A&P 102 Ch. 24 Digestion pre-lab/recall

Muscularis externa

Contains two layers of smooth muscle (inner circular and outer longitudinal) that contract alternately producing rhythmic contractions of peristalsis

Duodenum

First part of the small intestine

Jejunum

Middle part of the small intestine; between the duodenum and the ileum

Colon

Section of the large intestine containing four divisions (ascending, transverse, descending, and sigmoid colon); it extends to the rectum

Emulsification

The first step in the process of lipid digestion, it breaks up the fat globules into smaller pieces with the help of bile salts

Pancreas

-Exocrine and endocrine gland that sits posterior and inferior to the stomach -Its exocrine functions are digestive whereas its endocrine functions are metabolic

Liver

-Organ located on the right side of the abdominal cavity consisting of four lobes -Detoxifies, processes, and eliminates toxins in blood before it enters circulation in body -Produces bile for digestion

Alimentary canal

A tube extending from the mouth to the anus down which food travels; it includes the pharynx, esophagus, stomach, and intestines

Salivary glands

Accessory organs around the mouth that secrete saliva, which contains substances such as water, salivary amylase, antibodies, and lysozyme

Which is the most accurate description of salivary amylase?

Begin(s) carbohydrate digestion in the mouth

Micelles

Clusters of bile salts and digested lipids

Brush border enzymes

Digestive enzyme(s) associated with the enterocytes of the small intestine

Lacteal

Digestive enzyme(s) associated with the enterocytes of the small intestine

Bile salts

Emulsifies/emulsify fats

Pancreatic islets

Endocrine cells of the pancreas (islets of Langerhans) that secrete hormones such as insulin into the bloodstream

Chylomicrons

Enzyme(s) that digest(s) lipids into free fatty acids and monoglycerides

Pancreatic lipase

Enzyme(s) that digest(s) lipids into free fatty acids and monoglycerides

Digestive enzyme

Enzymes produced by organs of the digestive system that catalyze reactions that break food down chemically into smaller molecules

Acinar cells

Exocrine cells of the pancreas that produce and secrete pancreatic juice (i.e., digestive enzymes, bicarbonate, and water) into ducts

True or False? The gallbladder produces and stores bile.

False

True or False? The longest segment of the small intestine is the duodenum.

False

True or False? The peritoneal cavity is located between the visceral peritoneum and the mesentery.

False

Bile

Fluid produced by the liver and stored in the gallbladder that contains bile salts, amphipathic molecules that emulsify fats in the small intestine and aid in their digestion

Which of the following organs is not part of the alimentary canal?

Gallbladder

Liver lobule

Hexagonal plates of cells that have a vein in the center of each lobule that eventually drains into hepatic veins; at each lobule's six corners there are three vessels called portal triads

Ileum

Last part of the small intestine; between the jejunum of the small intestine and the cecum of the large intestine

Submucosa

Layer of connective tissue deep to the mucosa that houses blood vessels, nerves, lymphatics, and elastic fibers

How does the absorption of lipids differ from the absorption of carbohydrates and proteins?

Lipids are packaged into chylomicrons, which are too large to enter capillaries and must instead enter a lacteal.

Why is the digestion and absorption of lipids more complex than the digestion and absorption of carbohydrates and proteins?

Lipids have primarily nonpolar covalent bonds and are, therefore, not soluble in the water-based environment of the intestines. They, therefore, require other steps to be broken down and absorbed.

Peritoneal cavity

Located between a double-layered serous membrane that secretes serous fluid, allowing organs to slide over each other without friction; much of the alimentary canal and many accessory organs reside here

Accessory organ

Organs that assist in mechanical or chemical digestion, including the teeth, tongue, salivary glands, pancreas, and liver

Serosa

Outer connective tissue layer partially composed of the visceral peritoneum found throughout much of the alimentary canal

Chemical digestion

Process by which the chemical bonds between food molecules are broken in chemical reactions

Trypsin

Protein-digesting enzyme(s) produced by the pancreas

Pepsin

Protein-digesting enzyme(s) produced by the stomach

Hydrochloric acid

Required to activate pepsinogen

Gastroesophageal sphincter

Ring of smooth muscle located at the inferior end of the esophagus that prevents contents of the stomach from regurgitating up into the esophagus

Gallbladder

Sac-like organ located under the liver's right lobe that stores the liver's bile; when stimulated by certain hormones, it will contract and eject bile into the cystic duct to aid in digestion

Mucosa

The inner epithelial tissue lining of the alimentary canal; it's composed of simple columnar epithelium overlying the lamina propria and a layer of muscularis mucosa

True or False? The liver consists of plates of hexagonal liver lobules.

True

True or False? The small intestine features three sets of progressively smaller folds that increase surface area for absorption.

True

True or False? The stomach has three layers of smooth muscle that contract to churn food into chyme.

True

The exocrine cells of the pancreas are called __________ and secrete __________. The endocrine cells of the pancreas are called __________ and secrete __________.

acinar cells, pancreatic juice, pancreatic islets, hormones