This system is composed of many organs wgich intergrate to form a single system.Organs of the gastrointestinal system can be catagorised into two groups,the alimentary canal and accessoey digestive organs.
The anterior teeth are responsible for cutting foodThe posterior teeth are responsible for grindingToungue,a strong muscular organs is responsible for manipulation of food into a bolus and mixing it with saliva through a process called insalivation
salivation occurs in response to the taste,smell and even appearance of the foodThis occurs due to nerve signal thattells the salivary glands to secrete saliva in order to moisten foodSalivation makes food easier top swallow
It extends from the pharynx to the stomach after passsing through the diaphragmThe oesophogus functions as the transport route through compartments
It is divided into four regions and has two borders called greater and lesser curvaturesThe first region is Cardia which surround the cardiac orifice where the oesophogus enters the stomachFundus is the superior part of the stomach that is in touch with the diaphragmThe body is the larges region between the fundus and the curved portion of the JFinally the pylorus which is the curved base of the stomachFUNCTIONS OF THE STOMACH INCLUDE:The short term storage of ingested foodMechanical digestion through food mixingChemical digestion of proteinsAbsorption of substances
Small intestines occupy large portion of the abdominal cavityDuodenum is the c-shaped section that curves around the head of the pancreas.It mixes digestive secretions from liver and pancreas with the contnt expelled from the stomachThe sharp bend is the begining of the jejunum and it serves as the digestion and absorption siteIleum is the longest segment and it empties into the caecum
Its length is approximately 1.5m and width of 7.5cmCaecum compessess food into a faecal contentRectum is the final 15 cm of the large intestineIt holds faecal matter before it passess through the anorectal canal to the anus
These organs secrete chemical digestivesThese secretions help in the breaking down of food whilst it reaches the stomach
Liver has mNY functions but its primary function during digestion is to produce bile which is latyer stored in the gall bladderIt is also responsible for metabolism of the nutrients
It consists of a fundus,body and neckIts main function is to stotre bileBile is a thick fluid that contains enzymes which dissolves fats in the intestine
It has both the exocrine and endocrine functionsPancreas secretes fluids rich in carbohydrates and inactive enzymesThese fluids are released only after a trigger by duodenum to prevent pancreas from digesting itself
These includes mechanoreceptors,chemoreceptors and osmoreceptors.They are responsible for detecting mechanmical,chemical and osmotic stimuli respectively.They can detect what type of food has caused the stomach to expand,has the food been properly grinded and how much water is required for digestive process to continue.
The main hormone is gastrin which is secreted in the response of resence of foodGastrin stimulates the secretion of gastric acids..Duodenum secretes secretin which stimulates watery secretion of biocarbonateCholecykotinin which stimulates secretion of pancreatic enzymesOther hormones are secreted by epuithelium cells called endocrinocytes.