Anatomy and Physiology by Rod R Seeley 6th edition chapter 24 power-point

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Anatomy and Physiology, Sixth Edition
Rod R. SeeleyIdaho State University Trent D.
StephensIdaho State University Philip
TatePhoenix College
Chapter 24 Lecture Outline
See PowerPoint Image Slides for all figures and
tables pre-inserted into PowerPoint without notes.
Copyright The McGraw-Hill Companies, Inc.
Permission required for reproduction or display.
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Chapter 24

• Digestive System

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Digestive System Anatomy

• Digestive tract
• Alimentary tract or canal
• GI tract
• Accessory organs
• Primarily glands
• Regions
• Mouth or oral cavity
• Pharynx
• Esophagus
• Stomach
• Small intestine
• Large intestine
• Anus

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Functions

• Ingestion Introduction of food into stomach
• Mastication Chewing
• Propulsion
• Deglutition Swallowing
• Peristalsis Moves material through digestive
  tract

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Functions

• Mixing Segmental contraction that occurs in
  small intestine
• Secretion Lubricate, liquefy, digest
• Digestion Mechanical and chemical
• Absorption Movement from tract into circulation
  or lymph
• Elimination Waste products removed from body

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Digestive Tract Histology
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Digestive System Regulation

• Nervous regulation
• Involves enteric nervous system
• Types of neurons sensory, motor, interneurons
• Coordinates peristalsis and regulates local
  reflexes

• Chemical regulation
• Production of hormones
• Gastrin, secretin
• Production of paracrine chemicals
• Histamine
• Help local reflexes in ENS control digestive
  environments as pH levels

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Peritoneum and Mesenteries

• Peritoneum
• Visceral Covers organs
• Parietal Covers interior surface of body wall
• Retroperitoneal Behind peritoneum as kidneys,
  pancreas, duodenum
• Mesenteries
• Routes which vessels and nerves pass from body
  wall to organs
• Greater omentum
• Lesser omentum

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Oral Cavity

• Mouth or oral cavity
• Vestibule Space between lips or cheeks and
  alveolar processes
• Oral cavity proper
• Lips (labia) and cheeks
• Palate Oral cavity roof
• Hard and soft
• Palatine tonsils
• Tongue Involved in speech, taste, mastication,
  swallowing

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Teeth

• Two sets
• Primary, deciduous, milk Childhood
• Permanent or secondary Adult (32)
• Types
• Incisors, canine, premolar and molars

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Teeth
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Salivary Glands

• Produce saliva
• Prevents bacterial infection
• Lubrication
• Contains salivary amylase
• Breaks down starch
• Three pairs
• Parotid Largest
• Submandibular
• Sublingual Smallest

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Pharynx and Esophagus

• Esophagus
• Transports food from pharynx to stomach
• Passes through esophageal hiatus (opening) of
  diaphragm and ends at stomach
• Hiatal hernia
• Sphincters
• Upper
• Lower

• Pharynx
• Nasopharynx
• Oropharynx Transmits food normally
• Laryngopharynx Transmits food normally

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Deglutition (Swallowing)

• Three phases
• Voluntary
• Bolus of food moved by tongue from oral cavity to
  pharynx
• Pharyngeal
• Reflex Upper esophageal sphincter relaxes,
  elevated pharynx opens the esophagus, food pushed
  into esophagus
• Esophageal
• Reflex Epiglottis is tipped posteriorly, larynx
  elevated to prevent food from passing into larynx

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Phases of Deglutition (Swallowing)
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Stomach Anatomy

• Openings
• Gastroesophageal To esophagus
• Pyloric To duodenum
• Regions
• Cardiac
• Fundus
• Body
• Pyloric

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Stomach Histology

• Layers
• Serosa or visceral peritoneum Outermost
• Muscularis Three layers
• Outer longitudinal
• Middle circular
• Inner oblique
• Submucosa
• Mucosa

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Stomach Histology

• Rugae Folds in stomach when empty
• Gastric pits Openings for gastric glands
• Contain cells
• Surface mucous Mucus
• Mucous neck Mucus
• Parietal Hydrochloric acid and intrinsic factor
• Chief Pepsinogen
• Endocrine Regulatory hormones

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Stomach Secretions

• 2-3 Liters per day
• Mucus
• mucous neck cells produce a viscous and alkaline
  substance that is thick (1.5 mm thick)
• Protects lining of stomach from acids
• Intrinsic factor
• Glycoprotein that is secreted by parietal cells
• binds vitamin B12 increasing absorption in ileum.
• HCl
• Parietal cells produces low pH of stomach (pH
  1-3)
• HCl kills bacteria (some bacteria have a special
  coating making them impervious to HCl)
• inactivates salivary amylase (stops digestion of
  carbs)
• denatures proteins (provides proper pH for pepsin
  to act).

