Transcript Energy Systems

MACRONUTRIENTS
•These are out direct sources of energy for daily life, physical exercise and work
• consumed in large amounts
• There are 3 types:
1. Protein
2. Carbohydrate
3. Fat
PROTEIN
• directly involved in fundamental chemical processes of life
• when ingested:
-broken down into 20 amino acids
PROTEIN
• directly involved in fundamental chemical processes of life
• when ingested:
-broken down into 20 amino acids
- 9 essential amino acids  attained through food (body
produces 11 others)
• Complete protein – food that contains all 9
amino acids
- meat, eggs, cheese and milk
• Incomplete protein –foods containing one but
not all essential amino acids
- vegetables and fruits
• each gram of protein contains 4 Calories of energy
• for every kilogram of body weight, an adult needs 0.8
grams of protein
• necessary for growth and repair of all tissues, and a
critical component of hormones, enzymes and the immune
system
FAT
• insulate and protect vital organs
• highest energy yield = 9 calories of energy per gram
Saturated
-animal sources
-LDL (low-density lipoproteins)
-high levels LDL
artery walls
increased cholesterol
heart disease
Unsaturated
-plant sources
- high concentrations of high-density lipoproteins (HDL)
- flushed out of body
plaque on
CARBOHYDRATE
• most accessible energy source for the body  is the most abundant organic
substance in nature
• GLUCOSE -produced by photosynthesis, stored as GLYCOGEN in human
• each gram yields 4 Calories of energy
If not utilized,
becomes fat
• Complex (starch)
-takes body longer to absorb
-80 % of total carb intake
-cereals, fruits, vegetables, legumes and
pasta
• Simple (sugars)
-absorb MUCH faster
- refined white sugar, pop, candy, etc
. . .but why is it important that we ingest carbohydrates?
ATP (Adenosine Triphosphate)
- 3 phosphates attached to adenosine
Fritz Albert Lipmann and Herman Kalckar, 1941
ATP  ADP + P +ENERGY
The question we will be answering is not how the body uses
ATP, but rather how the body goes about resynthesizing ATP.
2 methods for resynthesizing ATP
1. Anaerobic System
-without oxygen
-muscle fibre
-quick; powerful short activities
2. Aerobic System
-with oxygen
-mitochondria
-several complex reactions
-endurance activities
-These systems work together
-coexist and overlap
-all physical activity relies on
some combination of these
systems
What we are going to examine are the three metabolic pathways
that make up these two systems.
• ATP-PC pathway
•Glycolysis
• Cellular Respiration
METABOLISM
ATP-PC System
Anaerobic alactic
Without O2
No lactic acid
-first and simplest of the 2 anaerobic pathways
-Short, powerful energy bursts  10-15 seconds
PC + ADP  ATP + Creatine
Phosphocreatine
-high energy molecule
-phosphate used to convert ADP to ATP
-small stores
-highest rate of ATP synthesis
-sprinting, high jump, powerlifting
-the replenishment of PC for this system needs ATP
-once levels of PC are depleted, a new system must take over for the
body to continue and also for the body to replenish its PC levels
Takes 2-5 minutes
Glycolysis
Anaerobic lactic
Produces lactic acid
-partial breakdown of glucose in cytoplasm
-plentiful in the human body
-holds useable energy (ATP)
Although ATP production is rapid, glycolysis is a much more complex process
-11 separate biochemical reactions
-yields twice as much ATP as the ATP-PC system
-lasts 1-3 minutes
C6H12O6 + 2ADP + 2Pi  2C3H6O3 + 2ATP + 2H2O
Glucose
Lactate
-if O2 present, pyruvate (pyruvic acid)
-if insufficient O2, pyruvate lactic acid
- hi Lacid  low Glucose breakdown
-decrease muscle contraction
-burning sensation
-basically glycolysis transfers energy from glucose to rejoin phosphate to
ADP
Total ATP count = 2
When sufficient O2 is present, the pyruvate left over from Glycolysis will move into a
new, even more complex pathway. . .
Cellular Respiration
Aerobic
-complete breakdown of glucose in the mitochondria of cells
-kicks roughly 90 sec into activity and lasts for endurance activities
-fats and proteins also used as energy sources in this pathway
As a last resort
Exercise longer than 20 minutes
-involves 3 separate pathways:
• Glycolysis
-same as before, but pyruvate  Acetyl CoA
• Kreb’s Cycle
(citric acid cycle)
(2 ATP)
-Acetyl CoA enters the more complicated pathway
-series of 8 reactions; also site of fat and protein
metabolism
The Kreb’s Cycle
When sufficient O2 is present, the pyruvate left over from Glycolysis will move into a
new, even more complex pathway. . .
