PoHS Digestive System

What is the digestive system?

a series of hollow organs joined in a long, twisting tube from the mouth to the anus

Basic functions of digestive system?

The food enters by mouth, breaking down of nutrients for cells, releasing food’s nutrients, and absorbing nutrients into te body (breaks down food into a form which the body can use)

Ingestion

process of food entering the body

mastification

(chewing) process where food is inserted into the mouth and chewed with teeth

propulsion

movement of food through the digestive tract

mixing

movement of food (back and forth) within the digestive tract to mix with digestive secretions

secretion

works to lubricate, liquefy, buffer, and igest food as it moves through the digestive tract

digestion

process of breaking down nutrients into forms which can be easily used by cells within the body

absorption

movement of nutrients out of the digestive system and into the bloodstream for cells

defecation

elimination of waste products from the body

Primary Organs of the Digestive System

−oral cavity

−pharynx

−esophagus

−stomach

−small intestine

−large intestine

Oral Cavity

•Supports mastication of food

•Starts the process of chemical digestion

−enzymes in saliva begin to break down food

•Includes:

−lips and cheeks

−palate

−tongue

−salivary glands

−teeth

Pharynx

•Is a passageway for food down the throat

•Consists of three parts:

−nasopharynx, oropharynx and laryngopharynx

Esophagus

•Is a tube connecting the pharynx to the stomach

−composed of smooth muscle
tissue

•Moves food to the stomach
by rhythmic waves of
muscle contractions,
known as peristalsis

Stomach

•Is a muscular organ which breaks down food through:

−secretion of acid and
enzymes in gastric juice

•hydrochloric acid

−muscles churning food

•Deflates when no food
is present

−called a ruga

Small Intestines

•Supports digestion and absorption of food

•Is the longest portion of the GI tract

•Is a coiled tube with three main regions:

−duodenum

−jejunum

−ileum

Contains intestinal glands; includes the crypt of Lieberkühn (secrete intestinal glands) and Brunner’s glands (secretes alkaline fluids that protect from acidic contents)

Large Intestine

Last portion of the digestive tract and frames the small intestine

It is responsible for the following:

• finishing the absorption of nutrients and water (cecum=absorption of water and salt, and it attaches to the appendix)

• synthesizing vitamin K and biotin

• forming and eliminating feces form the body

  • colon: prepares fecal matter

  • rectum: separates gas and feces

  • anus: controls defecation via two sphincters

Accessory Organs

Have a variety of functions within the digestive system

• includes the liver, gallbladder, and pancreas

Liver

-Beneath the diaphragm and is protected by the rib cage

-Produces bile

-Stores nutrients filtered from the bloodstream

-converts ingested nutrients into usable forms

-detoxifies the body

Gallbladder

Muscular sac located under the liver’s right lobe

-Concentrates and stores bile produced in the liver

Pancreas

-gland-like organ which sits behind the stomach and connects to the duodenum

-has both exocrine and endocrine functions

• exocrine: secreting digestive enzymes

• endocrine: releasing hormones into the blood

-Produces pancreatic juice to aid in digestion

-produces protein-digesting enzymes

-produces starch-digesting enzymes