Manual
Level 2 Certificate
in Gym Instructing
Version AIQ005803
The skeletal system
Section 1
Section 1: The skeletal system
Without the skeleton, we would be a heap of tissues all over the floor. It makes up almost one fifth of body weight to
give us a flexible framework with which to move, protect and support internal and external systems.
Structure of the skeleton
The skeletal system can be classified as two main structures:
Bone
Calcified connective tissue that forms most of the adult
skeleton. There are around 206 bones in the body and they
are connected via a series of different types of joint.
Cartilage Bone
Dense, durable, tough fibrous connective tissue that is able
to withstand compression forces. There are three types of
cartilage found in the body, each fulfilling a separate function.
Types of cartilage
The three types of cartilage found in the human body are:
• Hyaline cartilage: This is the tissue that forms the temporary skeleton of the foetus, which is eventually
replaced by bone when calcium is deposited. It is found at the end of the long bones that meet to form the
synovial joints.
• Elastic cartilage: This is similar to hyaline cartilage, except that it has more fibres and most of these are
made up of elastin as opposed to collagen. Elastic cartilage has the ability to regain and return to its original
shape. It is found in the ear, the walls of the Eustachian tube and the epiglottis, which are all places that
require a specific shape to be maintained.
• Fibrocartilage: This cartilage is thicker and stronger than the other types and has limited distribution within
the body. It forms various shapes depending on its role and acts like a shock absorber in cartilaginous joints.
The skeleton
The skeleton is split into two main sections:
cranium
cranium
Principles of anatomy, physiology and fitness
Axial skeleton
Bones that form the
main frame or axis:
The spine, ribs and
skull.
Appendicular skeleton
Bones that attach
to the main frame
(the appendages):
The upper and lower
limbs, the pelvic and
shoulder girdles.
clavicle
sternum
humerus
rib
lumbar vertebrae
ulna
radius
pubis
carpals
metacarpals
ischium
femur
patella
tibia
tarsals
metatarsals
phalanges
cervical
vertebrae
scapula
humerus
thoracic
vertebrae
ilium
sacrum
coccyx
phalanges
femur
fibula
tibia
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The neuromuscular system
Section 2
Section 2: The neuromuscular
system
All of the internal and external muscles in the body and the nerves serving them make up the neuromuscular
system. Every movement your body makes requires communication between the brain and muscles, some of which
you don’t even have to think about, such as your digestive muscles breaking down ingested food.
The muscular system
There are over 600 muscles in the body, making up around 40% of a person’s total weight.
The bones and joints create the framework of levers (bones) and pivots (joints) which give the body the potential to
move, but this framework cannot move on its own. It is the contraction and relaxation of muscles that bring about
movement.
The muscular system produces a continuous and wide-ranging number of actions, such as bodily movements
(e.g. walking and jumping) and the powering of internal processes (e.g. contraction of the heart muscle and focussing
of the eye).
KEY
POINT
Types of muscle tissue
There are three types of muscle tissue and each one has a different
function. The three types are:
• Cardiac muscle (myocardium), e.g. the heart.
• Smooth muscle, e.g. the walls of the small intestine.
• Skeletal muscle (striated), e.g. the hamstrings or triceps.
Contraction of the heart
is controlled by the
sinoatrial node (SAN).
The set rhythm of the
heart (on average,
72bpm at rest) is called
autorhythmicity.
Principles of anatomy, physiology and fitness
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The neuromuscular system
Section 2
To summarise:
• Whole muscle is wrapped in epimysium.
• Bundles of fibres, or fasciculi, are wrapped in perimysium.
• Single muscle fibres are wrapped in endomysium.
• Myofibrils are located inside single fibres.
• Myofilaments – myosin and actin ‒ are located inside sarcomeres.
Sliding filament theory
The sliding filament theory was proposed by
Huxley in 1954 to explain the contraction of
skeletal muscle. The theory states that the
myofilaments, actin (a thin protein strand)
and myosin (a thick protein strand) slide
over each other, creating a shortening of
the sarcomere (the contractile units in the
muscle where myosin and actin are found),
which causes the shortening or lengthening
of the entire muscle. The myofilaments do
not decrease in length themselves.
This proposed action is accomplished by
the unique structure of the protein, myosin.
The myosin filaments are shaped like golf
clubs and form cross bridges with the actin
filaments. Each myosin molecule (there
are many) has two projecting heads. These
heads attach to the actin filaments and
pull them in closer.
Actin filament
Myosin filament
Muscle fibre
Myofibril
Principles of anatomy, physiology and fitness
Stimulus from the nervous system and the
release of adenosine triphosphate (ATP)
– the high-energy molecule stored on the
myosin head – provide the impetus for the
head to ‘nod’ in what is termed the ‘power
stroke’. It is this nodding action which
‘slides’ the thin actin filaments over the
thick myosin filaments. The myosin head
then binds with another ATP molecule,
causing it to detach from the actin-binding
site, which is known as the ‘recovery
stroke’. It is then able to attach to the next
binding site and perform the same routine.
SARCOMERE IS RELAXED
SARCOMERE IS CONTRACTED
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Section 3
Cardiovascular and respiratory systems
Heart valves
There are a number of different valves around the heart, which all perform slightly different tasks.
The atrioventricular (AV) valves separate the atria and ventricles and prevent the flow of blood back into the atria
during ventricular contraction.
