Contents A detailed ladled description of the digestive system.

3 Outline the structure and function of the digestive system.. 4 Main Structure. 5 ?     Mouth. 5 ?     Teeth.

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5 ?     Pharynx. 5 ?     Oesophagus. 5 ?     Stomach. 5 ?     Duodenum.. 5 ?     Bile duct 5 ?     Ileum.

. 5 ?     Villus. 5 ?     Appendix. 5 ?     Caecum.. 5 ?     Colon.

5 ?     Rectum.. 5 ?     Anus. 5 ?     Hepatic Portal System..

5 Accessory Organs 5 ?     Salivary Glands. 5 ?     Liver 5 ?     Gall Bladder 5 ?     Pancreas. 5 Identify the four layers of the alimentary canal 6 Submucosa. 6 Muscularis layer 6 Serosa. 6 Explain the five stages of the digestion. 6 1.

    Ingestion. 6 2.    Digestion. 6 3.    Absorption. 6 4.    Assimilation. 6 5.

    Egestion. 6 Describe two disorders of the Digestive System.. 6 1.    Coeliac Disease. 6 Symptoms.

7 Available Treatments. 9 2.    Disorder Two Irritable Bowel Syndrome + Description. 9 Symptoms. 9 Treatments available. 9 References.

10   A detailed ladleddescription of the digestive system.                        Fig 1.0 – Diagram of the DigestiveSystem1 Outline thestructure and function of the digestive systemTheHuman Digestive System is the system used by the human body for the digestionof nutrients. It consists mainly of the Digestive tract, also known as theGastrointestinal Tract (G.I. Tract), and is supplemented by a number ofaccessory organs. This series of structures and organs are the methods throughwhich solids and liquids pass through the body and are converted into formabsorbable into the bloodstream.

The system also contains structures whichfacilitate the isolation and elimination of waste products from the body.TheG.I. Tract begins at the lips and ends at the anus, consisting of the mouth andteeth for mastication, and the tongue to mix food with saliva produced by thesalivary glands; the oesophagus; the stomach the small intestine, consisting ofthe duodenum, the jejunum and the ileum; and the large intestine, consisting ofthe cecum, the assenting colon, the transverse colon, the descending colon andthe sigmoid colon, which leads to the final section of the digestive system,the rectum.  Digestivejuices aiding digestion are produced in the salivary glands, the gastric glandsin the stomach lining, the pancreas, and the liver and the gall bladder. Theseorgans all contribute to the mechanical and chemical disintegration of ingestedfood and to the eventual elimination of non-digestible wastes2. Main Structure3·        MouthThe Mouth is the firstpart of the digestive system.

At this stage mechanical digestion occurs andsolid food is broken down into smaller pieces through the process ofmastication. The teeth are responsible for this mechanical digestion. Littledigestion takes place during this stage, it is mainly to prepare food forfurther digestion at later stages in the system. Bolus is formed in the mouthwhen food is mixed with saliva ·        TeethThe Teeth are hard,white structures found in the mouth and used in mastication. The shape and functionof the teeth are specific to the diet of the animal.

Because Humans areOmnivores, we contain a wide variety of teeth with specialisation somewherebetween Herbivores and Carnivores to consume both meat and plants. Because fewanimals can digest cellulose, the cells are broken apart through mastication sothat the cells condense are exposed to digestive enzymes4.There are 4 types of teeth: Incisors, Canines, Premolars and Molars.

 ·        PharynxThe Pharynx (also knownas the throat) is a “cone-shaped passagewayleading from the oral and nasal cavities in the head tothe oesophagus and larynx”5. The lower chambersof the Pharynx contain a small flat that separate the oesophagus from thetrachea.  Peristalsis begins in thePharynx.  ·        OesophagusThe oesophagus is a long muscular tubeabout 25 cm long who’s function is to pass food from the pharynx tothe stomach. The upper third of the oesophagus is composed of striated(voluntary) muscle. The movement of objects down through the oesophagus isaccomplished by peristalsis; which, as noted above, originate in the pharynx. Bolusenters the stomach at the base of the oesophagus6.

  ·        StomachThe Stomach is a muscularJ-shaped organ in the abdominal cavity. It has a capacity of approximately 1.5 Litresand can store food for up to 4 hours.

Food is churned in the stomach andgastric juices added to form Chyme (partially digested food). The highest partof the stomach is called the Fundus and acts as a reservoir to accept foodafter it enters the stomach. The largest anatomical structure of the stomach iscalled the body. This section maintains “the acid secreting glands whichcontributes to digesting semi-solid food in to smaller particles.”7The lowest part of the stomach is called the Antrum.

This is where liquified, Chymeis passed into the small intestine.  ·        Bile ductThebile duct is a long connecting tube line organ that connects the Liver to theIntestine though the Duodenum. “The bile from the liver is transported to theintestine by the bile duct. 8”  ·        DuodenumThe first part of the smallintestine is known as the Duodenum. The Duodenum is the shortest part of the intestine,receives Chyme from the stomach and begins the absorption of nutrients.

