DIGESTIVE SYSTEM
INGESTION: The taking in of food and liquids into the body.
TEETH: to break the food into smaller pieces.
SALIVARY GLANDS: produces saliva (moistens the food and
contains enzymes) 1st line of chemical digestion.
Mechanical digestion- your teeth ex: chewing up tiny pieces of apple
SALVIA: contains ptyalin which is an enzyme that digests starch
ESOPHAGUS: “food pipe” transports food and liquids from the
mouth to the stomach (smooth muscle)
PERISTALSIS: a muscle contraction to help move the food along the
digestive system
PEPSIN: an enzyme found in the stomach to digest proteins
STOMACH: involuntary muscle, muscular contractions
(peristalsis) churn the food while gastric juices and
hydrochloric acid chemically break down food.
SMALL INTESTINE: (long) where absorption of nutrients into
the bloodstream occurs (at capillaries surrounding the villi)
villi= fingers in the small intestine.
LIVER: produces bile  breaks apart fat molecules, regulates
(controls) sugar levels.
GALL BLADDER: stores bile and releases it into the small
intestine.
PANCREAS: produces pancreatic juices (enzymes) which aid
digestion in the small intestine, produces insulin – regulates
the amount of sugar in the body.
LARGE INTESTINE: (big around in size) where water is reabsorbed,
contains bacteria which produce vitamins (B & K), forms solid waste
(feces)
APPENDIX: no particular function
RECTUM: stores solid waste (feces)
ANUS: opening at end of the rectum where solid waste passes out of the
body
A TRIP THROUGH THE DIGESTION SYSTEM
~ digestion is the process by which food is broken down into useable
substances by the body (nutrients the body can use)
~ the two kinds of digestion are MECHANICAL and CHEMICAL.
MECHANICAL- physically breaking food into smaller pieces
CHEMICAL- breaking down food into useable substances using enzymes
and acids.
LET’S START WITH THE MOUTH
A person takes food into his/her body by eating. This is called
ingestion. The food is broken down by using the various teeth in the mouth.
Chewing helps to break the food down into smaller pieces. Saliva is
produced by the salivary glands (makes food slippery so it goes through the
digestive system). Saliva contains enzymes (ptyalin) which helps to break
down starches into sugars. The tongue helps to push the food around the
mouth and also helps to swallow the food. Thus begins the process of
digestion.
THE ESOPHAGUS
Peristalsis is the muscular contractions of the digestive system which
push food through the system. Food passes through the esophagus and
enters into the stomach. Food doe not enter the trachea (wind pipe) because
of the flap of preventive tissue called the epiglottis.
THE STOMACH
The stomach secretes a substance called gastric juice. The gastric
juice contains enzymes and hydrochloric acid. In particular, the enzyme
pepsin is secreted and used to break down proteins. In addition to chemical
digestion, the stomach continues to mash and grind the food. Muscular
contractions mix the food with the gastric juice as peristalsis pushes the food
towards the small intestine. When full, your stomach can contain
approximately 1.5 liters (16 oz) of food.
THE SMALL INTESTINE
After spending 3-6 hours in the stomach, the food enters the small
intestine. The small intestine is about 2.5cm around and 6 meters long.
Food continues to move through the small intestine by the process known as
peristalsis. Most digestion occurs in the first 30cm of the small intestine.
The cells that line the walls of the small intestine release enzymes to help
break down the food. In addition, the small intestine gets help from two
other organs, the liver and the pancreas. The pancreas releases pancreatic
juice which contains several enzymes to help break down the food. The
pancreas also produces insulin, which helps to regulate the amount of sugar
in your blood. The liver produces bile which is then stored in the gall
bladder. Bile helps to break down fats.
The inner lining of the small intestine walls is lined with millions of
tiny finger-like projections called villi. Here, digested food is absorbed into
the bloodstream through the capillary walls which surround the villi.
THE LARGE INTESTINE
Although most of the food you eat is digested in the small intestine,
some substances cannot be digested. An example of this is cellulose (plant
stuff), which is commonly referred to as roughage. The undigested food
along with water makes its way into the large intestine. Here, water is
reabsorbed into the bloodstream. If too little water is reabsorbed, diarrhea
occurs. If too much water is reabsorbed, constipation occurs. Also, helpful
bacteria living, inside the large intestine feed on the “leftovers” and make
essential vitamins such as vitamin B and vitamin K (helps the red blood
cells). These vitamins are absorbed into the bloodstream.
The large intestine is 6.5cm around but only 1.5 meters long. The
material not absorbed in the large intestine forms the solid waste feces. The
solid waste passes through the large intestine and is stored in the rectum
before exiting the body through the anus.
NUTRITION--Nutrients are the parts of food your body can use.
The four basic food groups and several examples:
DAIRY
MEAT &
GRAINS
PROTEINS (CARBOHYDRATES)
Milk
Beef- pork
Potatoes
Cheese
Poultry- nuts
breads
butter
Fish- beans
rice
Yogurt
Seafood
Pasta
Ice cream
Eggs
Cereals
FRUIT &
VEGETABLES
Apples- celery
Oranges
corn
cucumbers
carrots
PROTEINS- Make up all the cells in your body (most important)
The proteins are used to build and repair your body cells. The
building blocks of proteins are the amino acids. Your body obtains proteins
from meats, eggs, fish, and poultry.
CARBOHYDRATES- are a quick energy source. The two types of
carbohydrates are starches (big one) and sugars (smaller one). The faster
fuel source is the sugar. Your body can obtain carbohydrates from grains
(bread, pasta, and rice), fruits, vegetables, and sugars.
FATS- slow, long term sources of energy stored in the body. Fats have
more energy than carbohydrates, but fats last longer. Fats and oils are used
for a long term energy supply (stored energy). Fats support and cushion the
organs in the body. They also insulate against the cold. Good sources of
obtaining fats are meats, butter, dairy, vegetable oils, animal fats, salad
dressing, and fried foods.
VITAMINS and MINERALS- control normal growth and body
functions. Vitamins and minerals play at important role in your body, they
help to regulate (control) growth and control normal body functions. Your
body needs vitamin K to help with blood clotting and vitamin D for strong
bones and teeth. It also needs the minerals iron (Fe) to help carry oxygen in
the blood and calcium (Ca) for strong bones and teeth.
Calorie: amount of heat needed to raise 1 gram of water 1 degree Celsius.
It is also known as the energy value of food.
Water: Necessary to life. 55%-75% of your body is made up of water.