DigestionI.

Introduction

A. ProcessesThe basic digestive processes Ingestion,

Digestion (mechanical and chemical), Absorption (extra-cellular and intracellular), and Elimination.

Figure 41.7

B. Parts OverviewThe basic parts 1. tube (alimentary canal,

G-I tract, etc.) and 2. a series of glands (salivary, liver, pancreas, etc.)

Figure 41.8

II. Development

A. Simplest1. Direct ==

Poriferans

Figure 33.4

Choanocytes

2. Gastrovascular cavity Cnidarians through Platyhelminthes

Figure 33.10

Figure 41.7

B. Complex1. 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?

III. Mammalian StrategyA.

Tube1. 1. Sections

Figure 41.9

2. 2. Functionsa. Oral cavity = ingestion, chewing, &

chemical digestion

b. Pharynx = move & lubricating food

c. Esophagus = move, lubricating food, & peristalsis

d. Stomach = churn food & chemical digestion

e. Small Intestine = chemical digestion

& absorption Figure

41.12

via surface area

Figure 41.13

f. Large Intestine water absorption & packing

g. Rectal and Anal Canals = packing & eliminationmuscular

wall

B. Glands & Organs1. Salivary

GlandsSecrete mucin, salivary amylase, buffers, & antimicrobial agents

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

2. Gastric GlandsSecrete pepsinogen, HCl, &

mucous.

Figure 41.11begin protein digestion, activate pepsinogen to

pepsin, and buffer

3. Liver & Gall Bladdersecrete or

store bile

Figure 41.19

emulsifies fat

4. PancreasPancreas = secrete numerous

digestive enzymes

Figure 41.12

C. Absorption1. What are the molecules and the 2. mechanism

of absorption for each of the ingested nutrient molecules?

D. Regulation1.

CephalicA nervous response

a. Events: Stimuli related to food Salivary

secretionsStimulation of the stomach smooth muscle

b. Outcomes:

2. GastricA nervous response and endocrine input

a. Events: Stimuli is the stretching of the stomach wall?Release of stomach

secretionsPancreatic enzymes

Liver/GB bile releaseSmooth muscle

stimulation

b. Outcomes:

IV. ComparisonsA.

DentitionAdapted to accommodate different diets.Types of teeth = incisors, canines, premolars, & molars

Figure 41.16

B. Tubular DivisionsAdapted to accommodate

different diets.

Figure 41.17

Figure 41.18