Digestive System

1,769 views
1,460 views

Published on

anotamy3

Published in: Health & Medicine, Technology
1 Comment
1 Like
Statistics
Notes
No Downloads
Views
Total views
1,769
On SlideShare
0
From Embeds
0
Number of Embeds
9
Actions
Shares
0
Downloads
50
Comments
1
Likes
1
Embeds 0
No embeds

No notes for slide
  • Enamel: Calcium phosphates. Hardest biological material produced.
  • makes bile, stores excess nutrients, makes plasma proteins, detoxifies harmful materials, stores iron & fat soluble vitamins
  • makes bile, stores excess nutrients, makes plasma proteins, detoxifies harmful materials, stores iron & fat soluble vitamins
  • makes bile, stores excess nutrients, makes plasma proteins, detoxifies harmful materials, stores iron & fat soluble vitamins
  • Digestive System

    1. 1. Digestive System Objectives: Discuss the general functions and anatomy of the digestive tract Describe the individual organs of the system, including a discussion of the gross and microscopic anatomy.
    2. 2. Digestive System Muscular, hollow tube (= “digestive tract”) + Various accessory organs consists of:
    3. 3. Function <ul><li>ingestion </li></ul><ul><li>mechanical digestion </li></ul><ul><li>chemical and enzymatic digestion </li></ul><ul><li>secretion </li></ul><ul><li>absorption </li></ul><ul><li>compaction </li></ul><ul><li>excretion and elimination </li></ul>The function of the system as a whole is processing food in such a way that high energy molecules can be absorbed and residues eliminated. Individual parts function in:
    4. 4. Histological Organization <ul><li>Tube made up of four layers. </li></ul><ul><li>Modifications along its length as needed. </li></ul>Muscularis externa 1 2 3 4
    5. 5. The 4 Layers of the Gut <ul><li>1) Mucosa </li></ul><ul><li>Epithelium – usually simple columnar with goblets; may be stratified squamous if protection needed </li></ul><ul><li>Lamina propria - connective tissue deep to epithelium </li></ul><ul><li>Muscularis mucosae - produces folds - plicae (small intestine) or rugae (stomach) </li></ul><ul><li>2) Submucosa – made up of loose connective tissue contains submucosal plexus and blood vessels </li></ul><ul><li>3) Muscularis externa – smooth muscle, usually two layers (controlled by the myenteric plexus ) - </li></ul><ul><li>outer layer: longitudinal </li></ul><ul><li>inner layer: circular </li></ul><ul><li>4) Serosa </li></ul><ul><ul><li>visceral layer of mesentery or adventitia depending on location </li></ul></ul>
    6. 6. Membranes <ul><li>Peritoneum - generic serous membrane in abdominal cavity </li></ul><ul><li>Mesenteries - double sheets of peritoneum, surrounding and suspending portions of the digestive organs </li></ul><ul><li>Greater omentum - &quot;fatty apron&quot;, hangs anteriorly from stomach, double layer encloses fat </li></ul><ul><li>Lesser omentum - between stomach and liver </li></ul><ul><li>Mesentery proper - suspends and wraps the small intestine </li></ul><ul><li>Mesocolon - suspends and wraps the colon, parts are </li></ul><ul><li>i. transverse mesocolon </li></ul><ul><li>ii. sigmoid mesocolon </li></ul>
    7. 7. Oral Cavity <ul><li>Also called buccal cavity - lined with oral mucosa (type of epithelium ?) </li></ul><ul><li>Hard and soft palates - form roof of mouth </li></ul><ul><li>Tongue - skeletal muscle </li></ul><ul><li>Salivary glands - three pairs </li></ul><ul><li>Teeth </li></ul>
    8. 8. Three pairs of Salivary Glands <ul><li>Parotid – lateral side of face, anterior to ear, drain by parotid duct to vestibule near 2nd upper molar </li></ul><ul><ul><li>mumps </li></ul></ul><ul><li>Submandibular – medial surface of mandible – drain near lingual frenulum drain posterior to lower molars </li></ul><ul><li>Sublingual – in floor of mouth - drain near frenulum </li></ul>1-1.5 l / day for digestion (?) lubrication (swallowing) moistening (tasting)
    9. 9. Structure of Teeth <ul><li>Crown - exposed surface of tooth </li></ul><ul><li>Neck - boundary between root and crown </li></ul><ul><li>Enamel - outer surface </li></ul><ul><li>Dentin – bone-like, but noncellular </li></ul><ul><li>Pulp cavity - hollow with blood vessels and nerves </li></ul><ul><li>Root canal - canal length of root </li></ul><ul><li>gingival sulcus - where gum and tooth meet </li></ul>
    10. 10. Types and Numbers of Teeth Dental succession Deciduous (baby, milk) teeth - 20, replaced by Permanent teeth - 32 teeth
    11. 11. <ul><li>Lesser curvature </li></ul><ul><li>Greater curvature </li></ul><ul><li>Cardia - end under the heart </li></ul><ul><li>Fundus - bulge above the esophageal opening </li></ul><ul><li>Body - largest region </li></ul><ul><li>Pylorus - J curve, inferior end, terminates in </li></ul><ul><li>Cardiac and Pyloric sphincters (importance?) </li></ul><ul><li>Rugae – highly extendable interior folds </li></ul>Gross Anatomy of the Stomach
