Chapter 23: The Digestive System

Gingivae

(commonly called the gums) are soft tissues that line the alveolar processes and surround the necks of the teeth.

Mechanical digestion

is a purely physical process that does not change the chemical nature of the food.

Apron

- like structure that lies superficial to the small intestine and transverse colon; a site of fat deposition in people who are overweight.

inferior border

Suspends the stomach from the of the liver; provides a pathway for structures connecting to the liver.

Skin

helps protect digestive organs and synthesizes vitamin D for calcium absorption.

breakdown products of digestion

Distension in the stomach and the in the small intestine provoke the gastrocolic reflex, which increases motility, including mass movements, in the colon.

pyloric antrum

Cells that make up the secrete mucus and a number of hormones, including the majority of the stimulatory hormone, gastrin.

Chyme

released from the stomach enters the small intestine, which is the primary digestive organ in the body.

Deglutition

is another word for swallowing- the movement of food from the mouth to the stomach.

serosa

The is the portion of the alimentary canal superficial to the muscularis.

Mucosa

- associated lymphoid tissue and other lymphatic tissue defend against entry ofpathogens; lacteals absorb lipids; and lymphatic vessels transport lipids to bloodstream.

esophagus

The is a muscular tube that connects the pharynx to the stomach.

appendix

The (or vermiform ) is a winding tube that attaches to the cecum.

Sensory

and motor neurons help regulate secretions and muscle contractions in the digestive tract.

teniae coli

The are three bands of smooth muscle that make up the longitudinal muscle layer of the muscularis of the large intestine, except at its terminal end.

autonomic nervous system

The regulates salivation (the secretion of saliva)

presence of food residues

The in the colon stimulates a slow- moving haustral contraction.

emulsification of lipids

Bile is a mixture secreted by the liver to accomplish the in the small intestine.

Bones

help protect and support digestive organs.

Kidneys

convert vitamin D into its active form, allowing calcium absorption in the small intestine.

Enteroendocrine cells

found in the gastric glands secrete various hormones into the interstitial fluid of the lamina propria.

Peristalsis

consists of sequential, alternating waves of contraction and relaxation of alimentary wall smooth muscles, which act to propel food along.

Respiratory organs

provide oxygen and remove carbon dioxide.

salivary glands

Many small are housed within the mucous membranes of the mouth and tongue.

cheeks

The , tongue, and palate frame the mouth, which is also called the oral cavity (or buccal cavity)

plica circulare

Also called a(n) , a circular fold is a deep ridge in the mucosa and submucosa.

parotid glands

The lie between the skin and the masseter muscle, near the ears.

cardiac region

The cardia (or ) is the point where the esophagus connects to the stomach and through which food passes into the stomach.

hepatocyte

A(n) is the livers main cell type, accounting for around 80 percent of the liver's volume.

Muscularis

mucosa- This thin layer of smooth muscle is in a constant state of tension, pulling the mucosa of the stomach and small intestine into undulating folds.

deep crevices

The mucosa between the villi is dotted with that each lead into a tubular intestinal gland (crypt of Lieberkühn), which is formed by cells that line the crevices.

sharp front teeth

The eight incisors, four top and four bottom, are the you use for biting into food.

1067 meters

Also called the gastrointestinal (GI) tract or gut, the alimentary canal (aliment-="to nourish) "is a one- way tube about 7.62 meters (25 feet) in length during life and closer to (35 feet) in length when measured after death, once smooth muscle tone is lost.

mucous membrane

The mucosa is referred to as a(n) , because mucus production is a characteristic feature of gut epithelium.

oral vestibule

The pocket- like part of the mouth that is framed on the inside by the gums and teeth, and on the outside by the cheeks and lips is called the .

Endocrine hormones

help regulate secretion in digestive glands and accessory organs.

pectinate line

The (or dentate line) is a horizontal, jagged band that runs circumferentially just below the level of the anal sinuses, and represents the junction between the hindgut and external skin.

teeth

The , or dentes (singular= dens), are organs similar to bones that you use to tear, grind, and otherwise mechanically break down food.

porta hepatis

The " (gate to the liver) "is where the hepatic artery and hepatic portal vein enter the liver.

Lamina propria

- In addition to loose connective tissue, the lamina propria contains numerous blood and lymphatic vessels that transport nutrients absorbed through the alimentary canal to other parts of the body.

voluntary process

It includes both the of swallowing and the involuntary process of peristalsis.

upper esophageal sphincter

The , which is continuous with the inferior pharyngeal constrictor, controls the movement of food from the pharynx into the esophagus.

labial frenulum

The is a midline fold of mucous membrane that attaches the inner surface of each lip to the gum.

voluntary phase of deglutition

The (also known as the oral or buccal phase) is so called because you can control when you swallow food.

Epithelium

- In the mouth, pharynx, esophagus, and anal canal, the is primarily a non- keratinized, stratified squamous epithelium.

Also called the gastrointestinal (GI) tract or gut, the alimentary canal (aliment

= "to nourish") is a one-way tube about 7.62 meters (25 feet) in length during life and closer to 10.67 meters (35 feet) in length when measured after death, once smooth muscle tone is lost

Epithelium

In the mouth, pharynx, esophagus, and anal canal, the epithelium is primarily a non-keratinized, stratified squamous epithelium

Lamina propria

In addition to loose connective tissue, the lamina propria contains numerous blood and lymphatic vessels that transport nutrients absorbed through the alimentary canal to other parts of the body

Muscularis mucosa

This thin layer of smooth muscle is in a constant state of tension, pulling the mucosa of the stomach and small intestine into undulating folds

There are four main regions in the stomach

the cardia, fundus, body, and pylorus

The large intestine is subdivided into four main regions

the cecum, the colon, the rectum, and the anus

Chemical Digestion and Absorption

A Closer Look

Two types of pancreatic nuclease are responsible for their digestion

deoxyribonuclease, which digests DNA, and ribonuclease, which digests RNA