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69 Cards in this Set

  • Front
  • Back
Alimentary canal
Alimentary canal
Is a continuous, hollow, muscular tube that winds through the ventral body cavity and is open at both ends.

The organs in the alimentary canal include the mouth, pharynx, esophagus, stomach, small intestine, and large intestine.

The large intestine ends at the anus.

It performs the digestive functions (ingests, digests, absorbs, and defecates).
Accessory organs
(teeth, tongue, and glands) assist in the process of digestive breakdown.
The uvula
is a fleshy fingerlike projection of the soft palate, which extends inferiorly from the posterior edge of the soft palate.
The lingual frenulum
The lingual frenulum
is a fold of mucus membrane that secures the tongue to the floor of the mouth and limits its posterior movements.
The pharynx is subdivided into...
the nasopharynx, the oropharynx, and the laryngopharynx.

The walls of the pharynx contain two skeletal muscle layers. Alternating contractions of these two muscle layers propel food through the pharynx into the esophagus below.
The esophagus
runs from the pharynx through the diaphragm to the stomach.

The esophagus is about 10 inches long and conducts food by peristalsis to the stomach.

The walls of the alimentary canal from the esophagus to the large intestine are made up of the same four tissue layers or tunics.
The mucosa
is the innermost layer, a moist membrane that lines the cavity of the organ. The submucosa is found just beneath the mucosa. It contains blood vessels, nerve endings, mucosa-associated lymphoid tissue, and lymphatic vessels.
The muscularis externa
is a muscle layer.
The serosa
is the outermost layer of the wall.
A single layer of fluid-producing cells
the visceral peritoneum.
The stomach
The stomach
is on the left side of the abdominal cavity, behind the liver and diaphragm.

The stomach can hold up to 1 gallon of food. When it is empty, it collapses inward on itself, and its mucosa is thrown into large folds called rugae.
The different regions of the stomach include...
The different regions of the stomach include...
the cardiac region, which surrounds the cardioesophageal sphincter through which food enters the stomach from the esophagus.

The fundus is the expanded part of the stomach.

The body is the midportion, and at the terminal part of the stomach is the funnel shaped pylorus.

The pylorus is continuous with the small intestine through the pyloric sphincter, or valve.
The convex lateral surface of the stomach is...
The convex lateral surface of the stomach is...
the greater curvature; its concave medial surface is the lesser curvature.
The chief cells
produce protein-digesting enzymes.
The parietal cells
produce corrosive hydrochloric acid, which makes the stomach contents acidic.
After food has been processed in the stomach, it resembles heavy cream and is called
Chime.

The chime enters the small intestine through the pyloric sphincter.
The small intestine
is the body's major digestive organ where nearly all food absorption occurs.

The small intestine is a muscular tube extending from the pyloric sphincter to the large intestine.

It is the longest section of the alimentary tube with an average length of 7 to 13 feet.
The small intestine has three subdivisions, the...
duodenum, the jejunum, and the ileum.
ileum meets the large intestine at the...
ileocecal valve, which joins the large and small intestines.
The pyloric sphincter...
controls food movement into the small intestine from the stomach and prevents the small intestine from being overwhelmed. Some enzymes are produced by the intestinal cells.
More important are enzymes that are produced by the pancreas and then ducted into the duodenum through the...
pancreatic ducts, where they complete the chemical breakdown of foods in the small intestine.
Bile (formed by the liver) also enters the duodenum through the...
bile duct in the same area.
bile duct in the same area.
Local collections of lymphatic tissue...
Local collections of lymphatic tissue...
(Peyer's patches) increase in number toward the end of the small intestine.

The remaining (undigested) food residue in the intestine contains huge numbers of bacteria, which must be prevented from entering the bloodstream.
The large intestine
is much larger in diameter than the small intestine.

The large intestine is about 5 feet long and extends from the ileocecal valve to the anus.

