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The Digestive System
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Digestion
Processing of food
Types
Mechanical (physical)
Chew Tear
Grind
Mash
Mix
Chemical Catabolic reactions
Enzymatic hydrolysis
Carbohydrate
Protein
Lipid
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Digestion
Phases
Ingestion
MovementDigestion
Absorption
Further digestion
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Digestive System Organization
Gastrointestinal (Gl) tract (Alimentary canal)
Tube within a tube
Direct link/path between organs
Structures Mouth
Oral Cavity
Pharynx
Esophagus
Stomach Duedenum
Jejenum
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 ofmouth
Pharyngeal stage Raise
Soft palate
Larynx + hyoid
Tongue to soft palate
Esophageal stage
Contract pharyngealmuscles
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)
3 constrictions
Aortic arch
Left primary bronchus Diaphragm
Surrounded by
SNS plexus
Blood vessels
Functions
Secrete mucous
Transport food
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Peristalsis and Segmentation
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Esophagus
Sphincters
Upper
Lower
Abnormalities
Achalasia
Atresia
Hernia Barrets esophagus
Esophageal varices
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Stomach
Usually J shaped
Left side, anterior to the spleen
Mucous membrane
G cellsmake gastrin
Goblet cellsmake mucous
Gastric pitOxyntic glandParietal cellsMakeHCl
Chief cellsZymogenic cells Pepsin
Gastric lipase
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Anatomy of the Stomach
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Stomach
Muscularis membrane :
Oblique
Circular
Longitudinal
Serosa membrane
Regions
Cardiac sphincter
Fundus Corpus
Antrum Pyloric
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Stomach
Functions
Mix food
Reservoir
Start digestion of
Protein
Nucleic acids
Fats
Activates some enzymes
Destroy some bacteria
Makes intrinsic factorB12 absorption
Absorbs
Alcohol
Water
Lipophilic acid B 12
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Small Intestine
Extends from pyloric
sphincterileocecal
valve
Regions Duodenum
Jejenum
Ileum
Movements Segmentation
Peristalsis
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Small Intestine
Histology
Intestinal glandsIntestinal enzymes
Duodenal glandsAlkaline mucous
Paneth cellsLysozyme Microvilli
Lacteals
Plica circularis
Smooth muscle Lymphatic tissueGALT
Vascular
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Small Intestine
Absorbs
80% ingested water
Electrolytes
Vitamins
Minerals
Carbonates
Active/facilitatedtransport
Monosaccharides
Proteins Di-/tripeptides
Amino acids
Lipids
Monoglycerides
Fatty acids
Micelles Chylomicrons
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Structure of the Villi in the
Small Intestine
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Small Intestine
Secretes digestiveenzymes Peptidases
Amino-
Di- Tri-
Sucrases
Maltase
Lactase
Saccharidases Di-
Tri-
Lipase
Nucleases
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Small Intestine
Requires pancreatic
enzymes & bile to
complete digestion
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Large Intestine
Extends from ileocecal valve to anus
Regions
CecumAppendix
Colon
Ascending
Transverse
Descending
Rectum
Anal canal
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Anatomy of the Large Intestine
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Large Intestine
Histology
No villi
No permanent circular foldsSmooth muscle
Taeniae coli
Haustra
Epiploic appendages
Otherwise like rest of Gl tract
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Large Intestine
Functions
Mechanical digestion
Haustral churning
Peristalsis
Reflexes
Gastroileal
Gastrocolic
Chemical digestion
Bacterial digestion Ferment carbohydrates
Protein/amino acid
breakdown
Absorbs
More water
Vitamins
B
K
Concentrate/eliminatewastes
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Feces Formation and Defecation
Chyme dehydrated toform 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
R. Hypochondrium
Epigastric region
4 Lobes Left
Quadrate
Caudate
Right
Each lobe has lobulesContains hepatocytesSurround sinusoidsFeed into central vein
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Liver
Functions
Makes bile
Detergentemulsifiesfats
Release promoted by: Vagus n.
Secretin
Contains
Water
Bile salts
Bile pigments Electrolytes
Cholesterol
Lecithin
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Liver
Detoxifies/removes
Drugs
Alcohol
Stores
Gycolgen
Vitamins (A, D, E, K)
Fe and other minerals
Cholesterol
Activates vitamin D
Fetal RBC production
Phagocytosis
Metabolizes absorbed foodmolecules
Carbohydrates
Proteins
Lipids
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Liver
Dual blood supply
Hepatic portal vein
Direct input from small
intestine Hepatic artery/vein
Direct links to heart
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The Duodenum and Related
Organs
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The Organs and Positions in the
Abdominal Cavity
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Structures of the Alimentary
Canal
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