BTECLEVEL 3 PHARMACEUTICAL SCIENCES Assignmenton  DIGESTIVESYSTEM (UNIT14 – PHYSIOLOGY)  Task1 (P6, P7)  DigestiveSystem: Weneed a continuous supply of nutrients to maintain the proper functioning andstructure of our body. Digestive system ensures that these nutrients are madeavailable for the body. These nutrients are derived from the food we eat. Foodcomes from water, organic molecules such as fats, carbohydrates, proteins,vitamins etc, and inorganic salts.

Food provides fuel to the body in the formof calories which are required by the body to carry out daily activities. Thesecalories mainly come from carbohydrates and fats. Proteins support the growthand repair functions of the body. Inorganic salts are important to keep runningmany of the body processes e.g.

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sodium, potassium, and chloride act aselectrolytes and maintain fluid balance and normal blood pressure. Thedigestive system consists of a group of organs which help in the ingestion,breakdown, digestion, absorption, and egestion (excretion) of the food. Theseorgans make up the Digestive Tractand the Accessory Structures thatlie outside the tract but are connected to it through tubes or ducts. TheDigestive Tract is composed of the mouth, pharynx, oesophagus, stomach, andsmall and large intestines. The accessory structures that lie outside the tractare the salivary glands (parotid, submandibular, sublingual glands), pancreas,liver, and gallbladder.

 Circulationof blood also plays an important part in the digestive system. The circulationinvolving stomach, small and large intestines, pancreas, and liver is calledthe Splanchnic Circulation. Blood tothese organs is pumped by the heart through the arteries coming from theabdominal aorta. The blood that leaves these organs then goes to the liverthrough portal vein. This part is called PortalCirculation. Flow of blood through the splanchnic circulation increaseswhen we eat a meal. This helps in taking up of the digestion products from thedigestive tract. This also supplies extra oxygen and other important nutrientsto meet the extra energy demands created by the processes which occur after ameal.

 Thereare different sections of the digestive system each having a differentfunction. Mouth: Whenwe eat, the food is broken down into smaller pieces by the act of chewing. Thischewing is aided by biting and grinding of teeth which helps in mechanicaldigestion. Skeletal muscles of the jaws, lips, cheeks, and tongue aid in theprocess of chewing.

The food is reduced to particles of a size which isconvenient for swallowing. This constitutes mechanical digestion.Thedigestion is facilitated by the release of saliva by salivary glands, whichlubricates the food.

The saliva contains an enzyme called Amylase which beginsthe chemical digestion of starch.Thereare  Pharynx: Oesophagus: Stomach: Foodis propelled along the Oesophagus into the stomach. Churning of the stomachhelps in mechanical digestion which further breaks the food into even smallerpieces. This is aided by the water and mucous which is secreted by the glandsin the stomach lining. Hydrochloric acid is also secreted into the stomachwhich kills microorganisms and makes the stomach environment acidic. The enzymePepsin is activated in the acidic condition which begins the chemical digestionof proteins. Small Intestine:   Duodenum: Theportion of food which is mostly liquidised passes through the Pyloric Sphincterinto the Duodenum. The sphincter is a muscular constriction at the base of thestomach.

The mucus in the duodenum is mildly alkaline. Pancreatic juice issecreted into the duodenum through a duct. It contains digestive enzymes whichhelp in the digestion of food. Bile is also released from the bile duct whichhelps in the digestion of fats. Ileum:Itis the longest part of the digestive system. This is where most of thenutrients from the food are absorbed into the blood stream.

The internal liningof the ileum consists tiny finger like projections called Villi which increasethe surface area for absorption.  Large Intestine: Inthis part of the digestive system, water is reabsorbed from the food so itforms a semi solid mass called Faeces. This is composed of a mixture ofundigested material from the food, dead cells from gut lining, and bacteriawhich is then excreted out of the body. Certain minerals and vitamins are alsoabsorbed here. Thefaeces is excreted from the rectum through the opening called Anus.


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