A&P1, Chapter 10
Tutor: Eleshia Howell
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 As we have previously learned in our study of the
digestive system, the cells of the body need
energy for all of their metabolic activities.
 Most of this is derived from chemical reactions
which can only take place in the presence of
Oxygen (aerobic catabolism).
 The main waste product produced is carbon
 The respiratory system provides the route of
supply of oxygen, and excretion of carbon
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 The respiratory system, organised into Upper
and Lower respiratory systems, is composed of
structures involved in ventilation and gas
 Upper = nose, nasal cavity, paranasal sinuses,
pharynx. Purpose: filter, warm, humidify the air.
 Lower = Larynx, trachea, bronchi, bronchioles and
alveoli of the lungs.
 The term respiratory tract refers to the
passageways that carry air to and from the
exchange surfaces of the lungs.
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 The condition of the atmospheric air varies
according the to external environment. Air
breathed in through the passageways is warmed
/ cooled to body temperature, moistened and
‘cleaned’ and distributed throughout the body
via the blood.
 Exchange of gases between the lungs and the
blood is called external respiration
 Exchange between the blood and cells is called
internal respiration.
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The organs / structures of the resp. system are:
 Nose
 Pharynx
 Larynx
 Trachea
 Two bronchi
 Bronchioles & smaller air passages
 Two lungs & their pleura
 Muscles of respiration (intercostals &
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Functions of Respiratory
1. Provide extensive surface area for gas
exchange between air & circulating blood
2. Movement of air to & from exchange
3. Protecting respiratory surfaces from
dehydration, temperature changes & other
environmental variations; defence against
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4. Producing sounds involved in speaking,
singing and other forms of communication
5. Facilitating detection of olfactory stimuli
(olfactory receptors in nasal cavity).
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Nose / Nasal cavity
 The main route of air entry.
 Nose is a large irregular cavity divided into
two equal sections by the septum.
 The anterior nares, or nostrils, are the
openings into the nasal cavity; nasal hairs and
sticky mucous serve to trap foreign particles
and pathogens as part of non-specific
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 The nose is lined with highly vascular ciliated
columnar epithelium which contains mucous
secreting goblet cells.
 the conchae, within the nasal cavity, increase
the surface area and cause turbulence,
spreading the air across the nasal surfaces,
maximising the warming, filtering and
humidifying functions.
 Warming ~ occurs due to the immense
vascularity of the mucosal lining.
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 Filtering & cleaning ~ hairs trap larger
particles, mucous traps smaller ones such as
dust & microbes. Mucous also protects the
underlying epithelium from irritation &
prevents drying. The cilia move the trapped
particles towards the throat, to be either
swallowed or coughed up (expectorated).
 Humidification ~ as air travels over the moist
mucosa it becomes saturated with water
vapour. Irritation of the mucosa = sneezing, a
reflex action that forcibly expels an irritant.
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 Smell ~ the nose is the organ for our sense of
smell (olfaction). As we have already
discovered during our study of Special Senses
there are millions of specialised sensory nerve
endings in the roof of the nose which, when
stimulated by airborne odours, carry signals
via the olfactory nerves to the brain where
the smell is perceived.
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 Encompasses the nasopharynx, oropharynx
and laryngopharynx.
 Dual purpose – passageway for food and air.
 Is also responsible for warming & humidifying
the air as it is inhaled
 Assists hearing – air from nasopharynx enters
the auditory tubes to establish the
atmospheric pressure required for tympanic
membranes to detect sound waves.
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 Aka ‘voice box’...links the laryngopharynx and
the trachea at the level of 3rd- 6th Cervical
 During puberty, in males the larynx enlarges
and becomes more prominent (adam’s apple)
creating a deeper voice.
 It is composed of several sections of cartilage
attached by ligaments & membranes.
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Anterior view of Larynx, p238
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 Thyroid cartilage – most prominent, lays at the
anterior throat, visible adam’s apple part. Bound
by ligaments to hyoid bone; site of numerous
attachments for anterior neck muscles.
 Cricoid cartilage – lies below the thyroid cartilage,
completely encircling the larnyx. The lower border
marks the end of the upper respiratory tract.
 Arytenoid cartilages – paired pieces of cartilage
situated on top of cricoid. Provide attachment for
vocal cords.
