Download Anatomy Info Pack. - Keswick School PE Department.

BTEC National Diploma in
Public Services
Unit 5
Physical Preparation, Health and
Lifestyle for the Public Services
Learner Resource Pack
Introduction
The human body is a very complex piece of machinery. It is made up of
many different systems that work together to allow us to take part in a wide
range of sports and everyday activities.
It is important that anyone working with clients in the sport and exercise
industry has a good understanding of how each of these systems works and
copes with the stresses of exercise.
This unit will explore the structure and the functions of the skeletal, muscular,
cardiovascular and respiratory systems and how each of them is affected by
exercise. It will also focus on the energy systems and their role in sport and
exercise performance.
Section One - The Structure and Function of
The Skeletal System and How it Responds to
Exercise
Part 1.1: The structure of the skeleton system
The skeleton provides us with a complex framework of bones, joints and
cartilage without which we could not stand upright or move. It consists of
206 bones which can be divided into the axial and appendicular skeleton.
The axial and appendicular skeleton
The axial skeleton provides the supportive structure of the skeleton and is
made up of the skull, vertebral column, sternum and ribs. The appendicular
skeleton is made up of the upper limbs, shoulder girdle, lower limbs and hip
girdle and provides the framework for movement.
The table below outlines the axial and appendicular skeleton in further detail.
Axial
skeleton
Skull (cranium)
The skull is made up of approximately 28 bones which are
fused
Vertebral column
The vertebral column is made up of 33 bones called
vertebrae
Sternum
The sternum commonly known as the breast bone is a flat
bone which is at the front of the rib cage
Ribs
There are 12 pairs of ribs which join onto the vertebral
column. 3 pairs are attached and the last 2 pairs are
unattached; these are called floating ribs
Appendicular Shoulder girdle (scapula and clavicle)
skeleton
The shoulder girdle consists of two scapula (shoulder blades)
and 2 clavicles (collar bones)
Upper limbs (humerus, radius and ulna)
The arms are made up of the humerus (upper arm bone)
and the radius and ulna (lower arm bones). There are also 8
carpal bones in the wrist, 5 metacarpal bones in the hand
and 14 phalanges (finger bones)
Lower limbs (femur, tibia, fibula and patella)
The legs are made up of the femur (thigh bone), patella
(knee cap), tibia (shin bone) and fibula. There are also 7
tarsals in the foot, 5 metatarsals also in the foot as well as
14 phalanges (toes)
Hip/pelvic girdle (ilium, ischium and pubis)
The hip girdle is made up of 2 halves that are fused
together. The bones that make up each side are the ilium,
ischium and pubis
Anterior view of the skeleton
© Loughborough College
Posterior view of the skeleton
© Loughborough College
The vertebral column (spine)
The vertebral column makes up two fifths of the total height of the body and
is made up of 33 bones called vertebrae. It can be divided into five different
sections:
Different sections of the vertebral column
Section
Cervical
Thoracic
Lumbar
Sacrum
Coccyx
Number of vertebrae
in each section
7 vertebrae
12 vertebrae
5 vertebrae
5 fused vertebrae
4 fused vertebrae
The vertebral column
© Loughborough College
The vertebrae interlock to form a strong hollow column through which the
spinal cord travels. Between each vertebra are discs of fibrous cartilage
called intervertebral discs which allow for movement and absorb shock.
The functions of the vertebral column






