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Digestion and Nutrition. As heterotrophs, animals need to get “food” in form of organic nutrients from their environments. Although different animals will have varying nutritional requirements, they will all require: 1. Molecules that can be broken down for energy
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Digestion and Nutrition As heterotrophs, animals need to get “food” in form of organic nutrients from their environments. Although different animals will have varying nutritional requirements, they will all require: 1. Molecules that can be broken down for energy 2. Chemical building blocks that can be used for making more complex molecules 3. Minerals and vitamins that facilitate the various metabolic chemical reactions within the body
Digestive Systems In order for “food” to be converted to a useful state for the body, organisms have developed complex digestive systems… The basics “steps” for digesting food are however about the same for most animals… 1. Ingestion 2. Mechanical breakdown 3. Chemical breakdown 4. Absorption 5. Elimination of waste Note however that the relative length, duration, or complexity of each of these steps will vary greatly as a function of diet, as well as the specific animals in question…
Human Digestion Whereas herbivores primarily eat plants, and carnivores primarily eat other animals, as omnivores, the human digestive system requires the complexity to handle a vary high variety of food types…
Mechanical and chemical breakdown of foodMouth… Mechanical and chemical breakdown in the mouth: Note how the teeth differ as a function of the diet of each of the different groups of animals… Whereas the teeth are used for mechanical breakdown, saliva contains the enzyme amylase which begins to break down starches into sugars… Saliva also contains antibacterial agents, water that helps dissolve some of the food molecules, and the capacity to act as a lubricant that helps with the swallowing process.
The Human Digestive System Food travels from the mouth, through the esophagus, and into the stomach… from there food then moves to the small and then large intestines, before the waste product is released… Most digestion occurs in the mouth, stomach, and small Intestines (primarily in the Small intestines); whereas Absorption occurs primarily in the small and partially in the large (for water) intestines…
The Human Digestive System Food moves through the digestive system by peristalsis – rhythmic contraction of circular and longitudinal muscles lining the digestive system…
The Human Digestive System Note that the function of the gallbladder is store and concentrate the bile produced by the liver…
Absorption of the food occurs primarily within the intestines… The Human Digestive System
The Human Digestive System The remaining food that is not absorbed in the small intestine, travels to the large intestine… The bacteria in the intestine live on the unabsorbed food remaining there and Synthesize important components such as vitamin B12, riboflavin, thiamin, and vitamin K. The large intestine absorbs the vitamins, as well as some of the remaining salts and water. The remaining waste product is then released as feces…
The Human Digestive SystemDigestion is controlled by nervous system and hormones
