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Digestion I. Introduction A. Processes
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The basic digestive processes Ingestion, Digestion (mechanical and chemical), Absorption (extra-cellular and intracellular), and Elimination. Figure 41.7
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B. Parts Overview
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The basic parts tube (alimentary canal, G-I tract, etc
The basic parts tube (alimentary canal, G-I tract, etc.) and a series of glands (salivary, liver, pancreas, etc.) Figure 41.8
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II. Development A. Simplest
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1. Direct to gastrovascular cavity == Poriferans through Platyhelminthes
Poriferans simply absorb molecules gathered from their watery homes. Choanocytes Figure 33.4
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1. Direct to gastrovascular cavity == Poriferans through Platyhelminthes
Figure 33.10 Figure 41.7
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B. Complex
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1. Alimentary canal == Nemertea through the Chordates
Figure 41.8 How is food moved through the tube? What forces are involved? Why have the segmentation of the tube?
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III. Mammalian A. Tube 1. Sections
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Figure 41.9
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2. Functions
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a. Oral cavity = ingestion, chewing, & chemical digestion
teeth, tongue, buccal surfaces, and salivary glands b. Pharynx = move & lubricating food muscular wall and mucous glands c. Esophagus = move, lubricating food, & peristalsis muscular wall and sphincter d. Stomach = churn food & chemical digestion muscular wall and gastric glands
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e. Small Intestine = chemical digestion &
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e. Small Intestine = chemical digestion & absorption
Figure 41.12
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e. Small Intestine surface area
Figure 41.13
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f. Large Intestine = water absorption & packing
surface area and muscular wall
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g. Rectal and Anal Canals = packing & elimination
muscular wall
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B. Glands & Organs 1. Salivary Glands
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Salivary Glands = mucin, salivary amylase, buffers, & antimicrobial agents
Saliva to coat food, start carbohydrate digestion, control acidity, and prevent infection
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2. Gastric Glands
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Gastric Glands = pepsinogen, HCl, & mucous.
Figure 41.11 begin protein digestion, activate pepsinogen to pepsin, and buffer
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3. Liver & Gall Bladder
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3. Liver and Gall bladder = secrete or store bile
Figure 41.19 emulsifies fat
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4. Pancreas
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Pancreas = secrete numerous digestive enzymes
Figure 41.12
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C. Absorption
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1. What are the molecules and the mechanism of absorption for each of the ingested nutrient molecules?
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D. Regulation 1. Cephalic
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Digestion regulation can be divided into the cephalic and the gastric phases?
Cephalic phase == nervous response Events: Stimuli related to food starts? Salivary secretions Stimulation of the stomach smooth muscle
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2. Gastric
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Gastric phase == nervous response and endocrine input
Events: Stimuli is the stretching of the stomach wall? Release of stomach secretions Pancreatic enzymes Liver/GB bile release Smooth muscle stimulation
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IV. Comparisons A. Dentition
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Dentition is adapted to accommodate different diets.
Types of teeth = incisors, canines, premolars, & molars Figure 41.16
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B. Tubular Divisions
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Tubular divisions are adapted to accommodate different diets.
Figure 41.17 Figure 41.18
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