Basic Anatomy and Basic Anatomy and PhysiologyPhysiology

Basic Anatomy and Basic Anatomy and PhysiologyPhysiology

Respiratory SystemRespiratory System

CELLULAR RESPIRATIONCells continuously use O2 in the metabolic

reactions in the body to create energy. At the same time, these reactions produce CO2.

The cardiorespiratory system O2 provides and eliminates CO2 and other wastes through the

blood in a process known as respiration.The bloodstream delivers chemical fuels to the

cell. Fuels are broken down in the cell to release energy and this is called cellular

respiration.

As CO2 in the cell accumulates, the concentration is higher than that in the bloodstream. The CO2 diffuses to the bloodstream.

As O2 concentration is higher in the bloodstream, O2 diffuses to the cells.

How does the circulatory system release CO2 from the body into the atmosphere?How does O2 get into the blood?

This occurs in the lungs.

Glucose + O2 → CO2 + H2O + Energy

RESPIRATORY SYSTEM

STRUCTURES OF THE RESPIRATORY SYSTEM

STRUCTURES OF THE RESPIRATORY SYSTEM

UPPER RESPIRATORY TRACT

1. NASAL PASSAGES Air enters through nostrils Small hairs filter out dust and large particles Air passes through to the nasal passageways

2. NASOPHARYNX Mucus layer traps finer particles, which are carried by cilia to

the pharynx (throat) to be swallowed3. PHARYNX

Passageway for air and food and to provide a resonating chamber for speech sounds

4. OROPHARYNX and LARYNGOPHARYNX Oropharynx connects nasopharynx to laryngopharynx Laryngopharynx extends to the oesophagus and larynx

5. LARYNX Contains the vocal cords and connects the pharynx with the

trachea Thyroid cartilage (Adam’s Apple) gives its triangular shape

Epiglottis is a large leaf shaped piece of cartilage lying on the top of the larynx. It forms a lid over the trachea to prevent foreign bodies and liquid going down.

STRUCTURE OF THE LARYNX

LOWER RESPIRATORY TRACT

1. TRACHEA C-shaped cartilage rings reinforce and protect

the trachea to prevent it from collapsing Conducts air through to bronchi

2. BRONCHI Right and left primary bronchi are formed

from the branching of the trachea Inside each lung, the primary bronchus

branches into secondary and then tertiary bronchi

The process continues until the tiniest branches of the whole system are the air passages called the bronchioles (less than 1 mm in diameter)

Known as bronchial tree

3. LUNGS Paired organs lying in the thoracic cavity that sit either

side of the heart Each is surrounded by a strong connective tissue called

the pleura membrane. This contains two layers: the parietal pleura, which are attached to the thoracic cavity, and the visceral pleura that cover the lungs. Between them is the pleural cavity, which contains lubricating fluid to prevent friction between the membranes when breathing

Each lung is divided by fissures into lobes. The left lung has 2 lobes; the right lung has 3

The left lung has a ‘cardiac notch’ to accommodate the shape of the heart

4. ALVEOLI At the end of the bronchioles are small sacs called alveoli The total surface area of the alveoli amounts to about 1

square meter per kilogram of body weight. Therefore, a person who is around 65kg would have 65m² of alveoli surface area (nearly half a tennis court)

Alveoli are covered in tiny capillaries Exchange of gases occurs between the alveolar and

capillary walls across a thin membrane. This is called diffusion.

STRUCTURE OF THE LUNGS

STRUCTURE OF AN ALVEOLUS

LUNG FUNCTION

Respiration is the exchange of gases between the cells, blood and atmosphere

It involves four processes

1. Pulmonary Ventilation (breathing) – the movement of air from the atmosphere into the alveoli

2. Pulmonary Diffusion – exchange of O2 and CO2 between the lungs and the blood

3. Transport of Respiration Gases – transportation of O2 and CO2 between the lungs and the tissue cells of the body via the blood

4. Internal Respiration – gas exchange between the blood capillaries and the tissue cells.

INSPIRATION AND EXPIRATION

Pulmonary ventilation (breathing) allows a continuous flow of air from the outside into and out of the lung alveoli

Air flows in to the body and out of it for the same reason that blood flows through the body – a pressure gradient exists.

Gases will generally move from areas of high pressure into areas of low pressure

Breathing in (inspiration) occurs because the air outside has a higher pressure than the air in the lungs as your muscles have increased the size and the volume inside the lungs

When the diaphragm and external intercostals relax, the pressure inside the lungs is greater than that outside as the lung size and volume has decreased. Hence we breathe out in the process of expiration.

