Essay on the Digestive System (For Students)


In this article we shall discuss concerning the gastrointestinal system in humans. After reading this essay you will see about:- 1. Organs of Digestive System 2. Accessory Glands for Digestion of Foods.

Essay number 1. Organs of Digestive System:

food digestion means simplification of complex meals. It is the procedure for breaking different foodstuff into easy services and products. The complex meals like carbohydrates, proteins and fats are became glucose, proteins and fatly acids correspondingly by the action of digestion enzymes. These simple substances come right into the blood flow after consumption after which these are typically employed by the human body.

Digestive system is composed of two main organs:


(1) Alimentary Canal

(2) Digestive Glands

1. Alimentary Canal:

that is also known as digestive system or gastrointestinal tract. Its an extended pipe of varying diameter which begins within lips and comes to an end at rectum. The length of this tube is all about 8-9 meters. It opens at both the ends. The alimentary canal begins at mouth into which cavity, the glands associated with the lips afin de the juice. Since it passes backwards, it spreads into a funnel shaped cavity called-pharynx.

The pipe then narrows into a soft muscular pipe about ten ins in long, called the foodstuff pipeline or gullet. This passes down the throat into the chest. It then opens to the belly by piercing the diaphragm. The stomach is a big bag lying a little left under the diaphragm. It has two spaces, one where the meals pipe ends plus the other in which the intestines begin. The alimentary canal narrows once again and passes to the little intestine that will be about twenty two legs in total.


The first ten ins for the small intestine is named as Duodenum which types a ‘C’ shaped loop. All of those other small intestine is like a coiling pipe, whoever finishes starts into a broad but comparatively short pipe known as large intestine. It is about six legs very long. The final the main big Intestine is recognized as Anus.

2. Digestive Glands:

Various digestion glands aid in the digestion of meals.


(1) Salivary glands into the mouth,

(2) Gastric glands inside belly

(3) Pancreas,

(4) Liver,

(5) Intestinal glands in tiny intestine.

These digestive glands secrete digestive juices containing different enzymes which digest carbohydrate, protein and fatly meals.


Digestive juices:

Five digestive juices are secreted from digestion glands associated with the human anatomy. The enzymes within these juices aid in the digestion of different types of meals.

These juices are:

1. Salivary juice from salivary glands in mouth.


2. Gastric juice from Gastric glands in the stomach.

3. Pancreatic juice from Pancreas.

4. Intestinal juice from Small Intestine.

5. Bile juice from Liver.

Why many digestion juices are essential for digestion of food?

You will find three good reasons for the clear presence of a lot of digestion juices:

1. One digestion juice cannot digest three types of foods i.e. proteins, fats, and carbohydrates around their conclusion.

2. One digestion juice cannot digest one kind of food up to its completion, because meals cannot stay static in one destination for a longer time of the time.


3. The medium of action of enzymes present in different digestive juices will vary. Some work on acid medium plus some on alkaline medium.

Digestion in Different Elements Of Alimentary Canal:

The alimentary canal is composed of the next organs in which meals are digested:

1. Lips

2. Oesophagus

3. Stomach

4. Duodenum

5. Small Intestine

6. Big intestine

1. Mouth:

The lips cavity could be the front spread out end associated with the food pipeline. The edges associated with cavity are formed by the cheeks, the roof by the palate, and flooring by the tongue. Whenever closed, it's bound in-front by the top of together with reduced sets of teeth fulfilling in the centre. The opening behind the lips is recognized as throat for each side that there is certainly a mass of muscle called tonsils. In outside of the mouth cavity there's a slit like opening that is bounded by two soft movable lips.


During our life time two sets of teeth are developed:

1. Temporary teeth or milk teeth:

They're twenty in number, five in each 50 % of the jaw. They appear at about the age of half a year. They normally are smaller and delicate.

2. Permanent teeth:

They are thirty two in quantity sixteen in top and sixteen in the reduced jaw. They look gradually and push out all the short-term teeth. By the age of 14th, twenty eight permanent teeth are erupting. The last four teeth called as knowledge teeth look after you were 21 years old years of age.


The teeth are essential for efficient mastication. They cut, crush and grind the food.


The tongue is a muscular organ that is present on the floor of the mouth area. The anterior part of the tongue is tiny that may move easily into the internal the main mouth.


1. It mixes the food well using the salivary juice by moving it into various way.

2. The taste buds present in the tongue detect the type of the food. Sweet style are experienced by the preferences contained in the anterior tip for the tongue and salty flavor at a small area behind this tip. Buds at the posterior area of the tongue feel bitter flavor and sour flavor can be simply known by the tastebuds situated in the center and part area of the tongue.

Salivary Glands:

There are three pairs of salivary glands in the lips which secrete a fluid called saliva.

