Digestion

I. Introduction

A. Processes

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

Figure 41.7

B. Parts Overview

The basic parts tube (alimentary canal, G-I tract, etc.) and a series of glands (salivary, liver, pancreas, etc.)

Figure 41.8

II. Development

A. Simplest

1. Direct to gastrovascular cavity == Poriferans through Platyhelminthes

Poriferans simply absorb molecules gathered from their watery homes. Choanocytes

Figure 33.4

1. Direct to gastrovascular cavity == Poriferans through Platyhelminthes

Figure 41.7

Figure 33.10

B. Complex

1. Alimentary canal == Nemertea through the Chordates

How is food moved through the tube? What forces are involved? Why have the segmentation of the tube?

Figure 41.8

III. MammalianA.

Tube1. Sections

Figure 41.9

2. Functions

a. Oral cavity = ingestion, chewing, & chemical digestion

teeth, tongue, buccal surfaces, and salivary glands

b. Pharynx = move & lubricating foodmuscular wall and

mucous glandsc. Esophagus = move, lubricating food, & peristalsismuscular wall and

sphincterd. Stomach = churn food & chemical digestionmuscular wall and

gastric glands

e. Small Intestine = chemical digestion &

e. Small Intestine = chemical digestion & absorption

Figure 41.12

e. Small Intestine surface area

Figure 41.13

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

muscular wall

g. Rectal and Anal Canals = packing & eliminationmuscular

wall

B. Glands & Organs1. Salivary

Glands

Salivary Glands = mucin, salivary amylase, buffers, & antimicrobial agents

Saliva to coat food, start carbohydrate digestion, control acidity, and prevent infection

2. Gastric Glands

Gastric Glands = pepsinogen, HCl, & mucous.

begin protein digestion, activate pepsinogen to pepsin, and buffer

Figure 41.11

3. Liver & Gall Bladder

3. Liver and Gall bladder = secrete or store bile

emulsifies fat

Figure 41.19

4. Pancreas

Pancreas = secrete numerous digestive enzymes

Figure 41.12

C. Absorption

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

D. Regulation1.

Cephalic

Digestion regulation can be divided into the cephalic and the gastric phases?Cephalic phase == nervous

responseEvents: Stimuli related to food starts?

Salivary secretionsStimulation of the stomach

smooth muscle

2. Gastric

Gastric phase == nervous response and endocrine inputEvents: Stimuli is the stretching of the stomach wall?Release of stomach

secretionsPancreatic enzymesLiver/GB bile

releaseSmooth muscle stimulation

IV. ComparisonsA.

Dentition

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

Figure 41.16

B. Tubular Divisions

Tubular divisions are adapted to accommodate different diets.

Figure 41.17

Figure 41.18

Believe to Achieve.