Download Digestion in Animals

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  1. tube (alimentary canal, G-I tract,
etc.) and 2. a series of glands (salivary, liver, pancreas, etc.)
Figure 41.8
II. Development
A. Simplest
1. Direct == Poriferans
Choanocytes
Figure 33.4
2. Gastrovascular cavity  Cnidarians through Platyhelminthes
Figure 33.10
Figure 41.7
B. Complex
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?
III. Mammalian Strategy
A. Tube
1. Sections
Figure 41.9
2. Functions
a. 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 & elimination
muscular wall
B. Glands & Organs
1. Salivary Glands
Secrete mucin, salivary amylase, buffers, & antimicrobial agents
Saliva to coat food, start carbohydrate digestion, control acidity,
and prevent infection
2. Gastric Glands
Secrete pepsinogen, HCl, & mucous.
Figure 41.11
begin protein digestion, activate pepsinogen to pepsin, and buffer
3. Liver & Gall Bladder
secrete or store bile
emulsifies fat
Figure 41.20
4. Pancreas
Pancreas = secrete numerous digestive enzymes
Figure 41.12
C. Absorption
1. What are the molecules
2. Mechanism/Pathways of absorption
D. Regulation
1. Cephalic
A nervous response
a. Events: Stimuli related to food
b. Outcomes:
Salivary secretions
Stimulation of the stomach smooth muscle
2. Gastric
A nervous response and endocrine input
a. Events: Stimuli is the stretching of the stomach wall?
b. Outcomes: Release of stomach secretions
Pancreatic enzymes
Liver/GB bile release
Smooth muscle stimulation
IV. Comparisons
A. Dentition
Adapted to accommodate different diets.
Types of teeth = incisors, canines, premolars, & molars
Figure 41.16
B. Tubular Divisions
Adapted to accommodate different diets.
Figure 41.17
Figure 41.19