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Digestive System. AKA. G-I Tract Alimentary Canal. Overview. Consists of Mouth, pharynx, esophagus, stomach, small intestine, large intestine, anus About 30’ in length Accessory Organs Teeth, tongue, gall bladder, salivary glands, liver and pancreas

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Digestive System

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Digestive system

Digestive System


Digestive system

AKA

  • G-I Tract

  • Alimentary Canal


Overview

Overview

  • Consists of

  • Mouth, pharynx, esophagus, stomach, small intestine, large intestine, anus

  • About 30’ in length

  • Accessory Organs

    • Teeth, tongue, gall bladder, salivary glands, liver and pancreas

    • Glands secrete saliva, bile and enzymes


Gi system

GI System


Process includes

Process Includes

  • Ingestion

  • Mechanical – chewing, churning

  • Propulsion – swallowing and peristalsis

  • Chemical – breakdown via enzymes

  • Absorption – transport of end products into blood

  • Defecation – elimination as feces


Gi process

GI Process


Peritoneum and cavity

Peritoneum and cavity

  • Parietal peritoneum surrounds cavity, lines body wall

  • Visceral surrounds organ

  • Serous membrane allows organs to glide/expand

  • Retroperitoneal refers to organs in the dorsal region

  • Peritonitis = inflammation of peritoneum

  • Perforation = infection


Peritoneum

Peritoneum


Regions

Regions


Mesentery

Mesentery

  • Double layer of peritoneum, holds organs in place

  • Omentums - protection

  • Lesser = fatty skin, superficial near the stomach

  • Greater = deeper, made of connective tissue, significant fat

  • Three layers of fascia – Skin, Fascia, mesentary


Messentery

Messentery


Messentary

Messentary


Omentum

Omentum


Histology

Histology

  • Smooth muscle - peristalsis

  • Glands with ducts

  • Nerves, arteries and veins


Histology1

Histology


Mouth point of origin

MouthPoint of Origin

  • Oral cavity

  • Tongue

  • Soft and hard palate

  • Uvula

  • Oropharynx

  • Epiglottis

  • Larynx/pharynx

  • Esophagus


Mouth anatomy

Mouth Anatomy


Mouth anatomy1

Mouth Anatomy


Salivary glands

Salivary glands

  • Produce saliva, a mixture of water, ions, mucous, and enzymes

  • Dissolve food

  • Wets food to help bind it to become a bolus

  • Neutralizes acids, helps growth of beneficial bacteria

  • Intrinsic –in tongue, palate, lips and cheeks

  • Extrinsic = outside mouth

    • Parotids

    • Submandibular

    • Sublingual


Salivary glands1

Salivary Glands


Pharynx

Pharynx

  • Oso

  • Laryngopharynx

  • Lined with epithelial cells for protection


Pharynx1

Pharynx


Esophagus

Esophagus

  • Muscular tube

  • Propels swallowed food to stomach

  • Passes through diaphragm (esophageal hiatus) into abdomen

  • Join the stomach at cardiac orifice

  • Cardiac sphincter prevents reflux or regurgitation of acid


Esophagus1

Esophagus


Esophagus2

Esophagus


Stomach

Stomach

  • Food churned into chyme; a paste

  • Secretes pepsin – a protein digesting enzyme and HCl

  • Waters, electrolytes, some drugs absorbed through stomach

  • Anatomy

    • Cardiac orifice, fundus, lesser and greater curvature, pylorus

    • Rugae = numerous longitudinal folds of mucosa which flatten as stomach fills, allows expand


Stomach1

Stomach


Stomach2

Stomach


Small intestine

Small Intestine

  • Longest part of alimentary canal

  • Most enzymes involved in small intestine come from pancreas

  • Three divisions

    • Duodenum – 5%

    • Jejunum – 40%

    • Ileum – almost 50%


Duodenum

Duodenum

  • Receives digestive enzymes from pancreas

  • Bile from gall bladder and liver

  • Almost all nutrients are absorbed in small intestine

  • Large surface area, great length


Small intestine1

Small Intestine


Small intestine2

Small Intestine


Gall bladder

Gall Bladder

  • Cystic duct

  • Bile duct – empties into small cystic duct

  • Secrete bile for duodenum digestion

  • Bile – Right and Left hepatic ducts to common cystic duct to Gall bladder for storage

  • From GB to bile duct to duodenum


Pancreas

Pancreas

  • Exocrine gland – produces most enzymes for digestion in small intestine

  • Endocrine function = produce hormones that regulate levels of sugar in the blood

  • Main pancreatic duct


Gall bladder and pancreas

Gall Bladder and Pancreas


Large intestine

Large Intestine

  • Most material has been digested by the time it reaches LI

  • 12-24 hours in large bowel

  • Little breakdown

  • Performs some absorption, especially water

  • Components

    • Ascending colon

    • Transverse colon

    • Descending colon

    • Sigmoid to rectum and anus


Large intestine1

Large Intestine


Cecum and appendix

Cecum and appendix

  • Cecum is a small sac (blind pouch)

  • Valve prevents a back up of fecal matter to ileum

  • Appendix

    • Lymph tissue neutralizes bacteria

  • Diverticulosus – a small outward herniation of colon, especially sigmoid

  • Diverticulitis – infection with leaks into peritoneal cavity may lead to peritonitis


Anal canal

Anal Canal

  • ANS balance between defecation or not

  • PNS = increase movement

  • SNS = decrease

  • Voluntary control via external sphincter muscles


Anal canal1

Anal Canal


Defecation

Defecation


Liver

Liver

  • Largest gland in the body (1.4 kg – 3 lbs.)

  • Produces bile

  • Stored in GB

  • Emulsifies fats

  • Involved in metabolism

  • Diaphramatic and visceral surface

  • Right and left lobes

  • Porta hepatis = major vessels and nerves

  • Right and left hepatic ducts, common bile, common


Liver1

Liver


Liver2

Liver


Liver3

Liver


Study points

Study Points

  • Know the components of GI Tract

  • Know the peritoneum

  • Understand smooth muscle control

  • Know the various ducts and how they connect to specific organs

  • Understand the role of the stomach v. small intestine v. large intestine


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