Chapter 15

How does Bile form?

1. Bile is a yellowish-green liquid that hepatic cells secrete; it includes water, bile salts, bile pigments, cholesterol, and electrolytes. 2. Bile pigments are breakdown products from red blood cells. 3. Only the bile salts have a digestive function.

Major events during Swallowing

1. Food is mixed with saliva and voluntarily forced into the pharynx with the tongue. 2. Sensory receptors in the pharynx sense food, which triggers swallowing reflexes. 3. In the third stage of swallowing, peristalsis transports the food in the esophagus to the stomach.

structure of the gallbladder

1. The gallbladder is a pear-shaped sac lying on the interior surface of the liver. 2. It is connected to the cystic duct, which joins the hepatic duct; these two ducts merge to form the common bile duct leading to the duodenum.

Differences Between the structures of the small and large intestine

1. The large intestinal wall has the same four layers found in other areas of the alimentary canal, but lacks many of the features of the small intestinal mucosa such as villi. 2. Fibers of longitudinal muscle are arranged in teniae coli that extend the entire length of the colon, creating a series of pouches (haustra).

Liver Functions

1. The liver carries on many diverse functions for the body. 2. The liver is responsible for many metabolic activities, such as the metabolism of carbohydrates, lipids, and proteins. 3. The liver also stores glycogen, vitamins A, D, and B12, iron, and blood. 4. The liver filters the blood, removing damaged red blood cells and foreign substances, and removes toxins. 5. The liver's role in digestion is to secrete bile.

Peristalsis in the large intestine vs. peristalsis in the small intestine

1. The movements of the large intestine are similar to those of the small intestine. 2. Peristaltic waves happen only two or three times during the day. 3. Defecation is stimulated by a defecation reflex that forces feces into the rectum where they can be expelled.

Absorption of Proteins/Amino Acids

Amino acids are absorbed into the villi by active transport and are carried away in the blood.

Bile Salts Function

Bile salts emulsify fats into smaller droplets and aid in the absorption of fatty acids, cholesterol, and certain vitamins.

Explain how a tooth is anchored in its socket.

Cementum and the periodontal ligament anchor the tooth.

Hepatic Lobule

Consist of hepatic cells radiating from a central vein. Hepatic sinusoids separate groups of hepatic cells.Blood from the hepatic portal vein carries blood rich in nutrients to the liver.

Types of Teeth

Different teeth are adapted to handle food in different ways, and include incisors, cuspids, bicuspids, and molars.

Liver Structure

Divided into right and left lobules, and is enclosed by a fibrous capsule

Parts of the Small Intestine

Duodenum - the shortest and most fixed portion of the small intestine jejunum - the rest is mobile and lies free in the peritoneal cavity. ileum. - " "

Structure of the Tooth

Each tooth consists of two main portions called the crown and the root. The crown is the portion above the gum and is covered by glossy white enamel. Beneath the enamel is the bulk of the tooth, which is made up of dentin. Dentin surrounds the central cavity, which houses the blood vessels, nerves and connective tissue. The root is enclosed by cementum, which is surrounded by the periodontal ligament. The region where the crown and root meet is called the neck.

Intestinal digestive Enzymes

Epithelial cells of the mucosa have embedded digestive enzymes on their microvilli, including peptidases, sucrase, maltase, lactase, intestinal lipase.

Absorption of Fats

Fatty acids and glycerol are absorbed by diffusion into the lacteals of the villi. They are then carried away by lymph

What makes up feces?

Feces are composed of undigested material, water, electrolytes, mucus, and bacteria.

How is chyme produced?

Following a meal, mixing actions of the stomach turn the food into chyme and pass it toward the pyloric region using peristaltic waves.

What stimulus relaxes the ileocecal sphincter?

Gastroileal reflex increases peristalsis and forces some of the contents into the cecum.

Function of Intestinal villus

Greatly increase the surface area available for absorption and aid in mixing actions. 2. Each villus contains a core of connective tissue housing blood capillaries and a lymphatic capillary called a lacteal.

How is secretion of bile regulated?

Hepatopancreatic sphincter muscle controls the release of bile from the common bile duct. Cholecystokinin stimulates the gallbladder to contract.

Function of intestinal glands

Intestinal glands at the bases of the villi secrete large amounts of watery fluid that carry digestive products into the villi.

Other digestive Enzyme

Intrinsic factor = helps with absorption of B12 and vitamins

Where are the tonsils located?

Lingual tonsils are lymphatic tissues located at the root of the tongue. The Palatine tonsils lie beneath the epithelial lining of the mouth and, help protect the body against infection. The pharyngeal tonsils are on the posterior wall of the pharynx, above the soft palate.

Describe the two basic movements in the alimentary canal

Mixing and Propelling movements - Mixing movements occur when smooth muscles contract rhythmically in small sections of the tube. Propelling movements include a wavelike motion called peristalsis, which is caused by contraction behind a mass of food as relaxation allows the mass to enter the next segment of the tube.

Absorption In the small intestine (carbohydrates/simple sugars)

Monosaccharides are absorbed by the villi through active transport or facilitated diffusion and enter blood capillaries.

anal canal

Opens to the outside as the anus. Guarded by an involuntary internal anal sphincter and a voluntary external sphincter muscle.

Structure of Pancreas

Pancreatic acinar cells merge to form pancreatic duct. The pancreatic and bile ducts join and empty into the small intestine, which is surrounded by the hepatopancreatic sphincter.

Enzymes in Pancreatic Juice

Pancreatic amylase Pancreatic lipase Trypsin Chymotrypsin Carboxypeptidase Two nucleases.

