Health Assessment!!!digestive System

Digestive System

The Components of the Digestive System

Principle Parts of Alimentary Canal • Mouth- mechanical breakdown of food; tasting; secretion of salivary glands (salivary amylase) • Esophagus- muscular tube that connects the mouth with the stomach • Stomach- large muscular storage organ; functions in storage, mixing, some secretions (acid and pepsinogen) • Small intestine (3 parts) • Duodenum, jejunum, ileum • Receives bile, pancreatic amylase, other secretions; absorption of nutrients (most sugars absorbed here) • Large intestine- reabsorption of water; bacteria in colon produce Vit. K • Anus- external opening surrounded by sphincter muscle

DIGESTIVE SYSTEM….. • Makes up: 1. digestive tract Mouth, pharyx, esophagus, stomach, small intestine, large intestine, rectum, and anus. 2. accessory organs of digestion salivary glands, teeth, liver, gallbladder, and pancreas Functions: • Ingest and mechanically break down food. • Digest food: Stomach and small intestine mainly. • Absorb nutrients and water. • Eliminate waste.

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Stages of Food Processing Ingestion: The act of eating. Involves placing food in mouth or oral cavity. 2. Digestion: Macromolecules in food (fats, proteins, polysaccharides, etc.) are too large to be absorbed by digestive system. Must be broken down into small molecules (amino acids, simple sugars, etc.) so they can be absorbed and utilized by the body. Involves two processes: Mechanical: Chewing, peristalsis, and churning movement of the stomach and small intestines to mix food with enzymes and digestive juices. Chemical: Enzymatic breakdown of food. 3. Absorption: Cells lining the digestive cavity take up building blocks (simple sugars, amino acids, etc.), which then enter the bloodstream. 4. Elimination: Undigested food materials are discharged from body.

The Mouth

The digestive tract begins with Mouth (Oral Cavity) Processes of the Mouth • Mastication (chewing) of food • Mixing masticated food with saliva • Initiation of swallowing by the tongue • Allowing for the sense of taste Structures include: 1. Teeth break down food into small pieces. (Chewing or mastication) 2 sets of teeth a. deciduous teeth (20 milk teeth) b. permanent teeth (32) Parts of a tooth 1. Crown – covered with hard brittle enamel 2. Neck – connects the crown and neck 3. Root - anchored to the periodontal membrane by cementum • dentin – nerves, blood vessels, and connective tissue called pulp that supply the tooth with sensation and nutrients

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Tongue

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Muscular organ that occupies the floor of the mouth 2 Major Functions a. facilitates chewing and swallowing. It mixes the chewed food with saliva and then forms the mixture into a mass called a bolus in preparation for swallowing.

b. contains the taste bud and allows us to taste food. Structures: a. Frenelum – anchors the tongue to the floor of the mouth (reason you cannot swallow your tongue) “Children born with extremely short frenulum are often referred to as “tongue tied” b. Extensive capillary network that provides the sublingual area with a rich supply of blood. 3. The Salivary Glands

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A number of glands both inside and outside the oral cavity produce and secrete saliva Saliva functions to • Cleanses the mouth • Dissolves food chemical so that they can be tasted • Moistens food and aids in compacting it into a bolus • Contains enzymes that begin the chemical breakdown of starches • Most saliva is produced by three pairs of extrinsic salivary glands • • •

Parotid – largest of the 3 glands - glands infected by mumps virus Submandibular – located on the floor of the mouth Sublingual – under the tongue; smallest

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SALIVA – watery fluid that contains mucous and digestive enzyme called salivary amylase or ptyalin - approximately 1 L of saliva is secreted per day *Sialolithiasis – obstruction of the salivary ducts by a stone.

