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The Digestive System
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Digestion Processing of food Types Mechanical (physical) Chemical Chew
Tear Grind Mash Mix Chemical Catabolic reactions Enzymatic hydrolysis Carbohydrate Protein Lipid
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Digestion Phases Ingestion Movement Digestion Absorption
Further digestion
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Digestive System Organization
Gastrointestinal (Gl) tract (Alimentary canal) Direct link/path between organs Structures Mouth Oral Cavity Pharynx Esophagus Stomach Duodenum Jejunum Ileum Cecum Ascending colon Transverse colon
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Digestive System Organization
Descending colon Sigmoid colon Rectum Anus Accessory structures Not in tube path Organs Teeth Tongue Salivary glands Liver Gall bladder Pancreas
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Anatomy of the Mouth and Throat
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Human Deciduous and Permanent Teeth
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Dorsal Surface of the Tongue
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The Major Salivary Glands
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Deglutition (swallowing)
Sequence Voluntary stage Push food to back of mouth Pharyngeal stage Raise Soft palate Larynx + hyoid Tongue to soft palate Esophageal stage Contract pharyngeal muscles Open esophagus Start peristalsis
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Deglutition (swallowing)
Control Nerves Glossopharyngeal Vagus Accessory Brain stem Deglutition center Medulla oblongata Pons Disorders Dysphagia Aphagia
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Esophagus Usually collapsed (closed) Functions Secrete mucous
Transport food
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Esophagus Sphincters Upper Lower
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Stomach Usually “J” shaped Left side, anterior to the spleen
Mucous membrane G cells – make gastrin Goblet cells – make mucous Gastric pit – Oxyntic gland – Parietal cells – Make HCl Chief cells – Zymogenic cells Pepsin Gastric lipase
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Anatomy of the Stomach
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Stomach 3 muscle layers Regions Vascular
Oblique Circular Longitudinal Regions Cardiac sphincter Fundus Antrum (pylorus) Pyloric sphincter Vascular Inner surface thrown into folds – Rugae Contains enzymes that work best at pH 1-2
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Stomach Functions Absorbs Mix food Reservoir Start digestion of
Protein Nucleic acids Fats Activates some enzymes Destroy some bacteria Absorbs Alcohol Water Lipophilic acid
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Small Intestine Extends from pyloric sphincter ileocecal valve
Regions Duodenum Jejenum Ileum Movements Segmentation Peristalsis
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Small Intestine Absorbs 80% ingested water Electrolytes Vitamins
Minerals Lipids Monoglycerides Fatty acids
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Structure of the Villi in the Small Intestine
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Small Intestine Control
Requires pancreatic enzymes & bile to complete digestion
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Large Intestine Extends from ileocecal valve to anus Regions
Cecum – Appendix Colon Ascending Transverse Descending Rectum Anal canal
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Anatomy of the Large Intestine
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Large Intestine Functions Mechanical digestion
Haustral churning Peristalsis Chemical digestion – Bacterial digestion Ferment carbohydrates Protein/amino acid breakdown Absorbs More water Vitamins Concentrate/eliminate wastes
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Feces Formation and Defecation
Chyme dehydrated to form feces Feces composition Water Inorganic salts Epithelial cells Bacteria Byproducts of digestion Defecation Peristalsis pushes feces into rectum Rectal walls stretch Control Parasympathetic Voluntary
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Liver Location 4 Lobes Each lobe has lobules – Contains hepatocytes
Left Quadrate Caudate Right Each lobe has lobules – Contains hepatocytes
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Liver Functions Makes bile Detergent – emulsifies fats Contains Water
Salts Pigments Electrolytes Cholesterol
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Liver Detoxifies/removes Stores Activates vitamin D
Drugs Alcohol Stores Glycogen Vitamins (A, D, E, K) Fe and other minerals Cholesterol Activates vitamin D Fetal RBC production Phagocytosis Metabolizes absorbed food molecules Carbohydrates Proteins Lipids
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The Organs and Positions in the Abdominal Cavity
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