Lecture 11a- 17 November 2014

This lecture is based largely on CHAPTER 23 IN KRAUSE'S FOOD NUTRITION AND DIET THERAPY (ON RESERVE IN LIBRARY) AND CHAPTERS 7,8,9 IN ROLFES ET AL.

Final exam-120 multiple choice-120 marksfrom vitamins to end of course

-4 short answer questions-15 points each for a total of 60 points

covers whole course

-3 hours- 180 marks

Lecture 11

OutlineMetabolic aspects of Nutrition and fitness/Sports Nutrition

Energy production            ATP            Anaerobic pathway            Aerobic pathway            Energy continuum            Sources of fuel           

Outline of lectures 11ab

Energy production

Substrate choice

Intensity         Duration          Effect of training          Diet

Outline of lectures 11ab

Nutritional Requirements            Fluid                 Fluid Balance                 Fluid Absorption

Factors affecting fluid absorption                 Requirements                         Short duration                         Endurance

Outline of lectures 11ab

Nutritional Requirements           Carbohydrate                        Types of carbohydrate

                        Pre-event

                        During event                         Post-event

Outline of lectures 11ab

Nutritional Requirements           Protein                Endurance

                Resistance Exercise

                Amino acid supplementation

Outline of lecture 11Nutritional Requirements            Lipid

            Minerals                        Iron                        Calcium            Vitamins                        Anti-oxidant vitamins and B-

carotene                       C                        E                        B vitamins

Outline of lectures 11ab

Regulation of metabolism

More Detailed Comments

Energy production

Aerobic and anaerobic both provide ATP but which system predominates depends on oxygen supply to the tissues   

Energy productionATP    Energy currency of the cell                        ATP to ADP plus Pi                                    -done by ATPase      Creatine phosphate is split to creatine and

phosphate                     -this provides the energy to

resynthesise ATP via creatine kinase

 

Energy production

ATP

    limited amount of creatine phosphate in the body so this is a very limited way to replace ATP- creatine phosphate process is anaerobic                if all-out exercise -this process can only go

on for 5-8 seconds- eg power lifting

 

Energy production Anaerobic pathway            No oxygen 

            Glycolysis is the quickest way to make ATP             Lactic acid is endproduct (enzyme

implications) 

Two hydrogens transferred to pyruvate thus making lactate- This results in the freeing of NAD to participate further in making ATP-but relatively small amount of ATP synthesis

Energy production Anaerobic pathway Lactic acid is rapidly removed from the muscle

and transported in the blood and is eventually converted to energy in the muscle, liver or brain OR it is converted to glycogen

        Conversion to glycogen occurs largely in the

liver and to some extent in the muscle  Lactic acid buildup in the blood leads to drop

in pH resulting in enzymatic activity drops which in turn results in fatigue

 

Energy production   Anaerobic pathway

Oxygen debt-recovery oxygen consumption- the difference between oxygen consumption in the post-exercise recovery phase and the

oxygen consumption at rest

Fuel source is limited to glucose and produces a relatively small amount of ATP relative to aerobic metabolism

  All out effort for 60-120 seconds       

Energy productionAerobic pathway

If going for continued muscle activity of more than 90-120 seconds one needs oxygen

 

Energy is stored in high-energy phosphate bonds in ATP through a complex series of enzymatically guided reactions involving separation of hydrogen atoms from the parent compounds 

                       

Energy production

Aerobic pathway

Vital to this process is the presence of coenzymes which act as hydrogen acceptors until the process of oxidative phosphorylation results in the formation of ATP

Ultimately hydrogen combines with O2 to

form water and the coenzymes are freed to accept more hydrogen so as to continue the process                   

Energy productionAerobic pathway

           Glucose is broken down much more efficiently than is the case with anaerobic glycolysis

  In the presence of oxygen, pyruvate is

converted to Acetyl CoA  Acetyl CoA enters the mitochondria and is

then introduced into the Kreb’s cycle

       

Energy production Aerobic pathway

      Proteins and lipids can also be metabolized to produce ATP

      Lipids- the beta oxidation of lipids produces a large amount of ATP

       Proteins can be catabolised to Acetyl CoA or

to Kreb’s cycle intermediates and in this way produce ATP

       

Break