4. Cheeks- forms its lateral wall 1) Hard palate forms its anterior roof. 2) Soft palate- forms its posterior roof.

5. Uvula – V- shaped piece of soft tissue that hangs down at the upper back region of the mouth. -prevents food from entering the nose

6. PHARYNX

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Upon swallowing bolus enters the oropharynx Pushed downward into the laryngopharynx Epiglottis closes and bolus enters the Esophagus

Oesophagus “food tube”

The Oesophagus. “food tube” • • •

Passes food down to your stomach. Food moves through the esophagus by Peristalsis [wave of contractions that pushes foods] Contains 2 sphincters a. pharyngoesophageal sphincter - located at the top of esophagus b. gastroesophageal or lower esophageal sphincter (LES) – at the base of the esophagus Gastroesophageal Reflux Disease – poorly functioning LES - allows reflux of stomach into the stomach

Paralytic ileus - Intestinal obstruction involves a partial or complete blockage of the bowel that results in the failure of the intestinal contents to pass through.

Gastroesohageal Reflux Disease -A result of stomach acid backwash into the esophagus, commonly known as heartburn -The lower esophageal sphincter is normally tightly closed, however, fatty foods, cigarettes, alcohol, chocolate, caffeine, and certain meds can relax the sphincter. Deglutition (Swallowing) • Three phases • Voluntary

Bolus of food moved by tongue from oral cavity to pharynx • Pharyngeal Reflex: Upper esophageal sphincter relaxes, elevated pharynx opens the esophagus, food pushed into esophagus • Esophageal • Reflex: Epiglottis is tipped posteriorly, larynx elevated to prevent food from passing into larynx •

The Stomach

STOMACH • Pouch like organ that lies in the upper part of the abdominal cavity under the diaphragm. •

5 digestive functions 1. Secretion of gastric juice Hydrochloric acid (HCl) Mucus (protective) Pepsinogen (inactive form of a protein-digesting enzyme) 2. Secretion of gastric hormones and intrinsic factor (Gastrin Hormone) 3. Regulation of the rate at which the partially digested food is delivered to the small intestine. 4. Digestion of food. 5. Absorption of small quantities of water and disolved substances. absorbs alcohol efficiently.

Regions of the Stomach

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Fundus - is the expanded part of the stomach lateral to the cardiac region. Body- is the mid portion. Pylorus- funnel shaped terminal part of the stomach. -The pylorus is continuous with the small intestine through pyloric sphincter or valve.

Rugae – accordion like folds that allows the stomach to expand. The Stomach • Food digestion starts in stomach with pepsin. • Food is churned in stomach with gastric juice (HCl) to form chyme. • Food remains in stomach from 2 to 6 hours, after which it is released into the small intestine

Small Intestine

Small Intestine Around 6m in an adult Food takes 1-6 h to pass through 2 main tasks = digestion, absorption 3 parts Duodenum Jejenum Ileum • •

Plays important roles in digestion and absorption PARTS: 1. Duodenum – Most digestion and absorption occur in the doudenum 2. Jejunum – Have folds and villi (finger like projections) - Villi have microvilli - Surface area for absorption increases 3. Ileum - Contains fewer folds and villi - Less absorption occurs and passes undigested food to large intestine Ileocecal Valve – prevents reflux of contents from the cecum (part of the large intestine) back into the ileum. • • • • • • • • • • •

Pancreas and liver empty digestive enzymes and bile into the small intestine. Pancreatic amylase: Breaks down starch Trypsin and Chymotrypsin: Break down proteins Lipases: Break down fats Peptidases: Break down proteins Nucleases: Break down DNA and RNA Bile: Helps fat digestion by emulsifying fats. Very large surface area for absorption due to: Large circular folds (villi) Tiny cell surface projections (microvilli). Capillaries drain nutrients from small intestine and then sends them to first to liver and then rest of body.

Large Intestine

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Mainly fibre, dead cell, bacteria and water reach here! As it moves along here most of the water is absorbed into the blood. Faeces are stored in the rectum. Eventually egested out of the anus, roughly 24 –48 hours after eating.