 Epiglottis – flexible stalk of cartilage emanating
from the anterior thyroid cartilage ; rises obliquely
upwards to behind the tongue & hyoid bone,
acting as a lid, to close off larynx during
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 Comprise of two folds of mucous membrane
with cord-like free edges, extending from the
inner wall of the thyroid prominence
anteriorly, and the arytenoid cartilages
 When the muscles controlling the vocal cords
are relaxed, the vocal cords open and the
passageway for air arising from the larynx is
clear  cords abducted.
 When the muscles contract, the cords are
stretched tightly across the larynx – adducted
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 Production of sound ~
 Pitch: length & tightness of cords
 Volume: depends upon force of vibration
 Resonance/ Tone: determined by shape of the
mouth, position of tongue & lips, facial muscles &
air in paranasal sinuses.
 Speech – when sounds produced by vocal
cords are manipulated by the tongue, cheeks
& lips
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 Protection of lower respiratory tract – during
swallowing the larynx moves upwards to
block the opening to the trachea, ensuring
food passes into the oesophagus.
 Airway – passageway for air to enter trachea
 Humidifying, filtering & warming .
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 Aka ‘windpipe’ extends down from larynx,
dividing into right & left bronchi at approx T5
 A series of C-shaped rings of hyaline cartilage
are embedded into the anterior surface of the
trachea to help stabilise & protect the airway.
 Parasympathetic stimulation (via branches of
Vagus nerve) constricts the trachea;
Sympathetic stimulation (via sympathetic
ganglia) dilates it.
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 Support & Patency: tracheal cartilage holds it
permanently open (patent) but the soft tissue
at the posterior of the bands allows flexibility
so that the trunk can move freely without
obstructing or kinking . The absence of
cartilage posteriorly also allows the trachea
to dilate & constrict in response to nerve
stimulation, and to allow indentation as bolus
is swallowed down oesophagus.
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 Cough reflex: nerve endings in the larynx,
trachea and bronchi are sensitive to irritation,
generating impulses conducted along the
Vagus nerve to the respiratory centre of the
brain stem, initiating a motor reflex response
to expel the irritant. The ciliated mucous
membrane cells assist the movement of
captured particles upwards towards the
larynx to be either swallowed or coughed out.
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 Two lungs, one each on either side of the
midline in the thoracic cavity.
 Cone shaped with an apex, base, tip; costal &
medial surfaces.
 The concave medial surface of the lung has a
hilum (indented area) where structures enter/
exit the lung, eg primary bronchus,
pulmonary artery, pulmonary veins (2),
bronchial artery & vein, lymphatics & nerves.
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 The area between the lungs (mediastinum) is
occupied by the heart, great vessels, trachea,
right & left bronchi, oesophagus, lymph
nodes/vessels and nerves.
 The right lung is divided into 3 lobes (superior,
middle, inferior).
 The left lung is smaller due to the heart
occupying space just left of the midline. It is
divided into only two lobes (superior &
 The divisions between lobes are called
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 The pleura consists of a closed sac of serous
membrane (one for each lung) containing a
small amount of serous fluid. The lung is
invaginated into this sac so that it forms two
 Visceral pleura – adherent to the lung, covering
each lobe & passing into the fissures
 Parietal layer – adherent to the inside of the chest
wall & thoracic surface of diaphragm.
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 The pleural cavity is only a potential space &
contains no air. The two layers of pleura are
separated by a thin layer of serous fluid,
allowing them to glide over each other,
preventing friction during breathing. The
serous fluid is excreted by the epithelial cells
of the pleural membrane.
 If either layer of pleura is punctured, the
underlying lung collapses.
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 The interior of the lungs are composed of
 The bronchi
 Alveoli
 Connective tissue
 Blood vessels
 Lymph vessels
 Nerves
...all embedded in an elastic connective
tissue matrix.
 Each lobe consists of a large number of
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Pulmonary blood supply
 The pulmonary trunk divides into left and
right pulmonary arteries, transporting
deoxygenated blood to each lung.
 Inside the lungs, each artery divides into
numerous branches, eventually ending in a
dense capillary network around the walls of
the alveoli.
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 The walls of the alveoli and capillaries are just
a single layer of epithelial cells, allowing the
rapid diffusion of gases across the
 The pulmonary capillaries join to form two
pulmonary veins in each lung, leaving the
lung at the hilum to carry oxygenated blood
to the left atrium of the heart.
 The innumerable capillaries and blood vessels
are supported by connective tissue.
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Bronchi & Bronchioles
 Two primary bronchi are formed when the
trachea divides at T5.
