Chapter 8: Digestive System and Nutition

What is the lumen?

Lumen is the hollow space of an organ or vessel and in the GI tract, the central space where food is digested. the moment has four layers each layer has a particular function and disorder.

What is mechanical digestion

Mechanical digestion occurs when our teeth chew food into pieces convenient for swallowing. We have 20 smaller deciduous, or baby teeth that are eventually replaced by 32 adult teeth.

How does movement contribute to the digestive system?

Movement of the GI tract contents along the digestive tract is very important for the checkbook to its other functions food must be passed along one organ to the next normally by contractions of the smooth muscle tissue called peristalis and indigestible remains must be expelled.

What is saliva? What is amylase?

Saliva is a solution of water and mucus. It also contains amylase, an enzyme that begins chemical digestion of starch, as well as bicarbonate and the anitmicrobial compound called lysozymes.

What are sphincters? What does the sphincter do when swallowing food, describe the process?

Sphincters are muscles that encircle tubes and act as valves. The tubes close when the sphincters contract and they open when relaxed. When swallowing the sphincter relaxes for a moment to allow the food to enter the stomach, then it contracts, preventing the acidic stomach contents from backing into the esophagus.

What is the second layer of the GI tract?

Submucosa is the second layer of the GI wall. The submucosa layer is a broad band of loose connective tissue that contains blood vessels lymphatic vessels and nerves. These vessels carry nutrients absorbed by the mucosa.

What occurs when swallowing?

Swallowing has a voluntary phase. Once food and drinks are pushed back into the pharynx, swallowing becomes reflex action performed automatically. During swallowing the food normally enters the esophagus, a muscular tube that moves food into the stomach because other possible avenues are blocked. The soft palates moves back to close off the nasal passages, and the trachea moves up the epiglottis to cover the glottis.

What are the two main parts of teeth? What materials make up these two parts?

Teeth have two main divisions: 1. a crown, the portion of the tooth above the gum line. 2 a root , the portion below the gum line. The crown has a layer of enamel, an extremely hard outer covering of calcium compounds, detention, a thick layer of bonelike material; and an inner pulp that contains the nerves and the blood vessels. Dentin and pulp also make up a portion of the root, which includes periodontal membranes to anchor the tooth to the jawbone.

What is the fourth layer of the GI tract?

The fourth layer is the outermost layer and it is called the serosa, which secretes a lubricating fluid. The serosa is part of the peritoneum, the internal lining of the abdomin cavity.

What is the glottis?

The glottis is the opening to the larynx and therefore the air passage. We do not breathe when we swallow.

What is the 1st layer of the GI tract? What does it do? Name an example of a digestive enzyme?

The inner layer of the wall next to the lumen is called the mucosa. The mucosal layer contains cells that produce and secrete mucus used to protect all layers of the tracts from the digestive enzymes inside the lumen. Glands in the mucosa of the mouth, stomach and small intestine also release digestive enzymes. Hydrocloric acid, an important digestive enzyme is produced by glands in the mucosa of the stomach.

How does absorption contribute to the digestive system?

Absorption occurs at subunit molecules produced by chemical digestion cross the wall of the GI tract and into the cells my name to tract. From there the nutrients into the blood for delivery to the cells.

What is digestion?

Digestion involves the breakdown of larger pieces into smaller pieces that can then be acted on by digestive enzymes. Digestion can be mechanical or chemical. Mechanical digestion occurs in the mouth by chewing or by wavelength contractions of the smooth muscle in the stomach. Chemical digestion is when digestive enzymes hydrolyzed food macromolecules into absorbable subunits. The digestive enzymes all have a pH range at which they function best. Hence the compartmentalization of the digestive tract establishes ideal Ph ranges. Chemical digestion begins in the mouth, moves to the stomach, and ends in the small intestines.

What is Diverticulosis? Where does it occur? What does it do?

Diverticulosis is a condition in which portions of the mucosa any part of the GI tract but primarily the large intestine pushes through other layers and form a pouch where food can collect. When the pouches become infected or inflamed the condition is called diverticulitis.

How does elimination contribute to the digestive system?

Elimination removes molecules that cannot be digested it needs to be discharged from the body the removal of indigestible wases through the anus is called defecation.

What other disorders occur in the mouth?

Gum disease known to be linked to cardiovascular disease, is more apt to occur with aging. Inflammation of the gum is called gingivitis, can spread to the periodontal membrane, which lines the tooth socket. A person then has periodontitis, characterized by a loss of bone and loosening of the teeth.

When does heartburn occur?

Heartburn occurs when the lower esophageal sphincter fails to open and allow food into the stomach or when the sphincter is opened and food moves from the stomach back to the esophagus. This damages the esophagus and lower esophageal sphincter.

What is ingestion?

Ingestion occurs when the mouth takes in food. Ingestion can be associated with our diet

What is irritable bowel syndrome? What do people suggest is the cause behind IBS?

Irritable bowel syndrome occurs when contractions of the wall cause abdominal pain, constipation, and diarrhea. The underlying cause of irritable bowel syndrome is not known, although some people believe it's because this area is under nervous system control. Stress might be an underlying cause.