Structures: 1. Cecum - sac like; the first part of the large intestine. • Appendix - Hanging from cecum Function unknown – in herbivores they contain bacteria that help digest cellulose 2. Colon - Reabsorbs water – so waste is converted to semi-solid = faeces a. Ascending colon - on right, between cecum and right colic flexure b. Transverse colon - horizontal portion c. Descending colon - left side, between left colic flexure d. Sigmoid colon - S bend near terminal end 3. Rectum – short, terminal segment of the digestive tube, continuous with the anal canal 4.

Anus - external body opening

Food Breakdown and Absorption in the Large Intestine • • • •

No digestive enzymes are produced Resident bacteria digest remaining nutrients • Produce some vitamin K and B • Release gases Water and vitamins K and B are absorbed Remaining materials are eliminated via feces • Defecation occurs with relaxation of the voluntary (external) anal sphincter and iinvoluntary sphincter (internal)

Associated Structures of Digestive System

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3 important organs – the liver, gallbladder, and the pancreas – empty their secretions into the duodenum. These secretions are necessary for the digestion of food.

A. LIVER - Composed of 2 lobes made up of about 100,000 lobules •

Functions • Removes bilirubin, a hemoglobin breakdown waste product, from the blood and incorporates it into bile. • Produces bile which is stored in gallbladder. • Bile is released into the small intestine after a meal. • Bile contains no enzymes, but helps solubilize fat particles. • Detoxifies blood by removing and metabolizing poisonous substances • Stores iron and fat-soluable vitamins A, D, E, K, and B12 • Produces urea after breaking down amino acids

B. Gallbladder • • •

Liver produces about 1,000 ml of bile a day with excess being stored in the gallbladder. Gallbladder reabsorbs water making bile thick and mucus like. Gallstones may form due to precipitation of cholesterol.

C. Gallstones Most commonly caused by too much cholesterol in bile, these stones are typically green or yellow. People with gallstones suffer from “attacks”, in which extreme pain is experienced in the upper abdominal region and steadily increases for approx. 30-60 min. D. Pancreas Exocrine gland between stomach and small intestine. Produces several digestive enzymes: trypsin: digests proteins

pancreatic amylase: digests starches lipase: digests fats

Processes of the Digestive System • •

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Ingestion – getting food into the mouth Propulsion – moving foods from one region of the digestive system to another peristalsis - a series of involuntary muscle contractions that moves food through the digestive tract. (alternating waves of contraction Absorption - End products of digestion are absorbed in the blood or lymph - Food must enter mucosal cells and then into blood or lymph capillaries Defecation - Elimination of indigestible substances as feces

Propulsion in the Stomach • The pylorus meters out chyme into the small intestine (30 ml at a time) • The stomach empties in four to six hours

NUTRITION •

The science that studies the relationship of food to the functioning of the body.

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Food provides us with fuel to live, energy to work and play, and the raw materials to build new cells. All the different varieties of food we eat are broken down by our digestive system and transported to every part of our body by our circulatory system.  We eat about 500kg of food A Year! Nutrient – substance used by the body for growth, maintenance, and repair Categories of nutrients • Carbohydrates: simple sugars, starches, fiber • Lipids: triglycerides, phospholipids, fatty acids • Proteins: amino acids • Vitamins • Mineral • Water

Carbohydrates • These include simple sugars such as glucose and sucrose and polysaccharides such as starch and cellulose • They are important as structural compounds and as a source of energy that can be used as ATP

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Starch is a complex polysaccharide made in plants cells for the storage of energy • Foods such as potatoes and pumpkins are rich in starch and can be good sources of energy Cellulose is one of the most common carbohydrates and can be found in the cell walls of plants • Human digestive system is unable to break down cellulose and is the largest component of dietary fiber

Vitamins and Minerals • Small organic molecules that serve as coenzymes in metabolic reactions or have highly specific functions. • Must be obtained from the diet because the body does not produce them, or does so in insufficient amounts. • Certain vitamins function as antioxidants. • 2 classes of vitamins: • Fat-soluble • Water-soluble

GROUP NUTRTION: SOLIMEN, Katelyn TERNOLA, Shari Anne VALLES, Leo Karlo WAKAT, Wennie Clare WALSI-EN, Marianne