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Digestive System

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Title: Digestive System


1
Digestive SYSTEM
2
Introduction
  • The organs of the human digestive system execute
    the basic function of digesting or breaking down
    the foods into appropriate substances and
    nutrition, that can be easily assimilated by the
    human body. Throughout the process of digestion,
    there are several organs which contribute to the
    breaking-down process of food.
  • The human digestive system can be classified into
    two basic sections, namely the upper
    gastrointestinal tract and the lower
    gastrointestinal tract.

3
Upper Gastrointestinal Tract
  • Mouth The first organ that directly contributes
    to the digestion process is the mouth.
  • Tongue It also helps in chewing and swallowing,
    which is also known as deglutition. This process
    is basically, the physical simplification of
    food.
  • Teeth we have 36 teeth are responsible for
    physical breakage of food. chewing makes
    digestion easier for the other organs of the
    digestive system to break down the food and its
    nutrients.
  • Pharynx and Esophagus pharynx, which lies
    behind the mouth Instead, the pharynx diverts the
    food to the esophagus, a muscular tube that
    connects the mouth to the stomach. Though, the
    pharynx and esophagus are not directly related to
    the actual simplification of food.
  • Stomach food is broken down into simpler
    nutrients, like vitamins, carbohydrates, proteins
    etc.

4
Lower Gastrointestinal Tract
  • Small Intestine One of the most important
    functions of this organ is abrogation of
    nutrients.
  • Large Intestine responsible for the abrogation
    of water and salts from the digested foods.
  • Anus The anus is among the organs of the
    digestive system that does the job of ejecting
    the waste matter from the body.

5
Auxiliary Organs
  • The human body has some very important organs in
    the digestive system which can be classified as
    the auxiliary organs. Without these auxiliary
    organs, the process of digestion would become
    almost impossible.
  • Gallbladder The gallbladder is a very important
    organ that is responsible for the storage of bile
    that has been produced by the liver.
  • Liver The liver is one of the most important
    organs of the human body, as it is also necessary
    for survival. The liver basically performs the
    task of producing digestive juices, biochemicals
    and also helps in protein synthesis.
  • Pancreas Pancreas consists of glandular tissue
    and a system of ducts. The main pancreatic duct
    is responsible for carrying the pancreatic fluid
    to the duodenum. The endocrine and exocrine
    parts of pancreas play an important role in
    digestion.

6
Anatomy
  • The Mouth and Throat

7
The Major Salivary Glands
8
Esophagus
  • Sphincters
  • Upper
  • Lower

9
Stomach
  • Functions
  • Mixes food
  • Reservoir
  • Starts digestion of Protein , Nucleic acids ,
    Fats.
  • Activates some enzymes
  • Destroys some bacteria
  • Makes intrinsic factor B 12 absorption
  • Absorbs Alcohol , Water , Lipophilic acid , B
    12

10
Small intestine
  • Extends from pyloric sphincter ? ileocecal valve
  • Regions Duodenum , Jejunum, Ileum.
  • Absorbs 80 ingested water , Electrolytes ,
    Vitamins , Minerals , Carbonates
    (Active/facilitated transport , Mono saccharides
    ) , Proteins(Di-/tripeptides , Amino acids),
    Lipids(Monoglycerides , Fatty acids , Micelles ,
    Chylomicrons)
  • Requires pancreatic enzymes bile to complete
    digestion

11
Large intestine
  • Extends from ileocecal valve to anus
  • Regions
  • Cecum Appendix
  • Colon
  • Ascending
  • Transverse
  • Descending
  • Rectum
  • Anal canal

12
Liver
  • Makes bile Detergent emulsifies fats.
  • Release promoted by Vagus n., CCK, Secretin.
  • Contains
  • Water
  • Bile salts
  • Bile pigments
  • Electrolytes
  • Cholesterol

13
Enzyme that secrete each organ
  • The Mouth or Buccal Cavity
  • The mouth or the oral cavity is the starting
    point of the human digestive system. The buccal
    cavity, which is one of the main parts of the
    digestive system, has a set of 32 teeth, a
    tongue, and salivary glands. All these parts help
    in the chewing and breakdown of the food
    particles. There are three types of salivary
    glands, categorized according to their placement
    in the mouth - parotid, submandibular and
    sublingual. The salivary glands release enzymes
    that partially digest the food in the mouth
    before it is passed to the stomach through the
    esophagus. There is also another part in the oral
    cavity in the throat, known as the pharynx. The
    pharynx is the common pipe for the esophagus and
    the trachea (also known as wind pipe). The main
    pharynx function is the passage of food and air
    to the respective organs.

