Download Document

The Process of Digestion
- Digestion is the process by which your body breaks down food, and the
nutrients in food, into simpler substances. So it can perform the three
functions of nutrients
o Mechanical Digestion: Happens as food is crushed and churned
o Chemical Digestion: food mixed with powerful acids and
enzymes.
- Enzymes are a type of protein produced by cells that cause a specific
chemical reaction.
- As food is digested, it passes through a muscular tube leading from the
mouth to the anus – called the gastrointestinal tract (GI) – about 25-30
feet long!
In the Mouth
- Food enters the GI tract through the mouth. Mastication (chewing) is
the first step in the digestive process.
- There are about 9,000 taste buds that cover the surface of the tongue.
These sense the flavor of the food.
o They also sense the taste of food, and trigger the salivary glands
in your mouth.
o Saliva is a mixture of 99% water plus a few chemicals. One
enzyme is called a saliva amylase – which is found only in the
mouth helps to chemically break down the starches in food.
o Saliva moistens, softens, and dissolves food. It also helps to
clean the teeth, and neutralize mouth acids.
In the Esophagus
- Your tongue helps you to chew and swallow.
- The esophagus is a tube that is about 10 inches long. It connects the
mouth to the stomach.
- One of only two tubes in the throat – the other being the trachea.
- When you swallow, a flap of skin called the epiglottis closes to keep
food from entering the trachea.
- Peristalsis helps food move through the tube. It is involuntary, and
happens automatically when food is present.
In the Stomach
- When you eat, your stomach produces gastric juices which contain
hydrochloric acid, digestive enzymes, and mucus.
o This mixture is called chyme
- The acid in the stomach is almost as strong as the acid found in a car
battery.
- Stomach has a thick lining called Mucosa.
o Helps to soften and lubricate food.
In the Small Intestine
- 95% of digestion occurs here
- It has 3 sections:
o The Duodenum – 12 inches long
o The Jejunum – 4 feet long
o The Ileum – 5 feet
- When stretched, the small intestine is about 20 feet in length
- Takes 5 – 14 hours for food to travel from mouth through the small
intestine.
- The pancreas is a gland that helps to create the correct environment.
o It secretes bicarbonate which neutralizes hydrochloric acid that
comes from the stomach.
o Also produces digestive enzymes that break down proteins, fats,
carbs
- Amino acids are the most basic parts of protein
- The liver is the large gland that sits above the stomach which produces
a juice called bile – adds to fat digestion.
o Bile helps to disperse fat in the water based digestive fluids so
they can break down fat.
o Bile is stored in a muscular sac called the gallbladder until it is
needed for digestive purposes
In the Large Intestine
-
Small intestine connected to large intestine
Sometimes called the colon
Main job = to absorb water
Very little digestion occurs here
Chyme is liquid when it enters the large intestine.
o Usually stays in colon for 1-3 days before elimination.
o During the this time, water is absorbed through the walls of the
colon
- Feces – solid wastes that result from digestion
The Process of Digestion
- Digestion is the process by which your body breaks down food, and the
nutrients in food, into simpler substances. So it can perform the three
functions of nutrients
o Mechanical Digestion:
o Chemical Digestion:
- Enzymes are a type of protein produced by cells that cause a specific
chemical reaction.
- As food is digested, it passes through a muscular tube leading from the
mouth to the anus – called the gastrointestinal tract (GI) – about
_________ feet long!
In the Mouth
- Food enters the _______________ through the mouth. Mastication
(___________) is the first step in the digestive process.
- There are about _____________taste buds that cover the surface of the
tongue. These ______________________________________
o They also sense the taste of food, and trigger the ___________
______________ in your mouth.
o Saliva is a mixture of 99% ___________ plus a few chemicals.
One enzyme is called a saliva amylase – which is found only in
the mouth helps to chemically break down the starches in food.
o Saliva_______________, ________________ and
__________________. It also helps to clean the teeth, and
neutralize mouth acids.
In the Esophagus
- Your tongue helps you to _______________________________.
- The esophagus is a tube that is about 10 inches long. It connects the
mouth to the stomach.
- One of only two tubes in the throat – the other being the trachea.
- When you swallow, a flap of skin called the epiglottis closes to keep
food from entering the___________________.
- ___________________ helps food move through the tube. It is
involuntary, and happens automatically when food is present.
In the Stomach
- When you eat, your stomach produces gastric juices which contain
hydrochloric acid, digestive enzymes, and mucus.
o This mixture is called ____________
- The acid in the stomach is almost as strong as the acid found in a car
battery.
- Stomach has a thick lining called Mucosa.
o _____________________________________________
In the Small Intestine
- _____ of digestion occurs here
- It has 3 sections:
o The ____________– 12 inches long
o The ___________ – ___ feet long
o The Ileum – ____ feet
- When stretched, the small intestine is about 20 feet in length
- Takes ____________ hours for food to travel from mouth through the
small intestine.
- The ____________ is a gland that helps to create the correct
environment.
o It secretes ________________ which neutralizes hydrochloric
acid that comes from the stomach.
o Also produces digestive enzymes that break down__________,
________, ___________
- Amino acids are the most basic parts of protein
- The liver is the large gland that sits above the stomach which produces
a juice called bile –__________________________.
o Bile helps to disperse fat in the water based digestive fluids so
they can break down fat.
o Bile is stored in a muscular sac called the gallbladder until it is
needed for digestive purposes
In the Large Intestine
-
Small intestine connected to ___________________
Sometimes called the ___________
Main job =
Very little digestion occurs here
Chyme is ____________ when it enters the large intestine.
o Usually stays in colon for __________days before elimination.
o During the this time, water is absorbed through the walls of the
colon
- Feces – solid wastes that result from digestion