These are:

(1) Parotid Gland

(2) Submandibular Gland and

(3) Sublingual Gland.

Perotid Glands:

A couple of perotid gland is found inside cheeks, facing each ear inside the mouth cavity. They are the greatest of this salivary glands. Each gland is attached with an extended duct referred to as Stenson’s duct by which salivary juice is carried toward lips.

Submandibular Glands:

This might be also known as Sub-maxillary gland. A set of submandibular gland can be found on each part under the jaw bone tissue. They're the following largest glands, and are usually concerning the size of a walnut. Their release is carried through a duct called as Wharton’s duct.

Sublingual Glands:

It's the smallest couple of salivary glands. Its current underneath the tongue. The release of these glands is carried through Duct of Rivinus to the mouth cavity. The salivary glands secrete about 800 to 1500 ml of saliva perday. Saliva is a watery alkaline fluid. It includes 90per cent water, a thick lubricant called mucin, handful of calcium salts, maltose, urease and lipase. A starch splitting enzyme known as ptyalin and a bacteriolytic enzyme called as lysozyme can be found in saliva.


The action of saliva is both physical and chemical.

1. The enzyme ptyalin within saliva functions on starchy meals and converts them to dextrin and maltose.

Starch + Ptyalin → Dextrin

Dextrins + Ptyalin → Maltose

2. Saliva constantly moistens the lips and tongue.

3. It lubricates and moistens the food, so the meals can be simply swallowed.

4. It cleanses the tongue and makes speech easier.

5. Saliva dissolves the foodstuff particles, which stimulate the taste buds. It makes food delicious.

6. The antibacterial enzyme “lysozyme” present in salive kills the germs. Salivary juice has antiseptic property.

Secretion of saliva is managed by the parasympathetic nervous system.

Food digestion in Mouth:

Whilst the food enters into the lips, perhaps the smell, the sight or the thought of food, the salivary glands are stimulated and saliva is secreted. This will be poured to the lips. One's teeth chew the meals and breaks into small pieces whilst the tongue thoroughly mixes the saliva because of the food.

The enzyme ptyalin in the saliva acts on starch and converts it first to dextrins and lastly to maltose. For that reason, it is critical to chew the meals well to get the starch changed into maltose. When some prepared rice or a piece of bread is chewed well in mouth, it becomes somewhat sweet in taste, since the starch contained in them was became sugar.

Then your chewed meals is collected into a ball or bolus and set down the pharynx into the gullet or food pipeline. The wind pipe (passage the atmosphere) is situated while watching gullet. The foodstuff is prevented from starting the wind pipeline by a lid like organ called as epiglottis.

It really is a cartilaginous muscular flap which stops the entry of food to the windpipe during swallowing together with food gets in into the food pipe or gullet. If a particle of solid meals or water enters into the wind pipeline, it is expelled by violent coughing.

2. The Oesophagus or Gullet:

Its a collapsible muscular pipe of 9 to 10 ins in length, which extends from pharynx on cardiac orifice associated with the stomach. It passes downwards through the neck, the thorax together with abdominal cavity.

The oesophagus comprises four layers of muscle:

1. an exterior covering of connective cells.

2. A muscular layer made up of two layers of muscle mass fibers.

3. A sub-mucous layer containing blood vessels, nerves and mucous glands.

4. an inner mucous membrane layer layer.


The meals passes through oesophagus by peristaltic action. It passes down the meals pipe by the action of its muscular wall surface which agreement above it and push it along. Food will not merely collapse the gullet, but every part of the gullet agreements following the part next above therefore squeezes the food along till it passes through opening and gets in the stomach.

3. Stomach:

The belly is a dilated the main alimentary canal. It's a bag like expansion for the meals pipeline along with its broad end left and slim end toward right. It's situated between your oesophagus as well as the start of the small intestine. It lies close to the diaphragm and somewhat towards the left for the stomach cavity. The dimensions of the belly varies based on the age and sex.


The stomach comprises of a top part, the fundus. The main area of the stomach is named the Body and this narrows at its lower end to become the Pyloric Antrum.

The walls regarding the stomach include four levels of cells:

1. an outer covering of serous membrane.

2. A muscular layer consisting of longitudinal, circular and oblique muscle fibers.

3. A sub mucous layer.

4. a liner mucous membrane layer layer.

Gastric Glands:

Into the mucous membrane layer you will find a large number of moment blind pipes which are called as gastric glands. These are microscopic holes which form the lips of the gastric glands. Connective muscle exists between your tubules that have bloodstream and lymphatic’s.

When the meals enters the belly, the bloodstream dilate and bring extra bloodstream towards the belly. Then gastric glands secrete gastric juice. The gastric juice is poured in to the cavity regarding the stomach and mixed with the food. Form gastric glands, the walls of the belly also contain other glands like pyloric glands, cardiac glands, and mucous secreting cells which secrete mucous, pepsinogen, hormones gastrin an such like.

