Biochemistry

Epinephrine and glucagon activate hormone-sensitive lipase via cAMP signaling in adipose tissue, promoting lipolysis and release of free fatty acids during fasting or stress.

High triglycerides with low HDL is characteristic of metabolic syndrome, often associated with insulin resistance, obesity, and increased cardiovascular risk.

Bone marrow shows the highest pentose phosphate pathway activity because rapidly dividing cells require maximum ribose-5-phosphate for nucleotide (DNA/RNA) synthesis during cell division. While adipose tissue needs NADPH for lipogenesis and RBCs need it for antioxidant defense, bone marrow's continuous hematopoiesis demands the most nucleotide precursors. This is clinically relevant in leukemia and chemotherapy patients.

Aldolase A catalyzes the cleavage of fructose-1,6-bisphosphate into DHAP and G3P. Its deficiency blocks glycolysis at this critical step.

In diabetes, impaired insulin secretion (due to reduced glucokinase in beta cells) leads to inadequate glucose sensing and utilization by tissues despite hyperglycemia.

McArdle disease (GSD Type V) results from muscle phosphorylase deficiency. Glycogen accumulates but is structurally normal. Exercise intolerance and myoglobinuria are characteristic.

All hexoses yield approximately the same amount of ATP (~32-38 ATP) through complete oxidation. The ATP yield depends on the metabolic pathways utilized, not intrinsic energy differences.

The Warburg effect describes the metabolic shift in cancer cells toward anaerobic glycolysis, producing lactate even in the presence of oxygen, resulting in high glucose consumption.

BCAA metabolism produces acetyl-CoA and increases the acetyl-CoA/CoA ratio, which inhibits pyruvate dehydrogenase, reducing glucose oxidation and affecting carbohydrate metabolism.

In muscle, phosphorylase a (phosphorylated form) is active. It is further activated by AMP, which signals energy depletion during exercise.