OVERVIEW OF THE MECHANICS OF BREATHING

INSPIRATION

The diaphragm muscle contracts and flattensThe intercostals raise the thorax and the sternum outThe chest cavity is enlarged and pressure is reducedAir is drawn in

EXPIRATION

The diaphragm relaxes and forms a dome shapeThe chest cavity is reducedThe pressure is increasedAir is forced out

CONTROL OF BREATHING

The basic pattern of breathing is set by the activity of neurons in the Medulla and Pons (base of the brain)

This centre in the brain senses the level of CO2 in the blood and signals the body to breathe out (to get rid of CO2) and to breathe in as O2 is needed

INSPIRATORY CENTRE

Neurons fire, nerve impulses travel along the intercostal nerves to excite the diaphragm and external intercostal musclesThe thorax expands and air rushes into the lungsThe inspiration centre becomes dormant and the muscles recoil allowing expiration

Rate = 12 – 18 breaths / minInspiratory Phase is approximately 2 secondsExpiratory Phase is approximately 3 seconds

LUNG VOLUMES

During normal, quiet respiration, about 500mL of air is inspired (350 mL reaches the alveoli; the other 150 mL remains in the respiratory space). The same amount of air moves out with expiration. This volume of air is called the Tidal Volume.

The total amount of air breathed in over one minute is about 6 litres, and is called the Minute Volume of Respiration (ventilation). Tidal volume x Number of breaths per minute (0.5L x 12 breaths / min = 6L/min)

We can forcibly take in a deep breathe, we can take in up to 3100 mL above the tidal volume. This additional air is the Inspiratory Reserve Volume

We can forcibly breathe out (exhale). This is termed the Expiratory Reserve Volume, and can amount up to 1200 mL more than the tidal volume.

Even after the expiratory reserve volume is expelled, some air is still trapped in the lungs because of pressure. This is the Residual Volume, and it is usually around 1200 mL.

LUNG CAPACITIES

The lung capacities are various combinations of the lung volumes:

Tidal Volume + Inspiration Reserve Volume = Inspiratory Capacity (3600 Ml)

Residual Volume + Expiratory Reserve Volume = Functional Residual Capacity (2400 mL)

Tidal Volume + Inspiratory Reserve Volume + Expiratory Reserve Volume = Vital Capacity (4800 mL)

To find the Total Lung Capacity, add all volumes = 6000 mL

MEASUREMENT

The apparatus commonly used to measure the volumes of air exchanged and the rate of ventilation is called a spirometer or respirometer.

The record of these readings is called a spirogram.Inspiration is the upward deflection and expiration is the downward deflection.

During exercise:

Tidal volume (TV) increasesInspiratory Reserve volume (IRV) decreaseExpiratory Reserve volume (ERV) slightly decreasesResidual volume (RV) slightly increasesTotal lung capacity (TLC) slightly decreasesVital capacity (VC) slightly decrease

When at rest, a total of 6 litres of blood passes through your lungs every minute. This figure increases enormously during

exercise. (Davis et al, p.67, 1986)

IMMEDIATE RESPONSES TO EXERCISE

Before exercise, rate and depth of breathing increases as nervous activity is increased.Once exercising, rate and depth increase greatly because increased amounts of CO2 in the blood trigger greater respiratory activity.The increase in frequency (rate) and depth (TV) provides greater ventilation and occurs in proportion to the exercise effort Lung volumes also change:

Increased TV – up to 5 or 6 timesEVR and IRV utilised more, thus decrease in volume

Blood flow is greater, therefore there are more open capillaries at the alveolar-capillary membrane, increasing the surface area in the lungs for gaseous exchange

RECOVERY PERIODWhen exercise ceases, the body returns to pre-exercise condition or recovery period.Here:

Ventilation decreasesCO2 is reducedStimulation from muscles and joints is reduced

RESPIRATORY ADAPTATIONS TO EXERCISE

1. EFFECTS ON VENTILATION Ventilation increases from 6L/min at rest to more than

100L/min during exercise. This is achieved by increases in:

Respiration rate – from 15 to 40 or more breaths/minTidal Volume – from 10% of vital capacity to more than

50%

2. EFFECTS ON LUNG DIFFUSION During strenuous exercise there is a threefold increase in

oxygen diffusion from the alveoli to the blood

3. EFFECTS ON OXYGEN UPTAKE (VO2) Oxygen uptake is the amount of oxygen taken up and used by

the body. It reflects the total amount of work being done by the body.

During strenuous exercise there can be a 20-fold increase in VO2, which increases linearly with the increase of exercise intensities. As a person approaches exhaustion, their VO2 will reach a maximum that will not go any higher. This is a person’s VO2 max, the largest amount of oxygen that a person can utilise within a given time.

LONG TERM RESPONSES TO EXERCISE

Regular exercise causes adjustments to the respiratory system

ie adaptation and benefit = improved lung function

The muscles involved in breathing are conditioned and strengthened and the chest therefore has a greater ability to expand

Trained athletes have improved lung volume and lung function and can therefore take in more air per breath, require less breathing work to maintain same levels of O2 in the blood and can utilise air more efficiently.

Increased lung volume results in improved diffusion of O2 from lungs to the blood.