The semilunar valves prevent the flow of blood back into the right (pulmonary valve) and left ventricles (aortic valve)
during ventricular relaxation.
Heart rate
The heart is stimulated to contract by a complex series of integrated systems. The heart’s pacemaker – the sinoatrial
node (SAN) – initiates cardiac muscle contraction. The SAN is located in the wall of the right atrium. The myocardium
(heart muscle) is stimulated to contract about 72 times per minute by the SAN as part of the autonomic nervous
system.
28
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Cardiovascular and respiratory systems
Section 3
Nose and mouth
Nose
Larynx
Trachea
Pharynx (throat) and
larynx (voice box)
Lungs
Trachea
Bronchi
Bronchioles
Diaphragm
Bronchi / bronchus
The mechanics of breathing
The two main mechanisms that trigger the human body to breathe are:
• Rising levels of carbon dioxide in the blood.
• Stretch receptors in the respiratory muscles (intercostal muscles) becoming stretched.
The main muscles involved in the action of breathing are the diaphragm and the internal and external intercostal
muscles.
The main phases of the breathing cycle are:
• Inspiration/inhalation – drawing air
into the lungs.
• Expiration/exhalation – expelling air
from the lungs.
Right lung
Trachea
Bronchioles
Alveoli
Left lung
Principles of anatomy, physiology and fitness
There is also a short pause before both
inspiration and expiration.
During inspiration, the diaphragm muscle
contracts, causing the normal ‘dome shape’
to flatten. The external intercostal muscles
also contract, raising the ribcage. These
actions increase the chest cavity volume.
This increase in volume creates a negative
pressure between the air in the lungs and
air in the atmosphere. This is very much
like a vacuum effect in which the negative
pressure sucks air into the lungs until the
two pressures are balanced.
Right
bronchus
Left
bronchus
Bronchiole
Terminal
bronchiole
Alveoli
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The digestive system
Section 5
Section 5: The digestive
system
The digestive system is responsible for the intake, breakdown, use and removal of food and drink. An efficient
digestive system tells us when we are hungry, full and thirsty by sending messages to and from the brain via the
nervous system. It extracts important nutrients for storage and immediate use and removes any waste.
The digestive system has four stages:
Ingestion
Digestion
Absorption
Elimination
Food entering
the body
through
the mouth
and being
chewed.
Breaking
down of
food through
mechanical
(smooth
muscle
action) and
chemical
(release of
enzymes)
processes.
The passing
of food
into the
bloodstream
to be used
by the body’s
tissues.
The removal
of waste.
Journey through the alimentary canal (also known as
the digestive tract/gastrointestinal tract/gut)
Food’s journey through the alimentary canal can take up to 24 hours and covers a distance of around 9m (30 feet)
from ingestion through the mouth to excretion through the anus.
Mouth
This is the entry point of food and where it begins to be broken down
through the process of mastication (chewing) into a ball, or bolus.
Principles of anatomy, physiology and fitness
Oesophagus (gullet)
This is a thick-walled, muscular tube that carries broken down food
from the mouth to the stomach.
Stomach
The stomach is a muscular bag located on the left side of the upper
abdomen. It breaks down food further by releasing enzymes, and also
kills bacteria.
Small intestine
The small intestine is a small, tightly folded tube that receives
food from the stomach. It is the major site of digestion within the
alimentary canal. Its role is to absorb important nutrients into the
bloodstream to be passed to the body’s tissues and used for energy.
The small intestine is divided into three sections: the duodenum,
jejunum and ileum.
The small intestine is about as large
as an adult’s middle finger but, when
stretched out, it is about 22 feet
(6.7m) long.
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The importance of a healthy lifestyle
Section 3
Section 3: The importance of a
healthy lifestyle
Current prevalence of obesity in the UK
27% of adults in England are obese and a further 36% are overweight. A summary of the most recent findings can
be found below:
Obesity is normally
defined as having a
BMI of 30+
18.5
25
30
Underweight
Normal Weight
Overweight
Obese
Men are more likely to be
overweight, but obesity
rates are the same for
both genders
Obese
Overweight
Female
Male
Female
Male
9% of children in
England are obese by
the age of 4-5
9%
27% of adults in England
are obese. A further 36%
are overweight
27%
Those aged 55-64 are
most likely to be obese;
16-24s are least likely
Least
deprived
Most
deprived
16%
36%
16-24 55-64
10-11 year olds in the
most deprived areas
are much more likely
to be obese
15%
26%
Rates of excess weight
are highest in the North
East and lowest in
London
NE
Yorks
E Mids
W Mids
NW
East
SW
SE
London
69%
59%
Obesity rates have
grown slightly in the
last decade
52.9%
61.8%
62.9%
1993 2004 2015
In England, rates
of obesity drug
prescriptions are highest
in Stoke North
Stoke-on-Trent N
Leigh
Camborne & Rrth
Knowsley
Barnsley E
22 per 1,000
Conducting client consultations to support positive behaviour change
Prescribing rates for
obesity drugs have
fallen in all UK countries
since 2008
The number of bariatric
surgeries on obese
patients fell in the last
three years
UK obesity rates are
below those of USA and
Australia but above those
of France & Germany
ENG
SCO
WAL
NI
2008
2014
1,951
2006/07
8,794
6,032
2014/15
USA
AUS
UK
GER
FRA
JAP 3.9
38.2
27.9
25.6
23.6
16.9
House of Commons briefing paper – Obesity statistics, 2017
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