.
The digested food passes from the small intestine into the bloodstream through
finger-like projections in the wall of the small intestine called villi. The surfaces of
the villi are covered with a network of blood capillaries, or t iny blood vessels. All
digested food, except fats, enter s 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?
Activities
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.
Copr. Christopher Lee Publ., 1978, Route 1, Box 582A, Houghton Lake, Mich. 48629
Study Sheet F
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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 of 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 the 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 is reabsorbed into the
bloodstream 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
_________.
Activities
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.
Copr. Christopher Lee Pub!., 1978, Route 1, Box 582A, Houghton Lake, Mich. 48629