It
It
It
It
It
It
encloses and protects the spinal cord
supports the head
serves as a point of attachment for the ribs and muscles of the back
supports the body
allows movement to occur
provides shock absorption
Function of the skeleton
The skeleton is made up of 206 bones of different shapes and sizes and has a
variety of different functions. Outlined below are a number of these
functions.
Support
The skeleton provides shape and support for the organs and tissues of the
body. Without this support they would collapse under their own weight.
Protection
The skeleton provides protection for internal organs. For example the
cranium protects the brain, the sternum together with the ribs form a cage to
protect the heart and lungs and the pelvic girdle protects the reproductive
system and lower abdominal cavity.
Movement
The skeleton provides a large surface area for muscle attachment and so
allows movement with the bones acting as levers.
Red and white blood cell production
Both red and white blood cells are produced in the bone marrow cavities of
larger bones.
Storage of fats and minerals
The skeleton serves as a storage area for minerals such as calcium and fats
required for body functions.
Part 1.2: Joints
A joint is a site in the body where two or more bones come together.
Generally the closer the bones fit together, the stronger the joint. Tightly
fitted joints restrict movement; loosely fitted joints have greater movement
but are often prone to dislocation.
Joints can be classified in two ways according to their function and their
structure.
Functional classification is based upon the amount of movement available and
structural classification is based on the presence / absence of a synovial
cavity (a space between the articulating bones) and the kind of tissue that
bonds the bones together.
Fixed or fibrous joints
A fibrous joint has no movement at all. There is no joint cavity and the bones
are held together by tough fibrous tissue. Examples are sutures in the skull.
Slightly moveable or cartilaginous joints
A cartilaginous joint allows some slight movement. The ends of bones, which
are covered in articular or hyaline cartilage are separated by pads of
fibrocartilage. In addition the pads of cartilage act as shock absorbers.
Examples include the vertebrae.
Freely moveable or synovial joints
A synovial joint is a freely movable joint and is characterised by the presence
of a synovial cavity. The synovial joint is the most commonly occurring type
of joint in the body. The bony surfaces, covered by articular cartilage, are
separated by a joint cavity and enclosed by a fibrous capsule lined by a
synovial membrane. Examples include the knee, hip and ankle joint.
Structures common to synovial joints
The table below outlines a number of structures that are common to all
synovial joints.
Structure
Hyaline cartilage
Joint / articular
capsule
Ligaments
Synovial
membrane
Synovial fluid
Pads of fat
Function
Hyaline / articular cartilage covers the ends of the
articulating bone. It smoothes and facilitates gliding
movements between the bone ends
This is a fibrous tissue encasing the joint, forming a
capsule
Ligaments are white fibrous connective tissue, joining
bone to bone. They restrict the amount of movement
that can occur at the joint
The synovial membrane acts as a lining to the joint
capsule and secretes synovial fluid
Synovial fluid fills the joint capsule; it nourishes and
lubricates the articular cartilage
Pads of fat act as buffers to protect the bones from wear
and tear
A typical synovial joint
© Loughborough College
Different types of synovial joints and their movement range
There are six different types of synovial joints, which have varying ranges of
movement.
1)
2)
3)
4)
5)
6)
Hinge
Ball and socket
Pivot
Gliding
Saddle
Condyloid
Type of synovial joint Range of movement and examples
Hinge joint
The hinge joint allows movement in only one
direction due to the shape of the bones and the
strong ligaments which prevent side to side
movement. Examples of hinge joints are the knee,
elbow and ankle.
Ball and socket joint
A ball like head fits into a cup shaped socket. This
joint allows a wide range of movement. The hip
and shoulder are examples.
Pivot joint
The pivot joint allows only rotation. An example is
the joint which allows us to turn our heads from
side to side (between the atlas and axis vertebrae),
and the joint, which allows us to turn our hand
over and back (radioulna joint below the elbow).
Gliding joint
The gliding joint occurs where two bones with flat
surfaces slide on each other, but are restricted to
limited movement by the ligaments. Such joints
are found between the small bones of the hand
(carpals).
Saddle joint
Convex and concave surfaces are placed against
each other. This allows movement in two
directions. An example is the carpometacarpal
joint at the base of the thumb.
Condyloid joint
The condyloid joint is basically a hinge joint which
allows some sideways movement. The dome
shaped surface of one bone fits into the hollow
formed by one or more other bones forming the
joint. The joint between the radius and carpal
bones in the wrist is an example.
© Loughborough College
Types of movement
The body is jointed in such a way so as to allow movement to occur. The
range of movement allowed at each joint can be described specifically using a
range of technical terms outlined below.
Movement
Definition
Flexion
Pronation
Reducing the angle at a joint or bending a limb. For example
bending the arm at the elbow.
Increasing the angle at a joint or straightening a limb. For
example straightening the arm at the elbow.
The sideways movement of a limb away from the mid line of
the body. For example raising the arm out to the side.
Bringing a limb towards or across the mid line of the body.
For example lowering the arm on a lateral raise.
When the end of the bone moves in a circle. For example
the serve action of a tennis player.
A turning movement, when a limb rotates about its own axis.
For example turning your head to the side.
When the palm of the hand faces downwards.
Supernation
When the palm of the hand faces upwards.
Plantar flexion
Extending the foot downwards or pointing the toes.
Dorsi flexion
Pulling the toes upwards toward the shin.
Inversion
At the ankle when the sole of the foot is turned inwards.
Eversion
At the ankle when the sole of the foot is turned outwards.
Hyperextension
When joints are extended excessively in the opposite
direction to flexing the joint. This is evident in some
gymnastic and diving routines. For example, lifting the chest
off the floor when lying on front.
Extension
Abduction
Adduction
Circumduction
Rotation
Ankle
Knee
Hip
Spine
Elbow
Wrist
Joint/ Movement
Shoulder
Range of movement at each joint
The following table summarises which movements are possible at each of the
major joints of the body.
Flexion