Gastric juice is a colourless, acid liquid containing water, minimal volume of salt, 0.2 – 0.4 percent hydrochloric Acid (HCL) and enzymes like Renin, Pepsin and Gastric Lipase. The stimulation regarding the release of gastric juice is partly nervous and partly chemical.

Digestion in belly:

After the food comes into the stomach for some fifteen to twenty minutes, the action of saliva continues which transformation of starchy meals to maltose. The gastric juice by that time is secreted in enough quantity and mixed with the foodstuff entirely. Whenever food associated with belly becomes acidic by hydrochloric acid, the action of ptyalin of saliva stops, because it can act just upon alkaline medium. Then the action of digestion enzymes within gastric liquid begin, while they become active on acid medium.

The functions of gastric juice are as follows:

1. The enzyme Renin coagulates milk and converts milk protein into casein.

2. The enzyme pepsin in existence of hydrochloric acid acts upon protein meals and the casein, and converts them into more dissolvable substances called peptone.

3. Gastric Lipase (touch is secreted) helps in splitting the molecules.

4. Hydrochloric acid acidifies all foods. It has an antiseptic and disinfectant property which kills germs and bacteria’s through the meals.

5. The stomach acts as the reservoir of food for a short time.

6. An anti-anaemic factor is created in the stomach.

7. Stomach also secretes a protein ingredient called intrinsic element that will be required to facilitate the absorption of supplement from alimentary canal.

8. Liquid, alcohol plus some drugs are absorbed in the belly.

9. Besides digestion, the essential functions of stomach are to safeguard the tiny intestine from injury specially very hot and incredibly cool meals, chemical irritants, chilies, liquor etc.

10. Additionally assists in softening hard particles of food which may have escaped chewing within the mouth.

The gastric juice has no action upon the carbohydrate food. The time taken the gastric digestion is mostly about 3 to 4 hours. The acid combination of gastric juice and partly digested food is known as “chyme”. Some of the sugar and peptone is consumed in to the arteries regarding the stomach. This ‘chyme’ then passes to the Duodenum, the first element of small Intestine.

Small Intestine:

The small intestine is a coiled tube extending from the pylorus associated with belly and leads into the large intestine. Its about 5 to 6 meters (16-20 feet) long pipe. It is based on the umbilical area of this stomach and is surrounded by the large intestine. You can find four coats of small intestine such as the stomach. Small-intestine is composed of three parts that are constant together.

You will find:

(1) Duodenum

(2) Jejunum

(3) Ileum.

4. Duodenum:

The duodenum is the first part of the little intestine. It is approximately 25 – 30 cm (10 – 20 ins) very long and is curved like English page ‘C’. The form is like a horse-shoe. Within the curve, the head for the pancreas is encircled. It is fixed towards the posterior stomach wall surface by peritoneum. The bile duct through the liver together with pancreatic duct from the pancreas unite to start together to the lower part and from the back part for the duodenum. This place of entry is recognized as “Ampulla of Vater” which is situated 10 cm (4 ins) from the pylorus.

Food digestion in Duodenum:

The bile duct brings bile juice therefore the pancreatic duct, pancreatic juice. Those two liquids mix aided by the chyme and continue the entire process of food digestion a stage further.

Pancreatic Juice:

The pancreatic juice is an alkaline colourless fluid. It functions upon alkaline medium. It has three enzymes.

(1) Amylopsin or Amylase

(2) Trypsin,

(3) Lipase which consume carbs, protein and fats respectively.

Amylopsin acts upon uncooked plus cooked carbohydrate meals and converts them into disaccharides. Trypsin is made by the enzyme trypsinogen. It functions upon undigested protein foods and peptones and converts them into polypeptides. Lipase acts upon fatty food and converts them into fatty acid and glycerol. The fat splitting action of lipase is greatly facilitated by the clear presence of bile juice. Fat food digestion is completed by lipase within the duodenum.

Bile Juice:

Bile juice is carried by the bile duct from the liver. Though it has no direct action on food digestion of meals, however it aids the pancreatic juice in its action for digestion of fat.

The functions of bile juice are as follows:

1. Bile juice helps in splitting the fat into small particles and thus helps the action of lipase because of its food digestion.

2. As bile juice is alkaline, it helps to transform the acid food of this belly to alkaline medium in duodenum, so that the enzymes for the pancreatic juice can simply do something about various types of meals.

3. Bile juice has essential antiseptic properties and kills the germ and bacteria’s from meals in intestine.

4. Additionally promotes the consumption regarding the products of digestion.

5. Bile stops development of gall rock.

6. It provides colour to the stool.

5. Tiny Intestine (Jejunum):

It comprises the upper two 5th associated with remaining small intestine. It is the middle portion of the little intestine. Intestinal juice is secreted from simple tubular glands which are operating out of the mucous membrane layer layer associated with small intestine.

