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ditive system by aqsa

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Presentation on: HUMAN DIGESTIVE SYSTEM Presented by: Dr. AQSA AFZAL Pharm-D B.Z.U Session (2004-09)

HUMAN DIGESTIVE SYSTEM:

HUMAN DIGESTIVE SYSTEM

CONTENTS:

CONTENTS Food & Parts of nutrition Theory of Nutrition OUR DIET Phases of nutrition Digestion defination

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Parts of digestive System Hormones of digestive system

FOOD & PARTS OF NUTRITION :

FOOD & PARTS OF NUTRITION BIGGER MOLECULES They are complex & need to be converted into simple & small molecules for absorption. SMALLER MOLECULES They are simple and as such absorbed in blood stream.

BIGGER MOLECULES:

BIGGER MOLECULES PROTEINS which are then broken down into amino acids CARBHYDRATES which are then broken down to mono saccharides FATS which are then broken down to fatty acids & mono glycerides for absorption

SMALLER MOLECULES:

SMALLER MOLECULES VITAMINS MINERALS WATER IONS

OUR DIET INCLUDE:

OUR DIET INCLUDE

NUTRITION & Theory of digestion :

NUTRITION & Theory of digestion Our cells require oxygen, water, salts, amino acids, simple sugars, vitamins & fatty acids These can cross cell membranes to enter cells but these are rare in our environment.

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Such substances are usually parts of larger molecules like Proteins, Polysaccharides, & Lipids Which cannot cross the membranes.

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Before food can be used up by the body it must be DIGESTED & ABSORBED.

Phases of nutrition :

Phases of nutrition INGESTION DIGESTION ABSORPTION ASSIMILATION DEFECATION

INGESTION:

INGESTION The Process of taking in food.

DIGESTION:

DIGESTION The process of breaking up Complex substances into simpler substances.

ABSORPTION:

ABSORPTION Diffusion of digested food Into blood & lymph.

ASSIMILATION:

ASSIMILATION Conversion or Incorporation of absorbed simple food into the complex substances constituting the body.

DEFECATION:

DEFECATION Elimination of undigested food from body.

DIGESTION:

DIGESTION Digestion is a process of breaking Up of large, complex, non diffusible substances into small, simple, diffusible substances which are then assimilated to get energy & Synthesize our own body structures

PARTS OF DIGESTIVE SYSTEM:

PARTS OF DIGESTIVE SYSTEM It consist of a long muscular Hollow tube ( Gastro intestinal Tract) GIT or Alimentary tract) which extends from mouth to Anus.

Parts of ALIMENTARY CANAL:

Parts of ALIMENTARY CANAL ORAL CAVITY PHARYNX OESOPHAGUS STOMACH SMALL INTESTINE BILE & PANCREATIC JUICE LARGE INTESTINE

ORAL CAVITY:

ORAL CAVITY 1 st part of digestive system INVOLVED IN Selection, Grinding, Partial chemical Digestion,& lubrication of food. Grinding also called mastication it is done by teeth.

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Chewing process stimulates 3 pairs of salivary glands (Sublingual, Submendibular, Parotid gland) to release a juice called SALIVA in oral cavity. pH of SALIVA is 7.0 & contains 99.5% water & 0.5% solutes like ions ( sodium & chloride ions), & organic Substances (urea, uric acid, albumin, mucin)

VARIOUS GLANDS OF ORAL CAVITY:

VARIOUS GLANDS OF ORAL CAVITY

SALIVARY ENZYMES:

SALIVARY ENZYMES Salivary amylase or PTYALIN BACTERIOLYTIC ENZYME LINGUAL LIPASE

Salivary amylase or PTYALIN:

Salivary amylase or PTYALIN For the digestion of carbohydrates like poly saccharides, disaccharides SALIVARY AMYLASE is active at pH Of 6 to 7 and inactive at pH 4

BACTERIOLYTIC ENZYME :

BACTERIOLYTIC ENZYME Which kill all bacteria & Provide immunological defence against bacteria & viruses.

LINGUAL LIPASE:

LINGUAL LIPASE It brings about digestion of lipids but to Minor extent major digestion of fats & Lipids Takes place in the small intestine

PHARYNX:

PHARYNX The pharynx is the part of the neck and throat situated immediately behind the mouth and nasal cavity, & superior to the esophagus.

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It is part of the digestive system and respiratory system . Because both food and air pass through the pharynx, a flap of connective tissue, the epiglottis closes over the trachea when food is swallowed to prevent choking or asphyxiation.

ESOPHAGUS:

ESOPHAGUS The esophagus is a narrow muscular tube about 20-30 centimeters long which starts at the pharynx at the back of the mouth, and ends at the cardiac orifice of the stomach . The wall of the esophagus is made up of two layers of smooth muscles

STOMACH:

STOMACH

STOMACH SHAPE & PARTS:

STOMACH SHAPE & PARTS The stomach is a small, 'J'-shaped pouch with walls made of thick, elastic muscles , which stores and helps break down food. It has three parts BODY, FUNDUS, PYLOROUS.

HUSTRATIONS:

HUSTRATIONS Food which has been reduced to very small particles in the oral cavity is further reduced in size here due to mixing movements (HUSTRATIONS) of stomach walls.

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Food enters the stomach through the cardiac orifice where it is further broken apart and thoroughly mixed with gastric juice ( pH 0.9 – 1.5) that contain water , mucous, HCL, pepsin and other digestive enzymes to break down proteins into amino acids.

