Backcontentsnext cardiovascularrespiratorymusculo-skeletaldiet & healtheffect of exercise A guide to respiratory fitness THE RESPIRATORY SYSTEM main listing

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cardiovascular respiratory musculo-skeletal diet & health effect of exercise

A guide to respiratory fitness

THE RESPIRATORY SYSTEM

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Contents - Respiratory

Introduction

Structure of the respiratory system

Breathing

Lung function

Lung capacity

Summary

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Introduction

what is the respiratory system

function of the respiratory system

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The respiratory system is made up from the following components;

What is the respiratory system?

Lungs Airways Blood supply Respiratory muscles

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Function of the respiratory system

To remove the waste gas carbon dioxide from the body

To get air into the body so oxygen can be added to the blood

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The respiratory system

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Structure of the Respiratory System

upper airways

lower airways

structure of the airways

lungs

blood vessels

respiratory muscles

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Respiratory – move air in/out of the airways & lungsmuscles

The respiratory system is made up from several components

Structure of the respiratory system

Airways – allow oxygen into the body

Lungs – deliver oxygen to the bloodstream

Blood vessels – deliver oxygen to the body tissues

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The upper airways

The airways are divided into upper & lower

The upper airways begin in the nose/throat region, or nasopharynx

Inhaled air travels down through the ‘voice-box’ (or larynx) before entering the ‘windpipe’, also called the trachea

The trachea then divides into the right & left main bronchus, supplying air to each lung

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The lower airways

Each main bronchus splits into increasingly smaller branches, called bronchioles, that reach every part of the lung tissue

The bronchioles finally divide into tiny sacs, called alveoli, where the exchange of oxygen (O2) for waste carbon dioxide (CO2) in the blood takes place

There are more than 300 million alveoli in each lung, providing a huge total surface area for oxygenation to take place (equivalent the to area of a tennis court!)

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Structure of the airways

Lower airways

nasal cavity

Upper airways

nasopharynx

epiglottis

tracheaoesophaguslarynx

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The lungs are the organs that allow us to breathe Each lung is joined to a main bronchus, which is then

attached to the trachea (windpipe)

The lungs are surrounded by a thin membrane called the pleura

Each lung is divided into regions called lobes

The lungs have a soft, spongy texture that allows them to stretch as we take a breath

The inside of the lung contains numerous airways that divide many times to resemble the branches of a tree

The lungs

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Structure of a lung

Alveolar sacs

Lungs

Windpipe (Trachea)

Lung tissue

Bronchus

Bronchiole Pleural membrane

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Lung tissue has a very rich blood supply

This allows as much blood as possible to pass through the alveoli (air sacs) for oxygenation

The oxygenated blood travels to the heart to be pumped to the body tissues

Deoxygenated blood containing waste CO2 travels to the heart & is then pumped back to the lungs for more O2 to be added (& so on…)

This movement of blood between the heart & lungs is called the pulmonary circulation

Blood vessels

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Blood vessels

Pulmonary circulation

Lung Capillaries

Left heart

To Body

From Body

Right heart Blood vessels in the lung

Pulmonary Vein

Pulmonary Artery

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Various muscles are required to contract & relax in order to move air in & out of the lungs

Respiratory muscles

Intercostal Muscles

Diaphragm

These are called the ‘respiratory muscles’ and include the

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Respiratory muscles

Diaphragm A large, dome-shaped muscle that divides the chest from the

abdomen The base of each lung is attached to it It contracts & flattens, pulling the lungs down to expand them

& opening the chest

Intercostal muscles Lie between the ribs They contract to pull the ribs up & out, opening up the chest

& expanding the lungs

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Respiratory muscles

Diaphragm

LarynxTrachea

Lung

Sternum

Nasopharynx

Diaphragm

Intercostal muscles

Intercostals (shaded)

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Breathing

how oxygen gets in

how carbon dioxide is removed

mechanisms for breathing

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The air we breathe passes through the upper airways first; nasopharynx, larynx, trachea & main bronchi

It then enters the lower airways of the lungs; small bronchi & bronchioles

Finally, the air enters the many tiny air sacs, or alveoli

How does oxygen get in?

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The alveoli are covered with microscopic, thin-walled blood vessels, called capillaries

O2 from the air is taken up into the blood within these capillaries, it then flows into the larger blood vessels & eventually ends up in the heart

Oxygenated blood is pumped out of the heart & into the blood vessels supplying the body’s tissues

Upon reaching the tissues, the O2 is released & the blood is said to be deoxygenated

How does oxygen get to the tissues?

