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LU 2 : Digestive Physiology (Food Digestion (Digestive Tracts of animals,…
LU 2 : Digestive Physiology
Food Intake
Voluntary Food Intake (VFI)
Control Mechanism at 3 Levels:
Metabolites detection
Hunger and satiety
centres in the brain (hypothalamus)
Sensors
: Located in stomach, hepatic blood vessels, liver and in the brain
Detects levels of metabolites or some chemicals in the blood system.
Short Term Control
Pressure receptors
in the crop of poultry and stomach of other animals provide information om whether the stomach is full or empty to stimulate satiety or hunger.
Long Term Control
Fat deposition
act as agent associated with long term regulation of food intake
Food Digestion
Extracellular Digestion
Complete Digestive tract
food move unindirectional through the tubular system
Enzymes are secreted into the lumen of the digestive tracts .
More efficient
Intracellular Digestion
Simple but incomplete digestion
Food enters via phagocytosis or pinocytosis
Food digested in food vacuoles (vesicles) within the cell
Less efficient
Digestive Tracts of animals
Digestion system in Invertebrates
simple alimentary canal
digestive enzymes are usually secreted by a single gland
-
Foregut:
crop
-
Midgut:
active digestion takes place
-
Hindgut:
nutrients are absorbed
Annelid (earthworm)
Athropoda (ant)
Digestion system in Fish
Spiral valve
- increases the surface area for digestion and absorption
Foregut
Midgut
Hindgut
Digestion system in Amphibians
Digestion system in Aves
Proventriculus
: secretes HCL, pepsinogen, and mucus, which are important for chemical digestion of food substances.
Ruminant
- 4 Chamber stomach
Both soluble and insoluble material fermented before reach enzymatic digestion site
Advantages
enable to extract from fibrous part of diet
able to use non-protein energy
microbes can synthesis vitamin
Monogestric
Single chamber
soluble : stomach & intestine
insoluble : large intestine
Digestion in mammals
Stomach
secretion
digestion
absortion
Small intestine
motility
secretion
digestion
Mouth
peristalsis
segmentation
Food Absorption
Absorption
is the movement of end-products of digestion across the epithelial lining of the gut into the circulatory system
Digestion & absorption of lipid
Minerals absorption
Absorption of amino acids & glucose