Intestinal Juice:

The digestive process is finished by the job of abdominal juice secreted form the abdominal glands. It completes the food digestion of carbs and proteins. About 1800 ml of abdominal juice is secreted a day. That is also referred to as Saccus Entericus. The enzymes within this ferment do something about alkaline medium.

Saccus Entericus contains enzymes like:

(1) Invertase /sucrase,

(2) Lactase,

(3) Maltase,

(4) Enterokinase,

(5) Erepsin.

1. Invertase:

It acts on cane sugar and converts them into simple sugar or glucose.

2. Lactase:

This enzyme splits lactose into sugar and galactose. This galactose is once again converted into sugar in liver at time fundamentally.

3. Maltase:

It converts maltase into dextrin.

4. Enterokinase:

This enzyme activates the proteolytic enzyme of pancreatic juice. It activates trypsinogen to trypsin which helps within the digestion of protein meals.

5. Erepsin:

The enzyme completes the digestion of protein meals. It converts peptone polypetide alongside undigested protein foods into amino acids. Inside element of tiny Intestine the digestion of all the three kinds of meals are completed. Carbohydrate foods are simplified into glucose, protein into proteins and fat into fatty acids and glycerol.


Once the means of digestion is finished, they are carried towards the final an element of the tiny intestine in other words. Ileum. The digested food reaches this invest about four hours. Ileum comprises the final three fifth of little intestine. It's relatively thinner than jejunum. Using this spot the absorption of simplified and digested food begins.

By the action of numerous digestion juices, saliva, gastric, juice, pancreatic juice and abdominal juice, different meals materials are simplified and ready for absorption. Proteins have now been separated to peptone by gastric juice, polypeptide by pancreatic juice and finally to proteins by abdominal juice.

Carbs happen converted into maltose by salivary juice, other disaccharides by pancreatic juice and lastly mono-saccharides of sugar or simple sugar by abdominal juice. Fat is simplified into fatly acids and glycerol by the action of gastric lipase and pancreatic lipase.

Absorption of Digested Food:

Absorption of digested food take place in epithelial area of this villi in the Ilium section of small intestine. The mucous membrane layer of the little intestine is line by a number of projections like substances referred to as villi. These help in consumption by increasing the surface area. The consumption of digested food happens totally into the little intestine through two networks, the capillary bloodstream additionally the lymphatic’s of villi on inner area associated with little intestine.

A villus contains a lacteal, bloodstream, epithelium and muscular tissue, that are connected together by lymphoid muscle. Carbohydrates by means of glucose are directly found by the bloodstream from the villi. Proteins are absorbed by the blood vessels from villi in the shape of proteins. Fats, by means of fatly acids and glycerol are absorbed into the lacteals.

Small amount of emulsified fats from water soluble substances with bile, which are easily consumed. Fat dissolvable nutrients have absorbed alongside fats. Mineral salts and little bit of water pass in to the arteries along side sugar and proteins. Proteins, sugar and fatly acid are passed from small intestine toward liver for oxidation and metabolism. The extra amount of glucose is transformed into glycogen and it is saved in liver for future use.

After consumption, abdominal articles are slowly propelled over the Alimentary canal. The onward movement associated with the meals is affected by way of waves of contraction associated with intestines called peristalsis. This peristaltic task is named “Segmentation”.

6. Big Intestine:

The large intestine or colon is all about 1-5 meters or 5 foot long. Its wider than tiny intestine. The colon starts as a dilated punch the “Caecum” to which the “Vermiform Appendix” is attached. All the digested meals having been consumed in little intestine, a semifluid mass is left to pass into big intestine.

The big intestine absorbs the substances that aren't absorbed in tiny intestine also a lot of water. The contents of the large intestine therefore become firmer. The materials finally thrown out are known as faeces which contain undigested and un-absorbable portions of food. These faeces are decomposed and putrefied by a form of bacteria Bacillus coli and give increase to bad odour, which are passed away through the Anus.

Functions of Big Intestine:

1. Water, minerals, salts and some drugs are consumed in to the bloodstream capillaries.

2. Mucin is secreted which assists in lubricating the faeces and facilitates their passage.

3. Overabundance calcium, iron drugs of heavy metals are excreted from the walls of large intestine and mix utilizing the faeces.

Movements of Gastro Intestines:

Motions of Gastro intentional Tract is due to the existence of muscular muscle inside alimentary canal. Various areas of the alimentary canal have actually different types of motion.

Movements inside tract are essential for three reasons:

1. To push the food particles ahead to ensure that various digestive juices may be blended properly because of the food in different elements of alimentary canal.

