Digestive system of humans
- 3. Digestion
- 6. • MOUTH OR BUCCAL CAVITY • PHARYNX • ESOPHAGUS • STOMACH • SMALL INTESTINE • LARGE INTESTINE • ANUS
- 8. • PANCREAS • LIVER • GALL BLADDER
- 10. INNER LINING IT HAS MUCUS EPITHELUM CALLED AS LAMINA PROPRIA. PLICAE MEANS FOLDS FUNCTION :- IT HELPSIN ABSORBTION AND SECRETION.
- 11. IT LIES OUTSIDE MUCOSA THICK LAYER OFLOOSE CONNECTIVE TISSUE WITH BLOOD VESSESL AND NERVE ENDINGS.
- 12. IT HAS SMOOTH MUSCLE INNER SMOOTH MUSCLE IS CIRCULAR OUTER LAYER IS LONGITUDINAL FUNCTION:- IT CONTROLLS MOVEMENT AND SECRETION
- 13. IT IS SMOOTH EPITHELIAL LAYER IT IS THE OUTER LAYER THUS CALLED AS ADVENTITIA
- 14. • The digestive system includes the gastro-intestinal tract (mouth to anus) and the glandular organs. • Human digestive system is in the ventral cavity of human body. • This system serves to transfer organic molecules, salts and water from the external environment to the body’s internal environment.
- 15. • Most of the food taken into the mouth are large particles containing macromolecules such as polysaccharides , fats , lipids and proteins. • As such they cannot be absorbed by the intestinal wall. They must be dissolved and broken down into much smaller molecules. • This process is named as digestion. • Digestion is accomplished by substances called enzymes produced from the digestive glands. • The enzymes are biocatalysts in the food breakdown process.
- 16. • SALIVARY AMYLASE BY SALIVARY GLANDS • TRYPSIN , CHYMOTRYPSIN , PANCREATIC AMYLASE , PANCREATIC LIPASE ETC BY EXOCRINE PANCREAS • ENTEROPEPTIDASE , LACTASE , MALTASE , SUCRASE ETC BY INTESTINAL MUCOSA
- 18. • The first part is mouth. • This is also called as buccal cavity or oral cavity . • Lips surround the orifice of the mouth , cheeks are the side walls , tongue is at the floor and the hard and soft palates are the roof .
- 19. • Lips are very sensitive and are very easily irritated . • Upper lip has groove called as philtrum . • When the libs are closed , the line of contact is known as the oral fissure.
- 20. • Cheeks are the lateral bountaries of the oral cavitiy. • They are formed by a muscle is called as buccinater muscle
- 21. • Palate separates nasal cavity from oral cavity. • There are hard and soft palates. • Soft palate is which forms partition between Mouth and naso pharynx . • Hard palate is made up of our bones. • At the end of hard palate, there hangs a cone shaped process called uvula.
- 23. • Tongue is made up of skeletal muscle and covered by a mucuos membrane. • The muscle of the tongue is called as Intrinsic muscle. • Both origin and insertion of intrinsic muscle is tongue itself. • During Mastication , the contraction of intrinsic muscle assist in the placement of food between teeth. • Tongus has another muscle called as Extrinsic muscle. • Example of an Extensic muscle is genioglussus. • It is inserted in theHyoid bone of the skull.
- 24. • These muscles help during Swallowing or deglutititon and speech . • Upper tongue is usually covered by elevations called as Papillae . • There are three types of Papillae - Valalte - Fungiform - Filiform
- 25. • They have taste buds on their upper surface which can distinguish the tastes like sweet, sour, bitter, salty, and umami. • Lingual Frenulum helps to anchor tongue to the floor of the mouth. • Folds of mucuos membrane called Plica fimbriata extend towards the either side of the Lingual Frenulum • This regions helps in the absorption of certain drugs like Nitroglycerin.
- 26. • Parotid • Sublingual gland • Submandibular gland
- 27. There are three types of major salivary -Parotid -Submandibular -Sublingual They are tubule alveolar in nature. About 1 liter saliva is secreted every day
- 28. • They are the largest of all salivary glands. • They produce watery serous type of saliva which does not have mcous. • They are located between skin and masseter muscle below external ear. • They open into mouth piercing Buccinater muscle .