Extension






Abduction



Adduction



Circumduction

Rotation

Pronation

Supination



Plantar flexion

Dorsi flexion

Inversion

Eversion

NB. Pronation and supination actually occurs at the radioulna joint just below
the elbow.
Part 1.3: Responses to exercise
Short term effects of exercise on bones and joints
When exercise is undertaken it causes the joints to stimulate the secretion of
synovial fluid. As exercise continues the fluid will become less viscous (thick)
and thus the range of movement around the joint will increase.
Long term effects of exercise on bones and joints
If an extensive period of training is undertaken the following long term effects
will occur on the skeletal system.

Exercise stimulates an increase in the amount of calcium salts deposited
in the bones making them stronger. This in turn reduces the risk of
osteoporosis (bone wasting disease)

Exercise improves tendon thickness and ligament strength which in turn
helps the joints to become more stable

The hyaline cartilage becomes thicker which provides more protection
and there is an overall increase in the production of synovial fluid
Section Two - The Structure and Function of
The Muscular System and How it Responds to
Exercise
Part 2.1: The muscular system
The muscular system is a network of fibres that work together to create
movement by contracting and extending (shortening and lengthening).
There are in fact approximately 600 voluntary muscles in our body which
make up approximately 40-50% of body weight.
Types of muscle
There are three different types of muscle within the human body, skeletal,
smooth and cardiac.
Skeletal or voluntary muscles – these are striated in appearance in other
words striped. The skeletal muscles are voluntary and are under our control.
We use these muscles when we carry out daily tasks and sports activities,
e.g. football, walking, running, swimming and gardening.
Smooth or involuntary muscles – these are smooth in appearance and
work involuntarily in other words they work without us thinking about them.
They are found in the walls of internal organs such as the intestine.
Cardiac muscle – this muscle is also striated in appearance and is only
found in the heart. This muscle is also controlled involuntarily and is under
constant nervous and chemical control.
Skeletal muscles
Skeletal muscles have a number of important functions which are outlined
below:



