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BIOS 105 Chapter 3
1. What are the 4 basic stages to the digestive process?:
Answer Ingestion, Digestion, Absorption, Excretion
2. Describe Ingestion:
Answer Food is ingested through the mouth and enters the tubular channel, called the alimentary canal, also called the Gastrointestinal Tract.
3. Where does the gastrointestinal tract extend from?:
Answer Extends from the mouth to the anus, and includes the mouth, esophagus, stomach, small intestine, and large intestine.
4. Describe Digestion:
Answer As food passes down the GI tract it is digested, or broken down into smaller units. -- > Food is mechanically and chemically broken down into absorbable units
5. Describe Absorption:
Answer The smaller nutrients are absorbed, meaning that they pass into the bloodstream or lymphatic system, which transports them throughout the body. The substances are taken up from the gastrointestinal tract into the body.
6. Describe Excretion:
Answer Anything leftover from absorption is excreted through the opening (anus) at the end.Undigested material in our diet and other waste products are eliminated from the body.
- Why is the section of the GI tract that is responsible for absorption so elongated?:
Answer The portion of the gastrointestinal tract responsible for absorption is elongated to allow the maximum uptake of nutrients.
8. What is the inside space of the GI tract called?:
Answer Lumen, which is lined with a thick layer of fluid called mucus.
9. What are mucosal cells?:
Answer They allow our body to absorb nutrients, so that they can be transported by the blood 1 / 2
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or lymph to where they are needed.
10. How long is the GI tract?:
Answer 8 to 9 m long (26-30 feet)
11. What is the digestive system comprised of?:
Answer The organs of the GI tract (mouth, esophagus, stomach, small intestine, large intestine) and accessory organs (the salivary glands, liver, gallbladder, and pancreas).
12. What is the main function of the accessory organs?:
Answer They all secrete fluids containing a variety of agents, such as enzymes and acids, that aid in digestion.
- What accessory organ produces a compound that is required for lipid digestion and
absorption, but is not an enzyme?:
Answer The accessory organ that produces a compound required for lipid digestion is the liver.The liver produces bile, which aids in lipid digestion, but is not an enzyme. Bile is stored in the gallbladder.
14. What are the two processes that digestion is comprised of?:
Answer Mechanical and chemical digestion.
15. Describe mechanical digestion:
Answer The physical fragmentation of foods into smaller particles. Starts in the mouth, where teeth crush and tear food into small bits. It continues in the stomach, as forceful contractions vigorously churn food. This churning action disperses the small food fragments and exposes large moleculesto the digestive fluids that will dismantle them. In many cases, mechanical digestion is all that is required to release many vitamins, minerals, and phytochemicals from foods that are then taken up by mucosal cells lining the small intestine.
16. Describe chemical digestion:
Answer Breaks chemical bonds to cleave large mole- cules into smaller ones
17. What is motility?:
Answer A term used to describe the contractions of the GI tract's smooth muscles to mix food with digestive fluids and propel food along the length of tract.
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