Intro Flashcards
Skeletal Muscle Metabolism
- Energy source - fatty acids at rest and glucose in exertion **for intermittent mechanical work
- White muscle fibers (rapid, limited duration, aerobic oxidation b/c low # mito)
- Red muscle fibers (slower contracting, high # mito)
- Store glycogen
Heart Metabolism
- Needs cont O2 b/c cont contraction
- High oxidative capacity; high # mito
Liver Metabolism
- Energy source- variety
- Primary role in glucose homeostasis
- Location of synthesis (glucose, urea, ketones) and conversion of fuels)
Brain and Nerve Metabolism
- Energy source- glucose or ketones during starvation
- CANNOT oxidize fatty acids
- Needed for its electrical work
Adipose Tissue Metabolism
- Major function- storage, mobilization and synthesis of triglycerides
- Reg by hormones
Kidney Metabolism
- Major function- fluid homeostasis
- Energy sources- FAs, ketones and lactate
- Needs energy for osmotic work
- 2nd behind liver in terms of gluconeogenesis
- Also ammonia synthesis
RBC Metabolism
- Major function - exchange O2 and CO2
- Mature RBCs have NO MITO (all energy from anaerobic glycolysis)
GI Metabolism
- Energy source- glutamine and glutamate
- Major function- digestion and absorption
3 Major Dietary Fuels + Interconversions
- Fats, carbohydrates and proteins
- Interconversion
- Carbs —> fats (lipogenesis)
- Protein —> fats (ketogenesis)
- Protein —> carbs (gluconeogenesis)
- Carbs —> protein (synthesis of non-essential AAs)
**Note: bidirectional relationship b/n proteins and carbs but only unidirectional in fat formation (cannot convert fat back to protein or carbs)
Energy Value of 3 Major Dietary Fuels
- Carbs…4kcal/gram
- Proteins…4kcal/gram
- Fat…9kcal/gram
Cytosolic Paths (5)
- Glycolysis
- Pentose Phosphate Pathway
- FA synthesis
- Nucleotide synthesis
- Protein synthesis
Mitochondrial Paths (4)
- Tricarboxylic acid cycle (TCA)
- Oxidative phosphorylation
- Beta oxidation of FAs
- Ketogenesis and ketone oxidation
Paths that Use Mito and Cytosol (3)
- Gluconeogenesis
- Urea synthesis
- Steroid hormone synthesis
Smooth ER Paths (4)
- Triglyceride synthesis
- Phospholipid and glycolipid synthesis
- Cholesterol synthesis
- Hydroxylation and detox rxns
ATP
NAD+ / FAD
NADPH
acetyl-CoA
- universal source of chemical energy (made in catabolism and used in synthesis)
- carriers of electrons in oxidative rxns (electrons conserved in chem bonds)
- supplies reducing power for synthetic rxns
- universal carrier of acetyl groups
3 Stages of Energy Extraction
Stage I- degradation of macromolecules - no useful energy gained
Stage II- conversion of building blocks to common intermediates - small amount of energy extracted
- Common intermediates include acetyl CoA & pyruvate
Stage III- terminal oxidation of acetyl Coa —> CO2 and H2O - most energy extraction
- REQUIRES OXYGEN (occurs in mito)
Storage Form of Molecules
Glycogen, proteins, triglycerides
Circulation Form of Molecules
Glucose, AA, triglycerides, FAs, ketones, lactose
Tissue/Cell Form of Molecules
Glucose-6-P, pyruvate, acetyl-CoA, ATP
4 Metabolites at Major Branch Points in Metabolism
1- Glucose-6-P
2- Acetyl CoA
3- Pyruvate
4- Glutamate
Major Goals of Metabolism (2)
- 1- Extract energy and reducing power from environment
- Catabolic pathways - degradative —> release energy
- Oxidative, involve breaking covalent bonds
- Catabolic pathways - degradative —> release energy
- 2- To synthesize building blocks to make more complex macromolecules
- Anabolic pathways - synthesis —> consume energy
- Reductive, involve bond formation
- Anabolic pathways - synthesis —> consume energy