They give shape and support to our bodies
They allow movement to occur
They generate heat
Not all skeletal muscle fibres are the same; in fact there are three different
type, each of which has particular characteristics that affect sports
performance. Initially scientists identified through observation of colour that
there were 2 types of fibres, which they called type 1 and type 2. However,
later research then showed that the type 2 fibres could be further divided into
two types, which have become known as type 2A and type 2B.
Type 1 fibres (slow twitch)
Type 1 fibres are also referred to as slow twitch fibres as they are best suited
to producing lower levels of speed and power. However, they can maintain
this for prolonged periods of time withstanding the onset of fatigue.
Type 2b fibres (fast twitch)
These are the opposite to type 1 fibres; they can contract quickly and
forcefully but have a poor endurance capacity.
Type 2a fibres (fast twitch)
These fibres are situated somewhere between type 1 and type 2b fibres.
They have a more even mix of both power and endurance capacities.
The table below illustrates the differences between the 3 types of muscle
fibre.
Slow twitch (1)
Fast twitch (2a)
Fast twitch (2b)
Speed of
contraction
Fatigue rate
slow
fast
fast
low
medium
high
Force of
contraction
Size
low
high
high
small
large
large
Myoglobin
content
Aerobic capacity
high
medium
low
high
medium
low
Anaerobic
capacity
Capillary density
low
medium
high
high
high
low
Colour
red
white
white
Typical sports
marathon runner
games player
sprinter
Muscles tend to be composed of both types of fibres, although the amounts
may vary from muscle to muscle and from person to person. Top endurance
athletes have a greater proportion of slow twitch fibres whereas sprinters and
power athletes have more fast twitch fibres. Team sports players often have
more type 2a fibres as they require both power and endurance capabilities.
Fibre types are genetically determined at birth and cannot be changed.
However, recent research has shown that training can lead to small changes
in the fibres types characteristics.
Part 2.2: Major muscles of the human body
As mentioned earlier there are over 600 skeletal muscles in the body. The
major muscles are illustrated on the diagrams below.
Anterior muscles of the body
© Loughborough College
Posterior muscle of the body
© Loughborough College
The quadriceps and hamstring muscles
The quadriceps is made up of four separate muscles (rectus femoris, vastus
lateralis, vastus medius, and vastus intermedius) and the hamstrings three
separate muscles (semimembranosus, semitendinosus and biceps femoris).
Part 2.3: Muscle movement
Movement occurs when muscles shorten (contract) and lengthen (extend).
Muscles work in groups rather than on their own, with most arranged in
opposing pairs. The muscle responsible for the movement is called the prime
mover or agonist. When the agonist contracts the opposing muscle has to
relax to allow the movement to occur and this muscle is called the
antagonist. Muscles known as fixators or stabilisers hold or fix the joint in
a stable position; these tend to be large postural muscle groups which work
the trunk and legs. Other muscles known as synergists (which tend to be
smaller muscles) assist the prime mover.
For example:
Movement
Agonist
Antagonist
Fixator
Synergist
Elbow flexion
Biceps
Triceps
Deltoids
Brachialis
Types of muscle contraction
When a muscle contracts it either shortens, lengthens or stays the same
length. When it shortens or lengthens it is known as an isotonic
contraction. If it stays the same length it is referred to as an isometric
contraction. There are two types of isotonic contractions – concentric and
eccentric. When an agonist muscle shortens under tension it is referred to
as a concentric contraction, and when it lengthens under tension it is known
as an eccentric contraction.
For example the bicep curl
During the upward phase of the exercise the biceps are the agonist and are
contracting concentrically. During the downward phase the biceps are still
the agonist but this time they are contracting eccentrically as they are
lengthening. In effect they are acting as a brake to slow the movement
down.
Type of contraction
Concentric
Description
The muscle shortens
Eccentric
The muscle lengthens
Isometric
The muscle stays the
same length throughout
Example
Upward phase of a
bicep curl
Downward phase of a
bicep curl
Holding a weight at
arm’s length
The structure of muscle
The diagram below illustrates the complex structure of skeletal muscles. Each
muscle is made up of many bundles of muscle fibres which in turn are made
up of even smaller fibres known as myofibrils. Myofibrils consist of two
protein filaments known as myosin and actin which make up a sarcomere (the
contractile unit of the muscle). The myosin filament is a thick protein strand
with cross-bridge projections and the actin filament is a thin protein strand.
© Loughborough College
Sliding filament mechanism
The sliding filament theory was put forward by Huxley in 1969 to explain how
a muscle alters it length. During contraction the actin and myosin filaments
slide over each other; this brings about an overall shortening of the
sarcomere. The muscle fibre is made up of many sarcomeres attached in a
chain; the shortening of each sarcomere gives the overall shortening of the
muscle fibre and therefore the muscle.
The components of a contractile unit
Sarcomere
Actin
Z line
A Band
Myosin
Relaxed
muscle
I band
H zone
Contracting
muscle
A band
Details of the component parts of the sarcomere (contractile unit)
Sarcomere
This is the name for the basic unit within the muscle
Z Line
The Z line is the join between 2 sarcomeres. During muscle
contraction these lines move closer together
This is the area where the myosin is. This does not change
in length during the contraction
This is the area within the A-band where there is myosin
only. This appears dark under a microscope. During
contraction this band shortens and disappears as the actin
filaments overlap each other
This is the area containing actin only. This appears light
under the microscope. This shortens during contraction
A band
H Zone
I Band
Muscular contraction
Muscular contraction involves the interaction of muscles with the nervous
system. An electrical impulse is sent from the brain to the muscles via the
spinal cord and nerve cells (motor neurones). Muscle fibres within the muscle
contract according to the ‘all or nothing’ principle. That is, when they
contract, they all contract maximally or not at all. Collectively, the motor
nerve and the muscle fibres it innervates is known as a motor unit.
The two factors which affect the force of a contraction are the number of
motor units activated and the frequency of the nerve impulses.
1. Number of muscle units activated.
When a muscle contracts not all of the motor units will be activated. If the
intensity of exercise increases then more units will be activated enabling more
muscle fibres to be recruited.
2. Frequency of stimulation.
If the fibres contract in quick succession then they can exert greater forces.
Part 2.4: Responses to exercise
Short term effects of exercise on the muscular system
Exercise has the following short term effect on the muscular system:


