Section one – Know the different types of injury and ...



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 skeleton |Shoulder girdle (scapula and clavicle) |

| |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

[pic]

© Loughborough College

Posterior view of the skeleton

[pic]

© 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 |Number of vertebrae in each section |

|Cervical |7 vertebrae |

|Thoracic |12 vertebrae |

|Lumbar |5 vertebrae |

|Sacrum |5 fused vertebrae |

|Coccyx |4 fused vertebrae |

The vertebral column

[pic]

© 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 encloses and protects the spinal cord

• It supports the head

• It serves as a point of attachment for the ribs and muscles of the back

• It supports the body

• It allows movement to occur

• It 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 |Function |

|Hyaline cartilage |Hyaline / articular cartilage covers the ends of the articulating bone. It smoothes and |

| |facilitates gliding movements between the bone ends |

|Joint / articular capsule |This is a fibrous tissue encasing the joint, forming a capsule |

|Ligaments |Ligaments are white fibrous connective tissue, joining bone to bone. They restrict the amount |

| |of movement that can occur at the joint |

|Synovial membrane |The synovial membrane acts as a lining to the joint capsule and secretes synovial fluid |

|Synovial fluid |Synovial fluid fills the joint capsule; it nourishes and lubricates the articular cartilage |

|Pads of fat |Pads of fat act as buffers to protect the bones from wear and tear |

A typical synovial joint

[pic]

© 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) Hinge

2) Ball and socket

3) Pivot

4) Gliding

5) Saddle

6) 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 |

|[pic] |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 |

|[pic] |movement. The hip and shoulder are examples. |

|Pivot joint |The pivot joint allows only rotation. An example is the joint which allows us to |

|[pic] |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|

|[pic] |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 |

|[pic] |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. |

|[pic] |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 |Reducing the angle at a joint or bending a limb. For example bending the arm at the elbow. |

|Extension |Increasing the angle at a joint or straightening a limb. For example straightening the arm at the |

| |elbow. |

|Abduction |The sideways movement of a limb away from the mid line of the body. For example raising the arm out |

| |to the side. |

|Adduction |Bringing a limb towards or across the mid line of the body. For example lowering the arm on a |

| |lateral raise. |

|Circumduction |When the end of the bone moves in a circle. For example the serve action of a tennis player. |

|Rotation |A turning movement, when a limb rotates about its own axis. For example turning your head to the |

| |side. |

|Pronation |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. |

|Hyper-extension |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. |

Range of movement at each joint

The following table summarises which movements are possible at each of the major joints of the body.

| |Wrist |Elbow |Shoulder |Spine |Hip |Knee |Ankle |

|Joint/ Movement | | | | | | | |

|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 |slow |fast |fast |

|Fatigue rate |low |medium |high |

|Force of contraction |low |high |high |

|Size |small |large |large |

|Myoglobin content |high |medium |low |

|Aerobic capacity |high |medium |low |

|Anaerobic capacity |low |medium |high |

|Capillary density |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

[pic]

© Loughborough College

Posterior muscle of the body

[pic]

© 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 |Description |Example |

|Concentric |The muscle shortens |Upward phase of a bicep curl |

|Eccentric |The muscle lengthens |Downward phase of a bicep curl |

|Isometric |The muscle stays the same length |Holding a weight at arm’s length |

| |throughout | |

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.

[pic]

© 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

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 |

|A band |This is the area where the myosin is. This does not change in length during the contraction |

|H Zone |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 |

|I Band |This is the area containing actin only. This appears light under the microscope. This shortens |

| |during contraction |

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.

[pic]

© 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).

[pic]

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 |Veins |Capillaries |

|Vessel wall |Thick & muscular |Thin |Very thin |

| | | |(one cell thick only) |

|Diameter |Small |Large |Very small |

|Valves |No |Yes |No |

|Pressure |High |Very low |Low |

|Blood |Oxygenated* |De-oxygenated* |Both |

|Blood flow |Away from heart |Towards heart |From artery to vein |

|Function |Carry nutrients and oxygen to|Carry waste products including |Allow diffusion of nutrients, oxygen |

| |working tissues |carbon dioxide away from the |and carbon dioxide between the blood |

| | |working tissues |and the working tissues |

* 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 |

|Red blood cells |Known as erythrocytes |

| |Contain haemoglobin which carries oxygen |

| |Produced in bone marrow |

| |Typically 40-45% of total blood volume |

|White blood cells |Known as leucocytes |

| |Fight infections |

| |Produced in bone marrow |

| |Fewer in number than red blood cells |

|Platelets |Thrombocytes |

| |Control bleeding after injury |

| |Help in process of blood clotting and repairing damaged tissues |

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 |

|Pharynx |Both food and air pass through the pharynx |

| |Food is then directed into the oesophagus |

|Larynx |Commonly known as voice box. The opening is covered by epiglottis (a flap of cartilage) which |

| |prevents food entering |

|Trachea |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 |

|Bronchi |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 |

|Bronchioles |The bronchioles further divide into smaller pathways, leading to the alveoli |

|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 |

The structure of the respiratory system

[pic]

© 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

[pic]

© 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 oxy-haemoglobin. 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 |Definition |Approximate normal values |

|Tidal volume (TV) |The amount of air inspired / expired per breath |500ml |

|Inspiratory reserve volume (IRV) |The amount of air forcibly inspired above tidal volume |3300ml |

|Expiratory reserve volume (ERV) |The amount of air forcibly expired above tidal volume |1000 – 1200ml |

|Residual volume (RV) |The lungs never completely empty, and the air that is left |1200ml |

| |after a maximum exhalation is the residual volume. | |

|Vital capacity (VC) |Vital capacity is the maximum amount of air that you can |5500ml |

| |breathe out after breathing in as deeply as you can. | |

| |IRV + TV + ERV | |

|Total lung capacity |VC + RV |Up to 8000ml |

|Minute ventilation |The volume of air inspired / expired per minute. |7500ml |

| |Minute volume = TV x RR | |

|Respiratory rate (RR) |How many breaths you take per minute |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. The phosphocreatine (ATP-PC) system

2. The lactic acid system (anaerobic alactic system)

3. 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

Pyruvic acid

Acetyl CoA

Krebs cycle

Electron transport chain

Summary of the three different energy systems

|Energy system |Fuel used |Oxygen required |Rate of production |Duration |By products |Example activities |

|The lactic acid system |Glucose /glycogen |No oxygen is required |Rapid |10seconds – 2minutes |Lactic acid |High intensity short duration e.g. 200 and 400metres |

|(anaerobic gylcolysis) | | | | | |sprint. Short sprint bursts in team games |

|Aerobic system |Glucose /glycogen and |Oxygen is required |Slow |2 minutes plus |Carbon dioxide and water |Long distance events such as running, cycling and team |

| |fatty acids | | | | |games. |

| | | | | | |Everyday activities |

-----------------------

Sarcomere

Z line

Actin

A Band

Myosin

Relaxed muscle

I band

H zone

Contracting muscle

A band

2 ATP

2 ATP

34 ATP

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