    12. 12. Histology of Stomach <ul><li>Type of epithelium lining stomach? </li></ul><ul><li>Gastric pits – shallow pits, external half rapidly reproduces for replacement </li></ul><ul><li>Gastric glands – deep in lamina propria, 3 types of cells </li></ul><ul><li>Parietal cells (produce HCl and intrinsic factor) </li></ul><ul><li>Chief cells (produce pepsinogen ) </li></ul><ul><li>Enteroendocrine cells – G cells ( several hormones including gastrin which stimulates both parietal and chief cells) </li></ul>
    13. 13. Regions of Small Intestine <ul><li>SI is longest part of dig. tube </li></ul><ul><li>Duodenum (short, 12 inches) </li></ul><ul><ul><li>fixed shape & position </li></ul></ul><ul><ul><li>Mixing bowl for chyme & ? </li></ul></ul><ul><li>Jejunum (2.5 m long) </li></ul><ul><ul><li>Most of digestion </li></ul></ul><ul><li>Ileum (longest at 3.5 m) </li></ul><ul><ul><li>Most of absorption, ends in </li></ul></ul><ul><li>Ileocecal valve – slit valve into large intestine (colon) </li></ul>
    14. 14. <ul><li>Plicae circulares – circular pleats around the interior of the small intestine </li></ul><ul><li>Villi – minute finger-like projections, contain capillaries & lacteals </li></ul><ul><li>Microvilli – sub-microscopic size, projections on single cells </li></ul><ul><li>Function of all three? </li></ul><ul><li>Intestinal glands (crypts) </li></ul><ul><ul><li>intestinal juice production </li></ul></ul><ul><ul><li>Cell regeneration </li></ul></ul><ul><li>Histology in lab </li></ul>Structure of Small Intestinal Wall
    15. 15. <ul><li>Cecum – pocket at proximal end with Appendix </li></ul><ul><li>Colon </li></ul><ul><li>Ascending colon - on right, between cecum and right colic flexure </li></ul><ul><li>Transverse colon - horizontal portion </li></ul><ul><li>Descending colon - left side, between left colic flexure and </li></ul><ul><li>Sigmoid colon - S bend near terminal end </li></ul>Regions of Large Intestine Fig 25-17 Rectum – terminal end is anal canal - ending at the anus - which has internal involuntary sphincter and external voluntary sphincter
    16. 16. Rectum and Anus <ul><li>Rectum – terminal end is anal canal - ending at the anus - </li></ul><ul><ul><li>which has internal involuntary sphincter and external voluntary sphincter </li></ul></ul><ul><ul><li>Retroperitoneal </li></ul></ul><ul><ul><li>Mucus glands </li></ul></ul><ul><ul><li>Rectal and Anal valves </li></ul></ul>
    17. 17. <ul><li>1. Mucosa - abundant goblet cells, stratified squamous epithelium near anal canal </li></ul><ul><li>2. No villi </li></ul><ul><li>3. Longitudinal muscle layer incomplete, forms three bands or taenia coli </li></ul><ul><li>4. Circular muscle - forms pockets or haustra between bands </li></ul>Histology of Large Intestine
    18. 18. Liver <ul><li>On right under diaphragm, largest organ made up of 4 lobes (left and right, caudate, and quadrate) </li></ul><ul><li>Hilus (porta hepatis) – underside &quot;entry&quot; point </li></ul><ul><li>Extremely versatile: Know a few functions? </li></ul><ul><li>Gall bladder </li></ul><ul><li>Blood supply to liver </li></ul>Microscopic anatomy: Liver lobules and triads
    19. 19. Liver <ul><li>Located in RUQ, adjacent to the diaphragm, largest organ made up of 4 lobes (left and right, caudate, and quadrate) </li></ul><ul><li>Falciform ligament (remnant of fetal blood supply </li></ul><ul><li>Hilus (porta hepatis) – &quot;entry&quot; point on the visceral surface </li></ul>
    20. 20. Liver, cont’d <ul><li>Extremely versatile: Know a few functions? </li></ul><ul><li>Gall bladder-storage of bile </li></ul><ul><li>Blood supply: hepatic artery (1/3) and portal vein (2/3); Return via Central V. to vena cava </li></ul>
    21. 21. Microscopic anatomy: Liver lobules and portal triads <ul><li>100,000 Lobules (the basic functional unit) </li></ul><ul><li>Hepatocytes are arranged like spokes in a hexagonal wheel </li></ul><ul><li>Bathed in blood of hepatic sinusoids </li></ul><ul><ul><li>From Portal V. and Hepatic A. </li></ul></ul><ul><ul><li>Triads at each corner </li></ul></ul><ul><li>Kupffer Cells are phagocytic </li></ul>See Fig 22.23
    22. 22. Gall Bladder <ul><li>Fundus, body, neck </li></ul><ul><li>Hepatic Duct and Cystic duct connect to form the Common Bile Duct </li></ul><ul><li>Enters at the proximal duodenum </li></ul><ul><li>Storage and Concentration of Bile </li></ul>Gall Stones
    23. 23. Pancreas <ul><li>Retroperitoneal </li></ul><ul><li>Endocrine or exocrine gland? Both! </li></ul><ul><ul><li>Only 1% is endocrine </li></ul></ul><ul><ul><ul><li>Insulin, et al. </li></ul></ul></ul><ul><li>Simple Cuboidal Epith arranged in Acini </li></ul><ul><li>Digestive enzymes excreted into the pancreatic duct </li></ul><ul><li>Common bile duct and pancreatic duct lead to duodenal ampulla and papilla </li></ul><ul><ul><li>Controlled by hepatopancreatic sphincter </li></ul></ul>
    24. 24. Pancreas <ul><li>Acinar Cells </li></ul><ul><ul><li>Several types of digestive enzymes e.g., trypsin </li></ul></ul><ul><ul><li>Used as diagnostic tools for pancreatitis </li></ul></ul><ul><li>Islets of Langerhans </li></ul><ul><ul><li>AKA pancreatic islets </li></ul></ul><ul><ul><li>Insulin </li></ul></ul><ul><ul><li>Chapt 25 </li></ul></ul>

    ×