LIFESCI 2N03 Study Guide - External Anal Sphincter, Sigmoid Colon, Stomach

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Published on 4 Oct 2014
Department
30
LS 2N03 Human Nutrition for Life Sciences
D.M. Pincivero, 2013
ANATOMY AND PHYSIOLOGY OF DIGESTION
DIGESTIVE SYSTEM
2 main groups:
1) Alimentary canal
Gastrointestinal tract
Continuous digestive tube through whole body
Function:
A) Digestion
breaks food into smaller fragments
B) Absorption
moves the digested fragments from the alimentary canal into the blood
Anatomical structures
Mouth (lips, cheeks, palate, tongue, teeth, salivary glands)
Pharynx
Esophagus
Stomach (cardiac orifice, fundus, body, pyloric canal, pylorus, pyloric sphincter, omentum)
Small intestine (duodenum, jejunum, ileum)
Large intestine (cecum, ascending colon, transverse colon, descending colon, sigmoid colon,
rectum, anal canal)
consideredtobe“outside”thebody(stillinexternalenvironment)
2) Accessory digestive organs
teeth, tongue, gallbladder, liver, pancreas
Key: maximize the absorption of nutrients into the cardiovascular system
starts with chewing
throat
long tube: connects to stomach
absorption begins here
If the cardiovascular system does not receive the nutrients it does not benefit in anyway
secrete enzymes that help break down
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31
LS 2N03 Human Nutrition for Life Sciences
D.M. Pincivero, 2013
DIGESTIVE SYSTEM ANATOMY
Small pinches: regulates movement of food from
one part to another
Problem: too much dietary fibre,
speeds up digestion and not allows
nutrients to be absorbed
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32
LS 2N03 Human Nutrition for Life Sciences
D.M. Pincivero, 2013
Digestive System Activities
6 essential activities:
1) Ingestion
physically taking food into the digestive system
2) Propulsion
moving food through the alimentary canal
a) Swallowing
voluntary activity moving food down into the esophagus
b) Peristalsis
involuntary movement of food through the esophagus, stomach and intestine
involvesalternative“waves”ofcontractionandrelaxationofsmoothmuscle
alters intestinalvessel(“tube”)diameter
Smooth muscle: contracts and applies force, the contents move
First Phase: voluntary
Second Phase: involuntary
Bolus: food, after we ingest it after enzymes break it down
Chyme: When bolus reaches stomach and becomes a liquid substance
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Document Summary

2 main groups: alimentary canal, gastrointestinal tract, continuous digestive tube through whole body. Function: digestion, breaks food into smaller fragments, absorption, moves the digested fragments from the alimentary canal into the blood. Anatomical structures: mouth (lips, cheeks, palate, tongue, teeth, salivary glands, pharynx, esophagus, stomach (cardiac orifice, fundus, body, pyloric canal, pylorus, pyloric sphincter, omentum, small intestine (duodenum, jejunum, ileum) Large intestine (cecum, ascending colon, transverse colon, descending colon, sigmoid colon, rectum, anal canal) considered to be outside the body (still in external environment: accessory digestive organs teeth, tongue, gallbladder, liver, pancreas. Pincivero, 2013: mechanical digestion, physical preparation of food for absorption chewing, mixing food with enzymes (tongue), churning of food in stomach. Segmentation: mixing of food in intestine with digestive juices smooth muscle contraction and relaxation. Alimentary canal structure: esophagus to anal canal. Four tunics: mucosa, submucosa, muscularis externa, serosa. Moist epithelial layer that lines the lumen of the alimentary canal.

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