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Chapter 8
Digestive System
Objectives
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Identify the organs of the digestive system
Determine root words, prefixes and suffixes
appropriate to this system
Identify portions of the tooth
Identify and define some common disorders
Identify and explain medical treatments and
procedures pertaining to the digestive system
Gastroenterology
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Branch of medicine specializing in the
diagnosis and treatment of diseases,
conditions, affecting the lower gastrointestinal
tract. (GI tract)
Gastroenterologist is the physician who treats
abnormal conditions of the GI tract
Digestive system
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Also called the gastrointestinal system or
Alimentary system (Latin alimentum) means
nourishment
Provides a tube like passage through a maze
of organs and body cavities
Begins at the mouth
Ends at the anus
The three main functions:
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Digestion
Absorption
Elimination
Digestion
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Complex food material is taken in through the
mouth and is digested (broken down)
Digestive enzymes speed up chemical
reactions and aid in the break down of
complex nutrients
Complex proteins are digested to amino acids
Digestion contd:
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Complicated sugars are reduced to simple
sugars such as glucose
Large fat molecules are broken down into
fatty acids and triglycerides
Absorption:
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Takes place when the digested food is
absorbed into the blood stream
It is absorbed by going through the walls of
the small intestine
Fatty acids and glycerol enter the lymphatic
vessels mostly
Absorption contd:
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By this method valuable nutrients such as
sugar, fatty acids and amino acids, travel to all
cells of the body
Cells then catabolize (burn) nutrients in the
presence of oxygen to release energy stored
within the food
Cells also use amino acid nutrients to
anabolize (build) large protein molecules
needed for growth and development
Elimination:
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Third function is the elimination of solid
waste material that cannot be absorbed into
the blood stream.
The large intestine concentrates these solid
wastes and pass it out of the body through the
anus
The waste is commonly known as ‘feces’
Organs of the Digestive system
Mouth = or/o pertaining to the oral cavity
 Also known as the buccal cavity
 Includes the lips surround the opening to the cavity
Cheeks: form the walls of the oval shaped cavity
Hard palate: forms the anterior portion of the roof of
the mouth
Soft palate: muscular portion behind the hard palate.
Made up of skeletal muscle and connective tissue
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Mouth contd:
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Rugae: Are irregular ridges in the mucous
membrane covering the anterior portion of the
hard palate
Uvula: small soft tissue projection , hangs
from the soft palate. Aids in sound and speech
Tonsils: masses of lymphatic tissue located in
depressions of the mucous membranes. They
act as filters to protect the body from the
invasion of microorganism
Mouth contd:
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Tongue: solid, strong, flexible structure
covered with mucous membranes.
It extends across the floor of the oral cavity,
and muscles attach it to the lower jaw bone
(mandible)
It moves food around during chewing
(mastication) and swallowing (deglutition)
Principle organ for taste
Mouth contd:
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Papillae: small raised areas on the tongue
Contain taste buds
Gums: Fleshy tissue that surround the sockets
of the teeth
Teeth:
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Every individual has two sets of teeth in their
lifetime. The shape of the tooth determines its name
First set is ‘baby teeth’ (usually beginning to appear
around age 6 months) are the primary teeth or
deciduous teeth) and usually consist of 20 teeth.
Second set ‘permanent teeth’ (usually starting at age
6 years) consist of 32 teeth
Molar usually appear at age 17 years
Pharynx:
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Also known as the throat
A muscular tube lined with mucous
membranes
Food passes from the mouth to the pharynx to
the esophagus
Passageway for air traveling from the nose to
the windpipe
Esophagus:
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9 to 10 inch muscular tube from pharynx to
stomach
Transports the food by means of peristalsis
(involuntary process of wave like
contractions)
Esophagus
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the tube that connects your
mouth and your stomach
Stomach:
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Food passes from esophagus to stomach
Made up of the Fundus – upper potion, bodymiddle portion, and antrum- lower portion
Stomach contd:
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Lining consists of folds called Rugae
This allows the stomach to stretch when food
enters
Sphincters are rings of muscle that control the
openings into and from the stomach
The cardiac sphincter relaxes and contracts
moving food from the esophagus into the
stomach
Stomach contd:
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Pyloric sphincter allows food to leave the
stomach when it has been broken down
Food is churned and mixed with gastric juices
to make semi liquid called chyme
The stomach controls passage of food into the
first part of the small intestine (duodenum)
Food leaves the stomach in 1 to 4 hours or
more
Small intestine:
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Also known as small bowel
Extends from the pyloric sphincter to the first
part of the large intestine
It is about 21 feet long
Three parts; duodenum, jejunum, ileum.
Completes digestion by way of intestinal
enzymes, pancreatic enzymes and bile from
the liver
Large Intestine:
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Extends from the end of the ileum to the anus
Four parts: cecum, colon, sigmoid colon, and
rectum
About five feet long
Absorbs about 80% to 90% of fluids and
electrolytes
Excretes waste and feces
Accessory Organs:
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Salivary glands
Liver
Gallbladder
Pancreas
Salivary Glands:
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Around the oral cavity there are three pairs of
salivary glands.
Parotid gland, Submandibular gland,
Sublingual gland
These glands produce saliva, which contain
digestive enzymes
Narrow salivary ducts carry the saliva into the
oral cavity
Liver:
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Produces a thick greenish fluid called bile
Bile contains cholesterol, bile acids, and
several bile pigments
Bile is continuously released from the liver
It then travels down the hepatic duct to the
cystic duct which leads to the gallbladder
which stores the bile
Liver contd:
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Bile acts as an emulsifying agent on large fat
globules
Without bile most of the fat in the body
remains undigested
The liver also maintains normal blood glucose
Manufactures blood protein particularly the
ones used for blood clotting
Remove poisons from the blood
Gall bladder:
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Stores bile from the liver until needed in the
duodenum to aid in digestion
We can do without our gallbladder
If removed bile will find another home in the
biliary ducts to continue its process
Pancreas:
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Both an exocrine and endocrine organ
As an exocrine gland it produces enzymes to
digest starch, fat, and proteins
As an endocrine gland it secretes insulin,
which is used as a carrier to bring glucose into
cells of the body for energy
Root words:
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An/o
Appendic/o
Bil/I
Bucc/o
Cec/o
Cheio/o
Chol/e
Anus
Appendix
Gall, bile
Cheek (Facial)
Belly
Saliva
Gall, bile
Root Words contd:
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Cholecyst/o
Col/o Colon/o
Dent/o
Duoden/o
Enter/o
Esophag/o
Gall bladder
Colon
Teeth
Duodenum
Small intestine
Esophagus
Root words contd:
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Gastr/o
Gingiv/o
Gluc/o
Glyc/o
Hepat/o
Ile/o
Jejun/o
Stomach
Gums
Sugar
Sugar
Liver
Ileum
Jejunum
Root words contd:
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Labi/o
Lingu/o
Gloss/o
Lip/o
Or/o
Pancreat/o
Peritone/o
Lips
Tongue
Tongue
Fat, lipids
Mouth, oral
Pancreas
Peritoneum
Root words contd:
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Pharyng/o
Proct/o
Rect/o
Sigmoid/o
Splen/o
Pharynx
Anus, rectum
Rectum
Sigmoid colon
Spleen
Prefix:
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ReRetro-
Back
Backward, back
Suffix:
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-ase
-flux
-iasis
-lithiasis
-lytic
-pepsia
-prandial
Enzyme
Flow
Abnormal condition
stone
destruction, breakdown
digestion
meal
Suffix contd:
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-orrhaphy
-ostomy
-tresia
-tripsy
suturing
artificial opening
opening
crushing