What is the difference between digestion absorption and metabolism

What is Digestion — Definition, Process, Importance 2. What is Metabolism — Definition, Process, Importance 3. Digestion is one of the four processes responsible for obtaining nutrients by higher animals. The other three are the ingestion , absorption of nutrients, and the elimination of waste.

Here, the absorption of nutrients follows the digestion of food. Generally, digestion occurs in the alimentary canal of higher animals. But, in single-celled animals, it occurs inside vacuoles in the cytoplasm. The main importance of digestion is the breaking down of large food particles into small molecules, which can be readily absorbed by the digestive tract.

Furthermore, digestion occurs by means of both mechanical and chemical digestion. Mechanical digestion is responsible for the breaking down of large food particles into small particles, facilitating the chemical digestion.

Moreover, the three events of mechanical digestion are chewing in the mouth, churning in the stomach, and segmentation in the small intestine. Chewing occurs by the action of teeth in the mouth while churning is the squeezing and mixing up of food with the gastric juice by the action of the muscles of the stomach.

Diet during pregnancy. Food related Illnesses 2. Related Books Free with a 30 day trial from Scribd. Dry: A Memoir Augusten Burroughs. Related Audiobooks Free with a 30 day trial from Scribd. Empath Up! Views Total views. Actions Shares. No notes for slide. Digestion, Absorption, and Metabolism 1. Digestion, Absorption, and Metabolism Introduction: Nutrients released from food remain unavailable to the body until they cross the intestinal wall and enter the circulatory system for transport to tissues 2.

Objectives - Describe the processes of digestion, absorption, and metabolism. Digestive System GI tract alimentary canal composed of :- 1. Mouth 2. Stomach 4. Digestive System 7. Functions of the GI Tract : 1- Receives Food 2- Releases nutrients from food 3- Delivers nutrients into the blood 4- Excretes indigestible foods waste 8. Case Files Collection. Clinical Sports Medicine Collection.

Davis AT Collection. Davis PT Collection. Murtagh Collection. About Search. Enable Autosuggest. You have successfully created a MyAccess Profile for alertsuccessName. Previous Chapter. Next Chapter. Barrett K. Kim E. Barrett, et al. McGraw Hill; Accessed November 11, The process of combining oxygen with a molecule is called oxidation. A person needs hemoglobin to supply oxygen to the cells, and a low level of hemoglobin means oxygen is not available for energy production, which results in a tired feeling.

The teeth provide the first mechanical function of chewing, with the cutting action of the anterior teeth incisors and the grinding action of the posterior teeth molars.

Chewing aids the digestion of food for a simple reason: the digestive enzymes act only on the surface of food particles, and thorough chewing increases the amount of food surface area available to these enzymes. Another mechanical function is performed by saliva, which moistens food and prepares it for swallowing. A chemical function of the mouth is changing cooked starch to dextrin and then to maltose by the salivary enzyme amylase. Physical disorders can begin where digestion starts—in the mouth, or oral cavity.

One type of birth defect of the oral cavity is cleft palate an opening or hole in the roof of the mouth sometimes extending to the lip, which may be referred to as have lip. Severe cases may require surgical correction. Babies with less severe forms of cleft palate, however, may benefit from special bottle nipples that do not require suction or from a slightly larger hole in the bottle nipple. Mothers who are motivated to continue nursing until the problem is resolved should be encouraged to do so with supplemental bottle feedings as needed see Chapter 11 for more ideas.

Missing teeth, severe dental caries, or ill-fitting dentures can adversely affect food choices. Without adequate nutritional knowledge, omitting food groups may not seem important to a person with dental problems. Alternatives should be discussed, such as eating applesauce in place of fresh apples or eating cooked or soft vegetables in place of raw or hard-to-chew vegetables. Prevention of dental caries is addressed in Chapter Swallowing problems, referred to as dysphagia, are often related to stroke, head injury, cerebral palsy, and other conditions Figure Inability to swallow correctly may result in aspiration of food into the lungs.

Aspiration pneumonia is a frequent complication of dysphagia. Dysphagia requires a review of the swallowing process to determine the best means of feeding.

A speech pathologist is trained to help assess swallowing problems. An x-ray examination called videofluoroscopy is used in conjunction with a barium swallow to objectively diagnose dysphagia. The swallowing problem is generally at the pharyngeal area. Liquids are usually the most difficult food to swallow for persons with dysphagia. Liquids that are of a nectar consistency can be used for mild swallowing problems, progressing to the thickness of honey, and as needed the thickness of pudding.