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Hydrochloric Acid Production
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Stomach Secretions

• Pepsinogen
• precursor to the active pepsin
• secreted by chief cells in glands of stomach
• packaged and released in as zymogen granules
• converted to pepsin by Hcl
• most active at pH below 3.
• catalyzes the cleavage of proteins into smaller
  peptide chains
• Gastrin
• produced by endocrine cells of gastric pits.
• stimulates additional Hcl and pepsinogen
  secretion.
• secreted in response to stomach filling,
  caffeine, alcohol consumption

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Phases of Gastric Secretion
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Movements in Stomach
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Small Intestine

• Site of greatest amount of digestion and
  absorption
• Divisions
• Duodenum
• Jejunum
• Ileum Peyers patches or lymph nodules
• Modifications
• Circular folds or plicae circulares, villi,
  lacteal, microvilli
• Cells of mucosa
• Absorptive, goblet, granular, endocrine

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Small Intestine Secretions

• Mucus
• Protects against digestive enzymes and stomach
  acids
• Digestive enzymes
• Disaccharidases Break down disaccharides to
  monosaccharides
• Peptidases Hydrolyze peptide bonds
• Nucleases Break down nucleic acids
• Duodenal glands
• Stimulated by vagus nerve, secretin, chemical or
  tactile irritation of duodenal mucosa

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Duodenum and Pancreas
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Duodenum Anatomy and Histology
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Liver

• Lobes
• Major Left and right
• Minor Caudate and quadrate
• Ducts
• Common hepatic
• Cystic
• From gallbladder
• Common bile
• Joins pancreatic duct at hepatopancreatic ampulla

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Functions of the Liver

• Bile production
• Salts emulsify fats, contain pigments as
  bilirubin
• Storage
• Glycogen, fat, vitamins, copper and iron
• Nutrient interconversion
• Detoxification
• Hepatocytes remove ammonia and convert to urea
• Phagocytosis
• Kupffer cells phagocytize worn-out and dying red
  and white blood cells, some bacteria
• Synthesis
• Albumins, fibrinogen, globulins, heparin,
  clotting factors

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Blood and Bile Flow
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Duct System
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Gallbladder

• Bile is stored and concentrated
• Stimulated by cholecystokinin and vagal
  stimulation
• Dumps into small intestine
• Production of gallstones possible
• Drastic dieting with rapid weight loss

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Pancreas

• Anatomy
• Endocrine
• Pancreatic islets produce insulin and glucagon
• Exocrine
• Acini produce digestive enzymes
• Regions Head, body, tail

• Secretions
• Pancreatic juice (exocrine)
• Trypsin
• Chymotrypsin
• Carboxypeptidase
• Pancreatic amylase
• Pancreatic lipases
• Enzymes that reduce DNA and ribonucleic acid

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Bicarbonate Ion Production
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Pancreatic Secretion Control
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Large Intestine

• Extends from ileocecal junction to anus
• Consists of cecum, colon, rectum, anal canal
• Movements sluggish (18-24 hours)

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Large Intestine

• Cecum
• Blind sac, vermiform appendix attached
• Colon
• Ascending, transverse, descending, sigmoid
• Rectum
• Straight muscular tube
• Anal canal
• Internal anal sphincter (smooth muscle)
• External anal sphincter (skeletal muscle)
• Hemorrhoids Vein enlargement or inflammation

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Secretions of Large Intestine

• Mucus provides protection
• Parasympathetic stimulation increases rate of
  goblet cell secretion
• Pumps
• Exchange of bicarbonate ions for chloride ions
• Exchange of sodium ions for hydrogen ions
• Bacterial actions produce gases called flatus

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Histology of Large Intestine
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Movement in Large Intestine

• Mass movements
• Common after meals
• Local reflexes in enteric plexus
• Gastrocolic Initiated by stomach
• Duodenocolic Initiated by duodenum
• Defecation reflex
• Distension of the rectal wall by feces
• Defecation
• Usually accompanied by voluntary movements to
  expel feces through abdominal cavity pressure
  caused by inspiration

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Reflexes in Colon and Rectum
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Digestion, Absorption, Transport

• Digestion
• Breakdown of food molecules for absorption into
  circulation
• Mechanical Breaks large food particles to small
• Chemical Breaking of covalent bonds by digestive
  enzymes
• Absorption and transport
• Molecules are moved out of digestive tract and
  into circulation for distribution throughout body

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Carbohydrates

• Consist of starches, glycogen, sucrose, lactose,
  glucose, fructose
• Polysaccharides broken down to monosaccharides
• Monosaccharides taken up by active transport or
  facilitated diffusion and carried to liver
• Glucose is transported to cells requiring energy
• Insulin influences rate of transport

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Lipids

• Include triglycerides, phospholipids, steroids,
  fat-soluble vitamins
• Emulsification breaks down large lipid droplets
  to small

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Lipoproteins

• Types
• Chylomicrons
• Enter lymph
• VLDL
• LDL
• Transports cholesterol to cells
• HDL
• Transports cholesterol from cells to liver

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Proteins

• Pepsin breaks proteins into smaller polypeptide
  chains
• Proteolytic enzymes produce small peptide chains
• Dipeptides, tripeptides, amino acids

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Water and Ions

• Water
• Can move in either direction across wall of small
  intestine depending on osmotic gradients
• Ions
• Sodium, potassium, calcium, magnesium, phosphate
  are actively transported

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Effects of Aging

• Decrease in mucus layer, connective tissue,
  muscles and secretions
• Increased susceptibility to infections and toxic
  agents
• Ulcerations and cancers