Its major functions are to dry out the indigestible food residue by absorbing water and to eliminate these residues from the body as feces.
It frames the small intestine on three sides and has five subdivisions:
cecum, appendix, colon, rectum, and anal canal.
The sac-like cecum...
is the first part of the large intestine.
The appendix
hangs from the secum and is a potential trouble spot because it is an ideal spot for bacteria to accumulate and multiply.

Inflammation of the appendix, appendicitis, is the usual result.
The colon is divided into several distinct regions:
ascending colon
transverse colon
descending colon
sigmoid colon
The ascending colon...
travels up the right side of the abdominal cavity and makes a turn to travel across the abdominal cavity as the transverse colon.

It then turns again and continues down the left side as the descending colon, to enter the pelvis, where it becomes the S-shaped sigmoid colon.
The sigmoid colon, rectum, and anal canal...
lie in the pelvis.
The anal canal has an external voluntary sphincter (the external anal sphincter) composed of...
skeletal muscle and an internal involuntary sphincter (internal anal sphincter) formed by smooth muscle. These sphincters open and close the anus, and are ordinarily closed except during defecation, when feces are eliminated from the body.
The accessory organs of the digestive system include...
the teeth, salivary glands, pancreas, liver, and gallbladder.
The first set of teeth that erupt are...
the deciduous teeth, or baby teeth.

The second set of teeth are the permanent teeth.
Permanent teeth are classified according to shape and function including...
incisors, canines, premolars, and molars.

The incisors are adapted for cutting and the canines are for tearing or piercing.

The premolars (bicuspids) and molars have broad crowns with rounded cusps (tips) and are best suited for grinding.
A tooth consists of two major regions:
the crown and the root.
The enamel-covered crown is...
the exposed part of the tooth above the gum.
The portion of the tooth embedded in the jawbone is the root; the root and crown are connected by the tooth region called the...
The portion of the tooth embedded in the jawbone is the root; the root and crown are connected by the tooth region called the...
neck Dentin

a bonelike material, underlies the enamel and forms the bulk of the tooth. It surrounds a central pulp cavity, which contains a number of structures collectively called pulp. Pulp supplies nutrients to the tooth tissues and provides for tooth sensations.
Where the pulp cavity extends into the root, it becomes...
Where the pulp cavity extends into the root, it becomes...
the root canal

which provides a route for blood vessels, nerves and other pulp structures to enter the pulp cavity of the tooth.
Three pairs of salivary glands empty secretions into the mouth. The large parotid glands lie...
anterior to the ears.
The submandibular glands and the small sublingual glands...
empty secretions into the floor of the mouth through tiny ducts. The product of the salivary glands is saliva.
The pancreas
is a gland that extends across the abdomen from the spleen to the duodenum. The pancreas produces enzymes that break down all categories of digestible foods.
The liver is...
the largest gland in the body and is located under the diaphragm. One of its functions is to produce bile.
Bile leaves the liver through the...
common hepatic duct and enters the duodenum through the bile duct.
The gallbladder
is a small green sac underneath the liver.
When food digestion is not occurring...
bile backs up the cystic duct and enters the gallbladder to be stored.

While in the gallbladder, bile is concentrated by the removal of water.

When fatty food enters the duodenum, a hormonal stimulus prompts the gallbladder to contract and spurt out stored bile, making it available to the duodenum
Ingestion:
The active, voluntary process of placing food in the mouth. Food must be placed into the mouth before it can be acted on.
Propulsion:
The process of propelling food from one organ to the next.
Swallowing is one example of food movement that depends largely on the propulsive process called...
peristalsis.

Peristalsis is involuntary and involves alternating waves of contraction and relaxation of the muscles in the organ wall.
Segmentation
normally moves food back and forth across the internal wall of the organ, serving to mix it with the digestive juices. Therefore, segmentation is an example of mechanical digestion than propulsion.
Food breakdown (mechanical digestion):
Food breakdown (mechanical digestion):
The mixing of food in the mouth by the tongue, churning of food in the stomach, and segmentation in the small intestine are all examples of processes contributing to mechanical digestion.