There is an increase in muscular temperature and metabolic activity
As the muscles become warmer through activity they become more
pliable which reduces the risk of injury. However, muscles can also be
damaged during exercise e.g. muscle strain
Long term effects of exercise on the muscular system
Exercise has the following long term effects on the muscular system:





Muscle bulk and size will increase. The increased size of the muscle
tissue is called hypertrophy
Tendons will become thicker and stronger helping to decrease the risk of
injury
The heart muscle will also increase in size (particularly that of the left
ventricle) leading to a more forceful contraction
There is an increase in the thickness of articular cartilage thus improving
shock absorption
There is an increase in muscle tone and possibly a reduction in body fat
All of these effects only occur if regular exercise is maintained. If the exercise
is stopped for a period of time then the training effects will be lost.
Section Three - The Structure and Function of
The Cardiovascular System and How it
Responds to Exercise
The cardiovascular system is composed of three main parts: the heart, the
blood vessels and the blood. Its function is to deliver oxygen and nutrients
and excrete waste products from all the cells of the body.
Part 3.1: The heart
The heart is about the size of a closed fist, and shaped like a cone. It is
located behind the sternum and ribs, slightly to the left of the centre of the
chest.
It is made up of four chambers, two upper atria and two lower ventricles.
© Loughborough College
Part 3.2: Circulation
The vascular system has two pathways of circulation, the pulmonary
circulation (to the lungs) and the systemic circulation (to the body).
Blood flow through the heart and lungs
Deoxygenated blood is returned from the muscles and the rest of the body
via the superior and inferior vena cava into the right atrium. It then passes
into the right ventricle and from here it is pumped into the pulmonary artery
where it travels to the lungs. It is in the lungs that pulmonary diffusion
occurs; the blood is removed of its waste produces and enriched with oxygen.
The blood is then returned to the heart via the pulmonary vein into the left
atrium. It is then pumped into the left ventricle and from here into the aorta
where the oxygenated blood is then delivered the working muscles.
Within the heart there are a number of valves which ensure that the blood
can only flow in one direction. Valves are found between atria and ventricles
(atrio-ventricular valves) and between ventricles and the main vessels
transporting blood away from the heart (semi-lunar valves). The blood
flow pushes the valve open and it is then closed by connective tissue called
chordae tendineae.
Part 3.3: Blood vessels
The blood and blood vessels are responsible for carrying blood and nutrients
around the body. There are 3 types of blood vessels: arteries, veins and
capillaries.
The arteries carry blood away from the heart to the working muscles and
other parts of the body where oxygen and nutrients are required. The
arteries branch off and progressively become smaller vessels known as
arterioles. These arterioles then join even smaller vessels known as
capillaries where diffusion takes place. The capillaries are the essential link
between arteries and veins; they are tiny vessels with semi permeable
membranes allowing oxygen and nutrients to be delivered to the tissues and
waste products such as carbon dioxide and water to be removed. Following
diffusion the blood moves from the capillaries into venules (small veins);
these then join together to form larger veins as the blood is moved back
towards the heart. Because the pressure of the blood in the veins is low they
have values to prevent back flow which helps the blood to travel in the right
direction.
The table below summaries the characteristics of the different blood vessels.
Arteries
Vessel wall
Veins
Capillaries
Thin
Diameter
Thick &
muscular
Small
Large
Very thin
(one cell thick only)
Very small
Valves
No
Yes
No
Pressure
High
Very low
Low
Blood
Oxygenated*
De-oxygenated*
Both
Blood flow
Away from
heart
Carry nutrients
and oxygen to
working tissues
Towards heart
From artery to vein
Carry waste
products including
carbon dioxide
away from the
working tissues
Allow diffusion of
nutrients, oxygen and
carbon dioxide
between the blood and
the working tissues
Function
* The pulmonary artery and vein are the exception. The pulmonary artery
carries deoxygenated blood away from the heart to the lungs and the
pulmonary vein carries the freshly oxygenated blood from the lungs back to
the heart.
The blood
The blood is the transport system of the body and it has many different
functions.




