Digestion

Standards: 6.1.1 Explain why digestion of large food molecules is essential 6.1.2 Explain the need for enzymes in digestion (the need for increasing the rate of digestion at body temp should be emphasized) 6.1.3 State the source, substrate, products and optimum pH conditions for one amylase, one protease and one lipase (any human enzymes can be selected. Details of structure or mechanisms of action are not required) 6.1.4 Draw and label a diagram of the digestive system (The diagram should show the mouth, esophagus, stomach, large intestine, small intestine, anus, liver, pancreas, and gall bladder. The diagram should clearly show the interconnections between these structures.) 6.1.5 Outline the function of the stomach, large intestine and small intestine 6.1.6 Distinguish between absorption and assimilation 6.1.7 Explain how the structure of the villus is related to its role in absorption and transport of products of digestion

** __Digestion__ **
 * Heterotrophs are dependant on a supply of food. They must satisfy the need for chemical energy, organic materials used in biosynthesis, and nutrients that cannot be made by the body. The digestive system is essential in processing food in order that the body can use it to satisfy these needs. **


 * __41.1- Homeostatic mechanisms manage an animal’s energy budget__ **


 * Production of ATP accounts for a large portion of an animal’s energy budget. ATP powers basal metabolism, activities, and in endotherms, thermoregulation. **


 * Four main feeding mechanisms of animals **


 * ** __Suspension Feeders__- Many species of aquatic animals who sift small food particles from the water. **
 * ** __Substrate Feeders__- Animals that live on or within their source of food. **
 * ** __Fluid Feeders__- Animals that suck nutrient rich fluid from a living host. **
 * ** __Bulk Feeders__- Animals that eat relatively large pieces of food. **


 * Glucose is a major fuel for cells and metabolism, regulation of glucose throughout the body provides homeostasis. Excess glucose is stored as fat when the body’s glycogen depots are full and caloric intake still exceeds caloric expenditure. **


 * __41.2- An animal’s diet must supply carbon skeletons and essential nutrients__ **


 * An animal’s diet must supply all the raw materials that it requires for biosynthesis. Animals must obtain organic precursors (carbon skeleton) in order to carry out functions such as growth, homeostasis, and reproduction. Aside from fuel and carbon skeletons, an animal must obtain essential nutrients (must be obtained in a preassembled form because they can’t be made from raw materials) in order to survive. Example: Humans need ascorbic acid (vitamin C) **


 * ** __Essential amino acids__- 20 amino acids required by animals to make proteins, most animals can synthesize these as long as their diet includes organic nitrogen. **
 * ** __Essential fatty acids__- Certain unsaturated fatty acids are required to make the phospholipids that are found in membranes. **
 * ** __Vitamins__- Organicsubstances essential in small quantities to normal metabolism, foundinminuteamountsin natural foodstuffs or sometimes produced synthetically:deficiencies of vitamins produce specific disorders. Examples: Vitamin A supports visual pigments in the eye. Vitamin D supports calcium absorption and bone formation.  **
 * ** __Minerals__- a nyoftheinorganicelements,as calcium, iron, magnesium , potassium, or sodium, thatareessentialtothe functioning of the human body and are obtainedfromfoods. Examples: Sodium plays a role in acid-base balance, water balance and nerve function. Iron contributes as a component of hemoglobin in blood and electron carriers in energy metabolism.  **


 * __41.3- The main stages of food processing are ingestion, digestion, absorption, and elimination__ **


 * ** __Ingestion__- The act of an organism consuming food. The organic material in the food contains proteins, fats, and carbohydrates in the form of starch and other polysaccharides which can not be used by the animal. The body must proceed to the next step in food processing in order for the polymers to be small enough to pass through membranes and enter the cells of an animal. **
 * ** __Digestion__- The second stage of food processing. It is the process of breaking down food into molecules small enough for the body to absorb.During digestion, macromolecules are broken down into their component monomers. These monomers are used to make molecules and fuel ATP production. **
 * ** __Enzymatic Hydrolysis-__ The breaking of bonds with the addition of water that occurs with the addition of water. Enzymes for breaking down specific macromolecules catalyze the chemical digestion. These are also important in that they allow digestion to occur at the normal body temperature. This process is preceded by mechanical fragmentation of food, such a chewing, which increases the surface area. **
 * ** __Absorption-__The first stage of food processing after the food is digested in which the animal’s cells absorb small molecules such as amino acids and sugars from the digestive compartment. This is not to be confused with the process of assimilation, which consists of the body making use of the materials processed and absorbed during digestion. **
 * ** Elimination-The final stage of digestion, in which undigested material passes out of the digestive compartment. **
 * __Digestive Compartments-__ **


 * Animals must reduce the risk of self-digestion by processing food in specialized compartments. **
 * (animals are made up of the same macromolecules they digest.) **
 * __Intracellular digestion-__ Digestion that occurs within the food vacuoles of a cell, which are the simplest digestive compartments. **
 * __Extracellular digestion-__ The breakdown of food outside of cells. It occurs in compartments that are continuous with the outside of the animal’s body. An extracellular compartment allows for the digestion of much larger animals. **
 * (than can be ingested with phagocytosis and digested intracellularly.) **
 * __Gastrovascular cavity-__a simple digestive compartment that functions in both digestion and distribution of nutrients. Hydras are an example of an animal with this kind of extracellular compartment. **
 * __Complete digestive tract-__ Also called an alimentary canal, this type of digestive compartment consists of food moving along a tube-like compartment in one direction. The tube is organized into specific regions that carry out specific functions in steps. These types of digestive compartments are allow an animal to eat more food before its earlier meals are fully digested. **
 * (Giving it an advantage over gastrovascular cavity) **

The rest of the information is here (41.4-41.5): https://docs.google.com/presentation/d/1AAk3PrdTbYZfOVTgTTOugpdVgrGqzN0-2ZpesQxv8FE/edit