2. To ensure blood supply through walls associated with tract so the secretion of juices may become easier plus the absorption work may continue quickly.

3. Movements are necessary for the procedure of Defecation.

More over, the proper functioning for the Gastro deliberate tract, movements are necessary. There are many kinds of movements like peristalsis, antiperistalsis, mass peristalsis, segmentation, pendular, tonus rhythm etc.

These motions can be grouped under two headings:

1. Translatory motion when the food are propelled forward. It offers peristalsis, antiperistalsis and mass peristalisis. Generally this motion occurs in almost every part of Gastrointestinal tract.

2. Stationary motions are localized and do not move the foods ahead. It includes segmentation, pendular and tonus rhythm etc.

Food enters to the belly through the oesophagus by the peristaltic movement regarding the circular muscles. By the contraction and relaxation for the circular muscle tissue attached to the meals pipe or oesophagus, meals propel ahead to your belly. In the belly the gastric juice is combined with the food by the rippling waves of peristalisis called tonus or blending waves.

The action of the waves moves the foodstuff ahead. The strong waves of peristalsis are able to force the chyme through pylorus of, the belly into the Duodenum. Duodenum could be the destination in which many peculiarities of movements are seen. It have peristaltic and segmentation movements through the duct.

Mainly there are two kinds of movements in individual small-Intestine:

1. Rhythmic Segmentation or Ludwigs Pendulum:

In rhythmic segmentation there is certainly alternative contraction and expansion for the abdominal wall surface where the abdominal juice may be blended thoroughly because of the “chyme”. It brings the chyme to the connection with mucosa for consumption.

2. Peristalisis:

Propulsive peristaltic movement push the chyme along the length of the little intestine until it reaches the ileocaecal valve which opens to permit the contents associated with the ileum to access the big intestine. In large intestine, there are two main types of movements like stationary and translatory peristaltic.

Motions associated with large intestine are often very sluggish. It contains a mixture of segmentation motions and mass peristalsis which transfers the faecal material into the colon. The motion helps you to clear of this articles of proximal colon into more distal part and lastly into the rectum for defaecation. One of the greatest functions of big intestine is its ability to maneuver.

Carbohydrate Digestion:

Carbohydrates consist of carbon, Hydrogen and oxygen. They truly are categorized into Mono-saccharides disaccharides and polysaccharides. The Carbohydrate foods which arc drawn in the food diet are high in sucrose, lactose, starch, dextrin and cellulose. A lot of them are disaccharides and polysaccharides. So they require simplification. They've been changed into simple sugar or sugar that will be a monosaccharide by the action of digestion enzymes for their utilization in the body.

Digestion in Mouth:

Inside the lips, the digestion of Carbohydrate starts. Salivary juice secreted from salivary Glands inside mouth do something about Carbohydrate foods. The enzyme ptyaline of saliva hydrolyzes starch into maltose and dextrins. In the lips 3 – 15per cent of starch is digested.

Starch→ Ptyalin → Maltose and Dextrin.

Digestion in Stomach:

Ptyalin present in saliva continue to work on starch for 15 minutes inside the stomach because Hydrochloric acid of gastric juice converts the alkaline meals into acidic medium by that point. The enzymes within the gastric juice cannot act upon Carbohydrate meals for food digestion.

Food digestion in Duodenum:

Pancreatic juice is carried through pancreatic duct from pancreas on duodenum. The enzyme Amylopsin or pancreatic amylase acts upon starch and dextrins and converts them to maltose.

Starch → Amylase→ Dextrins

Dextrins → Amylase→ Maltose

Digestion in Small Intestine:

The intestinal juice or Saccus Entericus provides the enzymes like maltase, sucrase or Invertase, Lactase etc. All of these enzymes do something about starch and other Disaccharides and transform them into easy mono-saccharides or glucose that is effortlessly absorbed by your body. Carbohydrate digestion is finished within the tiny intestine.

Maltose → Maltase→ Glucose

Sucrose→ Sucrase→ Glucose and Fructose

Lactose → Lactase → Glucose and Galactose.

Carbohydrates are turned into simple sugar or sugar by the digestion enzymes. By means of monosaccharides they truly are directly found by the blood from the villi. Simple sugars or glucose therefore consumed works extremely well for energy purposes after oxidation and metabolic process. The excess number of sugar is transformed into glycogen and it is saved in the liver for future use.

Protein Digestion:

Proteins will be the complex nitrogenous natural compounds. Small units of protein are known as proteins that are consists of elements like carbon, hydrogen, oxygen and nitrogen. Protein digestion starts inside belly.

Food digestion in belly:

A few of the starchy meals are digested by the enzyme ptyaline contained in saliva in the lips. Then it gets in in to the stomach that is a bag like expansion of Alimentary canal through the food -pipe or gullet. The gastric juice secreted from gastric glands contain Hydrochloric acid and three enzymes. Renin, Pepsin and gastric lipase.

