Tissue-Specific
Metabolism: The Division of Labor
The Liver
Processes and Distributes Nutrients
Adipose
Tissue Stores and Supplies Fatty Acids
Muscle
Uses ATP for Mechanical Work
The Brain
Uses Energy for Transmission of Impulses
Blood
Carries Oxygen, Metabolites, and Hormones
Hormones:
Communication among Cells and Tissues
Hormones
Are Chemically Diverse, Biologically Potent
Molecules
Hormones
Function in a Complex Hierarchy
Hormonal
Regulation of Fuel Metabolism
Epinephrine
Signals Impending Activity
Glucagon
Signals Low Blood Glucose
During
Starvation, Metabolism Shifts to Provide Fuel for
the Brain
Insulin
Signals High Blood Glucose
Diabetes
Is a Defect in Insulin Production or Action
Molecular
Mechanisms of Signal Transduction
Receptors
for Epinephrine Trigger Cyclic AMP Production
Cyclic
AMP Acts as a Second Messenger for a Number of
Regulatory Molecules
Cyclic
GMP Also Acts as a Second Messenger
The
Insulin Receptor Is a Tyrosine-Specific Protein
Kinase
Two
Second Messengers Are Derived from
Phosphatidylinositols
Calcium
Is a Second Messenger in Many Signal
Transductions
Ion
Channels Are Gated by Ligands and by Membrane
Potential
Toxins,
Oncogenes, and Tumor Promoters Interfere with
Signal Transductions
Steroid
and Thyroid Hormones Act in the Nucleus to Change
Gene Expression
Summary
Further Reading
Problems