Lung volume at rest also becomes greater

These adjustments increase efficiency of gaseous exchange and thus improve the amount of O2 to be transported to body cells.

OXYGEN DEBT AND DEFICIT

These terms refer to a lack of oxygen while training/racing and after such activity is over. To go into these areas of exercise are normal, but the goal is to not go too far into either category. Below is a brief description of each and a chart which will detail the process more clearly than we can explain with words alone.

Oxygen Deficit – while exercising intensely the body is sometimes unable to fulfil all of its energy needs. Specifically, it is unable to intake and absorbs enough oxygen to adequately ‘fee’ the muscles and amounts of energy needed to perform the tasks the athlete is requesting from the body. In order to make up the difference without sacrificing the output, the body must tap into its anaerobic metabolism. This is where the body goes into a mix of aerobic and anaerobic energy production. While not hugely detrimental, oxygen deficit can grow to a level that the anaerobic energy system cannot cover. This can cause performance to deteriorate.

Oxygen Debt – this term describes how the body pays back its debt incurred above after the exercise is over. You will notice that even after you have finished racing, you will continue to breathe hard. At this point your body is still trying to repay the oxygen debt that was created when you were working hard. Technically, it is excessive post-exercise oxygen consumption.

Check out the illustration below for a graphical description of these terms.

RESPIRATORY PROBLEMS

SMOKINGThe vital capacity of the lungs can be reduced by 10 – 15% after once cigarette.Narrowing of the airways increases the mucus secretion.Prolonged smoking results in tar and irritants coating the lungs and reducing the elasticity of the alveoli. This increases the resistance to airflow and decreases the oxygen transporting capacity of the blood.More oxygen is used for breathing when you are a smoker. As a result there is less available to the working muscles, which leads to fatigue at a faster rate.

ASTHMAAsthma is the result of an allergic reaction to pollen, dust mite, and animals and/or cold, exercise, fumes, smog, viral infection and anxiety.

Small muscles surrounding the bronchi constrict and there is an over secretion of mucus. The walls of the bronchi can swell and narrow the airways causing coughing, wheezing and shortness of breath.

BRONCHITISBronchitis is caused by bacterial infections, pollution and smoking.The symptoms include increased mucus, coughing, wheezing and expiration difficulties.Treatment is by antibiotics (usually penicillin)

EMPHYSEMAEmphysema is caused by smoking and prolonged exposure to pollution (eg coal miners)The lining of the airways is damaged (cilia) and cannot move dirt and mucus. This then accumulates and the alveoli become less elastic. Oxygen uptake is then decreased and breathing (expiration) becomes difficult.

PULMONARY FIBROSISPulmonary fibrosis is an abnormal formation of fibre-like

scar tissue in the alveoli (air sacs which take oxygen to the lungs and expel carbon dioxide) and interstitial tissue (the tissues between and surrounding the alveoli) of the lungs. It is a chronic lung disease associated with inflammation.

Pulmonary Fibrosis Cont.Symptoms• Breathlessness, especially during exercise • Chronic dry cough • Shortness of breath • Chest discomfort• Reduced VC and IRV

• Causes

• Exposure to cigarette smoke • Inhaled environmental pollutants • Occupational pollutants, including asbestos, ground stone,

metal dust or mouldy hay

Exercise at Altitude

Exercise at altitude can have a major effect on performance

Endurance performance is usually diminished and anaerobic performance unaffected. This is because ascent to altitude results in lower oxygen in inspired air, and therefore less oxygen delivery to active muscles.

The percentage of oxygen in the air is at the same at sea level, but the total amount of air is less.

A moderate altitude around 15oom can start to affect the athlete, and over 5000m can be extreme.

An increase of altitude results in a decrease of 2°C per 300m, so the cold also has to be dealt with.

Physiological responses to exercise:

Decreased arterial oxygen contentIncreased ventilationIncreased CO2 outputIncreased stroke volumeDecreased sub-max HRDecreased VO2 maxProgressive dehydration – increased breathing of colder / dryer air and increased urine.

Overcoming the Effects of Altitude

Live high / train low – maximise the resting adaptations to altitude and minimise the disruption to training caused by altitudeDaily transit – between high and low altitudeNitrogen houses – decreases O2 in the air by increasing nitrogen. Mimic high altitude conditions and you can set the height you require

Altitude tents – portable and have a decreased O2.

Acclimatisation at AltitudeAdaptations occur over 2 – 3 weeks:

Increased red blood cell concentration – over days due to dehydration and weeks / months due to increased cell productionPartial restoration of plasma volumeIncreased muscle capillarisation Increased muscle enzyme activity

Altitude Sickness

This generally occurs above 3000m and is most likely to happen in:

Unacclimatised individualsAfter rapid ascentIn combination with exerciseSymptoms:HeadacheDizziness

NauseaSleep disturbances due to cardiovascular responses to hyperventilation

* Pulmonary / cerebral edema may occur in extreme circumstances and requires immediate return to

lower altitudes.