After the transformation of meals into acidic medium by hydrochloric acid, the task of Renin and pepsin starts. Renin functions upon milk protein and converts them into casein. Pepsin acts upon casein alongside protein meals and converts them into peptones.

Milk protein → Renin→ Casein.

Protein → Pepsin → Proteoses + Peptones.

Digestion in Duodenum:

The food whenever arrives associated with stomach is named chyme or chyle. It enters to the ‘C shaped cycle Duodenum. Protein foods are digested by the pancreatic juice that will be carried from pancreas to Duodenum. The enzymes which digest protein foods in pancreatic juice is Trypsin. It functions upon peptone alongside undigested protein meals and converts them into polypeptides.

Peptones + Proteoses→Trypsin → Poly Peptides.

Digestion in Small Intestine:

The semi digested meals passes from the duodenum to the Jejunum an element of the tiny intestine. Intestinal glands secrete a ferment saccus Entericus. The enzyme Erepsin contained in this ferment helps in digestion of protein foods. Erepsin acts upon poly-peptides and coverts them into Amino acids. Right here the food digestion of protein meals is completed.

Polypeptides → Erepsin → Aminoacids.

Simplified proteins are absorbed by the bloodstream from villi as proteins and carried on liver via the portal circulation. Peptones can also be absorbed from villi. Within the liver Amino acids are oxidised and after metabolic process Ammonia is divided. This will be changed into urea and excreted through urine. The primary substance of protein in other words. carbon, hydrogen, air and nitrogen can be used by your body.

Fat Digestion:

Fats or Lipids are complex meals which are mostly utilized the availability of power on human body. Various types of Lipids are drawn in the dietary plan.

They've been:

(1) Neutral fat,

(2) Phospholipids,

(3) Cholesteroids,

(4) Complimentary Cholesterol,

(5) Fatly acids and glycerol.

Cholesterol and fatly acids don't require any digestion but other fats are digested by the digestion enzymes.

Food digestion in Stomach:

Digestion of fat begins from stomach. The enzyme gastric lipase within gastric juice breaks the neutral fat into one molecule of glycerol and 3 molecules of fatly acids. Only splitting process starts in the belly by gastric lipase. It acts best upon emulsified fat like egg yolk, milk an such like.

Food digestion in Duodenum:

Fat food digestion is mainly carried out into the duodenum by the enzyme Lipase of pancreatic juice. Pancreatic lipase functions in a somewhat alkaline medium. Bile juice helps in making the foodstuff alkaline and facilitates fat food digestion. Several other enzymes associated with the pancreatic juice acts on other lipids because of their food digestion. Pancreatic lipase converts the fatly food into fatly acid and glycerol.

Fat → Lipase → Fatlyacids and Glycerol.

Under normal conditions fat digestion is completed by pancreatic juice in the Duodenum.

Digestion in Small Intestine:

Intestinal Lipase has of small value. Little amount of fat is digested by intestinal lipase if some are unintentionally escaped from digestion by pancreatic Lipase. Some emulsified fats and phospholipids are digested by intestinal lipase into fatly acids and glycerol.

Emulsified fat → Intestinal Lipase → Fatly acids and glycerol

Phospholipids→ Intestinal Lipeise →Phosphoric Acid, Fatly acid, Glycerol.

Fat consumption differs from compared to sugar and proteins. It takes invest the lacteals into the villi. Fatly acids have phosphorylated that get transported over the lacteals as phospholipids. Small amount of emulsified fats, form water dissolvable compounds with bile that are readily consumed fat soluble nutrients.

Essay # 2. Accessory Glands for Digestion of Foods:

The liver and pancreas would be the accessory glands of digestion.

1. Liver:

Liver is the biggest gland of human body. Its located in the uppermost an element of the stomach cavity on the right side just below the diaphragm. Its fat is between 1.0 to 2.5 kg. It is thicker in males compared to females. Liver is a soft, solid and chocolate colored human body.


The liver is divided in to two primary lobes appropriate and left. The best lobe is larger than the left. The under surface of right lobe is further sub divided in to quadrate and caudate lobes.

The liver has four surfaces like:

(1) Superior

(2) Inferior

(3) Anterior

(4) Posterior surfaces.

Gall bladder is situated in ventral side regarding the liver.

The liver has a double blood circulation in the shape of:

(1) Hepatic artery

(2) Portal vein.

(1) Hepatic artery:

The hepatic artery comes from the aorta and materials ⅕ th the blood to your liver. This bloodstream has an oxygen saturation of 95 -100per cent.

(2) Portal Vein:

It's created from splenic vein and supplies ⅘ th for the blood towards the liver. This blood has an oxygen saturation of only 70percent. The portal vein brings the nutritional elements absorbed by the little intestine.

