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Digestion I. Introduction A. Processes.

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Presentation on theme: "Digestion I. Introduction A. Processes."— Presentation transcript:

1 Digestion I. Introduction A. Processes

2 The basic digestive processes  Ingestion, Digestion (mechanical and chemical), Absorption (extra-cellular and intracellular), and Elimination. Figure 41.7

3 B. Parts Overview

4 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

5 II. Development A. Simplest

6 1. Direct to gastrovascular cavity == Poriferans through Platyhelminthes
Poriferans simply absorb molecules gathered from their watery homes. Choanocytes Figure 33.4

7 1. Direct to gastrovascular cavity == Poriferans through Platyhelminthes
Figure 33.10 Figure 41.7

8 B. Complex

9 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?

10 III. Mammalian A. Tube 1. Sections

11 Figure 41.9

12 2. Functions

13 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

14 e. Small Intestine = chemical digestion &

15 e. Small Intestine = chemical digestion & absorption
Figure 41.12

16 e. Small Intestine surface area
Figure 41.13

17 f. Large Intestine = water absorption & packing
surface area and muscular wall


19 g. Rectal and Anal Canals = packing & elimination
muscular wall

20 B. Glands & Organs 1. Salivary Glands

21 Salivary Glands = mucin, salivary amylase, buffers, & antimicrobial agents
Saliva to coat food, start carbohydrate digestion, control acidity, and prevent infection

22 2. Gastric Glands

23 Gastric Glands = pepsinogen, HCl, & mucous.
Figure 41.11 begin protein digestion, activate pepsinogen to pepsin, and buffer

24 3. Liver & Gall Bladder

25 3. Liver and Gall bladder = secrete or store bile
Figure 41.19 emulsifies fat

26 4. Pancreas

27 Pancreas = secrete numerous digestive enzymes
Figure 41.12

28 C. Absorption

29 1. What are the molecules and the mechanism of absorption for each of the ingested nutrient molecules?

30 D. Regulation 1. Cephalic

31 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

32 2. Gastric

33 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

34 IV. Comparisons A. Dentition

35 Dentition is adapted to accommodate different diets.
Types of teeth = incisors, canines, premolars, & molars Figure 41.16

36 B. Tubular Divisions

37 Tubular divisions are adapted to accommodate different diets.
Figure 41.17 Figure 41.18

38 Believe to Achieve.

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