SEHS Topic 3.3 Nutrition and Energy Systems

Annotate a diagram of the ultrastructure of a generalized animal cell

Annotate a diagram of the ultrastructure of a mitochondrion

Define the term cell respiration

The controlled release of energy in the form of ATP from organic compounds in cells

Explain how adenosine diphosphate can gain and lose a phosphate molecule

• The ATP molecule acts as a chemical 'battery', storing energy when it is not needed, but able to release it instantly when the body requires it.

• ATP works by losing the endmost phosphate group when instructed to do so by an enzyme.

Cont’dThis reaction releases a lot of energy, which can then use to build proteins, contract muscles, etc.

-The end product is adenosine diphosphate (ADP), and the phosphate molecule.

-Additional energy can be extracted by removing a second phosphate group to produce adenosine -monophosphate (AMP).

-When the body is resting and energy is not immediately needed, the reverse reaction takes place and the phosphate group is reattached to the molecule using energy obtained from food.

Explain the role of ATP in muscle contraction

• Phosphorylation of a protein = a conformational change in that protein

• Skeletal muscle structure (review)

Actin, Myosin, Tropomyosin, Troponin, Ca++ , ADP, & ATP

http://www.youtube.com/watch?v=hqynCsign8E (SLIDING FILAMENT THEORY)

Describe the re-synthesis of ATP by the ATP-CP system

• Creatine phosphate (aka PCr) is a high energy molecule that is broken down to provide energy for the re-synthesis of ATP that has been utilized during the initial stages of exercise.

• serves as a rapidly available reserve of high-energy phosphates in skeletal muscle and the brain

PCr and its role during intense exercise• CAN NOT be used directly to drive muscle contraction• PCr + ADP + H Creatine + ATP• Provides energy QUICKLY but it is SHORT-LIVED (20

seconds)• When typically used?• When performing explosive short activities:• sprinting, explosive weight training lifts, shot-

putting, high jump, periodic in game movements…etc• What does your body do once your PCr is used?

Lactic Acid (Lactate) Fermentation System• We’ve seen this before:• Glucose Pyruvate Lactate• Occurs in the cytoplasm• Its an anaerobic pathway (PCr is too!) = NO O2

• Optimal for high energy demands of intense exercise since the energy is produced quickly

• HOWEVER (like PCr) it provides only a short supply of energy (ATP)…a couple minutes max… ALSO is lowers muscle pH (lactic acid is a moderately strong acid) = reduction in muscle’s ability to contract)

What energy system kicks in past 2:30 of intense activity?

• AEROBIC CELLULAR RESPIRATION of glucose and fat (beta oxidation)

Beta-Oxidation of Fatty Acids• We also get ATP production from our fat

consumption and fat storage via beta-oxidation:

Explain the phenomenon of oxygen deficit and oxygen debt

• Oxygen deficit – when oxygen need and oxygen supply do not match during the first moments of exercise

• Oxygen debt – (now better known as Excess Post-exercise Oxygen Consumption….(EPOC)) – during recovery from exercise , oxygen consumption continues at a greater rate than needed at rest

KEY POINTS of E.P.O.C.• O2 consumption remains elevated after exercise:• 1. to rebuild ATP and Pcr stores in the cells• 2. O2 is “borrowed” from hemoglobin and esp

myogloblin during initial stages of execise and must be “repaid”

• Oxygen cost to help offset increase body temp following intense exercise

Discuss the characteristics of the 3 energy systems and their relative contributions during exercise

Cont’d

• Based on the information on the previous slide:

• Write an analysis of each energy system and their roles during different types of exercise (endurance athlete, baseball player, sprinter), as well as the main nutrient(s) used and the byproducts produced

• Fig 3.20 from the text will help