The Chyme ismixed with chemical secretions form the Liver, Gall Bladder and Pancreas toprepare it for further digestion. This is where the pH of the Chyme is alteredto real a level more acceptable for digestion in the intestine.  ·        JejunumThis is the middle segment of the smallintestine between the duodenum and the ileum. “Most of the nutrients present infood are absorbed by the jejunum before being passed on to the ileum forfurther absorption.”9The nutrients in the Chyme are absorbed through making contact with the villi ·        IleumThis is the finalsegment of the small intestine. The Ileum is about 3.5 meters in length. This is wherethe absorption of the vitamin B12occurs and is also responsible forthe reabsorption of conjugated bilesalts.

10·        VillusThe Villus (Plural: Villi) are tiny projection like structures surrounding the walls of the interior ofthe small intestine. “The villinumber about 10 to 40 per square millimetre (6,000 to 25,000 per square inch)of tissue. They are most prevalent at the beginning of the small intestine anddiminish in number toward the end of the tract. They range in length from about0.5 to 1 mm (about 0.

02 to 0.04 inch).”11 Theprimary function of the Villi are to increase the available surface area in thesmall intestine so as to increase the rate of nutrients abortion.

 ·        AppendixThe Appendix is a organ located at intersection betweenthe large intestine and the cecum widely believed to be vestigial. However, thereare many in the field of immunology who believe the appendix serves a function inthe immune system12.”Also, the worm-shaped organ outgrowth acts like abacteria factory, cultivating the good germs… If a person’s gut flora dies,they can usually repopulate it easily with germs they pick up from other people…But before dense populations in modern times and during epidemics of cholerathat affected a whole region, it wasn’t as easy to grow back that bacteria andthe appendix came in handy,” said Duke surgeryprofessor Bill Parker. ·        Caecum·        Colon·        Rectum·        Anus·        Hepatic Portal System Accessory OrgansThe Accessory Organs have been determined using notesacquired during lectures13. ·        Salivary Glands Chemicaldigestion begins in the mouth by mixing with Saliva released from the salivaryglands.

The three major parts of the salivary glands are: the parotid, thesubmandibular, and the sublingual glands. The secreting cells of the parotidglands are of the serous type; those of the submandibular glands,of both serous and mucous types. Saliva contains a starch-digesting enzymecalled amylase which begins the process of enzymatic hydrolysis.14 ·        Liver·        Gall Bladder·        Pancreas·        TongueThe Tongue is an extremely mobileand muscular organ located on the floor of the mouth. Its function is the guideand maintain the food between the teeth during mastication. The tongue’s glandsproduce some of the saliva necessary to swallow.

  Identify the fourlayers of the alimentary canalAsshown in Chapter 23. The Digestive System15, thefour tissue layers of the Alimentary canal are as follows            Mucosa Submucosa Muscularis layer Serosa Explain the fivestages of the digestion1.     Ingestion2.

     Digestion3.     Absorption4.     Assimilation5.     EgestionDescribe twodisorders of the Digestive System1.     Coeliac DiseaseAccording to the website of the Irish Charity, CoeliacSociety of Ireland16,Coeliac Disease can be described as follows: Coeliac Disease is an auto-immune disease thatcauses some individuals to react to the protein (gluten) found in wheat, barleyand rye.

If a person with coeliac disease eats gluten, the small villi locatedalong the wall of the small intestine becomes damaged, reducing their abilityto absorb the nutrients from food. Coeliac is classified as an auto-immune disease because thebodily mistakenly identifies Gluten as a threat to the body and causes aninflammatory response in the small intestine damaging the micro-villi. Symptoms17Aslisted on the HSE’s public information website, the symptoms of Coeliac Disease”can vary widely from person to person. A methodthat is often used to classify possible symptoms of coeliac disease definesthree types of the condition, based on the associated symptoms.”1)      SilentCoeliac DiseaseNoSymptoms or very mild Symptoms.

·        Long-term complications can still occur,including: Osteoporosis, or failure to grow at a normal rate.  2)      MinorCoeliac Disease·        indigestion·        mild abdominal (stomach) pain·        bloating·        occasional changes in bowel habit, such as episodesof mild diarrhoea or constipation·        anaemia (tiredness, breathlessness and an irregularheartbeat, caused by a lack of iron in the blood)·        loss of appetite·        weight loss·        tingling and numbness in your hands and feet(neuropathy)·        vomiting (usually only affects children)·        some loss of hair (alopecia, usually onlyaffects adults) 3)      MajorCoeliac Disease·        diarrhoea, which can often suddenly occur duringthe night, resulting in incontinence·        weight loss·        stomach cramps·        muscle spasms·        swelling of your hands, feet, arms and legs, causedby a build-up of fluid (oedema) Available TreatmentsBecause Coeliac Disease is an adverse reaction to the Gluten Protein,abstaining from Glutton is the only way to relieve the systems of CoeliacDisease. Adhering to a Gluten Free diets is the main treatment option as thereis currently no cure.

Othertreatments may include18 Treatment of the small intestine with corticosteroids temporarily if the inflammation is severe. Taking dietary supplements if nutritional deficiencies are found. However, once the small intestine heals there should be no need for dietary supplements if your diet is well-balanced and nourishing. You should ask to see a dietitian to help you get started on a gluten-free diet which includes all the nutrients you need.  2.

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