Animal Nutrition

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8

Lumen

Slide 56

Each villus contains a network of blood vessels and a small lymphatic vessel called a lacteal.

After glycerol and fatty acids are absorbed by epithelial cells, they are recombined into fats within these cells.

These fats are mixed with cholesterol and coated with protein, forming molecules called chylomicrons, which are transported into lacteals.

Slide 57

Amino acids and sugars pass through the epithelium of the small intestine and enter the bloodstream.

Capillaries and veins from the lacteals converge in the hepatic portal vein and deliver blood to the liver and then on to the heart.

Slide 58

Absorption in the Large Intestine

The colon of the large intestine is connected to the small intestine.

The cecum aids in the fermentation of plant material and connects where the small and large intestines meet.

The human cecum has an extension called the appendix, which plays a very minor role in immunity.

Slide 59

Digital image of a human colon

Slide 60

A major function of the colon is water reabsorption, recovering water that has entered the alimentary canal.

Wastes of the digestive tract, the feces, become more solid as they move through the colon

Feces pass through the rectum and exit via the anus.

Slide 61

The L.I. colon houses strains of the bacterium Escherichia coli, some of which produce vitamins ++.

Feces are stored in the rectum until they can be eliminated.

Two sphincters between the rectum and anus control bowel movements.

Slide 62

Evolutionary adaptations of vertebrate digestive systems correlate with diet

Digestive systems of vertebrates are variations on a common plan. There are intriguing adaptations, often related to diet.

Dentition, an animal’s assortment of teeth, is one example of structural variation reflecting diet. Mammals have varying dentition that is adapted to their usual diet.

The teeth of poisonous snakes are modified as fangs for injecting venom. All snakes can unhinge their jaws to swallow prey whole.

Slide 63

Dentition and diet

Incisors

(c) Omnivore

Molars

(b) Herbivore

(a) Carnivore

Canines

Premolars

Slide 64

Stomach and Intestinal Adaptations