Organs of the Digestive System and Accessory Organs of the Digestive System

Main Functions of the Colon

-Absorption of water, minerals, and vitamins (80% of water is absorbed in the large intestine) -Support helpful bacteria that help produce Vitamins K, Vitamin B, and Folic acid for the body to use -Secretion of mucous to move fecal material along -Elimination of indigestible material

Salivary Glands Function to:

-Dissolve food for tasting -Moisten food for swallowing -Produce amylase for primary chemical digestion. This enzyme changes complex starch to simple organics. -Clean the mouth and teeth.

Nutrients needed by the body:

-Glucose/Monosaccharides -Ions (K, Na, Cl) -Amino acids -Water -Vitamins/Minerals -Fatty acids

Livers Metabolic Activities

-Metabolism of carbohydrates, amino acids, and fats -Storing and releasing nutrients and minerals such as glycogen, vitamins, iron, and copper -Metabolizing alcohol and other drugs -Detoxification-formation and excretion of bilirubin.

5 Functions of the Stomach

-Temporary storage of food -Mechanical breakdown/digestion of food -Chemical breakdown/digestion of food -Limited amounts of absorption (ions, water, and lip soluble compounds such as alcohol and caffeine) -Production of intrinsic factor (production from parietal cells and helps facilitate the absorption of vitamin B12)

Cardiac Sphincter

A circular muscle around the distal end of the esophagus where it joins the proximal end of the stomach. Helps prevent regurgitation of the stomach contents into the esophagus.

The Stomach

Connects the esophagus and the small intestine. It is a j-shaped pouch located in the upper left quadrant of the abdominal cavity to the left of the liver and anterior to the spleen. It is a highly acidic environment due to hydrochloric acid production and secretion. The external wall forms 2 curvatures.

The Common Bile Duct

Formed by the union of the hepatic and cystic ducts and empties into the duodenum.

Greater Curvature

Forms the lateral (lower) border of the stomach.

The Pancreas

Located across the posterior abdominal wall from the C-shaped curve of the duodenum. Has both endocrine and exocrine functions. As an exocrine gland the pancreas produces pancreatic juice which help the digestive system. As an endocrine gland it secretes the hormones insulin and glucagon. Produces digestive enzymes such as amylase to convert to complex molecule starch to the simple sugar. Produces Lipase to convert fats to fatty acids and glycerol. Produces trypsin the enzyme responsible for the conversion of protein polypeptides to amino acids. Pancreatic juice is also alkaline and neutralizes the substance that enters the duodenum.

Submandibular Salivary Gland

Located under the jaw.

Sublingual Salivary Gland

Located under the tongue.

The Small Intestine

Part of the digestive system that extends from the stomach to the large intestine. The mucosa of the small intestine consists of simple columnar epithelial cells containing microvillus. Goblet cells secrete mucous, endocrine glands secrete hormones, and lymph tissue destroys pathogens. Functions are digestion and absorption.

The Liver

The largest gland in the body. Located in the upper right portion of the abdominal cavity below the diaphragm. Divided into two lobes, a large right lobe and a smaller left lobe. The only digestive function is the production of bile which contains the waste products of erythrocyte destruction and functions in the physical breakdown of lipids. Oxygenated blood is carried by the hepatic artery while venous blood is carried by portal veins. In the sinusoids of the liver, products in the blood received from the digestive organs are secreted and removed. The central veins unite to form the hepatic vein and drain blood to the inferior vena cava.

The Mouth

(teeth and tongue) Involved in ingestion, chewing, and swallowing. This mechanical digestion breaks food into smaller pieces.

Organs of the Large Intestine:

-Cecum with appendix attached -Colon (ascending, transverse, descending, sigmoid) -Rectum -Anus

Sphincters

2 located at each end of the stomach.

Salivary Glands

3 pairs that secrete saliva. Saliva from the exocrine glands is carried via ducts into the mouth.

The Esophagus

A muscular mucous membrane lined tube located posterior to the trachea. Functions as a passageway to take food from the pharynx to the stomach. Peristalsis propels food into the stomach.

The Gallbladder

A pear shaped muscular sac attached to the inferior surface of the right love of the liver. Bile from the liver flows into the gallbladder where it is concentrated and stored until it is needed by the small intestine.

Cecum

A pouch at the proximal end of the large intestine.

Pyloric Sphincter

A powerful circular muscle around the distal end of the stomach where it joins to the proximal end of the small intestine. Functions as a valve to prevent regurgitation of food back into the stomach from the duodenum. Also controls gastric emptying.

The Large Intestine

AKA the colon, extends from the ileum of the small intestine to the opening of the outside of the body called the anus. No digestion takes place.

The Pharynx

Acts as a food passageway from the oral cavity to the esophagus. Is divided into the oropharynx and Laryngopharynx food passageways. The second function is swallowing. Swallowing is a three-staged coordinated reflex. As food enters the esophagus waves of muscular contractions called peristalsis propel the food further down the alimentary canal.

4 Colons

Ascending, Transverse, Descending, Sigmoid

4 Regions of the Stomach

Cardiac, Fundus, Body, Pylorus

The Pancreatic Duct

Carries pancreatic juice. Involves small ducts that unite to form larger ducts. These larger ducts unite to form the main pancreatic duct. The main pancreatic duct emerges from the medial side of the pancreas and joins the common bile duct and drains digestive juices into the duodenum.

Digestion

Completed in the small intestine. Presence of chyme in the duodenum stimulates enzyme production in the small intestine. Accessory organs such as liver, pancreas and gallbladder also produce digestive enzymes. In protein digestion, peptidases, such as pepsin, break down proteins into peptides and amino acids. In carbohydrate digestion, the action of enzymes such as sucrose, maltase, and lactase reduce complex carbohydrates to monosaccharides that can be absorbed and used by the body. In fat digestion, the enzyme lipase digests fat to form fatty acids and glycerol. Intestinal glands also secrete hormones.

The Hepatic Duct

Drains the bile directly from the liver.

The Cystic Duct

Drains the bile that is stored in the gallbladder.

3 Sections of the Small Intestine

Duodenum, jejunum, ilieum

Lesser Curvature

Forms the upper medial wall of the stomach.

4 Major Ducts Which Drain the Accessory Organs

Hepatic duct, cystic duct, common bile duct, pancreatic duct.

Sigmoid Colon

In here, feces are moved along by peristaltic action for elimination.

Rugae

Large folds of the stomach that flatten out to allow the stomach to expand when needed. Stretches so it doesn't burst.

Accessory Organs of the Digestive System

Liver, gallbladder, and pancreas.

Parotid Salivary Gland

Located close to the ear.

Absorption

Most absorption of body nutrients takes place in the small intestine.

Ilocecal Valve

Sphincter-like valve between the small and large intestine. After undigested food pass from the ileum to the cecum this valve prevents the back flow of fecal material.

Peristalsis

Squeezing motion like holding a yogurt tube and squeezing out the yogurt.

The Cardiac

The first region of the stomach that opens to the esophagus.

The Body

The large central portion of the stomach between the fundus and the pyloric regions.

The Fundus

The most superior region of the stomach as it sits above the level of the esophagus opening.

The Pylorus

The small narrow region of the stomach that connects to the duodenum of the small intestine.

Rectum and Anus

The terminal of the digestive system.