Applied Exercise Physiology

During intense exercise, your body maintains balance despite huge increases in energy demand. What is this called?

Steady State. Homeostasis is stable balance at rest with low effort. Steady state is balance maintained through elevated effort during exercise when supply must keep matching a much higher demand.

In a negative feedback, what role does the brain play?

Control center. The brain with structures like the hypothalamus, acts as the control center- it receive input from sensors and sends instructions to effectors like sweat glands or blood vessels.

WHich energy system provides ATP the fastest but only lasts about 10-15 seconds?

Phosphagen (PCr) system. The Pcr system uses stored phosphocreatine to instanly regenerate ATP. It’s the fastest system but has a very limited reserve, lasitn gonly about 10-15 seconds

During anaerobic glycolysis, pyruvate is converted into lactate. Why does this happen?

To regenerate NAD+ so glycolysis can keep running

Glycolysis needs NAD+ to keep breaking down glucose. Converting pyruvate to lactate regenerates NAD+ from NADH, allowing glycolysis to continue even without oxygen.

Which fuel source produces the MOST ATP per gram, but at the SLOWEST rate?

Fat

Fat provides about 9 kcal/gram, more than double carbs or protein (4 kcal/g each). However, breaking down fat (beta oxidation) is slower than glycolysis, so it can't fuel high-intensity efforts as quickly.

Where does the Electron Transport Chain (ETC) take place, and what does it require?

In the mitochondria; requires oxygen

The ETC occurs on the inner mitochondrial membrane and requires oxygen as the final electron acceptor. It produces the largest share of ATP — roughly 2.5 ATP per NADH and 1.5 ATP per FADH2.

Enzymes like phosphofructokinase (PFK) and isocitrate dehydrogenase are described as "rate-limiting." What does this mean?

They control how fast/slow the whole pathway can run

A rate-limiting enzyme acts like a gatekeeper — it controls the overall speed of its pathway. If temperature gets too high or pH drops too low (acidosis), these enzymes stop working well and the pathway slows down.