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DIGESTIVE SYSTEM
ALIMENTARY CANAL / GI TRACT & ACCESSORY ORGANS
Mar 1610:34 PM
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I. Digestive System Functions
> Ingestion
> Propulsion
> Digestion breakdown of food stuff
– Mechanical
– Chemical
> Absorption
> Defecation
the taking in of food
movement caused by force
intake of nutrients from food
elimination of indigestible waste
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• Oral Cavity: Mechanical & Chemical Digestion> Tongue mixes food with saliva & initiates swallowing
– contains taste buds
> Salivary Glands saliva is mixture of mucus & serous fluids (containing salivary amylase) moistens food and helps create a bolus, helps dissolve food so can taste it
> Teeth mastication/chew food (mechanical digestion)
> Epiglottis blocks opening to trachea to allow food to enter into esophagus instead of air passageway
> Hard & Soft Palate separates oral cavity & nasal cavity, when you swallow soft palate rises to close nasal passage
• Pharynx: this is subdivided into three parts: > nasopharynx respiratory passageway> oropharynx most posterior part of oral cavity> laryngopharynx most superior part of esophagus
II. Organs of the Alimentary Canal (GI tract)
Mar 218:05 AM
4Mar 168:07 AM
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• Esophagus: muscular tube for transport (peristalsis)
• Stomach: Mechanical & Chemical digestion
> Regions:
– Cardia
– Fundus
– Body
– Pylorus
> Rugae folds in the walls of the stomach
> Mucosa line with simple columnar epithelium with millions of gastric pits creating gastric juice
– chief cells produce pepsinogens– parietal cells produce HCl– mucous neck cells produce alkaline mucus
> Sphincter muscles on both ends of the stomach regulate entry and exit of food stuffs
> Stomach does aid in small amount of fat soluble substances (aspirin, alcohol)
II. Organs of the Alimentary Canal (GI tract) cont'd
Mar 1810:31 AM
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Mar 1610:33 PM
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