What parts lead to the pharynx?

The mouth and nasal passages lead to the pharynx, which is a hollow space at the back of the throat. The pharynx opens into both the food passage and air passage. These two tubes are parallel to each other, with the trachea anterior the esophagus.

How does the mouth contribute to the digestive? Where does the lips start and end? What bounds the mouth? Why is one portion of our lip more red than others?

The mouth received food and begins the process of mechanical and chemical digestion. The mouth is bounded externally by lips and cheeks. The lips extend from the base of the nose to the start of the chin. The red portion of the lip is poorly keratinized this allows blood to show through.

What is a rugae? What are gastric glands? What's the purpose th

The mucosa of the stomach has deep folds called the rugae. These disappear as the stomach fills to approximate capacity of 1 liter. The mucosa has gastric pits that lead to gastric glands, which produce gastric juice. Gastric juice contains enzymes called pepsin which digest protein plus HCL(causing the stomach to be very acidic pH 2) and mucus. The stomach's acidity kills bacteria

What is the gastro intestinal tract? What is its function?

The organs of the digestive system are within a tube called the gastrointestinal tract, where molecules that are too big to cross the plasma membrane are broken down by digestions or hydrolyzed. Hydrolyze is to use water to break down molecules into their subunits. Subunit molecules many monosaccharides amino acids, fatty acids, and glycerol can cross the plasma membrane with the use of facilitated or active transport. The nutrients made available by digestive processes are carried by the blood to our cells.

What does the peristalsis do? Does this help in the chemical digestion of food?

The peristalsis pushes food through the esophagus. The peristaltic contractions continue in the stomach and intestines. The esophagus plays no role in the chemical digestion of food. Its sole purpose is to move the food bolus from the mouth to the stomach. A constriction called the lower gastroesophageal sphincter marks the entrance of the esophagus to the stomach.

What function does the roof of the mouth serve? What are the two parts of the roof of your mouth?

The roof of the mouth separates the nasal cavities from the oral cavity. The roof has two parts: an anterior (toward the front) hard palate, which has several bones and a posterior (toward the back) soft palate, which is all muscle. The soft palate ends in a finger shape projection called uvala.

How many layer does the stomach have, list all each one? What are each of their functions?

The stomach has four layers, but two of them are modified for particular functions. The muscular is contains three laters of smooth muscle. In addition to the circular and longitudinal layers. The stomach also has a layer of smooth muscle that runs obliquely to the other two. The oblique layer also allows the stomach to stretch and to mechanically break down food into smaller fragments that are mixed with gastric juice.

Describe the physical characteristics of the stomach. What's its function?

The stomach is a thick walled, J-shaped organ that lies on the left side of the body beneath the diaphragm. The stomach is continuos with the esophagus above the duodenum of the small intestine below. The stomach stores food, initiates the digestion of protein and controls the movement of food into the small intestine. Nutrients are not absorbed by the stomach. But it does absorb alcohol.

What is the third layer of the GI tract?

The third layer is termed the muscularis which contains two layers of smooth muscle. The inner is a circular layer around the GI tract. The second is the outer which is longitudinal and lies in the same direction as the tract. The contraction of these muscles under nervous and hormonal control is peristalis. Movement after this is digested food moving from the esophagus to the anus. The muscularis is associated with irritable bowel syndrome.

Describe the properties of the tongue? What muscles is the tongue composed of? The tongue assist what other body part?

The tongue is covered by mucous membrane, which contains the sensory receptors called taste buds. When taste buds are activated by the presence of food, nerve impulses travel by way of nerves to the brain. The tongue is composed of skeletal muscle, and it assist the teeth in carrying out mechanical digestion by moving the food around th mouth. In preparation for swallowing, the tongue forms chewed food into a mass called bolus, which it pushes into the pharynx.

How do salivary glands secrete saliva? Where are they located?

There are three pairs of salivary glands. Salivary glands secrete saliva via ducts to the mouth. One pair is at the side of the face below and in front of the ears. The ducts open on the inner surface of the cheek just above the 2nd upper molar. This pair swells when a person has mumps, a viral disease. Another pair lies beneath the tongue and beneath the floor of your oral cavity. These ducts open under the tongue.

Where are your tonsils. What kind of tissue are they. Where is the adenoid and what is it?

Tonsils are also at the back the mouth on either side of the tongue. Tonsils are lymphatic tissue and help protect us from disease. In the nasopharynx, the location where the nasal cavity opens above the soft palate, there is a single pharyngeal tonsil. This is called the adenoids.

Who does tooth decay occur? What is another name for tooth decay?

Tooth decay, called dental caries or cavities, occurs when bacteria within the mouth metabolize sugar. Acids produced during this metabolism erode the teeth. Tooth decay can be painful when it is severe enough to reach the nerves of the inner pulp.

What can prevent tooth decay?

Two measures can prevent tooth decay: eating a limited amounts of sweets and daily brushing and flossing of teeth. Fluoride treatments, can make the enamel strong and more resistant to decay.

When does vomiting occur?

Vomiting occurs when strong contractions of the abdominal muscles and the diaphragm force the contents of the stomach into the esophagus and into the oral cavity.