Upload
mozil-fadzil-kamarudin
View
220
Download
0
Embed Size (px)
Citation preview
8/6/2019 5 Cell Metabolism
http://slidepdf.com/reader/full/5-cell-metabolism 1/21
8/6/2019 5 Cell Metabolism
http://slidepdf.com/reader/full/5-cell-metabolism 2/21
� Energy is measured in kilocalories(kcal)
¾ E.g., 1g of carbs ² 4kcal
� Food composed of carbon, hydrogen,O2 & nitrogen (protein only)
Food Adenosine Triphosphate(ATP)
8/6/2019 5 Cell Metabolism
http://slidepdf.com/reader/full/5-cell-metabolism 3/21
� Our muscles dependence on carbs
during exercise is related to carbs
availability & our muscle·s welldeveloped system for metabolism.
� Carbs are converted to glycogen
�
Glycogen storage¾ 40% liver 60% skeletal muscle
8/6/2019 5 Cell Metabolism
http://slidepdf.com/reader/full/5-cell-metabolism 4/21
� Our body stores more fat than carbs
� Energy reserve from fat is higher than
carbs¾ 1g fats ² 9 kcal energy
� But fat is less accessible for cellular metabolism.
� Why? It must first reduce from its complexform¾ triglycerides to its basic component: glycerol
& FFA
8/6/2019 5 Cell Metabolism
http://slidepdf.com/reader/full/5-cell-metabolism 5/21
Gluconeogenesis
AA/glycerol Glucose
Lipogenesis
Protein FA
� Protein supply 5 ² 10% of energy tosustain prolonged exercise
� Basic unit of protein - AA
8/6/2019 5 Cell Metabolism
http://slidepdf.com/reader/full/5-cell-metabolism 6/21
8/6/2019 5 Cell Metabolism
http://slidepdf.com/reader/full/5-cell-metabolism 7/21
8/6/2019 5 Cell Metabolism
http://slidepdf.com/reader/full/5-cell-metabolism 8/21
� ATP ² PCr system
� Glycolytic system
� Oxidative system
8/6/2019 5 Cell Metabolism
http://slidepdf.com/reader/full/5-cell-metabolism 9/21
� Release of energy is facilitated by
enzyme creatine kinase (CK), which acts
on PCr to separate Pi from creatine� The energy release used to couple Pi to
an ADP forming ATP.
PCr = Phosphocreatine / Creatine Phosphate
8/6/2019 5 Cell Metabolism
http://slidepdf.com/reader/full/5-cell-metabolism 10/21
8/6/2019 5 Cell Metabolism
http://slidepdf.com/reader/full/5-cell-metabolism 11/21
� Glycolysis produce pyruvic acid
� When conducted without O2, pyruvic
acid is converted to lactic acid.
� One mole of glucose yields 2 moles ofATP, but one mole of glycogen yields 3
mole of ATP.
8/6/2019 5 Cell Metabolism
http://slidepdf.com/reader/full/5-cell-metabolism 12/21
8/6/2019 5 Cell Metabolism
http://slidepdf.com/reader/full/5-cell-metabolism 13/21
� This energy system does not produce largeamounts of ATP.
� The ATP-PCr and Glycolytic systems aremajor contributors during the early minutesof high intensity exercise.
� Limitation:¾ causes accumulation of Lactic Acid.
¾
Acidification of muscle fiber inhibits further glycogen breakdown (impair glycolytic enzymefunction)
¾ Decrease the fiber calcium binding capacity(impede muscle contraction)
8/6/2019 5 Cell Metabolism
http://slidepdf.com/reader/full/5-cell-metabolism 14/21
� Involves breakdown of fuel with the aid ofO2.
� This system yield more energy
Oxidation of CarbohydrateOxidation of Carbohydrate� Involve 3 process:
¾ Glycolysis¾ Kreb cycle¾ Electron transport chain
8/6/2019 5 Cell Metabolism
http://slidepdf.com/reader/full/5-cell-metabolism 15/21
� Glycolysis
¾ In the presence of O2, the pyruvic acid is
converted to acetyl co enzyme (acetyl CoA)� Kreb cycle (citric acid cycle)
¾ Once form, acetyl CoA enters the KC
¾ End of cycle ² 2 mole of of ATP, carbon and
hydrogen¾ Remaining carbon then combine with O2 ² CO2
¾ The CO2 transported to the lung via blood to be
expired
8/6/2019 5 Cell Metabolism
http://slidepdf.com/reader/full/5-cell-metabolism 16/21
� Electron transport chain¾ During glycolysis, hydrogen is released
¾ More hydrogen is released during Kreb cycle.
¾ Hydrogen released by both cycle will combinewith two coenzyme
¾ NAD (nicotinamide adenine dinucleotide) andFAD (flavin adenine dinucleotide)
¾ NAD and FAD will carry the hydrogen atom to
the electron transport chain & split into protons &electron.
¾ End of chain ² H+ combine with O2 to form H2O(prevent acidification)
¾ End result ² H2O, CO2 and 38 or 39 ATP
8/6/2019 5 Cell Metabolism
http://slidepdf.com/reader/full/5-cell-metabolism 17/21
8/6/2019 5 Cell Metabolism
http://slidepdf.com/reader/full/5-cell-metabolism 18/21
� Only triglycerides are major energy source
� Triglycerides are stored in fat cell & skeletal muscle fiber.
� To be used as energy, a triglycerides must be broken down into 1glycerol + 3 FA
� This process is call lipolysis (enzyme ² lipase)
ßß OxidationOxidation,, KrebKreb Cycle & ETCCycle & ETC� Fat oxidation begins with ß oxidation of free fatty acids, then
follow the same path as carbohydrate oxidation.
� However the complete combustion of a FFA molecule requiresmore O2 because FFA carries more carbon than glucose ==
� (FFAFFA ² ² CC1616 HH3232 OO00; G C; G C66 HH1212 OO66)
� More carbon in FA - more acetyl CoA - more electron moreenergy
� However, only 40% energy release used to form ATP, 60%- heat
8/6/2019 5 Cell Metabolism
http://slidepdf.com/reader/full/5-cell-metabolism 19/21
8/6/2019 5 Cell Metabolism
http://slidepdf.com/reader/full/5-cell-metabolism 20/21
� Some amino acids (BCAA-leusine,isoleusine, valine) can be converted into
glucose(gluconeogenesis)� Our body utilized less protein (5-10% of
total energy expenditure) during restand exercise
� Chemically, protein contain the sameatoms as carbs & lipids ² carbon,hydrogen, oxygen. But protein alsocontain nitrogen.
8/6/2019 5 Cell Metabolism
http://slidepdf.com/reader/full/5-cell-metabolism 21/21