Liquids can be thickened with a commercial product or with baby rice cereal. Feeding positions can also help see Figure and Table Table lists a variety of food consistency considerations. See Chapter 15 for institutional issues and guidelines for provision of altered meal consistencies. Courtesy of the Occupational Therapy Department of the J. In general, swallowing can be divided into the following three stages: 1 the voluntary stage, which initiates the swallowing process, or mechanical function; 2 the pharyngeal stage, which is involuntary and involves the passage of food through the pharynx to the esophagus; and 3 the esophageal stage, which involves passage of food through the esophagus to the stomach through peristaltic wave contractions.

Food must be masticated chewed thoroughly so that it can be mixed with saliva, which aids digestion. However, a glass of water at mealtime is beneficial to the digestive process as long as it does not take the place of mastication. The esophagus transfers food from the oral cavity to the stomach.

This process is complicated and can go awry with neurologic or neuromuscular disorders. Respiration is generally only minimally stopped during the act of swallowing. Poorly chewed food, however, increases the risk of obstruction of the airway, especially for persons with an impaired swallowing reflex, in whom oxygen deprivation can occur because breathing and swallowing cannot be done simultaneously.

In achalasia the lower part of the esophagus fails to relax, and swallowing difficulty occurs. The individual senses fullness in the sternal region and may vomit; then there is danger that the contents of the esophagus may be aspirated into the respiratory passages.

Weight loss may become a problem that requires nutritional intervention. Dilation of the esophagus or surgical intervention can improve the condition. Including semisolid foods can help a person manage this condition. The presence of food in the stomach stimulates functioning of the digestive tract.

Food is kept in motion by the muscular walls of the stomach, which bring it into contact with the gastric juice secreted by stomach cells. The fundus of the stomach acts as a temporary storage place for food. Various gastric juice enzymes work in the stomach to digest the different macronutrients. Complex proteins are partially digested by pepsin protease ; milk protein is coagulated by renin, then is partially digested by pepsin.

Emulsified fats are digested to fatty acids and glycerol by lipase. Hydrochloric acid aids these digestive enzymes and increases the solubility of calcium and iron. Mucus protects the lining of the stomach from the hydrochloric acid. Once solid food is reduced to a semiliquid state chyme , it is passed from the stomach to the small intestine.

Functional disorders of the stomach reflex disorders involve a change in body functions without detectable changes in structural tissue.

One example is dyspepsia indigestion. Alterations in the hydrochloric acid content of gastric juice is another functional disorder. A hiatal hernia is a protrusion of a part of the stomach through the esophageal hiatus opening of the diaphragm Figure Persons with this disorder sometimes complain of heartburn because of the reflux of gastric contents into the esophagus. Medical treatment includes ingestion of antacids to neutralize or inhibit gastric secretions and possibly surgery.

Small, frequent meals are recommended to reduce symptoms, although dietary modifications cannot eliminate the cause. No food is advised for approximately 3 hours before bedtime, and the person should remain in the upright position after eating. For the obese person, weight loss is indicated to help relieve pressure on the diaphragm. Any source of pressure on the abdomen, such as bandages or clothes that fit too tightly, should be eliminated.

Gastritis acute or chronic is an inflammation of the lining of the stomach that results in abdominal pain, nausea, and vomiting. It may be caused by food poisoning, overeating, excessive intake of alcohol, or bacterial and viral infections. A chronic condition may be related to other disease states. It often precedes the development of ulcers or cancer. Acute gastritis, which usually heals within a few days, is often treated first with antibiotics and neutralization of the stomach contents.

The stomach is allowed to rest for a while, then the patient drinks clear fluids for the first day or two. A peptic ulcer is an eroded lesion in the lining mucosa of the stomach gastric ulcer or duodenum duodenal ulcer. Excess use of nonsteroidal antiinflammatory drugs NSAIDs can contribute to the erosion of the mucosal lining.

In recent years Helicobacter pylori infection has been increasingly recognized as being involved in the development of peptic ulcers.

Symptoms include burning or gnawing pain in the pit of the stomach. While an ulcer is bleeding, no food is allowed; instead the patient may be given intravenous feedings of dextrose and amino acids. As the condition improves, the patient usually progresses from a full liquid diet to a regular diet with the omission of irritants based on individual tolerances.

Common intolerances include caffeine, alcohol, and spicy foods, but some individuals have no adversity with these substances Table The dumping syndrome is a condition related to stomach surgery. Surgery for ulcers is not uncommon. Obesity surgery may also result in the dumping syndrome see Chapter 6. It has been found that the dumping syndrome may occur even years after gastrectomy removal of the stomach or portions of it. Hypoglycemia can be a consequence. Individuals presenting with hypoglycemia and a history of stomach surgery may have the dumping syndrome.

Seizures resulting from hypoglycemia may occur Harder and colleagues,