The digestive system is made up of the gastrointestinal tract and accessory organs. The gastrointestinal tract includes the mouth, esophagus, stomach, small intestine, large intestine, rectum and anus. Food is broken down mechanically and chemically as it passes through these organs. The accessory organs, including the liver, gallbladder and pancreas, produce enzymes and bile that aid in digestion. Nutrients are absorbed through the small intestine into the bloodstream and waste is eliminated as feces through the large intestine and anus.

1. DIGESTIVE SYSTEM Presented By: Lerma
Pendon

2. WHAT IS DIGESTIVE SYSTEM?
• A group of organs working together to convert
food into energy
• Breakdown of food into small molecules
• Absorbs nutrients and water to feed the entire
body

3. TWO MAJOR PARTS:
1. Alimentary Canal/Gastrointestinal Tract:
Food passes through a long tube inside the body known as
the alimentary canal or the gastrointestinal tract (GI tract).
It has two openings: the mouth and the anus.
The alimentary canal is made up of the mouth, pharynx,
esophagus, stomach, small intestines, large intestines,
rectum and anus.

4. Mouth
Pharynx
Esophagus
Stomach
Small intestine
Large Intestine
Rectum

5. TWO MAJOR PARTS:
2. Accessory Organs (the
Glands)
• Not part of the path of food, but
play a critical role.
• Include:
Liver
Gall bladder
Pancreas

6. ALIMENTARY CANAL /
GASTROINTESTINAL TRACK

7. MOUTH
• Teeth mechanically break down food into
small pieces.
• Tongue mixes food with saliva (contains
amylase, which helps break down starch).
• Responsible for mastication. Mastication
is the process of chewing. Also known as
mechanical digestion.
• Bolus is the product mechanical digestion.

8. PHARYNX
• Also called the throat.
• The portion of the digestive tract that receives the food from your
mouth.
• Its muscular walls function in the process of swallowing, and it
serves as a pathway for the movement of food from the mouth to
the esophagus.
• Epiglottis is a flap-like structure at the back of the throat that
closes windpipe over the trachea preventing food from entering it.
It is located in the pharynx.
• It has 3 divisions.

9. • Nasopharynx – located
superior and posterior to the
soft palate. Contains the
pharyngeal tonsils and tubal
tonsils.
• Oropharynx – Contains
palatine and lingual tonsils.
The tonsils remove pathogens
that enter the pharynx.
• Laryngopharynx – inferior to
the epiglottis and posterior to
the larynx. This division opens
into the esophagus and larynx.

10. ESOPHAGUS
• A muscular tube connecting the pharynx to the stomach. Approximately
10 inches long.
• It moves the food from the throat to the stomach using muscle
movement called peristalsis.
• Peristalsis is a wavelike contraction from the esophagus to large
intestine.
• At the inferior end of the esophagus is muscular ring called cardiac
sphincter or cardioesophageal sphincter.
• The function of this sphincter is to close the end of the esophagus and
prevent the backflow of food from the stomach to esophagus.

11. STOMACH
• A muscular sac that is located on the left side of the abdominal
cavity, just inferior to the diaphragm.
• This major organ acts as a storage tank for food so that the body has
time to digest large meals properly.
• Mixes food with digestive juices that contain enzymes such as lipase
to break down Proteins and Lipids, the process is called chemical
digestion.
• The product of chemical digestion is called Chyme. It is a the pulpy
acidic fluid which passes from the stomach to the small intestine,
consisting of gastric juices and partly digested food.
• The pH of gastric acid is 1.5 to 3.5 in the human stomach lumen.
• The stomach also contains hydrochloric acid (HCl) that kills bacteria.

