digestive system. aka g-i tract alimentary canal
Post on 22-Dec-2015
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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
• Glands secrete saliva, bile and enzymes
GI System
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
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
Quadrants
Regions
Regions
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
Messentary
Omentum
Greater Omentum
Histology
Smooth muscle - peristalsis Glands with ducts Nerves, arteries and veins
Histology
MouthPoint of Origin
Oral cavity Tongue Soft and hard palate Uvula Oropharynx Epiglottis Larynx/pharynx Esophagus
Mouth Anatomy
Mouth Anatomy
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 Glands
Pharynx
Oso Laryngopharynx Lined with epithelial cells for protection
Pharynx
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
Esophagus
Esophagus
Esophagus
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
Stomach
Stomach
Stomach
Junction
Stomach
Small Intestine
Longest part of alimentary canal Most enzymes involved in small intestine
come from pancreas Three divisions – each approximately
• Duodenum – 5%
• Jejunum – 40%
• Ileum – almost 50%
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 Intestine
Small Intestine
Duodenum
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
Gall Bladder
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
Pancreas
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 Intestine
Large Intestine
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
ANS balance between defecation or not PNS = increase movement SNS = decrease Voluntary control via external sphincter
muscles
Anal Canal
Defecation
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
Liver
Liver
Liver
Liver