PHYSIOLOGY AND ANATOMY OF

DIGESTIVE SYSTEM & TONGUE

By:Dilip Kumar Mahto

Virbhusan SonarAnand Peters

INTRODUCTION

The digestive system is used for breaking down foods into nutrients which then pass into the circulatory system and are taken to where they are needed in the body and remained matter are thrown out of the body.

PHASES OF DIGESTIVE SYSTEM

Ingestion Occurs when material enters

via the mouth

Mechanical Processing Crushing / Shearing – makes

material easier to move through the tract

Digestion Chemical breakdown of food

into small organic compounds for absorption

Secretion Release of water acids, buffers,

enzymes & salts by epithelium of GI tract and glandular organs

Absorption Movement of organic

substrates, electrolytes, vitamins & water across digestive epithelium

Excretion Removal of waste products from

body fluids

COMPONENTS Mouth Pharynx Esophagus Stomach Small Intestine Large Intestine Rectum Anus

MOUTH Begins when food enters

the mouth. It is physically broken

down by the teeth. It is begun to be

chemically broken down by amylase, an enzyme in saliva that breaks down carbohydrates.

PHARYNX

The tongue moves the food around until it forms a ball called a bolus.

The bolus is passed to the pharynx (throat) and the epiglottis makes sure the bolus passes into the esophagus and not down the windpipe!

ESOPHAGUS Approximately 10”

long Functions include:1. Secrete mucus2. Moves food from

the throat to the stomach using muscle movement called peristalsis

PERISTALSIS

The bolus passes down the esophagus by peristalsis.

Peristalsis is a wave of muscular contractions that push the bolus down towards the stomach.

STOMACH J-shaped muscular bag that stores

the food you eat, breaks it down into tiny pieces.

Mixes food with digestive juices that contain enzymes to break down proteins and lipids.

Acid in the stomach kills bacteria. Food found in the stomach is called

chyme.

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SMALL INTESTINE Small intestines are roughly 7

meters long

It has three parts –

1. Duodenum2. Jejunum3. Ileum

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1. DUODENUM Bile, produced in the

liver but stored in the gall bladder, enters through the bile duct. It breaks down fats.

The pancreas secretes pancreatic juice to reduce the acidity of the chyme.

2. JEJUNUM The jejunum is

where the majority of absorption takes place.

It has tiny fingerlike projections called villi lining , which increase the surface area for absorbing nutrients.

3. ILEUMThe last portion of the small intestine is the ileum, which has fewer villi and basically compacts the leftovers to pass through the caecum into the large intestine.

Nutrients from the food pass into the bloodstream through the small intestine walls.

Absorbs: 80% ingested water Vitamins Minerals Carbohydrates Proteins Lipids

• Secretes digestive enzymes

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LARGE INTESTINE

The large intestine (or colon) is used to absorb water from the waste material leftover and to produce vitamin K and some B vitamins using the helpful bacteria that live here.

It is 5 feet long. It has three parts…

1. Ascending Colon2. Transverse Colon3. Descending Colon

All leftover waste is compacted and stored at the end of the large intestine called the rectum.

When full, the anal sphincter loosens and the waste called feces, passes out of the body through the anus.

LIVER

LIVER FUNCTIONThe Physiology of the Liver

1. Metabolic regulation2. Hematological regulation3. Bile production

PANCREAS Lies posterior to stomach

From duodenum toward spleen

Is bound to posterior wall of abdominal cavity

Is wrapped in thin, connective tissue capsuleFunctions of the Pancreas

1. Endocrine cells of the pancreatic islets:

Secrete insulin and glucagon into bloodstream

2. Exocrine cells: Acinar cells and

epithelial cells of duct system secrete pancreatic juice

GALL BLADDER Storage tank for bile (a greenish-yellow

liquid) that helps your body break down and use fats

Located under your liver

Shaped like a pear Gall Bladder

TONGUE

The tongue is fleshy, movable, muscular organ, attached in most vertebrates to the floor of the mouth, that is the principal organ of taste, an aid in chewing and swallowing, and, in humans, an important organ of speech.

derived from 1st-4th branchial arches

manipulates food for chewing and swallowing

contains no bony supports for the muscles the extrinsic muscles of the tongue anchor the

tongue firmly to surrounding bones and prevent the mythical possibility of 'swallowing' the tongue

sensitive and kept moist by saliva, and is richly supplied with nerves and blood vessels to help it move

PHYSIOLOGY

ANATOMY made mainly of skeletal

muscle

dorsum oral part (anterior two-thirds

of the tongue) that lies mostly in the mouth

pharyngeal part (posterior third of the tongue), which faces backward to the oropharynx

separated by a V-shaped groove, which marks the sulcus terminalis

PAPPILAE The oral part of the tongue is covered with

small bumpy projections called papillae. There are four types of papillae:

filiform (thread-shape) fungiform (mushroom-shape) circumvallate (ringed-circle) foliate (leaf-shape)

All papillae except the filiform have taste buds on their surface