Chapter 10 - Digestion

Define the following terms in detail: AUTOTROPHS An autotroph is an organism that is capable of producing its own food. It does not rely on ingesting other organisms. Instead, autotrophs are often photosynthetic. e.g. plants, algae, photosynthesizing bacteria

Define the following terms in detail: HETEROTROPHS – organisms that must ingest other organisms to obtain required nutrients. These organisms lack organelles required to photosynthesize or otherwise create all required nutrients.

Define the following terms in detail ESSENTIAL NUTRIENTS Essential nutrients are nutrients that must be obtained through the diet. These are nutrients that are required for proper cellular functioning.

Define the following terms in detail DIGESTIVE SYSTEM All of the organs involved in processing food in order to break it down, absorb required nutrients, and eliminate waste products produced as a result.

Define the following terms in detail INTRACELLULAR DIGESTION The process of breaking down larger nutrient molecules within a cell. This process may involve using organelles such as the lysosome, or it may occur when macromolecules are broken down by HYDROLYSIS. This process is used by amoeba and paramecium, using phago and pinocytosis.

INTRACELLULAR DIGESTION

Define the following terms in detail EXTRACELLULAR DIGESTION The process of breaking down food outside of the cell, and absorbing only the required nutrients. Bacteria, fungi, and most animals use this method.

EXTRACELLULAR DIGESTION Cells excrete digestive enzymes onto food material. The enzymes work outside of the cell, and break down larger molecules into one that can be taken in across a cell membrane easily. Only nutrients needed by cells are absorbed, and wastes remain outside the cell.

EXTRACELLULAR DIGESTION CELL FOOD 1. Enzymes are secreted from the cell 4.Nutrients enter the cell from food 2. Food is broken down by enzymes 3. Required nutrients are released

Define the following terms in detail PERISTALSIS Involuntary muscle movements that causes food to move through the digestive system. This forces food to move in a one-way direction (usually) through all digestive organs, and past those that secrete important enzymes and juices for digestion

PERISTALSIS Peristalsis is the result of smooth muscle contractions in the hollow organs of the digestive tract (esophagus, stomach, intestines). It will force food material to move even against gravity (you can drink while standing on you head).

PERISTALSIS

Examples of organisms with one opening systems are hydra. 2. How is a one-opening digestive system different from a 2-opening digestive system? ONE-OPENING SYSTEM In organisms with a one-opening system, the “mouth” serves to allow food material into the organism, and it also releases wastes. Examples of organisms with one opening systems are hydra.

ONE-OPENING DIGESTIVE SYSTEM

ONE-OPENING SYSTEM Food is taken into a central body cavity where extracellular digestion breaks down the food material. Required nutrients are absorbed into surrounding cells, and waste products are pushed back out through the mouth.

TWO-OPENING DIGESTIVE SYSTEM In organisms with a 2-opening system, a mouth is used to take food into the body. The food passes through a tube (digestive tract) where it is processed and nutrients are absorbed. Wastes are excreted through a second opening called the anus.

TWO-OPENING SYSTEM

TWO-OPENING SYSTEM

What is digestion? DIGESTION is the process by which food materials are broken down into smaller enough pieces that they may be absorbed into the cells of an organism. There are 2 types of digestion: physical digestion and chemical digestion.

What is the difference between ingestion, digestion and egestion? These are the three processes involved in bringing food into the body (ingestion), processing it to obtain required nutrients (digestion) and eliminating wastes from the body (egestion).

What is the difference between physical (mechanical) digestion and chemical digestion? PHYSICAL DIGESTION This is the act of mechanically breaking down food into smaller pieces. This process is accomplished by chewing food, which physically breaks large food particles down into small enough pieces to be swallowed), and through the action of the stomach.

PHYSICAL DIGESTION Action of the stomach The lining of the stomach (the rugae) provides a rough, muscular surface. When the rugae rub together, they grind solid food particles into smaller and smaller bits. Eventually, with the addition of water and digestive chemicals, the solid food is converted into a liquid called chyme.

Rugae of stomach

CHEMICAL DIGESTION Chemical digestion involves adding digestive enzymes and juices to food in order to break the chemical bonds that hold larger food molecules together, to create particles that are small enough to move across cell membranes.

CHEMICAL DIGESTION Chemical digestion begins in the mouth (salivary amylase), continues in the stomach (gastric juice), and into the small intestine (intestinal enzymes, bile, pancreatic juice).