It transports oxygen and essential nutrients to the tissues
It returns carbon dioxide from the tissues to the lungs
It carries waste products from the tissues to the liver and kidneys to be
broken down / excreted
It distributes hormones
Composition
The average individual has between 4-6litres of blood in their body. Blood is
made up of the following components:
Component
Description / function
Plasma
Straw coloured liquid, mainly water
Carries nutrients
Known as erythrocytes
Contain haemoglobin which carries oxygen
Produced in bone marrow
Typically 40-45% of total blood volume
Known as leucocytes
Fight infections
Produced in bone marrow
Fewer in number than red blood cells
Thrombocytes
Control bleeding after injury
Help in process of blood clotting and repairing
damaged tissues
Red blood cells
White blood cells
Platelets
Part 3.4: Responses to exercise
Short term effects of exercise on the cardiovascular system
Exercise has the following short term effects on the cardiovascular system:

There is an increase in heart rate at the onset of exercise. This is due to
the release of the hormone adrenalin. Adrenalin prepares the body for
action by stimulating the respiratory and circulatory systems. It is often
associated with nerves, butterflies, rapid breathing, and sweating palms

There is an increase in stroke volume (the amount of blood pumped out
of the heart per beat). Because there is an increase in both heart rate
and stroke volume cardiac output (the amount of blood pumped by the
heart per minute) also increases. (Cardiac output (Q) = SV x HR)

The arteries and arterioles dilate in order to accommodate the increased
flow of blood. Dilation of the blood vessels also keeps blood pressure low

The working muscles’ demand for oxygen means that blood is redirected
away from areas which need it less. For example, when cycling blood
may be redirected from the gut to the legs

The body's temperature increases as does the temperature of the blood.
To cope with this increase in temperature more blood is shunted to the
skin surface to help it cool. Sweating cools you by evaporation

Blood pressure increases at the onset of exercise
Long term effects of exercise on the cardiovascular system
Exercise has the following long term on the cardiovascular system:

The heart muscle will also increase in size (cardiac hypertrophy),
particularly that of the left ventricle leading to a more forceful
contraction. More blood is pumped per beat (stroke volume) and
therefore per minute (cardiac output)

Resting HR decreases (bradycardia), but SV increases so the same
amount of blood is pumped out per beat at rest

There is an increase in the size and number of blood vessels feeding the
muscles and lungs

After endurance training (low intensity, long duration) the quantity and
quality of the blood improves. More red blood cells are produced. This
means that more oxygen can be transported to and used by the muscles

