Lecture 18 & 19 Digestive System 2010-2

Lecture 18 & 19 Digestive System 2010-2 - Anatomy of...

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Unformatted text preview: Anatomy of the Digestive System Angela Black, DVM, PhD Department of Animal and Avian Sciences University of Maryland, College Park Three main types of GI tract • Monogastric – Single stomach compartment – Carnivores (cats), some omnivores (pigs, dogs) • Ruminant – Multiple stomach compartments – Fermentation occurs there, before the small intestines – Only herbivores such as camelids, cattle, sheep, goats Three main types of GI tracts • Postgut fermenter – Fermentation mainly occurs in the cecum, between small and large intestine – Herbivores such as the rabbit, Guinea pig and horse. Fermentation allows animals to utilize the energy in cellulose. Cellulose is indigestible (fiber) in monogastrics. Elements of the Digestive System mouth pharynx esophagus forestomach (ruminants only) glandular stomach small intestine cecum large intestine rectum accessory glands (salivary glands, liver, pancreas) Primary Functions of the Digestive System • Mastication: Mechanical breakdown of food. • Digestion: Chemical (HCL), Enzymatic (lipase, amylase, pepsin, gastrin), Microbial Fermentation • Absorption: Primarily in the Jejunum • Elimination Mouth • Lined with mucous membrane (epithelium) • Mechanical breakdown of food :Teeth • Incisors: cutting • Canine/eye teeth/fangs/tusks: tearing • Premolars: grinding • Molars: grinding, no deciduous molars • Dental Formula (I)_/_ (C )_/_ (P)_/_ (M)_/_ Mouth Tongue • Intrinsic muscle - Fibers oriented in three directions • Papillae: • Vallate, fungiform – taste buds • Foliate, filiform – grooming, moving food around in mouth Tongue Mouth • Salivary Glands: parotid, sublingual,molar, submallialry. Ducts empty into mouth • Salivation: 1) Liquifies food so that it can be tasted, swallowed, digested. 2) Saliva contains bicarbonate to neutralize the HCL in the stomach. 3) Contains enzymes (amylase) that begin the Enzymatic breakdown of food particles. Mouth “ Enzyme” - a protein that speeds up the rate of a biochemical reaction without being consumed itself. Each enzyme can only interact with a specific type of substance: protein-protease fat-lipase carb-amylase lactase (milk sugar)-lactase In the case of digestive enzymes, the reactions being catalyzed are those that breakdown food into basic substrates. Pharynx The common passage for food and air, caudal to oral and nasal cavities, lined by mucous membrane and surrounded by muscles....
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This note was uploaded on 12/30/2011 for the course ANSC ANSC211 taught by Professor Black during the Fall '11 term at Maryland.

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Lecture 18 & 19 Digestive System 2010-2 - Anatomy of...

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