Chapter 8

Digestive System

Objectives 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 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 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: Digestion Absorption Elimination

Digestion 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: Complicated sugars are reduced to simple

sugars such as glucose Large fat molecules are broken down into

fatty acids and triglycerides

Absorption: 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: 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: 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

Mouth contd: 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: 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: Papillae: small raised areas on the tongue Contain taste buds Gums: Fleshy tissue that surround the sockets

of the teeth

Teeth: 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: 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: 9 to 10 inch muscular tube from pharynx to

stomach Transports the food by means of peristalsis

(involuntary process of wave like contractions)

Esophagus

the tube that connects your mouth and your stomach

Stomach: Food passes from esophagus to stomach Made up of the Fundus – upper potion, body-

middle portion, and antrum- lower portion

Stomach contd: 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: 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: 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: 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: Salivary glands Liver Gallbladder Pancreas

Salivary Glands: 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: 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: 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: 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: 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: An/o Anus Appendic/o Appendix Bil/I Gall, bile Bucc/o Cheek (Facial) Cec/o Belly Cheio/o Saliva Chol/e Gall, bile

Root Words contd: Cholecyst/o Gall bladder Col/o Colon/o Colon Dent/o Teeth Duoden/o Duodenum Enter/o Small intestine Esophag/o Esophagus

Root words contd: Gastr/o Stomach Gingiv/o Gums Gluc/o Sugar Glyc/o Sugar Hepat/o Liver Ile/o Ileum Jejun/o Jejunum

Root words contd: Labi/o Lips Lingu/o Tongue Gloss/o Tongue Lip/o Fat, lipids Or/o Mouth, oral Pancreat/o Pancreas Peritone/o Peritoneum

Root words contd: Pharyng/o Pharynx Proct/o Anus, rectum Rect/o Rectum Sigmoid/o Sigmoid colon Splen/o Spleen

Prefix: Re- Back Retro- Backward, back

Suffix: -ase Enzyme -flux Flow -iasis Abnormal condition -lithiasis stone -lytic destruction, breakdown -pepsia digestion -prandial meal

Suffix contd: -orrhaphy suturing -ostomy artificial opening -tresia opening -tripsy crushing