 The right bronchus is wider, shorter & more
vertical than the left and is more prone to
obstruction by an inhaled foreign body. It
sub-divides into 3 branches, one to each lobe,
before dividing further into numerous smaller
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 The left bronchus is shorter and narrower,
dividing into only 2 branches (one to each
lobe) before subdividing into progressively
smaller branches as it infiltrates further into
the lung tissue.
 The bronchial walls are composed of the
same tissue as the trachea (ciliated columnar
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 As the bronchi divide and become
progressively smaller, their structure also
changes to match their function:
 Cartilage – rigid cartilage would interfere with
the expansion of the lung tissue, hindering
gas exchange, so it is present only in the
larger airways. The cartilage rings gradually
become much smaller plates until, at the
bronchiole level, become non-existent.
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 Smooth muscle – as the cartilage disappears it
is replaced by smooth muscle, allowing the
diameter of the airways to be increased or
decreased (via ANS control) to regulate
 Epithelial lining – ciliated epithelium is
gradually replaced with non-ciliated
epithelium and goblet cells disappear.
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 The Vagus nerve supplies the lungs...
 Parasympathetic stimulation causes contraction
of the smooth muscle in the bronchial tree
(bronchoconstriction) while sympathetic
stimulation causes bronchodilation.
 Lymph is drained from the walls of the air
passes in a network of lymph vessels through
nodes situated around the trachea and
bronchial tree, then into the thoracic duct on
the left, right lymphatic duct on the other
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 Control of airway – diameter is altered
according to ANS stimulation
 Warming & humidifying
 Support & patency
 Removal of particulate matter
 Cough reflex
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Bronchioles & Alveoli
 The bronchioles subdivide into respiratory
bronchioles, alveolar ducts and large
numbers of air sacs known as alveoli (approx
150million in an adult lung). It is in these
structures that gas exchange occurs.
 As the airways progressively divide and get
smaller, their walls gradually become thinner
until muscle & connective tissue disappear,
leaving a single layer of squamous epithelial
cells in the alveolar ducts & alveoli.
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 These distal respiratory passages are
supported by loose, elastic connective tissue
in which macrophages, fibroblasts, nerves &
blood / lymph vessels are embedded.
 The alveoli are surrounded by a dense
network of capillaries.
 In healthy lung tissue the extensive air spaces
are clearly seen as a honeycomb-like
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 Lying between the squamous cells are septal
cells that secrete surfactant, a phospholipid
fluid which prevents the alveoli from drying
out. It also helps to reduce surface tension &
prevent the alveoli from collapsing during
expiration. Secretion of surfactant begins at
35wks gestation.
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 The exchange of gases between body cells
and the environment.
 Involves 2 processes:
 Breathing – movement of air into and out of the
 Exchange of gases – in the lungs (external
respiration) and in the tissues (internal
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 Supplies oxygen to the alveoli and eliminates
carbon dioxide
 Expansion of the chest during inspiration
occurs due to muscular activity ~ partly
voluntary & partly involuntary.
 The main muscles used in normal, quiet
breathing are the external intercostal muscles
and the diaphragm.
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Intercostal Muscles –
 11 pairs of muscles that occupy the spaces
between the 12 pairs of ribs.
 Arranged in 2 layers – external (used during
inspiration) & internal (used during active
expiration, eg exercise).
 The 1st rib is fixed, so when the external
intercostal muscles contract they pull all the
other ribs upwards towards it. The size &
shape of the ribs encourages an outward
movement of the ribcage, enlarging the
thoracic cavity.
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Diaphragm –
 A dome shaped muscular structure
separating the thoracic cavity & the roof of
the abdominal cavity.
 It consists of a central tendon from which
muscle fibres radiate to attach to the lower
ribs and sternum, and to the vertebral column
 When the diaphragm is relaxed, the central
tendon is at level of T8; when it contracts, the
tendon is pulled downwards to T9,
lengthening the thoracic cavity.
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 This decreases pressure in the thoracic cavity
and increases the pressure in the abdominal
and pelvic cavities.
 The diaphragm is innervated by the Phrenic
nerves (branching from C3-5).
 Quiet, restful breathing is often referred to as
diaphragmatic breathing as 75% of the work
is done by the diaphragm.
 The external intercostals & the diaphragm
contract simultaneously, enlarging the
thoracic cavity in all directions.
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 When extra respiratory effort is required,
additional muscles are used.
 Forced inspiration ~ sternocleidomastoid
(SCM) and scalene muscles of the neck, help
to increase ribcage expansion.