Blood pressure is decreased in individuals with hypertension
All of these effects only occur if regular exercise is maintained. If the exercise
is stopped for a period of time then the training effects will be lost.
Section Four - The Structure and Function of
The Respiratory System and How it Responds
to Exercise
Part 4.1: The structure and function of the
respiratory system
The respiratory system is responsible for supplying oxygen to the blood which
can then be delivered to the working tissues. It does this through breathing.
Outlined below is the pathway taken by air as we breathe in to the diffusion
of oxygen into the blood stream.
Pathway of air
Explanation
Nose
Air enters the body here. It is filtered by tiny hairs and
warmed
Both food and air pass through the pharynx
Food is then directed into the oesophagus
Commonly known as voice box. The opening is covered
by epiglottis (a flap of cartilage) which prevents food
entering
Commonly known as the windpipe it is about 10cm long
and supported by rings of cartilage. It contains cells
which remove foreign particles from the air
There are two bronchi (right and left branches) leading to
each lung (one on each side of the heart). The bronchi
further divide into bronchioles
The bronchioles further divide into smaller pathways,
leading to the alveoli
Alveoli are small air filled sacs. They have a large surface
area, thin walls and are surrounded by capillaries. It is
here that gaseous exchange takes place
Pharynx
Larynx
Trachea
Bronchi
Bronchioles
Alveoli
The structure of the respiratory system
© Loughborough College
Part 4.2: Mechanics of breathing
An average adult will inhale and exhale approximately 12 to 15 breaths per
minute. For air to be drawn into the lungs, the pressure of the air within the
lungs must be lower than that in the atmosphere. The greater the difference
in pressure, the faster air can be drawn into the lungs. The pressure
difference is created by altering the size of the thoracic cavity.
Inspiration
When an individual breathes in it is referred to as inspiration. During
inspiration the intercostal muscles contract pulling the ribs upwards and
outwards at the same time as the diaphragm contracts and flattens. These
combined actions increase the area inside the lungs meaning that air is then
drawn into the lungs until the pressure inside the lungs is equal to the
atmospheric pressure.
Expiration
When an individual breathes out it is known as expiration. During
expiration the intercostal muscles relax lowering the rib cage to its resting
position. The diaphragm also relaxes (moving upwards). This causes the
area inside the lungs to decrease, increasing the pressure inside. This greater
pressure forces the air out of the body until the pressure is equal to that of
the atmosphere.
Mechanics of breathing
© Loughborough College
Gaseous exchange
Oxygen passes into the body and carbon dioxide leaves the body through the
process of gaseous exchange. Gases move from an area of high
concentration to that of a low concentration; this process is known as
diffusion and occurs in the alveoli.
Gas exchange at the lungs
There is a high concentration of oxygen in the lungs as we breathe in, and a
low concentration in the capillaries surrounding the alveoli. There is a higher
concentration of carbon dioxide in the blood and capillaries than in the alveoli
air. Gaseous exchange is a two way process; as oxygen diffuses into the
capillaries to be delivered to the tissues, carbon dioxide diffuses into the
alveoli to be expired . The capillary walls are thin to allow efficient gaseous
exchange and the alveoli have a large surface area to allow for the optimal
exchange of gases.
Transport of oxygen and carbon dioxide
Oxygen combines with haemoglobin in the red blood cells to form oxyhaemoglobin. In the lungs, where there is little carbon dioxide
haemoglobin is said to be 100% saturated with oxygen. When large amounts
of carbon dioxide are present, the saturation of haemoglobin with oxygen is
reduced, enabling oxygen to disassociate (unload) and feed the working
tissues. At the site of the tissues, most oxygen is unloaded. Most carbon
dioxide is transported in the form of bicarbonate ion, and some combines with
haemoglobin to form carbaminohaemoglobin.
Gas exchange at the muscles and tissues
Oxygen is rich in the capillary blood, and low in the muscle cells. Because
oxygen moves from an area of high concentration to that of a low
concentration it moves into the muscle cells. Carbon dioxide produced in the
muscle passes into the capillary and is transported back to the lungs.
Part 4.3: Respiratory volumes
There are a number of measures or capacities that can be taken of the
amount of air moving into and out of the lungs:
Lung volume /
capacity
Tidal volume (TV)
Inspiratory reserve
volume (IRV)
Expiratory reserve
volume (ERV)
Residual volume
(RV)
Vital capacity (VC)
Total lung capacity
Minute ventilation
Respiratory rate
(RR)
Definition
Approximate
normal values
The amount of air inspired / expired
per breath
The amount of air forcibly inspired
above tidal volume
The amount of air forcibly expired
above tidal volume
The lungs never completely empty,
and the air that is left after a
maximum exhalation is the residual
volume.
Vital capacity is the maximum amount
of air that you can breathe out after
breathing in as deeply as you can.
IRV + TV + ERV
VC + RV
500ml
The volume of air inspired / expired
per minute.
Minute volume = TV x RR
How many breaths you take per
minute
7500ml
3300ml
1000 – 1200ml
1200ml
5500ml
Up to 8000ml
Average is 12-15
Part 4.4: Responses to exercise
Short term effects of exercise on the respiratory system
Exercise has the following short term effects on the respiratory system:
 Breathing rate increases
 Tidal volume increases (the amount of air inspired / expired per breath)
 Carbon dioxide production increases
Long term effects of exercise on the respiratory system
Exercise has the following long term effects on the respiratory system:

The intercostal muscles become stronger helping to make the respiratory
system more efficient

The lungs get bigger, increasing their capacity to draw in oxygen

There is an increase in the rate at which carbon dioxide is drawn out of
the lungs and oxygen is drawn in