Cellular Respiration
Aerobic
-complete breakdown of glucose in the mitochondria of cells
-kicks roughly 90 sec into activity and lasts for endurance activities
-fats and proteins also used as energy sources in this pathway
As a last resort
Exercise longer than 20 minutes
-involves 3 separate pathways:
• Glycolysis
-same as before, but pyruvate  Acetyl CoA
• Kreb’s Cycle
(citric acid cycle)
(2 ATP)
-Acetyl CoA enters the more complicated pathway
-series of 8 reactions; also sight of fat and protein
metabolism
-2 ATP produced along with 6NADH and 2FADH
The third and most “profitable” sub-pathway is the final stage of cellular respiration
• Electron Transport Chain
-occuring in the mitochondria, the ETC takes high energy electrons,
found within FADH and NADH molecules, through a chainlike
process
-this process creates VAST amounts of ATP with only
CO2 and water as by products
-video
The electron transport chain contributes a whopping 32 ATP to the cellular
respiration process
C6H12O6 + 6O2 + 36ADP + 36Pi  6 CO2 + 36ATP + 6H2O
• Glycolysis =
2 ATP/glucose
• Kreb’s Cycle = 2 ATP/glucose
• ETC =
32 ATP/glucose
36 ATP/glucose
Interplay of Energy Systems
-video
Copy 5.1: Three Energy pathways compared (p.86) into your notes
Lactic Acid
-we know that lactic acid is a painful by product of glycolysis when insufficient
oxygen is present
-one of the main causes of stopping activity
Anaerobic threshold
(Blood lactate threshold)
Point at which a large increase in blood lactate
occurs (compared to resting levels)
Onset of blood lactate
accumulation (OBLA)
Rapid accumulation of blood lactate; always
occurs after the lactate threshold
• The longer it takes a person to reach their threshold, the more “endurance” they have
•Elite endurance athletes will have a high lactate threshold
•Untrained individuals will have a low lactate threshold
Therefore, the lower your LT, the less efficient your energy systems
are working, or the poorer your energy systems are
The Cori Cycle
We can’t just think of lactic acid as a bad thing
Remember that blood lactate levels don’t ALWAYS increase
Therefore the body MUST have a way of ridding itself of
lactic acid
• takes lactic acid (lactate) and
converts it to pyruvate in the liver
• the pyruvate is then converted to
glucose/glycogen and re-enters the
energy pathways, allowing further
production of ATP
Better endurance athletes will
have a greater ability to
convert their lactic acid
So what is the difference between these two athletes?
What allows one athlete to excel at running for 5 hours and another to
excel at running for 10 seconds?
Muscle Fibre Types
In general there are 2 types:
• Slow-twitch muscle fibres: -dark in in colour
-low levels of ATPase (instant energy)
and glycolytic enzymes (promote
glycogen release)
-high levels of oxidative enzymes
(Oxygen storage)
-lower tension/contraction over longer
periods of time
-most active during endurance activities
• Fast-twitch muscle fibres: -paler colour
-high levels ATPase and glycolytic enzymes
-large amounts of tension with relatively low
endurance levels
-activate 2X’s faster than slow twitch fibres
-most active for fast, powerful activities
There are two main muscle fibres, but researchers are starting to lean towards
three different types:
• Type I –Slow Oxidative (SO)
•Type IIa –Fast Oxidative Glycolytic (FOG)
•Type IIb –Fast Glycolytic (FG)
Strong research evidence, that with consistent aerobic
training, the body can convert type IIb fibres into type Iia
-that is, fast twitch muscles fibres can become an
intermediary fibre that acts as both fast twitch and
slow twitch
-no evidence for Type II  Type I
Tonic versus Phasic muscles
The function of a muscle is a pretty good indicator of its fibre make up.
-muscles that create power and speed
-mainly type II  fast twitch fibres
-biceps brachii
-muscles that maintain posture and stability
-mainly type I  slow twitch fibres
-little explosiveness, considerable endurance
-soleus
Read page 91, “Kenya’s Famous Long-Distance Runners –The greatest
concentration of achievement in the annals of sport.”
From the reading, find and write down the FIVE most important points, that could
help you write a research paper on the topic of ENERGY SYSTEMS.