Chapter 8 - Metabolism Flashcards
What is energy?
Energy is the capacity to perform work. Energy has many forms including chemical, mechanical, electrical, heat, solar, and nuclear energy.
What 4 entities can be used for energy?
- Carbs
- Lipids
- Proteins
- Alcohol
True or False
Cells cannot release energy from vitamins, minerals, and water.
True
What is catabolic?
Energy releasing
What is anabolic?
Energy requiring
Most of energy released by the breakdown of macronutrients is capture in chemical form as …
Adenosine Triphosphate
Glycolysis
An anaerobic process that results in the conversion of glucose to 2 pyruvate molecules & a net gain of ATP molecules.
Citric Acid Cycle
Is a complex series of chemical reactions that result in the release of CO2 hydrogen ions, and electrons from intermediates of citrate.
Electron Transport Chain
The coenzymes NADH & FADH2 carry hydrogen ions and their high-energy electrons from the citric acid cycle to a linked series of enzymes called electron transport chain.
True or False
The electron chain does not produce water & ATP during aerobic energy metabolism.
False
What does the human body need to store more energy in fat cells that is in glycogen stores?
Triglycerides
What are the phases for “Fat Catabolism”
- Hormone sensitive lipase facilitates the removal of 3 fatty acids from the glycerol “backbone” of triglyceride molecule.
- In the cell’s cytoplasm, a fatty acid bonds to coenzyme A, forming an activated fatty acid.
- Fatty acid catabolism occurs in the mitochondria via beta-oxidation
- The acetyl CoA molecules that form during beta-oxidation enters the citric acid cycle and undergo catabolism for ATP production.
- The final step, carriers transport electrons to the electron transport chain, and ATP synthesis occurs.
What is Ketogenesis?
Occurs when acetyl CoA molecules cannot be used efficiently in the citric cider cycle. This condition results when the glucose supply in cells is insufficient and cells must rely on fatty acids as a major fuel.
What is a Ketogenic Diet?
Supplies most of its energy from fat. Such low-carbohydrate diets are often popular with people who want to lose weight. Limiting carbohydrate intake to less than 50 g per day not only rapidly depletes glycogen stores, but it also results in ketosis. Ketosis usually causes loss of appetite, so people who are trying to lose weight may find this symptom desirable. The long-term health effects of mild ketosis are unknown.
What are the side effects of “Ketogenic diet”?
constipation, hypoglycemia, hunger, vomiting, lack of energy, elevated blood lipids, and kidney stones.
a serious complication of diabetes that occurs when the body produces high concentrations of the ketone bodies, which lower the blood’s pH and cause severe ketosis.
Diabetic ketoacidosis (DKA)
What tissue is the main site to store triglycerides?
Adipose Tissue
What happens if the diet provides an excess of amino acids and cells do not need energy?
the amino acids will be stripped of their nitrogen group and used to make either glucose or fat.
“Chemical Messengers”
Stimulates & regulates cellular activities
Key hormones that direct or regulate metabolic activities are:
Insulin
Glucagon
Cortisol
Epinephrine
Thyroid hormone
Anabolic Metabolism
Insulin directs liver and muscle cells to slow down their glycogenolysis rates and increase their rates of glycogenolysis. Such actions shift glucose molecules into storage as glycogen.
Insulin also increases the fatty acid uptake and triglyceride synthesis of adipocytes. Furthermore, insulin stimulates protein synthesis in cells. To summarize, insulin promotes energy storage.
Catabolic Metabolism
Glucagon, cortisol, and epinephrine are hormones that instruct cells to use catabolic rather than anabolic pathways. The cells that synthesize these catabolic hormones release higher amounts of them in response to intense exercise, extreme stress, or starvation.
The collective activity of these hormones is to increase fuel mobilization from storage, so sources of energy are available for all of the body’s cells.
Overnight Fasting
The metabolic responses to an overnight fast include the use of liver glycogen stores, as well as glycogenesis, to maintain adequate blood glucose levels. Glucagon stimulates these pathways.
Starvation
During starvation, multiple catabolic hormones, including glucagon and cortisol instruct cells to release all fuel sources into the bloodstream.
Starvation is a highly catabolic state, characterized by glycogenesis, lipolysis, proteolysis, and ketogenesis. Although these metabolic responses are necessary for survival, the starving person is in a very dangerous metabolic state and will likely die if the lack of access to nourishing foods continues.
