Exercise Physiology APL2/L3

Exercise: What do you use/how does it happen?  1. When you exercise or exert yourself, where does the energy come from?  2. Is weight lifting the same as running on a treadmill in terms of energy usage?  3. Do you obtain the same results if you weight lift vs do cardio exercise?  4. Does the amount of time you exercise each session matter in ques #3?

ATP: Our Body’s “gasoline”  Adenosine Triphosphate  Energy storing molecule  “usable energy”

Three Main Energy Pathways  1.ATP (6 sec): stored in mitochondria.  2. CP: Creatine phosphate (10 sec) A lot of it in muscles and builds ATP back up. (Creatine phosphate + ADP ↔ ATP + creatine) (Creatine phosphate + ADP ↔ ATP + creatine)  3. Glycogen: stored glucose in liver and muscles.(anaerobic)  Fat: used last. Greatest potential energy source.

Cellular Respiration:  Process which releases energy from organic compounds in cells.  3 reactions make up Cellular Respiration: glycolysis, citric acid cycle (Krebs), electron transport chain  RESULT: CO2, H2O and energy. ½ IS HEAT, ½ IS USED TO MAKE ATP (ENERGY NEEDED BY MUSCLE CELLS)

Glycolysis:  Breaking of glucose: 6-carbon glucose molecule →two 3-carbon pyruvic acid molecules.  High energy electrons are delivered to ETC  2 molecules ATP produced

Krebs cycle: aka Citric Acid Cycle  Part II of Aerobic Respiration  Charged Ions are produced and gotten ready for ETC.  6-8 ATP produced

Electron Transport Chain

Put this info next to ETC slide  High energy electron carriers such as NADH and hydrogen (H+) generated from glycolysis and Krebs hold most of the energy (in the form of electrons) from the original glucose molecule.  These electrons are passed along in the mitochondria.  Energy from the “handing off” to oxygen (the last electron carrier) is used to make ATP from ADP and phosphate

ATP  Between ETC and Krebs Cycle: molecules of ATP are produced.  A lot of heat is given off

Put these notes next to last slide  If you want to lose fat or increase endurance: exercise needs to be slower, for longer periods of time. i.e min at % of max heart rate.  If you want to build muscle: muscles must be forcefully exercised to cause hypertrophy (increase in muscle fiber size, not increase in # of fibers or # of muscles)

Hypertrophy of Muscles  Muscles forcefully exercised will enlarge  There is ↑ in muscle fiber size, not number of muscles.  i.e: body builder/weight -lifter, prof. athlete

Atrophy of Muscles Atrophy of Muscles  Muscles not used will decrease in size  This is called muscle atrophy  i.e: spinal cord patients: very thin and frail

Muscle fatigue and Oxygen Debt  Normally, we breath enough O2 to support aerobic use of glucose. However…  Strenuous use of muscles result in: anaerobic respiration: glucose is broken into pyruvic acid → lactic acid  Lactic acid: not enough ATP to convert it to pyruvic acid at this time.  Results in: O2 debt= muscle cramping/fatigue

Cont.  If not enough oxygen coming in=electrons cannot continue to pass through.  Electrons will be given back to pyruvic acid in a Rx that forms lactic acid.  The debt will be repayed later when there is enough oxygen to make ATP to convert the lactic acid back to pyruvic and back to make glucose to re-enter krebs.

Quick Quiz (2 pts/bullet)  1. What is the gasoline for our body?  2. What are the 3 energy pathways in the cell?  3. What 3 reactions make up cellular respiration and what do they produce?  4. When (time-wise) and under what conditions (type of work-out) does anaerobic respiration occur?  5. How do muscles enlarge? What is increased muscle mass called?