Phosphagen System
What is the duration of the Phosphagen Energy System?
Begins immediately upon commencement of exercise, peaks around 3-8 s, and then slows rapidly until about 10-15 s.
What is the duration of the Glycolytic Energy System?
Begins around 6 s into high intensity exercise, and lasts around 10 s to 2 mins.
What is the duration of the Oxidative Energy System?
This is the primary energy system for physical activity lasting longer than 2 mins.
What is Lipolysis?
Activated by SNS nerves or epinepherine
Breakdown of TGs into 3FFAs and glycerol.
Adipose = FFAs into blood
SKM = FFAs into cytosol
What is transamination? What is deamination?
Transamination = conversion of one AA to another
Deamination = removal of amine group from an AA which is then used in the TCA cycle
Where does this energy system rank among the three systems?
This is the fastest energy system, followed by the Glycolytic System, and finally the Oxidative system.
Because it is the fastest, it is the primary energy system for high intensity exercise.
What is the primary fuel source of the Glycolytic Energy System?
Muscle glycogen is used first, followed by liver glycogen.
How much of ATP is produced from oxidative phosphorylation, and what substrates are used?
Over 90% of ATP is produced via this pathway using carbohydrates first, and fat when glycogen stores are depleted.
What enzymes are involved in TG oxidation?
HSL and LPL break down TGs into 3 FFAs and 1 glycerol.
3-HAD breaks down FFAs during beta-oxidation (when present, burning fat)
What is the efficiency of protein as a substrate for exercise?
15%
What controls ATP turnover in this system?
CK activates with large amounts of ADP and Cr
What is the importance of lactate in the glycolytic pathway?
Fights fatigue and allows glycolysis to continue. Some pyruvate is converted into lactate, which can then be converted back to pyruvate,which then becomes acetyl-CoA.
What is the role of cytochromes in the ETC? What is the final H+ acceptor?
They transport electrons and create a buildup of H+ between the inner and outer mitochondrial membranes, a kind of potential energy.
O2 is the final H+ acceptor, forms H2O as a byproduct
Where is IMTG located? Why?
In SKM tethered to mitochondria. This allows it to be used readily as a fuel source during exercise when glycogen stores are low or depleted.
What kind of exercise is each energy system used in?
Supramaximal exercise = glycolytic system
High intensity endurance exercise = glycolytic system and oxidative system
What happens to ATP resynthesis after this system is utilized? How long does it take to recover and how?
ATP resynthesis is halved due to depletion of ADP and PCr in the cytosol.
Mitochondrial ATP is shuttled to cytosol. In ~6 mins the majority of ATP and PCr are restored; in ~20 mins these are fully restored. (this is slow due to slow uptake of O2 into the mitochondria and its double membrane)
What is the limiting factor for this system?
Phosphofructokinase (PFK). Primary regulatory enzyme when energy is generated from carbohydrate; controls how fast glycolysis works.
ADP and AMP activate PFK while ATP and H+ inhibit PFK.
What is the chemiosmotic gradient used for?
Phosphorylation of ADP to ATP. Requires oxygen
What is beta-oxidation? How is it related to mitochondrial respiration?
Breakdown of FFAs into 2 C units of acetyl CoA, as well as NADH and FADH2.
Acetyl CoA is the oxidized in the TCA cycle, producing NADH, H+, FADH2, and GTP
NADH, H+, and FADH2 are oxidized by the ETC, producing ATP
What are misconceptions about lactate?
Lactate is a contributor to acidosis (actually buffers H+, increasing pH)
What is the reaction equation for this system? What is this an example of?
ATP is resynthesized from ADP using PCr, and is an example of reaction coupling.
ATP <-> ADP + Pi + energy <- energy + Pi + Cr <- PCr
SURPRISE MISCELLANEOUS QUESTION 2 (or 1 if you haven't found the first one)
What hormones increase glucose metabolism? Fat metabolism?Glucose metabolism = glucagon, epinepherine, NE, cortisol
Fat metabolism = cortisol, epinepherine, NE, GH
SECRET MISCELLANEOUS BONUS QUESTION!!
What is the primary determinant of VO2max?
What physiological factors influence VO2max?
Q is the primary determinant of VO2max (VO2 = Q x a-v O2 diff)
Ability of cardiorespiratory system to deliver O2 to muscles, ability of muscles to take up O2 and produce ATP
Explain the 5 steps of lipid metabolism (mobilization, circulation, uptake, activation, translocation)
Mobilization = IMTG used first (immediate activation) due to SNS activation, followed by adipose cells due to epinepherine binding to membrane receptor
Circulation = delivery of FFAs to muscle cells through blood
Uptake = transport of FFAs into muscle cells
Activation = energy level raised for FFA
Translocation = transport of activated FFA into mitochondria
What are the physiological regulators of acid-base balance?
Lungs = short and long term regulation via blood PCO2 (increased with acidity); CO2 blown off during exercise helps maintain balance.
Kidneys = long term regulation via blood bicarbonate concentration (more produced = greater buffer)