 Forced expiration ~ internal intercostal
muscles and abdominal muscles (mainly
transverse & oblique) help to increase the
pressure in the thorax by applying a
squeezing action.
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 Other muscles which can aid respiration are:
 Serratus posterior superior (inspiration)
 Pectoralis Minor (forced inspiration)
 Quadratus Lumborum (forced expiration)
 Transversus Thoracis & Subcostales (forced
 Latissimus Dorsi (accessory)
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 The average respiratory rate is 12-15 breaths
per minute
 Each breath consists of 3 phases
 Inspiration
 Expiration
 Pause
 Breathing is dependent upon changes in
pressure and volume in the thoracic cavity
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 The underlying physical principal is that
increasing the volume of a container
decreases the pressure inside it, and that
decreasing the volume of a container
increases the pressure inside it.
 Since air flows from an area of high pressure
to one of low pressure, changing the pressure
inside the lungs determines the direction of
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 Diaphragm + external intercostal muscles
contract, expanding the thoracic cavity...
 Pressure in the pleural cavity decreases in
relation to the pulmonary cavity, causing the
lungs to expand...
 The resultant decrease in pulmonary cavity
pressure (compared to the atmospheric
pressure outside the body) causes air to be
drawn into the lungs.
 This active process also aids venous return to
the heart ~ respiratory pump.
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 When the diaphragm & external intercostals
relax, the build up of pressure in the
abdominal cavity increases the pressure in
thoracic & pulmonary cavities, pushing the air
out of the lungs.
 This is a passive process.
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Variables Affecting Breathing:
 Elasticity – the ability of the lung to return to
its normal shape after each breath. Loss of
elasticity necessitates forced expiration &
increased effort on inspiration.
 Compliance – the measure of stretchability of
the lungs (effort required to inflate alveoli).
Little effort is required to inflate healthy
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 Airway resistance – bronchoconstriction
means more respiratory effort is required to
inflate the lungs.
 The lungs and air passages are never empty,
but gas exchange only occurs at the site of
the alveoli, so the remaining capacity of the
respiratory passages is known as anatomical
dead space.
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Lung function testing is carried out to
determine respiratory function and are based
on the following parameters:
 Tidal Volume (TV) – the amount of air
passing in & out of the lungs during each
breath cycle (about 500ml at rest)
 Inspiratory Reserve Volume (IRV) – the extra
volume of air that can be inhaled during max
 Inspiratory Capacity (IC) – the amount of air
that can be inspired with maximum effort
 TV + IRV = IC
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 Functional Residual Capacity (FRC) – the
amount of air remaining in the passageways
and alveoli at end of quiet expiration.
 Expiratory Reserve Volume (ERV) – the
largest volume of air that can be expelled
during maximum expiration.
 Residual Volume (RV) – the volume of air
remaining in the lungs after forced expiration
(cannot be directly measured).
 Vital Capacity (VC) – maximum volume of air
able to move in and out of lungs
 VC = TV + IRV + ERV
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 Total Lung Capacity (TLC) – maximum
amount of air the lungs can hold. In adult,
approx 6L.
 Alveolar Ventilation – is the volume of air that
moves into and out of the alveoli per minute.
It is equal to the tidal volume – anatomical
dead space x respiratory rate.
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 Is a continuous and ongoing process across
the respiratory membranes.
 Diffusion of oxygen and carbon dioxide
depends on pressure differences, eg between
atmospheric air and blood, or between blood
and the tissues.
 Atmospheric Air is a mixture of gases:
oxygen, carbon dioxide, nitrogen, water
vapour and small quantities of inert gases (eg
Argon, Helium, Hydrogen, Methane).
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 Each gas in the mixture exerts a part of the
total pressure, proportional to its
concentration. Known as partial pressure
Composition of inspired & expired air. p250
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 Alveolar air is different from atmospheric air;
it is saturated with water vapour and contains
more CO2 and less O2. The saturation of
water vapour reduces the partial pressure of
all the other gases present.
 Exchange of gases occurs when a difference
in partial pressure exists across a semipermeable membrane. Gases move by
diffusion from higher concentration to lower
until equilibrium is established.
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 External respiration – the exchange of gases
between the alveoli and the blood in the
capillaries, across the respiratory membrane.
 Internal respiration – the exchange of gases
between the blood in the capillaries and the
body cells.
 O2 and CO2 are transported in the blood in
different ways...