- 29. • They are called mixed salivary glands because they produce both serous and mucous saliva. • They are just located below the mandibular angle . • They open into mouth near lingual frenulum • They are the smallest salivary gland. • They open into the floor of the mouth
- 30. • Saliva also serves to lubricate the food bolus. • Saliva is also hypotonic and alkaline. • It is important to neutralize any gastric secretions that reflux into the esophagus. • The saliva also has some antibacterial action. • It facilitates swallowing and also keeps the mouth moist. • It helps in speech also.
- 31. • CROWN • NECK • ROOT
- 32. • They are the organs of mastication. • They cut , tear , grind the ingested food so that the ingested food mix well with saliva and swallowed. • A typical tooth has a crown . • This is covered by enamel – the hardest substances in the body . • The neck of the tooth is comparatively narrow. • The root of the tooth is covered by Peridontal membrane and anchored to the alveolar process
- 33. • It is to be noted that the tooth is covered by dentin and cementum other than enamel. • The dentin consists of a pulp cavity. • Pulp cavity consists of connective tissue blood vessels lymphatic vessels and sensory nerves. • Twenty deciduous or baby teeth is later replaced by 32 permanent teeth . • There are four kinds of teeth • Canine • Incisor • Molar • Premolar
- 34. • The bolus from the buccal cavity is pushed into the Pharynx. • The bolus actually moves into the oropharynx. • Pharynx is actually divided into three. • Nasopharynx • Oropharynx • Laryngopharynx • As the bolus passes Pharynx , it enters Esophagus.
- 35. • Esophagus is a muscualar tube extends from Pharynx to stomach. • It pierces Diaphram , a thin sheet an descends down into abdominal cavity. • The lumen is actually lined by Stratified squamous epithelial cells. • The esophagus opens into stomach by cardiac sphincter. • The food moves by peristaltic action of the esophagus. • The Esophagus has two sphincters o Upper esophageal Sphincter o Lower esophageal Sphincter • Lower Esophageal Sphincter is also called as the Cardiac Sphincter
- 36. • Fundus • Body • Pylorus
- 37. • The stomach lies at the upper part of the abdominal cavity. • The stomach actually posses three divisions • Fundus • Body • Pylorus • The curveformed by the upper right curvature is the Greater curvature. • The curve formed by the lower left stomach is the Lesser curvature
- 38. • The Stomach has sphincters Lower Esophageal Sphincter (or) Cardiac Sphincter Pyloric Sphincter • Phyloric Sphincter control the flow of food between Stomach and the small intestine (Duodenum) • The Epithelial lining of the stomach is thrown into folds called as Rugae. • The respective depressions are called as Gastic Pits. • There are numerous coiled-glands called as Gastric galnds
- 39. • PANCREAS • LIVER • GALL BLADDER
- 40. • The liver is the largest gland in the body. • It is essential for life because it conducts a vast array of biochemical and metabolic functions. • An important function of the liver is to serve as a filter be- tween the blood coming from the gastrointestinal tract and the blood in the rest of the body.
- 41. • PARIETAL CELLS OR OXYNTIC CELLS • CHIEF CELLS • ECL CELLS OR ENTEROCHROMA FFIN LIKE CELLS
- 42. • THIS IS ALSO CALLED AS OXYNTIC CELLS. • THIS SECRETES HYDROCHLORIC ACID AND INTRINSIC FACTORS. • IT IS STIMUATED BY NEUROTRANSMI TTER RELEASED FROM ENTERIC NERVE.
- 43. • THIS IS ALSO CALLED AS ZYMOGEN CELLS. • THIS SECRETES PEPSINOGENS. • IT IS STIMUATED BY NEUROTRANSMI TTER RELEASED FROM ENTERIC NERVE.
- 44. However mucus is also secreted on the surface of Epithelium. So acid won`t damage the inner layer
- 45. • IT IS ALKALINE IN NATURE. • IT CONTAINS WATER, MINERAL SALTS AND A VARIETY OF ENZYMES LIKE TRYPSIN, CHYMOTRYPSIN. • PRECURSORS ARE ACTIVATED BY ENTEROKINASE. • SECRETION OF PANCREATIC JUICE IS PRIMARILY UNDER HORMONAL CONTROL.
