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DIGESTIVE SYSTEM

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DIGESTIVE SYSTEM. GENERAL. 1st System to Develop 'Tube' ... Consists of Alimentary Canal/Digestive Tract and Accessory Organs. DIGESTIVE SYSTEM FUNCTIONS ... – PowerPoint PPT presentation

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Title: DIGESTIVE SYSTEM


1
DIGESTIVE SYSTEM
2
GENERAL
  • 1st System to Develop
  • Tube Within a Tube
  • Contents Remain External Until Absorbed Through
    Walls
  • Humans are (Anatomical) Omnivores
  • Consists of Alimentary Canal/Digestive Tract and
    Accessory Organs

3
DIGESTIVE SYSTEM FUNCTIONS
  • Ingestion Food Enters Through Mouth
  • Digestion Breaking Large Molecules into
    Smaller, Absorbable Molecules
  • Mechanical (Physical)
  • Chemical (Enzymatic)
  • Absorption Passage of Molecules Through GI
    Tract Wall into Blood or Lymph
  • Egestion Elimination of Non-digestible
    Substances Through Anal End

4
DIGESTIVE SYSTEM ORGANIZATION
  • Alimentary Canal (Gastrointestinal or Digestive
    Tract)
  • Mouth, Pharynx, Esophagus, Stomach, Small
    Intestine, Large Intestine
  • Lumen is part of External Environment
  • Accessory Organs
  • Salivary Glands
  • Liver
  • Gall Bladder
  • Pancreas

5
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6
ALIMENTARY CANAL HISTOLOGY
  • Mucosa
  • Innermost, Surrounds Lumen
  • Mucous Membrane
  • Secretes, Absorbs, Protects
  • Submucosa
  • Below Mucosa
  • C.T., Blood Vessels, Lymphatics, Nervous Tissue

7
ALIMENTARY CANAL HISTOLOGY continued
  • Muscularis (Externa)
  • Smooth Muscle
  • Inner, Circular, ? Diameter of Lumen
  • Outer, Longitudinal, ? Diameter of Lumen
  • Propels Substances
  • Serosa (Visceral Peritoneum)
  • Outermost
  • Serous Membrane, Lubricates
  • Adventitia outside of Ventral Body Cavity

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10
MOVEMENT OF FOOD
  • Peristalsis - Wave-like Contraction of Circular
    Longitudinal Smooth Muscle for Propulsion
  • ANS
  • Stimulated by Parasympathetic
  • Inhibited by Sympathetic

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12
ALIMENTARY CANAL ORGANIZATION
  • MOUTH
  • Oral (Buccal) Cavity Functions in Ingestion
  • Digestion
  • Mechanical (Teeth, Tongue)
  • Chemical (Saliva Begins Carbohydrate Digestion)
  • Cheeks
  • Hard Palate (Bony)

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14
MOUTH continued
  • Soft Palate (Muscular)
  • Blocks Nasopharynx During Swallowing
  • Uvula - Dangling end
  • Tongue
  • Frenulum Anchors to Floor of Mouth
  • Skeletal Muscle Tissue covered with Mucosa
  • Papillae with Taste Buds
  • Lingual Tonsil Sublingual Gland

15
MOUTH continued
  • Teeth
  • Vestibule Space between Teeth Lips
  • Two Sets Deciduous (20) Permanent (32)
  • Four Types
  • Incisors Biting
  • Canines Tearing Grasping
  • Bicuspids Molars - Grinding

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17
ALIMENTARY CANAL ORGANIZATION continued
  • PHARYNX
  • Connects Oral Cavity, Nasal Cavity, Larynx
    Esophagus
  • Passageway for Food, Water, Air
  • Muscular Walls (Swallowing)
  • 3 Regions Nasopharynx, Oropharynx, Laryngopharynx

18
ALIMENTARY CANAL ORGANIZATION continued
  • ESOPHAGUS
  • Collapsible, 10 Tube
  • Connects Pharynx Stomach
  • Lies Posterior to Trachea
  • Lower Esophageal Sphincter Prevents Stomach
    Contents from Entering Esophagus
  • Passes Through Neck ? Thoracic Cavity ?
    Esophageal Hiatus ? Abdominal Cavity

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20
ALIMENTARY CANAL ORGANIZATION continued
  • STOMACH
  • J-Shaped Organ, Inferior to Diaphragm
  • Functions
  • Storage
  • Digestion (Mechanical Chemical)
  • Protein Digestion Begins here
  • Absorption of Water, Alcohol, Drugs

21
STOMACH continued
  • Enters as Bolus Mixture of Food Saliva
  • Leaves as Chyme Milky Mixture of Partially
    Digested Food Gastric Juices

