1. 41.4: evolutionary adaptations Of vertebrate digestive systems

2. Evolutionary Adaptations
Digestive Systems of Vertebrates Associated with the Animal’s Diet
Form Fits Function

3. Dental Adaptations Dentition: an animal’s assortment of teeth
An example of structural variation reflecting diet
Mammals: successful because of adaptation of teeth for processing different food types

4. Incisors Molars Canines Premolars (a) Carnivore (b) Herbivore
Fig
Incisors
Molars
Canines
Premolars
(a) Carnivore
(b) Herbivore
Figure Dentition and diet
(c) Omnivore

5. Dental Adaptations Nonmammalian Vertebrates Snakes: an exception
Less specialized dentition
Snakes: an exception
Hollow fangs- venom
Jaws that unhinge

6. Stomach and Intestinal Adaptations
Carnivorous Vertebrates:
Expandable stomachs
Herbivores and Omnivores:
Longer alimentary canals (digestive tracts) for vegetation
More time for digestions
More surface area for absorption of nutrients

7. Colon (large intestine)
Fig
Small intestine
Stomach
Small intestine
Cecum
Figure The alimentary canals of a carnivore (coyote) and herbivore (koala)
Colon (large intestine)
Carnivore
Herbivore

8. Mutualistic Adaptations
Mutualistic Symbiosis: interaction that is beneficial for both species
Herbivores: have mutualistic relationship with microorganisms
Cannot digest cellulose from plant cell walls
Microorganisms contain enzymes that can digest cellulose

9. Mutualistic Adaptations
Ruminants: deer, sheep, and cattle
Contain most elaborate adaptations for diet

10. Rumen Reticulum Intestine Esophagus Abomasum Omasum 1 2 4 3 Fig. 41-20
Figure Ruminant digestion 4
Abomasum 3
Omasum

11. 41.5: Homeostatic mechanisms Contribute to an animal’s
Energy balance

12. Homeostatic Mechanisms
Animals balance energy from food with energy used for metabolism, activities, and storage

13. Energy Sources and Stores
ATP generations based on oxidation of carbohydrates, proteins, and fats
Excess calories stored as glycogen in liver and muscle cells
Glycogen oxidized when fewer calories are taken in than used

14. Energy Sources and Stores
Glycogen synthesis and breakdown: regulated by hormones
Insulin and glucagon

15. Stimulus: Blood glucose level rises after eating.
Fig
Stimulus: Blood glucose level rises after eating.
Homeostasis: 90 mg glucose/
100 mL blood
Stimulus: Blood glucose level drops below set point.
Figure Homeostatic regulation of cellular fuel

16. Energy Sources and Stores
Adipose (fat) cells: secondary site of energy storage
Body Needs Energy: Goes to…
Liver glycogen
Muscle glycogen
Muscle fat

17. Overnourishment and Obesity
Overnourishment: consumption of more calories than the body needs for normal metabolism
Causes obesity: excessive accumulation of fat
Obesity contributes to:
Type 2 diabetes
Cancer of colon or breast
Cardiovascular disease– heart attacks and strokes

18. Fig
100 µm
Figure Fat cells from the abdomen of a human

19. Overnourishment and Obesity
Homeostatic mechanisms: regulate body weight
Hormones regulate appetite by affecting a “satiety center” in the brain

20. Ghrelin Insulin Leptin PYY Fig. 41-23
Figure A few of the appetite-regulating hormones
Insulin
Leptin
PYY

21. Overnourishment and Obesity
Leptin: hormone made by fat cells
Sends signal to brain to reduce appetite
Mice used to study leptin and obesity

22. Fig
EXPERIMENT
Obese mouse with mutant ob gene (left) next to wild-type mouse.
RESULTS
Figure What are the roles of the ob and db genes in appetite regulation?

23. Obese mouse with mutant ob gene (left) next to wild- type mouse.
Fig a
EXPERIMENT
Figure What are the roles of the ob and db genes in appetite regulation?
Obese mouse with mutant ob gene (left) next to wild- type mouse.

24. Obesity and Evolution Fat hoarding: advantage in evolutionary past
Ex: hunter-gatherers on African Savannah
Relationship between fat storage and evolution can be complex
Ex: Seabirds called petrels

25. Fig
Figure A plump petrel