The bile juice opens into bile duct that will be carried toward duodenum and helps in the digestion procedure.


The liver is considered the most active and versatile gland of our body. Combined with digestive function liver executes a number of other functions regarding the human anatomy.

The functions are:

a. Secretion of Bile juice:

The secretion of bile is an exocrine function of the gland, liver. Bile juice is made by the liver cellular that will be passed away to your gall bladder for storage and to assist the digestion procedure.

b. Glycogenesis:

Liver cells produce glycogen from glucose by the action of an enzyme. This will be kept for future usage. This conversion of sugar into glycogen is known as glycogenesis.

c. Detox:

Sometimes some poisonous and toxins enter the human body through diet and drugs. The liver is able to destroy or change the toxins into harmless materials in the torso. There by protects your body.

d. Metabolic rate of Fat:

Fats are converted into fatly acids and glycerol by the enzyme lipase in the existence of bile juice. After absorption they visited the liver for metabolism and it is employed by the tissues associated with human body.

e. Glycogenolysis:

Whenever blood glucose level is low in the body or the dependence on glucose is increased for a few reasons, the glycogen kept into the liver is changed into glucose and it is employed by the body. This transformation of glycogen to glucose is recognized as glycogenolysis.

f. Gluconeogenesis:

Liver also converts amino acids, fatly acids and glycrol to glucose whenever carbohydrate is deficient for a longer period.

g. Deamination of Amino Acids:

After digestion of protein, proteins arc absorbed through villi into blood capillaries and carried towards the liver in which these are oxidized. Deamination procedure additionally take place in the liver cells. Deamination could be the procedure of removal of nitrogen from amino acids. Ammonia is divided and combines with co2 to form urea which can be excreted in urine by renal.

h. Urea Synthesis:

Synthesis of urea from ammonia is an important function of the liver.

i. Storage of Minerals And Vitamins:

The fat soluble vitamins A, D and K are saved in liver. Vitamin B12 also saved to stop deficiency as much as four months. The liver can synthesize supplement A from carotene within vegetables and fruit. The liver also stores iron in the shape of a protein mixture called as “Ferritin” which is based on the hemoglobin following the destruction of R.B.C. This reserve of iron is once more used to form haemoglobin in brand new R.B.C.

j. Maintenance of Normal Content of Blood:

Liver is worried with the normal content of bloodstream:

1. It forms red-cells in fetal life.

2. It plays a crucial role inside destruction of R.B.C.

3. It shops haematin necessary for the maturation of the latest red cells.

4. It manufactures 90 to 95% plasma proteins, albumin, globulin and fibrinogen.

5. It removes bilirubin from the blood.

k. Manufacturing of Blood Clotting Factors:

Liver cells synthesize proteins like pro-thrombin and fibrinogen that assist in clotting of blood. During hammer-age, the liver secretes an anti-coagulant called heparin which prevents coagulation of bloodstream inside arteries.

l. Repair of Body's Temperature:

The liver helps keep up with the temperature associated with the human anatomy through different metabolic activities.

Gall Bladder:

The Gall bladder is a pear-shaped muscular bag like organ. It is connected to the underneath surface of the right lobe associated with the liver. Its length is approximately 8 – 10 cm (3 – 4 ins) with a capacity of about 60 ml.


The Gall bladder is divided into three parts, fundus, body and neck. It is comprised of three coats.

1. an exterior peritoneal coating:

It binds the gall bladder constantly in place regarding the underneath area for the liver.

2. a center un-striped muscular tissue coat:

The gall bladder is able to clear its contents into the bile duct by the contraction with this layer.

3. an internal mucous membranes layer:

Its consists of epithelial cells which secrete mucin and rapidly absorbs water and electrolytes but not bile salts or pigments. Hence bile becomes focused. The cystic duct passes through the throat associated with the gall bladder and joins the hepatic duct which forms the most popular bile duct, making sure that bile juice can be easily carried on duodenum. The size of the cystic duct is all about 4cm (1 ½ ins).


1. The gall bladder acts as the reservoir of bile juice.

2. It reabsorbs water and electrolyte content of bile and so focus the bile about 10 times.

3. It absorbs inorganic salts from bile somewhat and reduces the alkalinity of liver bile.

4. It excretes cholesterol to varying degrees.

5. It secretes mucus, which is the key source of mucin in bile.

6. It can help in equalization of force in the biliary duct system.

Composition of Bile:

Bile is a product of release along with the excretion of this liver. Its an alkaline fluid secreted by the liver cells. It is stated in the liver in a dilute kind and is then concentrated by the gall bladder to yellowish-green fluid. The taste of bile is bitter. The amount secreted every day is from 500 to 1000 ml, regarding the average about 700 ml. The secretion is constant. The price of release is increased during food digestion of fats. Bile consists of water, bilesalts, bile pigments, cholesterol and mucin.