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 Oxygen is carried in the blood in chemical
combination with haemoglobin (as
oxyhaemoglobin) as well as in plasma water
 Carbon dioxide, a waste product of
metabolism, is excreted by the lungs and is
transported by 3 mechanisms:
 As bicarbonate ions in the plasma
 Some carried in RBC’s
 Some dissolved in the plasma
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Control of Respiration
 Effective control of respiration enables the
body to regulate blood gas levels over a wide
range of physiological, environmental and
pathological conditions, and is normally
 Voluntary control is exerted during activities
such as speaking and singing, but is
overridden if blood CO2 rises.
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Respiratory Centre –
 Is formed by groups of nerves in the medulla,
the respiratory rhythmicity centre, which
controls the respiratory pattern (rate & depth
of breathing).
 Regular discharge of inspiratory neurones
within this centre set the rate and depth of
 Activity in the respiratory centre is adjusted
by nerves in the pons (pneumotaxic &
apneustic centres) in response to input from
other parts of the brain.
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 Motor impulses from the respiratory centre
pass in the Phrenic and Intercostal nerves to
the diaphragm & intercostal muscles.
Chemoreceptors –
 Respond to changes in the partial pressures
of O2 and CO2 in the blood and CSF. They are
located centrally and peripherally.
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 Central chemoreceptors are located on the
surface of the medulla oblongata and are
bathed in CSF. When arterial CO2 rises even
slightly, these receptors respond by
stimulating an increase in respiration. A small
reduction in O2 has the same but less
pronounced effect, but a substantial
reduction depresses breathing.
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 Peripheral chemoreceptors are situated in the
arch of the aorta & in the carotid bodies. They
are more sensitive to rises in blood CO2 than
to small decreases in blood O2 levels. Nerve
impulses generated here are conveyed by the
Glossopharyngeal & Vagus nerves to the
medulla and stimulate the respiratory centre.
An increase in blood acidity stimulates the
chemoreceptors, resulting in increased
ventilation, increased CO2 output and
increased blood pH.
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Exercise and respiration –
 Physical exercise increases both the rate and
depth of respiration to supply the increased
oxygen requirements of the muscles. The
increased respiratory effort persists even
after exercise stops in order to repay the
oxygen debt (to rid the cells of waste, lactic
acid etc)
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Other factors that influence respiration include:
 Speech, singing
 Emotional displays, eg crying, laughter, fear
 Drugs, eg sedatives, alcohol
 Sleep
 Temperature, eg fever, hypothermia.
Breathing may be modified by the higher brain
centres during these activities.
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Respiratory Changes at Birth
 The respiratory system of foetuses and
newborns differ in several important ways.
Before delivery, pulmonary arterial resistance
is high because the pulmonary vessels are
collapsed. The ribcage is compressed and the
lungs & airways contain only small amounts
of fluid but no air.
 During delivery the lungs are compressed
further; as placental connection is lost, blood
O2 levels fall and CO2 increases rapidly...
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 At birth, the newborn takes its first breath
through powerful contractions of the
diaphragm and external intercostal muscles.
The inhaled air must enter the respiratory
passages with enough force to overcomes
surface tension and inflate the bronchial tree
and most of the alveoli.
 The same drop in pressure that pulls air into
the lungs pulls blood into the pulmonary
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 The changes in blood flow and rise in O2
levels lead to the closure of the foramen
ovale and the ductus arteriosus.
 The exhalation that follows that first breath
fails to empty the lungs completely, keeping
the airways open; surfactant is secreted to
prevent alveolar collapse.
 Subsequent breaths complete the inflation of
all of the alveoli.
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Age & respiratory
 Many factors interact to reduce the efficiency
of the respiratory system in elderly
individuals. Three noteworthy examples are:
 Deterioration of elastic tissue, altering the
compliance of the lungs and their vital
 Arthritic changes can limit chest movement,
limiting respiratory volume.
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 Some degree of emphysema is normal in
individuals over 50, however, the extent
increases considerably with exposure to
cigarette smoke and other respiratory
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Pathologies of the
Respiratory System
 Infectious & inflammatory disorders of the
upper respiratory tract can be caused by
inhaling irritants and pathogens. Infections
are usually caused by viruses that lower the
resistance to other pathogens, allowing
bacteria to invade the tissues, producing
inflammation & exudate.
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 Common cold (Coryza) is usually caused by
the rhinoviruses and is highly infectious.
