In Unit 5 you are currently studying cell respiration; basically oxidizing the sugar glucose into carbon dioxide and in the process making ATP. Naturally, things are more complicated than this. In this unit you will study two broad questions.
- How do cells acquire the glucose they use in cell respiration from the products of digested food?
- What are the major organs of the digestive system, how do they function, and how is their activity regulated?
Learning Objectives: the successful student will be able to ...
- describe the general metabolic pathways that take proteins, amino acids, carbohydrates, and lipids to the cell respiration pathway.
- explain alternative pathways of metabolism that store or dispose of compounds.
- Name and describe the function and interrelationships among the major organs of the digestive system.
- describe the anatomical and physiological controls that regulate the activity of the digestive system.
Lesson One: Intermediate Metabolism.
Go to this introduction to metabolism from the Virtual Chembook. Read through this material to familiarize yourself with the vocabulary you will need in this unit (e.g. nutrient, vitamin, mineral, etc.). Pay particular attention to the section vitamins. There is also a diagram that outlines the basic pathways of metabolism. Click on this to enlarge the image.
Homework, Due 23 November.
Write a brief description of the important functions that various vitamins play in the process of cell respiration. Email your answer using your FBA account.
Lesson Two: Carbohydrate Metabolism.
You are already familiar with much of this material from our study of cell respiration. Focus on two areas in this section of the Virtual Chembook, the alternative pathways that glucose can take back and forth from other compounds other than glycolysis and the relationship between carbohydrate metabolism and protein and lipid metabolism.
In addition, understand the role of the hormones insulin, glucagon, and epinephrine in the control of blood glucose levels.
Homework, Due 30 November.
For each of the following terms list what compound is being converted into what other compound and where this process takes place (e.g. all cells, mostly liver, etc.)
- Glycogenesis
- Glycogenolysis
- Glycolysis
- Gluconeogenesis
- Lactic Acid (Lactate) fermentation
Lesson Three: Protein and Lipid Metabolism.
Read this introduction to lipid metabolism and appreciate the important role fats play in energy storage compared to carbohydrates and proteins. Then return to the Virtual Chembook and read just the introduction to fatty acid oxidation (fatty acid spiral). Focus on where this process takes place and its relationship to the Krebs cycle and the Electron Transport System. Don't worry about the detailed steps in the process.
Finally, read the introduction to protein metabolism. Understand the function nitrogen plays in the production of amino acids and proteins. Know what the "nitrogen pool" is and the various sources to the pool and it daily turnover.
Homework, Due 3 December.
Email the answers to the following questions using your FBA account.
- Compare the relative amounts of energy stored in the typical human body in the form of carbohydrates, proteins, and lipids.
- What is the nitrogen pool and why does the process of cell respiration depend on this pool? Name specific compounds that depend on the nitrogen pool and explain this dependence.
Lesson Four: The Digestive System.
Go to the Kimball pages on the Gastrointestinal tract (the digestive system) and read the material there. The second diagram down from the top is a good summary of the major organs of this system. You should be able to identify these organs and describe their function, control, and relationships to one another. As you read through this material learn the following for each section.
- Location and connections: where is the organ in the body and to what other organs is it connected.
- Cell types: where given, the various types of cells present in the organ (e.g. Stomach: parietal cells etc.)
- Function: the function of the organ (e.g. large intestine absorbs water from the gut) and where given the function of the specific cell types (e.g. parietal cells secrete H+ and intrinsic factor).
- Enzymes produced and the substrate and product of their action.
Homework, Due 7 December.
List the major digestive organs from mouth to large intestine. Then for each list the following for a typical polysaccharide, protein, lipid, and water.
- What, if any, enzymes are produced in the organ that act on this material (e.g. the enzyme amylase is produced in the mouth and digests polysaccharides).
- What, if any, enzymes are produced by other organs and transported to the organ that act on this material (e.g. the various enzymes produced by the pancreas and transported to the small intestine).
- What, if any, co-factors, vitamins, or other supporting substances are involved in the digestive process along with the enzyme (e.g. small intestine receives bile produced in liver that emulsify lipids)
- Where the end products of digestion of each type of end product are absorbed into the circulatory system.
Note: you don't need to worry about the specific action of the various protease enzymes (e.g. which amino acid terminals, etc.). Just know that they are breaking down large polypeptides into smaller ones.
