The aim of this unit is to explore the structure and function of the skeletal, muscular, cardiovascular and respiratory systems and also to learn the fundamentals of the energy systems.
Energy Systems
The human body uses food for energy to fuel movement and also provide
nutrients for growth and repair, but the body cells cannot get energy straight
from the food. After food is eaten it is broken down into
soluble chemicals by digestion in the gut, for example
glucose. They then pass through the gut wall and absorbed
into the blood. The blood then transports the soluble food
chemicals to various cells throughout the body where they
will be used for energy, growth and repair. Adenosine
triphosphate is formed within these cells to provide fuel. The body uses 3
different systems to supply cells with the ATP they require to fuel energy
needs. Most of the body’s activities use a range of all three energy systems.
(Gomez, 2018)
ATP
ATP, adenosine triphosphate, is one of the most vital energy sources in the
body. It is found in every cell and is formed by two major processes: glycolysis
and Krebs cycle. ATP is the energy currency of life.
When ATP is broken down it gives energy for muscle contractions. It is the only
molecule that is able to supply energy used in muscle contractions and it can
be made in three different ways: the creatine phosphate energy system, the
lactic acid energy system and the aerobic energy system. (Adams, 2010)
ATP is bound to three phosphates
groups. There is a lot of energy
stored in the bond between the
second and third phosphate. This is
able to be used to fuel chemical
reactions. When a cell needs
energy, it the last phosphate group
splits away from the ATP molecule breaking the bond to form adenosine
diphosphate and a free phosphate molecule. These by-products along with the
energy gained from food form the building blocks for the production of new
, ATP. The second phosphate group can also be broken to form adenosine
monophosphate. When the cell has excess energy, it stores this energy by
forming ATP from ADP and phosphate. ATP is required for the biochemical
reactions involved in any muscle contraction. As the work of the muscle
increases more ATP gets used up and must be replaced so the muscle can keep
moving. (Bodybuilding.com, 2018)
There is only a small amount of ATP stored within the muscle cells about 85kg.
The body has enough to fuel only a few seconds of exercise. Because of this
the body must constantly make new ATP in order to constantly fuel
movement. The process of adding a phosphate group back to ADP is called
phosphorylation. If this occurs in the presence of oxygen it is called aerobic
metabolism. If it occurs without oxygen it is called anaerobic metabolism.
(Anon, 2018)
ATP needs to be regenerated by other chemical reactions if exercise is to
continue past 2 seconds. ATP is resynthesized from ADP within the following
reaction:
Energy + ADP + P1 = ATP
This is an endothermic reaction; this means energy is given to the molecule to
enable the reaction to happen. It is the energy we get from food that provides
this.
ATP/PC System
The ATP/PC system is made up of adenosine triphosphate (ATP) and
phosphocreatine (PC).
Phosphocreatine is a high energy compound found in the muscle sarcoplasm.
This energy system provides immediate energy through the breakdown of
these high energy phosphates. It is used for explosive actions that have a short
duration but a high intensity. If this energy system is 'fully stocked' it will
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