Transcript Document

Exercise.. Don’t Sweat It!
The Engine and Fuel
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During exercise, when skeletal muscles
contract, they may generate up to 50
pounds of pull.
If the muscles of the body are to be
active, they need fuel.
The fuel is supplied by ATP.
The body must continually replenish
the ATP to sustain the activity.
In order to refuel, cells need:
– Energy carrying molecules
– Oxygen
– A way to eliminate wastes
– A way to rid themselves of the heat
energy which accumulates
EVERY body system is used during
exercise
ATP
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ATP is composed of an adenine
nucleotide which is bound to three
phosphates.
Much of the energy is stored
between the second and third
phosphate groups.
As the body exercises, ATP is
converted to ADP.
The body must then convert the
ADP back to ATP for more energy
or fuel.
Since ATP is so crucial in exercise,
the body produces it in several
ways within the muscle cell.
ATP is derived from the
phosphagen system, the glycogenlactic acid system (glycolysisfermentation), as well as through
aerobic respiration.
The Phosphagen
System
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As the body begins to exercise, all of the
free ATP will be used up by the muscle cell
in the first few seconds.
After this, the muscle cell utilizes creatine
phosphate which is a high energy
phosphate molecule.
Creatine kinase catalyzes the removal of
phosphate from the creatine molecule and
then the phosphate is moved to an ADP to
form ATP.
The cell then uses the energy in the ATP
and it is converted back to ADP.
This ADP is then rapidly converted back to
ATP for more energy
The phosphagen system can only supply
energy needs for 8-10 seconds of exercise
as the creatine phosphate levels diminish.
Dietary Creatine
• Many people today
take dietary creatine.
• This is suspected to
increase the duration
of the effectiveness of
the phosphagen
system
Anaerobic Respiration
Pyruvic Acid + NADH => Lactic
Acid + NAD+
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After the first 10-15 seconds, muscles must tap into the energy held in the stored glucose
molecule to make ATP.
The contracting muscle taking part in the exercise constricts blood flow, and thus the flow of
oxygen to the muscle cells.
Thus, the cells breakdown the glucose to make ATP in the absence of oxygen.
Since there is no oxygen involved, this is called anaerobic metabolism.
This system acts very quickly and can provide enough ATP to last 90 seconds.
One product of this reaction is the build up of lactic acid. This causes fatigue and pain in the
muscle.
However, the lactic acid is changed to pyruvic acid in the liver.
This system keeps the muscles fueled initially as it takes some time for the heart and lungs to
react and increase blood flow and oxygen consumption.
Anaerobic Respiration--Fermentation
Aerobic Respiration at the 2 Minute Mark
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By 2 minutes, the body begins to respond
and is sending additional oxygen to the
muscle cells that are exercised.
In the presence of oxygen, aerobic
respiration can occur.
Aerobic respiration makes more ATP than
any other method through the electron
transport chain.
The glucose may come from the glycogen
supplies in the muscles, the breakdown of
glycogen into glucose in the liver, or the
absorption of glucose from food in the
small intestines
Aerobic respiration can also break down
fats and proteins to make ATP.
This supply of ATP can last for hours.
The Responding Systems
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Blood flow can be increased by
expanding the vessels.
As the byproducts of respiration
leave the muscle cells, they
stimulate the vessels to expand or
dilate.
Blood that would be going to the
stomach or kidneys will be diverted
to the dilated vessels in the area of
the muscles being exercised.
When exercising, the autonomic
nervous system stimulates the
nerves which enervate the heart.
This causes a constriction of the
vessels to the tissues not involved
in the activity and a lessening of
the blood flow to them.
Heart Rate During Exercise
•An increased heart rate also
contributes to the increased
flow of oxygen carried in the
blood to the exercised
muscles
•During activity the
autonomic nervous system
stimulates the heart to beat
faster and more forcefully
increasing the blood flow
•The blood flow of the heart
increases by about 4 or 5
times faster than it does at its
normal resting state.
The Phosphagen System, Glycolysis-Lactic Acid System, and
Aerobic Respiration all play a vital role in the production of ATP.
While the the contribution of Aerobic Respiration is the greatest,
the Glycolysis-Lactic Acid System and the Phosphagen system
are initially essential.
Contributing systems…
Heat
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BEING IN SHAPE
IS VITAL
Only 40% of the energy liberated from
glucose is used to make ATP.
The other 60% is released as heat
energy.
Sweating is an adaptation to release
heat energy.
Since water has a high heat of
vaporization, much heat energy is lost
in the process of evaporating the sweat.
Also, heat energy is transported away
from the muscles being exercised by the
dilation of the vessels.
This increases blood flow to the surface
causes skin to be hot and reddened,
enabling heat transfer to the
surrounding air.
If someone is exercising in a hot
environment,and the heat transfer can
not be made to the surrounding air, a
person may suffer a heat stroke.
This is when sweating stops, heart rate
increases, respiration increases, and the
victim becomes confused, nauseous,
and dizzy.
For exercise to occur, ATP must be produced by the body. It acts as the
fuel for exercise, just like gas acts as a fuel for a car. To produce this ATP,
the body relies on many systems and interactions.