BIO 12 Lecture 31: Bio_12_-_Human_Physio_-_31
Jeff Koo
Bio 12
Human Physio
Spring 2020
4 Units
Endocrine: Energy Metabolism
Energy Metabolism = the way our bodies store and utilize energy
Driven by:
1. Storage of nutrients with food intake and breakdown of stored nutrients between meals
for energy
2. Maintaining blood glucose levels at all times
Anabolic pathway – synthesis of larger biomolecules from smaller ones
● Absorbs energy
Catabolic pathway – breakdown of large biomolecules into smaller ones
● Releases energy
Absorptive & Post-absorptive States
● Absorptive state
○ After a meal (3-4 hours)
○ Anabolic pathways
○ Nutrients in bloodstream plentiful from absorption
○ Glucose serves as the primary fuel
■ Fats, amino acids, and excess glucose are stored
○ Energy input > Output
● Postabsorptive state
○ Between meals
○ Catabolic pathways
○ Maintain plasma glucose levels; energy stores must be mobilized
○ Expenditure > Intake
Glucose: Uptake, utilization, storage
● Uptake by glucose transporters
● Oxidized to yield energy
○ Can be used immediately as energy inside the cell
● Glucose itself can be metabolized to yield ATP (glycolysis, citric acid cycle)
● Glycogenesis (liver and muscles)
○ Can be converted
● Glycogenolysis (liver and muscle cells)
○ Can be converted
Proteins: Uptake, utilization, storage
1. Taken up by cells including muscle and liver cells
a. Used as building blocks for proteins that are needed
2. Protein synthesis
Document Summary
Energy metabolism = the way our bodies store and utilize energy. Driven by: storage of nutrients with food intake and breakdown of stored nutrients between meals for energy, maintaining blood glucose levels at all times. Anabolic pathway synthesis of larger biomolecules from smaller ones. Catabolic pathway breakdown of large biomolecules into smaller ones. Fats, amino acids, and excess glucose are stored. Maintain plasma glucose levels; energy stores must be mobilized. Can be used immediately as energy inside the cell. Glucose itself can be metabolized to yield atp (glycolysis, citric acid cycle) Circulating triglycerides (in lipoproteins) are broken down into monoglyceride and fatty acids by lpl (lipoprotein lipase) enzyme. Fatty acids are taken up by nearby cells. Oxidized to release energy, co2 and h20. Fatty acids can be combined with glycerol to form new triglycerides and stored in adipose tissue. Triglycerides can be broken down in fat cells to yield fatty acids and glycerol (lipolysis)