- 46. • IT IS ALKALINE IN NATURE. • BILE IS ONE OF THE IMPORTANT PANCREATIC SECETION . • SECRETIN STIMULATES PANCREATIC SECRETION. • THE GLUCURONIDES OF THE BILE PIGMENTS, BILIRUBIN AND BILIVERDIN, ARE RESPONSIBLE FOR THE GOLDEN YELLOW COLOR OF BILE.. • BILE SALT IS USUALLY ABSORBED IN THE SMALL INTESTINE.
- 47. • GASTRIN IS SECRETED IN THE GASTRIC MUCOSA. • THEY STIMULATE OYNTIC CELLS IN PRODUCING HYDRO-CHLRORIC ACID. • GASTRINS ARE INAC- TIVATED PRIMARILY IN THE KIDNEY AND SMALL INTESTINE
- 48. Small intestine has the following parts: -duodenum -jejunum -ileum Large intestine has the following parts: -cecum -colon -rectum
- 49. When the food enters the intestine , it is called as chyme. The pyloric sphincter located at the junction of stomach and duodenum regulates movement of chyme. The food in the small intestine is mixed with three juices namely bile juice, pancreatic juice and intestinal juice. The gastrointestinal system is the portal through which nutritive substances, vitamins, minerals, and fluids enter the body. Proteins, fats, and complex carbohydrates are broken down into absorbable units (digested), principally in the small intestine.
- 50. The colon serves as a reservoir for the residues of meals that can- not be digested or absorbed . The ileum is linked to the colon by a structure known as the ileocecal valve. It restricts reflux of colonic contents and the large numbers of commensal bacteria into sterile ileum. Each time a peri- staltic wave reaches ileocecal valve, it opens briefly, permitting some of the ileal chyme to squirt into the cecum.
- 51. When food leaves the stomach, the cecum relaxes and the passage of chyme through the ileo-cecal valve increases . This is actually a vagal nerve reflex. Then the undigested part reaches colon and then rectum. Distention of the rectum with feces initiates reflex contractions of its musculature and the desire to defecate. Defecation is therefore a spinal reflex that can be voluntarily inhibited by keeping the external sphincter contracted or facilitated by relaxing the sphincter and contracting the abdominal muscles.
- 53. • The intestine has an unusual circulation. • In that the majority of its venous outflow does not return directly to the heart but rather is directed initially to the liver via the portal vein. • Innervation is by Enteric nerve and also vagus nerve.
- 54. AFFERENT NERVES STIMULATE EFFERENT NERVES RESPONSE BUT IN CASE OF DIGESTIC SYSTEM , IT IS JUST TH E OPPOSITE. FOR EXAMPLE SWALLOWING IS INDUCED BY AFFERENT NERVE
- 56. • Gastric and duodenal ulceration in humans is related primarily to a breakdown of the barrier that normally prevents irritation and auto-digestion of the mucosa by the gastric secretions. • Infection with the bacterium Helicobacter pylori can also disrupts this barrier. • Aspirin and other non-steroidal anti-inflammatory drugs (NSAIDs) can also inhibit the production of prostaglandins and consequently decrease mucus. Due to decreased mucus , acid secreted can cause damage thus causing Peptic Ulcers. • The NSAIDs are widely used to combat pain and treat arthritis. • An additional cause of ulceration is prolonged excess secretion of acid due to some diseases.
- 57. • Cholera is a severe secretory diarrheal disease that often occurs in epidemics associated with natural disasters where normal sanitary practices break down. • The cholera bacillus stays in the intestinal lumen and it produces a toxin. • Because of the bacterial toxin , a series of reaction takes place thus there is an increase in electrolyte and water content of the intestinal contents causes the diarrhea. • Oral ingestion of Glucose and salt (NaCl) and Cereals containing carbohydrates are also useful in the treatment of diarrhea.
- 58. • Obesity is the most common and most expensive nutritional problem everywhere in the world. • Obesity is when BMI is more than 25. • BMI is body mass index. • It accelerates atherosclerosis, diabetes and many other body illness. • Consumption of excess foods with abundant fat , doing a very less manual work etc cause obesity.