Vital capacity increases

The combined respiratory and circulatory systems become more efficient

There is an increase in capillary density surrounding the alveoli thus
improving gaseous exchange
All of these effects only occur if regular exercise is maintained. If the exercise
is stopped for a period of time then the training effects will be lost.
Section Five - The Different Energy Systems
and Their Use in Sport and Exercise
Performance
Part 5.1: Energy systems
The body needs a constant supply of energy. This energy is used for growth,
repair and most importantly, in terms of sports participation, muscular
contraction. In order for the muscles to contract they need a constant supply
of energy.
The main energy providers are carbohydrates, fats and proteins, although
proteins are only used when the others are not available and as a last resort.
Energy is needed for muscular activity to take place. The only useable source
of energy in the body is a compound found in muscle cells called Adenosine
Triphosphate (ATP). ATP is broken down into Adenosine Diphosphate
(ADP) and Free Phosphate (Pi) releasing the stored energy.
ATP→ ADP + Pi + Energy
Therefore all sources of energy found in the food that we eat have to be
converted into ATP before the potential energy in them can be used.
Muscles can only store small amounts of ATP and this is used up very quickly.
There is enough ATP stored in the muscles to provide energy for about 2
seconds worth of activity; after this ATP has to be resynthesised and there
are three different energy systems that the body can use to this.
1.
2.
3.
The phosphocreatine (ATP-PC) system
The lactic acid system (anaerobic alactic system)
The aerobic system
Phosphocreatine system
This system uses a substance called Creatine Phosphate (CP) which is
found in small quantities the muscles. When the high energy bond in CP is
broken the energy is released and used to resynthesise ATP in the muscles.
There is enough CP in the muscles to provide about 10 seconds worth of
exercise.
Step 1: PC → P I + C + Energy
Step 2: Energy +ADP +P I → ATP
This system is essential at the onset of exercise and for high intensity
activities such as shot putt and weight lifting. It does not require oxygen and
there are no by products produced.
Lactic acid system
The lactic acid system also provides short-term energy. If an athlete works
beyond the capacity of the PC system, that is for longer than 10seconds,
energy is provided by the lactic acid system. No oxygen is required for this
system; however lactic acid is produced which causes the muscles to tire.
This system relies on the breakdown of carbohydrates to provide fuel.
Carbohydrate can be broken down and stored in the liver and working
muscles as glucose. The process by which glucose is broken down to release
energy is called glycolysis. It is the breakdown of glycogen that provides
the energy to rebuild ADP into ATP. Glycolysis is far more complex than the
ATP-PC system since it requires many complex reactions to occur. However,
from the breakdown of carbohydrate this system does provide 2 molecules of
ATP.
Since there is no oxygen present pyruvic acid is formed during glycolysis. It
is then converted by the enzyme lactate dehydrogenase (LDH) into lactic acid.
As the lactic acid accumulates in the body it causes pain and fatigue inhibiting
muscular contraction. It makes the limbs feel heavy and in some situations
as if they are burning.
The lactic acid system will provide energy for exercise that lasts between 10
seconds and 2 minutes. Once the exercise has stopped extra oxygen is taken
in to remove the lactic acid by changing it back into pyruvic acid. This is
known as repaying the oxygen debt.
Aerobic system
This system provides long term energy and is used in long distance events
such as marathons and cycling. The system relies on carbohydrates and
fats as fuels and produces carbon dioxide and water as waste products.
It can only be used in the presence of oxygen and thus energy is released
much more slowly, too slowly to fuel intense or explosive activity.
However, the energy yield is high; one molecule of glucose yields 36
molecules of ATP that’s 34 more than in the lactic acid system! Thus the
aerobic route is 18 or 19 times more effective than the anaerobic route.
The first stage of the aerobic pathway is the same as that of the anaerobic
lactic acid system i.e. the conversion of glycogen into two molecules of pyuvic
acid and two molecules of ATP. It is from this point forwards that all
reactions that are involved in the aerobic system then take place within the
mitochondria (often referred to as the power houses of the cells).
In the presence of oxygen the pyuvic acid no longer forms lactic acid, rather
it is converted to a form of acetyl coenzyme A (a two carbon compound) and
enters the citric acid and krebs cycle. A number of reactions occur in this
cycle and the net result is the production of 2 ATP molecules; carbon dioxide
is also given off.
From here the aerobic system moves into what is referred to as the electron
transport chain and it is here that the majority of ATP molecules are produced
(34molecules); water is also given off here.
Provided that there is an adequate supply of oxygen to the working muscles
glucose and fatty acids can be used to produce ATP. The major advantage of
this is that there is a much larger supply available to sustain steady state
endurance activities. This system could, at a steady state, continue to work
indefinitely or until the energy stores run out.
Aerobic system
Glycogen
2 ATP
Pyruvic acid
Acetyl CoA
Krebs cycle
Electron transport chain
2 ATP
34 ATP
Summary of the three different energy systems
Energy system
Fuel used
Rate of
production
Very rapid
Duration
By products
Example activities
Creatine
phosphate
Oxygen
required
No oxygen is
required
Phosphocreatine
0-10seconds
None
Very high intensity explosive
events e.g. shot putt
The lactic acid
system
(anaerobic
gylcolysis)
Aerobic system
Glucose
/glycogen
No oxygen is
required
Rapid
10seconds –
2minutes
Lactic acid
High intensity short duration e.g.
200 and 400metres sprint. Short
sprint bursts in team games
Slow
2 minutes
plus
Carbon dioxide
and water
Long distance events such as
running, cycling and team
games.
Everyday activities
Glucose
Oxygen is
/glycogen and required
fatty acids