Functions of Pancreatic Juice

Pancreatic juice contains enzymes that digest carbohydrates, fats, proteins, and nucleic acids.

Function of the Gallbladder

Pear shaped and connects to the cystic duct. Hepatopancreatic sphincter muscle controls the release of bile from the common bile duct.

Most Important digestive enzyme in gastric juice

Pepsin, or inactive pepsinogen

What regulates secretion of the pancreatic juice?

Protein-digesting enzymes are released in an inactive form and are activated upon reaching the small intestine.

Liver Color

Reddish-brown

What stimulates salivary glands to secrete saliva?

Salivary glands contain serous cells that produce a watery fluid with amylase, and mucous cells that produce lubricating and binding mucus. Salivary glands receive parasympathetic stimulation that triggers the production of a large volume of saliva at the sight or smell of food.

How do primary teeth differ from secondary teeth?

The 20 primary teeth are shed in the order they appeared and are replaced by 32 secondary teeth. Through the actions of chewing, teeth break food into smaller pieces, beginning mechanical digestion.

Organs of the Digestive System

The alimentary canal, extends from the mouth to the anus, and several accessory organs. The alimentary canal includes the mouth, pharynx, esophagus, stomach, small intestine, large intestine, rectum, and anus. The accessory organs include the salivary glands, liver, gallbladder, and pancreas.

Function of the esophagus

The esophagus functions as a tube that transports substances from the pharynx to the stomach. It is a collapsible structure. Has a lower esophageal sphincter that helps to prevent regurgitation of the stomach contents.

Mucosa

The inner layer is the mucosa, which is lined with epithelium attached to connective tissue; it protects tissues of the canal and carries on secretion and absorption.

Absorption of water

The intestinal villi also absorb water by osmosis.

Parts of the large intestine

The large intestine consists of Cecum - much at the beginning Colon - Ascending, Transverse, and Descending Appendix Rectum Anus

Why doesn't the stomach digest itself?

The mucous cells associated with the gastric glands and the stomach's inner surface release an alkaline secretion that coats the inside of the wall. Pepsinogen also helps.

The Muscular Layer

The muscular layer consists of inner circular fibers and outer longitudinal fibers that propel food through the canal.

Submucosa

The next layer is the submucosa, which is made up of loose connective tissue housing blood and lymph vessels and nerves; it nourishes the surrounding layers of the canal.

Serosa

The outer layer, or serosa, is composed of visceral peritoneum that protects underlying tissues and secretes serous fluid to keep the canal from sticking to other tissues in the abdominal cavity.

Where are the major salivary glands located?

The parotid glands are the largest salivary glands and are located in front of, and somewhat below, each ear between the skin of the cheek and the masseter muscle. The submandibular glands are located in the floor of the mouth on the inside surface of the lower jaw. The sublingual glands are the smallest of the salivary glands and are on the floor of the mouth under the tongue.

What factors influence how quickly chyme leaves the stomach?

The rate at which the stomach empties depends on the fluidity of the chyme and the type of food.

Function of Saliva

The salivary glands secrete saliva, which moistens and dissolves food particles, binds them together, allows tasting, helps to cleanse the mouth and teeth, and begins carbohydrate digestion.

Movements of the small intestine

The small intestine carries on segmentation and peristaltic waves.

Regions of the stomach

The stomach is divided into cardiac, fundic, body, pyloric regions and a pyloric canal.

Tongue Function in the Digestive System

The tongue is a thick, muscular organ covered by mucous membrane with taste buds within papillae; it is attached to the floor of the mouth by the frenulum. The skeletal muscles mix food with saliva during chewing and move food toward the pharynx during swallowing. The papillae also provide friction for moving food around in the mouth.

Wall of the alimentary canal

The wall of the alimentary canal consists of the same four layers throughout its length, with only slight variations according to the functions of specific sections of the canal. There is the mucosa, submucosa, the muscular layer, and the serosa.

Secretions of Chief and Parietal Cells

They are in the deeper part of gastric glands. Chief Cells = Digestive enzyme Parietal Cells = Hydrochloric acid Products of these form gastric juice.

Liver Location

Upper right hand quadrant of the abdominal cavity

What substances does the large intestine absorb?

Water and Electrolytes

Regions of the Pharynx

a. Nasopharynx b. Oropharynx c. Laryngopharynx

What is the function of the large intestine?

absorbs water and electrolytes and forms and stores feces. 1. The large intestine does not digest or absorb nutrients, but it does secrete mucus. 2. The large intestine absorbs electrolytes and water. 3. The large intestine contains important bacteria which synthesize vitamins and use cellulose.

What is the odor in feces?

action of bacteria

The teeth that are best adapted for grasping and tearing food are the

canines

Kupffer Cells

carry on phagocytosis in the liver

Pyloric Sphincter

controls release of food from the stomach into the small intestine.

Mesentery

double layers fold of peritoneum that suspends small intestine form posterior abdominal wall

Absorption of Electrolytes

electrolytes by active transport and diffusion

What bacteria inhabits the large intestine?

intestinal flora

Nasopharynx

located above the soft palate.

Oropharynx

located behind the soft palate and projects downward to the upper border of the epiglottis.

Laryngopharynx

located from the upper border of the epiglottis downward to the lower border of the cricoid cartilage of the larynx.

Cells that produce pancreatic juice

pancreatic acinar cells

Function of Small Intestine

receives secretions from the pancreas and liver, completes digestion of the nutrients in chyme, absorbs the products of digestion, and transports the remaining residues to the large intestine.