Download Anatomy Workbook - Wright Wonders

The Human Body
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, and
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 fibro cartilage. 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 characterized 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 carp metacarpal 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.
Super nation
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 summarizes 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 fibers 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 fibers are the same; in fact there are three different types, each of
which has particular characteristics that affect sports performance. Initially scientists identified
through observation of color that there were 2 types of fibers, which they called type 1 and
type 2. However, later research then showed that the type 2 fibers could be further divided
into two types, which have become known as type 2A and type 2B.
Type 1 fibers (slow twitch)
Type 1 fibers are also referred to as slow twitch fibers 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 fibers (fast twitch)
These are the opposite to type 1 fiber; they can contract quickly and forcefully but have a poor
endurance capacity.
Type 2a fibers (fast twitch)
These fibers are situated somewhere between type 1 and type 2b fibers. They have a more
even mix of both power and endurance capacities.
The table below illustrates the differences between the 3 types of muscle fiber.
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
Color
red
white
white
Typical sports
marathon runner
games player
sprinter
Muscles tend to be composed of both types of fibers, although the amounts may vary from
muscle to muscle and from person to person. Top endurance athletes have a greater
proportion of slow twitch fibers whereas sprinters and power athletes have more fast twitch
fibers. Team sports players often have more type 2a fibers as they require both power and
endurance capabilities.
Fiber types are genetically determined at birth and cannot be changed. However, recent
research has shown that training can lead to small changes in the fibers type’s 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
© Southborough 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 stabilizers 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
The structure of muscle
Example
Upward phase of a
bicep curl
Downward phase of a
bicep curl
Holding a weight at
arm’s length
The diagram below illustrates the complex structure of skeletal muscles. Each muscle is made
up of many bundles of muscle fibers which in turn are made up of even smaller fibers 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 fiber is made up of many
sarcomeres attached in a chain; the shortening of each sarcomere gives the overall shortening
of the muscle fiber 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
neurons). 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 fibers it innervates are 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 fibers to be
recruited.
2. Frequency of stimulation.
If the fibers 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:

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


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 (atria-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 chordate 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 colored liquid, mainly water
Carries nutrients
Known as erythrocytes
Contain hemoglobin which carries oxygen
Produced in bone marrow
Typically 40-45% of total blood volume
Known as leukocytes
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 esophagus
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
intercostals 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 intercostals
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 hemoglobin in the red blood cells to form oxy-hemoglobin. In the
lungs, where there is little carbon dioxide hemoglobin is said to be 100% saturated with
oxygen. When large amounts of carbon dioxide are present, the saturation of hemoglobin
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 hemoglobin 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 intercostals 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 dehydrogenize (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
Ex
Creatine
phosphate
Oxygen
required
No oxygen is
required
Phosphocreatine
0-10seconds
None
Ve
ev
The lactic acid
system
(anaerobic
gylcolysis)
Aerobic system
Glucose
/glycogen
No oxygen is
required
Rapid
10seconds –
2minutes
Lactic acid
Hi
20
sp
Slow
2 minutes
plus
Carbon dioxide
and water
Lo
ru
ga
Ev
Glucose
Oxygen is
/glycogen and required
fatty acids