Mechanical digestion prepares food for further degradation by enzymes by physically fragmenting the foods into smaller particles.
Food breakdown (chemical digestion):
Food breakdown (chemical digestion):
The sequence of steps in which large food molecules are broken down to their building blocks by enzymes is called chemical digestion. These reactions are called hydrolysis reactions, because a water molecule is added to each bond to be broken.

Water is also necessary as a dissolving medium and a softening agent for food digestion. The chemical breakdown of carbohydrates, proteins, and fats is summarized below.
Absorption:
The transport of digested end products from the lumen of the GI tract to the blood or lymph.

For absorption to occur, the digested foods must first enter the mucosal cells by active or passive transport processes.

The small intestine is the major absorptive site.
Defecation:
The elimination of indigestible residues from the GI tract via the anus in the form of feces.
Digestive activity is mostly controlled by...
reflexes via the parasympathetic division of the autonomic nervous system.
Swallowing is a complex process that involves the coordinated activity of several structures. The first phase is...
the voluntary buccal phase and occurs in the mouth.
Once the food has been chewed and well mixed with saliva, the bolus (food mass) is forced into the pharynx by the tongue. As food enters the pharynx, it is controlled by reflex activity. The second phase...
the involuntary pharyngeal-esophageal phase, transports food through the pharynx and esophagus.

The parasympathetic division of the autonomic nervous system controls this phase and promotes the mobility of the digestive organs forward from this point.
Once food reaches the distal end of the esophagus, it presses against the...
Once food reaches the distal end of the esophagus, it presses against the...
cardioesophageal sphincter, causing it to open, and the food enters the stomach.
Secretion of gastric juice...
is regulated by both neural and hormonal factors
The sight, smell, and taste of food stimulate...
parasympathetic nervous system reflexes, which increase the secretion of gastric juice by the stomach glands.
In addition, the presence of food and a rising pH in the stomach stimulate the stomach cells to release the hormone...
gastrin

Gastrin prods the stomach glands to produce still more of the protein digesting enzymes, mucus, and hydrochloric acid.
About _________ of gastric juice are produced every day.
2‒3 liters
Makes the stomach contents very acidic, which is necessary for protein digestion...
Hydrochloric acid
The pylorus of the stomach, which holds about ___ of chime, acts like a meter that allows only ____________________ to pass through the pyloric sphincter.
The pylorus of the stomach, which holds about ___ of chime, acts like a meter that allows only ____________________ to pass through the pyloric sphincter.
30 ml

liquids and very small particles
It takes about ______ for the stomach to empty completely after an individual eats a well-balanced meal and _______ if the meal has a high fat content.
It takes about ______ for the stomach to empty completely after an individual eats a well-balanced meal and _______ if the meal has a high fat content.
4 hours

6 hours or more
Food reaching the small intestine is _____________________________. Carbohydrate and protein digestion has begun, but virtually no fats have been digested up to this point.
only partially digested
By the time food reaches the end of the small intestine____________, digestion is complete and nearly all food absorption has occurred.
By the time food reaches the end of the small intestine____________, digestion is complete and nearly all food absorption has occurred.
(3‒6 hours)
The movements most seen in the colon are slow segmenting movements lasting about...
one minute that occur every 30 minutes or so.
The defecation reflex...
is a spinal reflex that causes the walls of the sigmoid colon and the rectum to contract and the anal sphincters to relax.
The liver produces bile which...
leaves the liver through the common hepatic duct and enters the duodenum through the bile duct.

Bile is a yellow-to-green, watery solution containing bile salts, bile pigments, cholesterol, electrolytes, and phospholipids.

Bile salts and phospholipids aid in the digestion of fats in the small intestine.

The bile salts emulsify fats by physically breaking large fat globules into smaller ones, thus providing more surface area for the fat-digesting enzymes to work on.