Energy Systems. PSK 4U Mr. S. Kelly North Grenville DHS

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1 Energy Systems PSK 4U Mr. S. Kelly North Grenville DHS

2 Review I hope Three key energy nutrients we get in our food: Carbohydrates: 4.1cal/g Protein: 4.3 cal/g Fats: 9.3 cal/g All three are used in various ways to build, re-synthesize, and expend energy.

3 Carbohydrates Derived from foods that originate as plants The usual form is glucose, which is stored in skeletal muscles as glycogen. Glycogen can be broken down and used as an energy source during muscular activity Metabolism refers to the process by which the body is supplied with energy through the assimilation of energy-rich materials.

4 ATP ADP + P + energy Adenosine triphosphate is the common energy molecule for all living things (Lipmann and Kalckar, 1941) Used to fuel cellular processes 3 phosphates attached by high-energy bonds to adenine, ribose (a building block that helps attach adenine and phosphates) Energy is released when the trailing phosphate is broken from the ATP.

6 Energy Systems? Why? ATP supplies are used very quickly because this form of energy is in high demand The body must then reconstruct its ATP supplies through the processes of two energy systems and three metabolic pathways: Anaerobic and Aerobic systems ATP-PC (anaerobic alactic), Glycolosis (anaerobic lactic), Cellular respiration (aerobic)

7 With or without O 2 The anaerobic system resynthesizes ATP quickly through the use of chemicals and enzymes This occurs without oxygen The aerobic system uses oxygen, enzymes, and sub-pathways in the mitochondria. Glucose is completely broken down, and fats and proteins are also used THESE TWO SYSTEMS OVERLAP AND INTERACT: THEY ARE NOT IN OPPOSITION!

8 Video Links Explanation of aerobic and anaerobic training there is a MAJOR error here see if you can spot it HERE Aerobic vs. anaerobic training (crossfit) and some benefits explained HERE

9 ATP-PC (Anaerobic-Alactic) Pathway The first and simplest of the two anaerobic energy pathways Provides ATP for a maximum of seconds of work Relies on phosphocreatine (PC) to convert ADP back to ATP (ATP resynthesis) Used in short, intense activities Produces the highest rate of ATP synthesis

ATP-PC (Anaerobic-Alactic) Pathway cont d PC is in short supply in muscles After 10-15s of activity, athlete must rely on a secondary system to resynthesize more

10 ATP-PC (Anaerobic-Alactic) Pathway cont d PC is in short supply in muscles After 10-15s of activity, athlete must rely on a secondary system to resynthesize more ATP Replenishing PC requires ATP itself and this happens during recovery (1-5 min) No lactic acid byproduct No metabolism of glucose P + C + energy ADP + P + energy ATP

11 The ATP-PC Pathway and Exercise What sports, exercises, and activities use this pathway? In ~30 seconds, make a list. How do you know if your list is accurate? Why is this a trick question? What happens when ATP supplies produced by this method are depleted?

12 Glycolysis (Anaerobic Lactic) Pathway Second energy pathway Produces enough ATP for an additional 1-3 minutes of high-intensity performance Involves 11 biochemical reactions and yields twice the ATP as the ATP-PC pathway See fig. 5.3 on pg. 84 of text C 6 H 12 O 6 + 2ADP + 2P i 2C 3 H 6 O 3 + 2ATP + 2H 2 O Glucose phosphates lactate water

13 Glycolysis (Anaerobic Lactic) Pathway cont d Pyruvic acid is the major byproduct of glycolysis and is the start of the aerobic phase Without O 2, (intense exercise, altitude), the process stops, PA converted to Lactic Acid LA causes muscle pain and exhaustion LA buildup inhibits glucose breakdown and decreases the ability of muscles to contract

14 Glycolysis (Anaerobic Lactic) Pathway cont d Activities relying heavily on this system often produce a burning sensation in the muscles during intense exercise Exercise recovery methods are recommended to counteract lactic acid min of exercise recovery (light aerobic activity + rest periods) or 1-2 hours of complete rest recovery are required

15 Exercise and lactic acid What is active recovery in terms of exercise? When should athletes use this? How does this apply to you and athletes you know?

17 The Aerobic System Cellular respiration in the mitochondria kicks in for activity longer than about 90s Energy source = fats and proteins Fats for activities longer than 20 min Proteins for chronic situations (starvation) Used in endurance-related events C 6 H 12 O 6 + 6O ADP + 36P 6CO ATP + 6H 2 O

) Can sustain activity essentially until physiological maximum is attained

18 The Aerobic System cont d Produces 36 molecules of ATP for every molecule of glucose (20x anaerobic syst.) Can sustain activity essentially until physiological maximum is attained There are three separate sub-pathways involved in cellular respiration: i) Glycolysis ii) Krebs Cycle iii) Electron Transport Chain

20 Glycolysis (revisited) Same as in the anaerobic lactic system except: In the presence of O 2, pyruvic acid converted to acetyl CoA (this is called beta oxidation) rather than LA Acetyl CoA enters Krebs (citric acid) Cycle to metabolize fats and proteins

21 Krebs Cycle A series of 8 reactions produces 2 ATP molecules and compounds for storing high energy electrons High energy electrons are sent to the electron transport chain within the mitochondria

The Electron Transport Chain Produces large amounts of ATP CO 2 and H 2 O are the only by-products There is controversy over the suggested production of free radicals

22 The Electron Transport Chain Produces large amounts of ATP CO 2 and H 2 O are the only by-products There is controversy over the suggested production of free radicals (highly reactive molecules) as the electrons pass down the chain It is suggested that these molecules contribute to long-term muscle fatigue (concept of overtraining )

2015 Thompson Educational Publishing, Inc. 3. What Are Nutrients?

2015 Thompson Educational Publishing, Inc. 3 What Are Nutrients? Nutrients are chemical substances obtained from food and used by the body for many different processes. They are the raw materials our bodies