Bile Salts:

Bile salts are sodium glycocholate and sodium-taurocholate. These salts are synthesized by the liver. They will have digestive function. Bile salts help in the action of pancreatic enzyme lipase for the digestion of fat. It also helps within the absorption of digested fat like fatly acids and glycerol within the villi. Bile salts cannot appear in the faeces because they are reabsorbed from the little intestine and returned to the liver.

Bile Pigments:

Bile pigments are formed into the reticula endothelial system of spleen and bone tissue marrow. If the haemoglobin associated with the worn-out Red bloodstream cells are divided, bile pigments are based on the unused “haem”. These pigments are conveyed towards bile on little intestine. The 2 chief bile pigments are bilirubin and biliverdin.

When there is an obstruction towards the excretion of bile, the bile pigments accumulate inside bloodstream when the epidermis and mucous membranes becomes yellowish colour. This disorder is called jaundice. Bile pigments do not have digestion action. These are typically excreted through the body.


This really is an excretory product. Its amount in bile differs using its degree in bloodstream.

Functions of Bile:

Bile is quite needed for life. Though it offers no direct digestive function it will help in the food digestion of meals.

Bile has following function:

a. Digestion:

Bile is important the complete digestion of fats by splitting them and activating the enzyme lipase.

b. Consumption:

Bile assists in absorption of numerous substances like fat, iron, calcium, fat dissolvable vitamins like ADEK and pro-vitamin carotene.

c. Excretion:

Bile excretes the unused and noxious substances of this body. These are metals like copper, zinc, mercury, toxins and bacteria’s, bile pigments, cholesterol levels an such like.

d. Laxative Action:

Bile salts stimulate peristalsis.

age. Maintenance of pH:

As a significant supply of alkali it neutralizes the hydrochloric acid and keeps the right pH associated with the duodenal contents.

f. Action as Buffer:

Mucin of bile acts as a buffer and a lubricant.

g. Antiseptic Function:

Bile has antiseptic properties. It kills the germs and bacteria’s from the meals within the intestine.

2. Pancreas:

Pancreas is a soft, irregularly shaped substance gland. The size of this gland is mostly about 23 cm (7 ins). It runs from the duodenum towards the spleen. It is situated behind the stomach and parallel to it. Pancreas is within the ‘C shaped curve of Duodenum. The color associated with pancreas is greyish-pink.


The pancreas is composed of three parts.

1. The Head:

It is the broadest component that will be situated toward right associated with stomach cavity and in the bend regarding the Duodenum.

2. Your Body:

It is the primary area of the gland, it lies behind the belly and in front of first lumbar vertebra.

3. The Tail:

This component may be the slim area of the pancreas. This is situated to the left component touching the spleen.

The Pancreas consist of a number of lobules. Each lobule contains public of secretory cells arranged in a grape like development. Tiny ducts from lobules are united together to make larger duct to create as pancreatic duct. This duct is extended from left to right in the exact middle of the gland and through the head of pancreas enters the Duodenum on Ampulla of Vater.

Another number of cells known as Islets of Langerhans can be found mostly within the tail percentage of the pancreas. There are about 1-2 countless islets inside pancreas. The islets contain three major kinds of cells, the Alpha, Beta and Delta cells.

The Islets secrete two hormones:

(1) Insulin.

(2) Glucagon which are directly poured to the bloodstream.

Functions of this Pancreas:

The pancreas is described as a dual organ which has two functions:

(1) Exocrine

(2) Hormonal Functions.

1. Exocrine Functions:

Here is the digestive function associated with pancreas. The Acinar cells of the pancreas secetes pancreatic juice which will be carried by the pancreatic duct towards duodenum through Ampulla of vater. 1200 ml of pancreatic juice is secreted daily.

Pancreatic juice contains three enzymes:

1. Amylase:

Functions upon carbohydrate meals and converts the starch, glycogen alongside carbs into disaccharides.

2. Trypsin:

Acts upon protein meals and converts them into polypeptide.

3. Lipase:

Functions upon fatly-food and simplifies them to fatly-acids and glycerol in the presence of bile juice.

2. Endocrine Functions:

“Islets of Langerhans” is called the endocrine cells associated with the pancreas. Because of this function pancreas can also be known as Endocrine gland. This ductless gland secretes two hormones which are directly poured in to the bloodstream.

These hormones are:

1. Insulin:

It's important for the metabolic rate of carbohydrate and keeping blood sugar level. Diabetes is caused due to the deficient secretion of insulin.

2. Glucagon:

This hormone is secreted through the alpha cells associated with the pancreas which escalates the blood glucose degree. Pancreas is a significant gland in the human body as it does both endocrine and exocrine functions.

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