12. SMALL INTESTINE
• A long, thin tube about 1 inch in diameter and about 10 feet long.
• The entire small intestine is coiled like a hose and the inside surface is full
of many ridges and folds. These folds are used to maximize the digestion of
food and absorption of nutrients.
• By the time food leaves the small intestine, around 90% of all nutrients have
been extracted from the food that entered it.
Absorbs:
 80% water
 Vitamins
 Minerals
 Carbohydrates
 Proteins
 Lipids
• Nutrients from the food pass into the bloodstream through the small

13. THREE (3) PARTS OF THE SMALL
INTESTINE
1. Duodenum - the first part of the small
intestine. After foods mix with stomach
acid, they move into the duodenum,
where they mix with bile from the
gallbladder and digestive juices from the
pancreas.
2. Jejunum - the middle segment of the
small intestine. Most of the nutrients
present in food are absorbed by the
jejunum before being passed on to the
ileum for further absorption.
3. Ileum - The function of the ileum is
mainly to absorb vitamin B12 and bile
salts and whatever products of
digestion were not absorbed by the
jejunum

15. LARGE INTESTINE
• A long, thick tube about 2.5 inches in diameter and about 5 feet
long. It is located just inferior to the stomach and wraps around the
superior and lateral border of the small intestine.
• The large intestine absorbs water and contains many symbiotic
bacteria that aid in the breaking down of wastes to extract some
small amounts of nutrients.
• It is where the feces are formed.
•It is also called “Colon"

16. THREE (3) PARTS OF THE LARGE
INTESTINE
1. Ascending Colon – the beginning part of
the colon which carries feces from the
cecum to the transverse colon.
2. Transverse Colon – the longest region of
the colon where much of the absorption
and feces formation takes place.
3. Descending Colon – the walls of the
descending colon absorb water as well as
remaining nutrients and vitamins from
the feces and depositing these
substances into our bloodstream before
they are eliminated from the body.

17. RECTUM
• The final straight portion of the large intestine, approximately 6
inches long.
• The rectum is a continuation of the large intestine and connects to
the anus.
• For temporary storage of feces.
• To expel solid and gaseous waste from the gastrointestinal tract.

18. ANUS
• The anus is the last part of the digestive tract. It is a 2-inch long
canal consisting of the pelvic floor muscles and the two anal
sphincters (internal and external).
• The lining of the upper anus is specialized to detect rectal contents.
It lets you know whether the contents are liquid, gas, or solid.
• The internal sphincter is always tight, except when stool enters the
rectum. It keeps us continent when we are asleep or otherwise
unaware of the presence of stool.
• When we get an urge to go to the bathroom, we rely on our external
sphincter to hold the stool until reaching a toilet, where it then
relaxes to release the contents.

20. SPHINCTERS
• A ring-like muscles that contract or close a bodily opening or
passage in the alimentary canal to prevent backflow.
• 3 Sphincters in the Alimentary Canal:
1. Cardioesophageal Sphincter – prevents the backflow of food
from the stomach to espophagus.
2. Pyloric Sphincter – prevents the backflow of food from the
small intestine to stomach.
3. Anal Sphincter – prevents the release of feces/wastes.

21. ACCESSORY ORGANS (THE
GLANDS)

22. LIVER
• The liver weighs about 3 pounds and is the second largest
organ in the body.
• The liver has many different functions in the body, but the
main function of the liver in digestion is the production of bile
and its secretion into the small intestine.
• Bile is a yellowish substance for fat digestion.
• Liver filters out toxins and waste including drugs and alcohol
and poisons.

23. GALL BLADDER
• A small, pear-shaped organ located just posterior to the liver.
• The gallbladder is used to store and recycle excess bile from
the small intestine so that it can be reused for the digestion of
subsequent meals.
• Stores bile from the liver, releases it into the small intestine.
• Fatty diets can cause gallstones.

24. PANCREAS
• A large gland located just inferior and posterior to the stomach. It is about 6
inches long.
• The pancreas secretes digestive enzymes into the small intestine to complete
the chemical digestion of foods, digest fats, carbohydrates and proteins.
• 2 kinds of Enzymes:
1. Amylase - a protein made by the pancreas and by glands in and around
your mouth and throat. It helps you break down carbohydrates and
starches into sugar.
2. Lipase - an enzyme that breaks down dietary fats into smaller molecules
called fatty acids and glycerol.
• Regulates blood sugar by producing hormones such as:
1. Insulin – lowers blood sugar level
2. Glucagon – increases blood sugar level

26. NORMAL FLORA
• Are bacteria inside human body:
1. Colon - Escherichia Coli (E. Coli); Bacteria that causes UTI. They are
found in urine through urinalysis.
2. Stomach – Helicobacter Pylori; acidophyllic or acid-loving bacteria;
pathogenic for chronic acidity; bacteria that causes ulcer.

27. ANY
QUESTIONS
?