22
STOMACH continued
  • 4 Regions
  • Cardia Connects with Esophagus
  • Body Principal, Main Part
  • Fundus Superior, Bulge, Food Storage
  • Pylorus Terminal Part, Pyloric Sphincter
  • 2 Curves
  • Greater Curvature
  • Lesser Curvature

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24
STOMACH continued
  • Wall Modifications
  • Rugae Expandable Folds, Accommodate More Food
  • Oblique Muscle in Muscularis
  • Gastric Glands in Mucosa
  • Mucus Cells (Protective Coating)
  • Parietal Cells (HCl, pH 2)
  • Chief Cells (Pepsinogen HCl ? Pepsin
    (Proteolytic)

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27
ALIMENTARY CANAL ORGANIZATION continued
  • SMALL INTESTINE
  • Site of Most Chemical Digestion
  • Site of 90 of Absorption
  • Monosaccharides ? Blood
  • Amino Acids ? Blood
  • Fatty Acids Glycerol ? Lymph
  • Nitrogenous Bases, Phosphates ? Blood

28
SMALL INTESTINE continued
  • 3 Subdivisions
  • Duodenum
  • First 10-12
  • Ampulla of Vater Receives Secretions from Liver
    Pancreas
  • Bile through Common Bile Duct
  • Pancreatic Juice through Pancreatic Duct
  • Jejunum Middle Length
  • Ileum Last, Joins with Large Intestine at
    Ileocecal Valve

29
Small Intestine
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31
SMALL INTESTINE continued
  • Wall Modifications
  • All Increase Surface Area for Maximum Absorption
  • Plicae Circulares Transverse Folds of Mucosa
    Submucosa
  • Villi Finger-like Projections of Mucosa,
    contain Capillaries Lacteal
  • Microvilli Microscopic Folds of Cell Membrane

32
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33
ALIMENTARY CANAL ORGANIZATION continued
  • LARGE INTESTINE
  • Functions
  • Secretes Mucus
  • Absorbs Water, Ions, Vitamins (From Bacterial
    Metabolism)
  • Forms Compacts Feces (Undigested Food,
    Bacteria, Water)

34
LARGE INTESTINE continued
  • 3 Divisions
  • Cecum
  • Blind Pouch
  • Appendix Attached
  • Colon - Divided into Ascending, Transverse,
    Descending, Sigmoid
  • Rectum Anal Canal
  • Internal Anal Sphincter (Smooth)
  • External Anal Sphincter (Skeletal)

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37
LARGE INTESTINE continued
  • Wall Modifications
  • Taenia Coli 3 Bands of Longitudinal Muscle from
    Muscularis of Colon
  • Haustra Pouches in Wall of Colon
  • No Villi

38
ALIMENTARY CANAL MOVEMENTS
  • Peristalsis - Wave-like Contraction of Circular
    Longitudinal Smooth Muscle for Propulsion
  • Segmentation Mixes Pushes Chyme Against Wall
    of Small Intestine
  • Haustral Churning Pouch-to-Pouch Movement in
    Large Intestine
  • Reverse Peristalsis

39
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42
ACCESSORY ORGANS
  • SALIVARY GLANDS
  • Exocrine Glands
  • Ducts Carry Secretions (Saliva) into Mouth
  • Saliva Amylase, Mucous, Water, Antibodies,
    Lysozyme
  • 3 Pairs
  • Parotid (Most Salivary Amylase)
  • Submandibular
  • Sublingual

43
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44
ACCESSORY ORGANS continued
  • LIVER
  • Largest Gland in Body (Exocrine)
  • Produces Secretes Bile (Fat Emulsifier)
  • Nutrient Storage Conversion
  • Synthesizes Blood Proteins
  • Detoxification

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47
ACCESSORY ORGANS continued
  • GALL BLADDER
  • Muscular Sac
  • Stores Concentrates Bile
  • Receives Bile from Liver via Common Hepatic Duct
    ? Cystic Duct
  • Releases into Duodenum via Cystic Duct ? Common
    Bile Duct ? Ampulla of Vater (Sphincter of Oddi)

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49
ACCESSORY ORGANS continued
  • Bile Release
  • Chyme Enters Duodenum
  • Cholecystokinin (CCK) Secretin Secreted by
    Duodenum, Enters Blood
  • Secretin stimulates liver to produce bile
  • CCK Stimulates Contractions in Gall Bladder
    Relaxation of Sphincter

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51
ACCESSORY ORGANS continued
  • PANCREAS
  • Exocrine ( Endocrine) Gland
  • Secretes Pancreatic Juice (Digestive Enzymes
    Buffers)
  • Leaves Pancreas Through Pancreatic Duct(s),
    Enters Duodenum Through Ampulla of Vater
    (hepatopancreatic ampulla)
  • Raises pH of Duodenum (pH 8) via bicarbonate ions

52
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