HYDROCHLORIC ACID:

HYDROCHLORIC ACID It does not digest walls of stomach because Of thick coating of mucous on walls of Stomach which is produced when food is in the oral cavity before the arrival of food in the stomach

PEPSIN:

PEPSIN It is produced in inactive form in the stomach PEPSINOGEN which then converted into PEPSIN by the action of HCL which is secreted by oxyntic cells of stomach. PEPSIN in the stomach work at a specific pH 2 – 3 & inactive at > 5 pH.

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The parietal cells of the stomach also secrete a glycoprotein called intrinsic factor which enables the absorption of vitamin B-12 .

CHYME:

CHYME Food in the stomach is in semi-liquid form, which upon completion is known as chyme (soup like mixture having salty taste) .

SMALL INTESTINE:

SMALL INTESTINE Maximum absorption of nutrients takes place in the intestine

PARTS OF SMALL INTESTINE:

PARTS OF SMALL INTESTINE It has three parts Duodenum ( 12 inches long ) Jejunum ( 2.4 meters long ) Ileum ( 3.5 meters long )

BILE JUICE:

BILE JUICE Yellowish green in colour & 500 – 1000ml. Of bile is produced every day. Bile is produced by the liver and then stored in the gallbladder. The bile in the gallbladder is much more concentrated.

COMPOSITION OF BILE:

COMPOSITION OF BILE pH of bile juice is 7.6 -8.6 Bile contain bile acids, pigments & end products of RBC destruction

BILE ACIDS:

BILE ACIDS Bile has no enzyme but contain bile acids Like cholic acid, chenodeoxycholic acid, Deoxycholic acid e.t.c for emulsification of lipids & in turn decrease the interfacial tension & Increase the surface area & solubility of fats for the action of lipases

STRUCTURE OF BILE ACID HAVING 2 PARTS ONE IS HYDROPHOBIC OTHER IS HYDROPHILLIC:

STRUCTURE OF BILE ACID HAVING 2 PARTS ONE IS HYDROPHOBIC OTHER IS HYDROPHILLIC

POLAR PART IS OUT SIDE WHILE NON POLAR PART IS INSIDE SOLUBILIZING THE FAT MOLECULES :

POLAR PART IS OUT SIDE WHILE NON POLAR PART IS INSIDE SOLUBILIZING THE FAT MOLECULES

PANCREATIC JUICE:

PANCREATIC JUICE Pancreatic juice made by the pancreas . Its pH is 7.1- 8.2 Enzymes include maltase , lactase and sucrase (all three of which process only sugars ), trypsin and chymotrypsin carboxypeptidase elastases ( all process prteins).

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Pancreatic amylase & lipase ( process carbohydrates & fats respectively) Water, ions Na, Cl, Mg, e.t.c

DUODENUM:

DUODENUM In duodenum the pH level increases BILE JUICE & PANCREATIC JUICE enters in DUODENUM through BILE DUCT & PANCREATIC DUCT.

DUODENUM & WAY HOW PANCREATIC &BILE DUCT ENTERS IN IT.:

DUODENUM & WAY HOW PANCREATIC &BILE DUCT ENTERS IN IT.

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Digestion of fats n carbohydrates takes place in duodenum by the action of lipases and amylases released from pancreas After digestion fats are converted to fatty acids & monoglycerides Proteins are converted into aminoacids Carbohydrates are converted into monosaccharides

ILEUM & JEJUNUM:

ILEUM & JEJUNUM Small, finger-like structures called villi , each of which is covered with even smaller hair-like structures called microvilli improve the absorption of nutrients by increasing the surface area of the intestine and enhancing speed at which nutrients are absorbed.

HEPATIC PORTAL CIRCULATION:

HEPATIC PORTAL CIRCULATION Blood containing the absorbed nutrients is carried away from the small intestine via the hepatic portal vein and goes to the liver for filtering, removal of toxins, and nutrient processing.

LARGE INTESTINE:

LARGE INTESTINE Roughly 1.5 meters long, with three parts: the cecum at the junction with the small intestine , the colon , and the rectum . The colon itself has four parts: the ascending colon , the transverse colon , the descending colon , and the sigmoid colon

BACTERIA IN COLON:

BACTERIA IN COLON There are various beneficial bacteria are present in colon who synthesize vitamins for our body.

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Function of large intestine is to absorb water & elimination of faeces

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Food products that cannot go through the villi , such as cellulose ( dietary fiber ), are mixed with other waste products from the body and become hard and concentrated feces .

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The feces is stored in the rectum for a certain period and then the stored feces is eliminated from the body due to the contraction and relaxation through the anus .

HORMONES OF DIGESTIVE SYSTEM:

HORMONES OF DIGESTIVE SYSTEM

GASTRIN :

GASTRIN is in the stomach and stimulates the gastric glands to secrete pepsinogen (an inactive form of the enzyme pepsin ) and hydrochloric acid . Secretion of gastrin is stimulated by food arriving in stomach. The secretion is inhibited by low pH .

Secretin :

Secretin is in the duodenum and signals the secretion of sodium bicarbonate in the pancreas and it stimulates the bile secretion in the liver . This hormone responds to the acidity of the chyme.

Cholecystokinin (CCK) :

Cholecystokinin (CCK) is in the duodenum and stimulates the release of digestive enzymes in the pancreas and stimulates the emptying of bile in the gall bladder . This hormone is secreted in response to fat in chyme.

Gastric inhibitory peptide (GIP):

Gastric inhibitory peptide (GIP) is in the duodenum and decreases the stomach churning in turn slowing the emptying in the stomach. Another function is to induce insulin secretion.

Motilin :

Motilin is in the duodenum and increases the migrating myoelectric complex component of gastrointestinal motility and stimulates the production of pepsin .

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