Symptoms include runny nose (rhinorrhoea)
sneezing, sore throat and slight fever.
 Influenza is caused by a different group of
viruses and produced far worse symptoms,
including very high fever and muscle pain.
Complete recovery can
take weeks and secondary
bacterial infections are
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 Sinusitis – usually spread by microbes from
the nose and pharynx to the mucous
membrane lining of the paranasal sinuses.
Congested mucous blocks the openings
between the nose and the sinuses, preventing
drainage of mucopurulent discharge.
Symptoms include facial pain and headache.
 Hayfever (allergic rhinitis) – hypersensitivity
to foreign antigens develops into acute
inflammation of the mucosa and conjunctiva.
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Obstructive Lung Disorders:
 Bronchitis – acute is usually secondary to a
bacterial infection of the bronchi (eg cold,
flu). Chronic is usually a progressive
inflammatory disease resulting from
prolonged irritation of the bronchial
 Emphysema – a chronic, progressive
condition where the destruction of alveolar
surfaces results in decreased surface area for
gas exchange. Characterised by shortness of
breath, unable to tolerate physical exertion.
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 Asthma – a common inflammatory disease of
the airways, associated with episodes of
reversible over-activity of the smooth muscle
in the airways. The mucous membrane &
muscle layers of the bronchi become
thickened and the mucous glands enlarge,
reducing airflow in the lower respiratory
tract. The walls swell and thicken with
inflammatory exudate and an influx of
inflammatory cells, especially eosinophils.
During an attack, spasmodic contraction of
bronchial muscle constricts the airway;
excessive secretion of thick, sticky mucous
further narrows the airway.
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(asthma cont’d)
 Inspiration is normal but only partial
expiration is achieved, so the lungs become
hyperinflated; there is severe dyspnoea and
wheezing. The duration of attacks varies from
minutes to hours. In severe cases the bronchi
may be obstructed by mucous plugs, leading
to acute respiratory failure, hypoxia and
possibly death.
(c)Eleshia Howell, 2012. All rights reserved.
 Cystic Fibrosis – a common genetic disorder
affecting 1 in 2500 babies. An estimated 5%
of people carry the recessive gene, which
must be present in both parents to cause the
disease. The secretions of all exocrine glands
have abnormally high viscosity, the most
severely affected are those of the lungs,
pancreas, intestines, biliary tract and
reproductive system (males). In less acute
stages there may be impairment of protein &
fat digestion.
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Restrictive Disorders:
 Are characterised by increasing stiffness of
lung tissue, making it harder to inflate the
lung and increasing the work of breathing.
Chronic restrictive disease is often associated
with progressive fibrosis caused by repeated
inflammation of the lungs.
 Pneumoconioses – a group of lung diseases
caused by inhaling dusts / work related
pollutants. Frequently affects people working
in coal / mineral mines, quarries, stone
masonry, sand blasting, glass / pottery.
(c)Eleshia Howell, 2012. All rights reserved.
Lung Infections:
 Pneumonia – infection of the alveoli
occurring when protective processes fail to
prevent inhaled or blood-borne microbes
from reaching and colonising the lungs.
Numerous causes.
 Tuberculosis – caused by mycobacterium;
highly infectious air-borne disease spread by
coughing, sneezing or droplet transmission.
Characterised by tubercles in lungs (walled
off infection sites), coughing of blood tinged
sputum, night sweats, fever & weight loss.
(c)Eleshia Howell, 2012. All rights reserved.
 Bronchial carcinoma – a very common
malignancy, with 90% occurring in smokers
(or passive smokers). Usually not detected
early, prognosis often poor. Tumour
fragments are spread by blood and lymph
producing metastases elsewhere in the body.
 Pleural mesothelioma – linked with exposure
to asbestos (particularly ‘blue’ asbestos).
Tumour involves both layers of the pleura and
as it grows obliterates the pleural cavity,
compressing the lung.
(c)Eleshia Howell, 2012. All rights reserved.
Lung Collapse:
 The clinical effects of all or part of a lung
depend on how much of the lung is affected.
 The four main causes of a collapsed lung:
 Obstruction of airway
 Impaired surfactant function
 Pressure collapse – when air or fluid enters the
pleural cavity, altering the pressure and
preventing lung expansion.
 Alveolar hypoventilation – may be due to pain
experienced on inspiration, post-operative, chest
(c)Eleshia Howell, 2012. All rights reserved.
(c)Eleshia Howell, 2012. All rights reserved.

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