14
The Esophagus
  • The EsophagusThe esophagus, which is also known
    as the gullet or food pipe, is a long narrow pipe
    that connects the mouth to the stomach. The
    primary esophagus function is transportation of
    food and liquid from the mouth to the stomach.
    The chewed food is passed through the food pipe
    by the process of peristalsis. Peristalsis is a
    process which consists of rhythmic contractions
    of the muscles in the inner wall of the esophagus
    to push the food through the pipe into the
    stomach.

15
Stomach
  • Once all the bolus (chewed food) is transported
    to the stomach the muscle closes and the stomach
    begins its process of churning the food. Gastric
    juices and enzymes (Gastric acid, pepsin (enzyme)
    and other digestive enzymes )are released in the
    stomach which aid in the further digestion of the
    bolus. Hydrochloric acid is also released during
    the process of digestion which helps break the
    protein molecules into peptides. The stomach wall
    has an inner lining that secretes peritoneal
    fluid and mucus to protect the stomach cavity
    from erosion due to the presence of gastric
    juices and acid.The pancreas is a small
    leaf-like gland located below the stomach. The
    pancreas secrete hormones, glucagon and insulin,
    through the pancreatic duct into the stomach to
    assist in the digestion of food. The main
    pancreas function is the metabolism of
    carbohydrates and lipids (or fats). The pancreas
    consist of tiny structures called the islets of
    Langerhans which secrete insulin for the
    additional function of maintaining the blood
    glucose levels.

16
Pancreas
  • The enzymes and sodium bicarbonate are constantly
    released by the pancreas but they are released in
    very small quantities (about 0.2 - 0.3 ml per
    minute). As soon as food is sensed in the small
    intestine, pancreas starts secreting greater
    amount of pancreatic fluid (about 3 mls per
    minute).
  • . As an endocrine gland, it produces hormones
    such as insulin, somatostatin and glucagon and as
    an exocrine gland it synthesizes and secretes
    pancreatic juices that contain digestive enzymes
    which are further passed into the small
    intestine. These digestive enzymes contribute to
    the breaking down of carbohydrates, fats and
    protein content present in the half digested food

17
The Liver and the Gallbladder
  • The liver and the gallbladder secrete enzymes for
    the complete assimilation of food. The liver,
    which is the largest gland in the body, also acts
    as a storehouse for glycogen, vitamins and
    minerals. The liver produces an enzyme called
    bile which metabolizes the fat and protein
    molecules into smaller molecules for the easy
    digestion. The gallbladder is a tiny organ near
    the liver and is a part of the biliary system.
    The gallbladder function is to act as a
    storehouse for bile and also to increase its
    concentration. Together, the liver and the
    gallbladder help to expel urea and other toxic
    wastes from the body, through urine.

18
The Small and the Large Intestine
  • While taking a look at the small intestine
    anatomy, it can be seen that the small intestine,
    also known as the duodenum, is a thin wire like
    structure intertwined and connected to the large
    intestine. The last stage of digestion takes
    place in the small intestine where all the
    nutrients from the food are absorbed. The main
    function of the small as well as the large
    intestine is the absorption digested food. The
    digested food is then assimilated in the small
    intestine and the waste is passed on to the large
    intestine. The last part of the large intestine
    consists of a finger-like structure called cecum
    or appendix, which is a vestigial organ. The
    large intestine then expels the waste out of the
    body to the rectum. The rectum stores the
    undigested food or fecal matter to be dispelled
    from the body through the anus, which is the
    final part of the human digestive system.
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