Lab 5 Digestion and Hormones of
Digestion
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Figure 23.1 Alimentary canal and related accessory digestive organs.
Mouth (oral cavity)
Tongue*
Esophagus
Liver*
Gallbladder*
Small
intestine
Salivary
glands*
Pharynx
Stomach
Pancreas*
Large
intestine
(Spleen)
Parotid gland
Sublingual gland Submandibular gland
Duodenum
Jejunum
Ileum
Anus
Transverse colon
Descending colon
Ascending colon
Cecum
Sigmoid colon
Rectum
Appendix
Anal canal 7/16/2015 2
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Figure 23.2 Gastrointestinal tract activities.
Ingestion
Mechanical
breakdown
Digestion
Propulsion
Absorption
Defecation
Food
Pharynx
Esophagus • Chewing (mouth)
• Swallowing (oropharynx) • Peristalsis (esophagus, stomach, small intestine, large intestine)
Stomach
Lymph vessel
Small intestine
Large intestine
Blood vessel
Mainly H2O
Feces
Anus
• Churning (stomach) • Segmentation (small intestine)
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Figure 23.7a Anatomy of the oral cavity (mouth).
Palatoglossal arch
Soft palate
Hard palate Oral cavity
Palatine tonsil
Tongue
Oropharynx
Lingual tonsil
Epiglottis
Hyoid bone
Laryngopharynx
Esophagus
Trachea
Uvula
Sagittal section of the oral cavity and pharynx 7/16/2015 4
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Figure 23.13 Deglutition (swallowing). Bolus of food
Tongue
Pharynx
Epiglottis
Glottis
Trachea
During the buccal phase, the upper esophageal sphincter is contracted. The tongue presses against the hard palate, forcing the food bolus into the oropharynx.
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Uvula
Bolus
Epiglottis
Esophagus
The pharyngeal-esophageal phase begins as the uvula and larynx rise to prevent food from entering respiratory passageways. The tongue blocks off the mouth. The upper esophageal sphincter relaxes, allowing food to enter the esophagus.
The constrictor muscles of the pharynx contract, forcing food into the esophagus inferiorly. The upper esophageal sphincter contracts (closes) after food enters.
Peristalsis moves food through the esophagus to the stomach.
The gastroesophageal sphincter surrounding the cardial oriface opens, and food enters the stomach.
Relaxed muscles
Circular muscles contract
Bolus of food
Longitudinal muscles
contract
Gastroesophageal sphincter closed
Relaxed muscles
Circular muscles contract
Gastroesophageal sphincter opens
Upper esophageal sphincter
Bolus
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Stomach
Slide 1
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Figure 23.14a Anatomy of the stomach. Cardia
Esophagus
Muscularis
externa
Lesser
curvature
Duodenum
Pyloric sphincter
(valve) at pylorus
Pyloric canal
Pyloric antrum
Greater curvature
Rugae of mucosa
Lumen
Body
Serosa
Fundus
• Oblique layer • Circular layer
• Longitudinal layer
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Digestive Processes in the Stomach
• Physical digestion
• Denaturation of proteins by HCl
• Enzymatic digestion of proteins by pepsin (and milk protein by rennin in infants)
• Lingual lipase digests some triglycerides before digested as any other protein
• Delivers chyme to small intestine
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Figure 23.19 Deglutition (swallowing). Slide 1
Pyloric valve closed
Pyloric valve slightly opened
Pyloric valve closed
Grinding: The most
vigorous peristalsis and
mixing action occur close to
the pylorus.
Retropulsion: The pyloric
end of the stomach acts as a
pump that delivers small amounts
of chyme into the duodenum,
simultaneously forcing most of its
contained material backward into
the stomach.
2 Propulsion: Peristaltic
waves move from the fundus
toward the pylorus.
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Figure 23.1 Alimentary canal and related accessory digestive organs.
Mouth (oral cavity)
Tongue*
Esophagus
Liver*
Gallbladder*
Small
intestine
Salivary
glands*
Pharynx
Stomach
Pancreas*
Large
intestine
(Spleen)
Parotid gland
Sublingual gland Submandibular gland
Duodenum
Jejunum
Ileum
Anus
Transverse colon
Descending colon
Ascending colon
Cecum
Sigmoid colon
Rectum
Appendix
Anal canal 7/16/2015 9
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Figure 23.29a Gross anatomy of the large intestine.
Right colic (hepatic) flexure
Transverse colon
Superior mesenteric artery
Ascending colon
IIeum
IIeocecal valve
Cecum
Appendix
Left colic (splenic) flexure
Transverse mesocolon
Epiploic appendages
Descending colon
Cut edge of mesentery
Tenia coli
Sigmoid colon
Rectum
Anal canal External anal sphincter
Haustrum
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Right and left hepatic ducts of liver
Common hepatic duct
Bile duct and sphincter
Accessory pancreatic duct
Tail of pancreas
Pancreas
Jejunum
Main pancreatic duct and sphincter
Head of pancreas Hepatopancreatic ampulla and sphincter Duodenum
Mucosa with folds
Gallbladder
Major duodenal papilla
Cystic duct
Figure 23.21 The duodenum of the small intestine, and related organs.
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Figure 23.28 Mechanisms promoting secretion and release of bile and pancreatic juice. Slide 1
Chyme enter -ing duodenum causes duodenal enteroendocrine cells to release cholecystokinin (CCK) and secretin.
CCK (red dots) and secretin (yellow dots) enter the bloodstream.
CCK induces secretion of enzyme-rich pancreatic juice. Secretin causes secretion of HCO3
− -rich pancreatic juice.
Bile salts and, to a lesser extent, secretin transported via bloodstream stimulate Liver to produce bile more rapidly.
CCK (via blood stream) causes gallbladder to contract and Hepatopancreatic Sphincter to relax. Bile Enters duodenum.
During cephalic and gastric phases, vagal Nerve stimu- lates gallbladder to contract weakly.
CCK secretion
Secretin secretion
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