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Waste CO2 produced by the cells is collected in the blood & travels back to the heart via the circulation

This deoxygenated blood is pumped from the heart into the blood vessels of the lung, eventually arriving in the capillaries

The capillaries lining the alveoli release CO2 into the air sacs, it then travels up the airways & out of the body into the atmosphere

How is carbon dioxide removed?

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This increase in chest volume makes the pressure inside the body lower than that outside the body

To move air into the lungs, the volume of the chest must be made to increase by contracting the respiratory muscles;Intercostals – pull ribs up & outDiaphragm – flattens downward, stretching lungs

This causes air to be sucked down the airways & into the lungs

How do we breathe in?

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Mechanism of breathing in

contractingDiaphragm

(Inspiration)

inspiration

Intercostals(Inspiration)

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How do we breathe out?

Moving air out of the lungs involves reducing chest volume by relaxing the respiratory muscles; Intercostals – ribs move in & down Diaphragm – pushes upwards

This decrease in chest volume makes the pressure inside the body higher than that outside

This causes air to be squeezed out of the lungs & up into the airways

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Mechanism of breathing out

Diaphragm(Expiration)

expiration

relaxingIntercostals(Expiration)

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Lung Function

gaseous exchange

respiration

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This is the addition of oxygen to the blood & the removal of waste carbon dioxide from it; i.e. it is the ‘exchange’ of one gas (CO2) for another (O2)

Gaseous exchange takes place in the air sacs of the lung, called the alveoli

The lining of each alveolus is very thin & is covered by a network of tiny blood vessels, called capillaries

O2 from inhaled air travels across the alveolar lining & enters the capillaries

Here, it is taken up by red blood cells in a special oxygen-carrying molecule called haemoglobin

Gaseous exchange: O2

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Waste CO2 must also be removed from the body

CO2 is released from the cells & taken up by the tissue capillaries, where it dissolves into the blood

CO2 is then carried in the blood vessels until it eventually reaches the capillaries that line the lung alveoli

CO2 travels out of the capillaries & across the alveolar lining to enter the ‘airway tree’

CO2 is then pushed out of the body during expiration

Gaseous exchange: CO2

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This is the process whereby cells breakdown O2 & nutrient (sugar) to release energy

CO2 is formed as a waste product during this process

Respiration can be expressed in this simplified equation:

Cellular respiration

O2 + sugar (oxygen) (water)(carbon

dioxide)

+ CO2 + H20energy

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Lung Capacity

lung capacity

lung capacity & fitness

effects of exercise

effects of smoking

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The amount of air breathed in/out during normal breathing is called the tidal volume

The largest amount of air that can be forced out of the lungs after taking as big a breath in as possible is called the vital capacity

The amount of air left behind is called the residual volume

Lung function is measured using a peak flow meter or a more complex machine called a spirometer

Lung capacity

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Lung capacitynormal breaths maximum exhalation

Tidal volume

Residual volume

Vital capacity

Total lung

capacity

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Lung capacity varies with age, sex, body shape, & level of fitness

‘Lung capacity’ is not the same as ‘respiratory fitness’

Respiratory fitness is determined by measuring the maximum amount of O2 that can be used by a person’s body, this is called VO2max

The higher VO2max the fitter the individual

Lung capacity & fitness

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The respiratory system responds to the demands of exercise

More O2 is required by the muscles & more CO2 is produced for removal

Breathing rate increases

Depth of breathing increases (maximum = vital capacity)

Blood flow through lungs increases

Effect of exercise

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Exercise

Exercise keeps the lungs in good condition

Gives your heart & lungs a good workout

Promotes a healthy lifestyle

Improves your quality of life

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Smoking damages your lungs

Reduces the amount of O2 that can be carried in the blood

Damages the lining of the airways & increases the amount of mucus produced

Reduces alveolar function

Increases the risk of lung infection, emphysema, bronchitis, asthma, & lung cancer

Effect of smoking

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Smoking & fitness

Smoking damages your fitness

Reduces lung vital capacity

Reduces aerobic fitness

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Respiratory system: summary

Respiratory system = lungs + airways + blood supply + muscles

Exercise keeps the respiratory system healthy

Exercise improves respiratory fitness

Adds O2 to blood & removes CO2 from it

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Backcontentsnext cardiovascularrespiratorymusculo-skeletaldiet & healtheffect of exercise A guide to respiratory fitness THE RESPIRATORY SYSTEM main listing