Download THE RESPIRATORY SYSTEM

THE RESPIRATORY SYSTEM
Air Supply
The wind beneath my wings
The Length and Breath of it..
• The Anatomy of the Respiratory Tract
• Mechanism of Respiratory movements
• The measurements of Pulmonary Function
Respiratory Organs
• Nose and nasal cavities
• Pharynx
• Larynx
• Trachea
• Bronchi -2
• Lungs and pleura
• Muscles of respiration
The Nose Job
• This cavity is divided into 2 halves separated by
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the Nasal Septum
The borders of the cavity are mostly bones of
the face and skull with the cartilages anteriorly
The cavity leads to the pharynx with their
meeting point – the Naso-pharynx.
The Para nasal sinuses –
maxillary/frontal/sphenoid/Ethmoid , all drain
into the nasal cavity.
The lining is a vascular mucous membrane
made of ciliated columnar epithelium which
produces mucous.
Functions of the nose
• Warming – by high vascularity
• Filtering – by hair in nostrils & sticky
mucous
• Moistening – picked up while flowing over
the mucous membrane
• Special sense of smell – endings of 1st
cranial nerve – olfactory which are
exposed by the pores in the cribriform
plate (part of Ethmoid bone)
Look at your nose- the inside story
The Pharynx
• It is a tube around 12-14cm long which runs
from the base of the skull to the position of
the 6th cervical vertebrae.
• It is lined by mucous membrane and has a
strong smooth muscle layer that helps to
propel food into the oesophagus.
• This lower end is narrower.
Pharynx – the 3 acts
Act 1 – Nasopharynx
• Nasal part above soft palate
• Auditory tubes drain into it
• Contains the nasal tonsils (adenoids) that
atrophy after age 7.
Act 2 - Oropharynx
• Oral part
• Palatine tonsils – that usually get
repeatedly infected due its position.
• The Uvula – that separates the oral and
nasal cavities during the act of swallowing.
Act 3 - Laryngopharynx
• The laryngeal part
• Composed of mucous membrane layer, fibrous
layer and muscle layer
Functions of Pharynx
• Passage for food and air
• Warming and humidifying air
• Taste – olfactory nerve ends in wall
• Hearing – auditory tube allows sound
to enter the middle ear
• Protection – lymphatic tissue – the
tonsils
Larynx
• The voice box – extends from tongue
to the trachea
• Composed of 3 main, different sized
cartilages, attached to each other by
ligaments.
• The smaller cartilages are involved in
voice production.
Three of the Throat
Thyroid
• Most prominent, lined by ciliated columnar
epithelium – whose function is to produce
mucous that traps foreign bodies and propels
them upwards.
Cricoid
• Ring shaped, encircles the larynx supportive
role
Epiglottis
• Responsible for closing the tracheal opening
when food is swallowed, to prevent choking.
Functions of Larynx
• Production of sound – through
vibration of vocal cords
• Speech
• Protection of lower respiratory
tract – epiglottis
• Passageway for air
• Humidifying, warming and filtering
of air
Trachea
• It is the continuation of the larynx beneath the
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epiglottis.
Around 10 cm long and has a series of 16-20
cartilages which share a wall with the
oesophagus posteriorly.
It ends at around the 5th thoracic vertebra,
where it bifurcates into the Left & Right
Bronchus- connected to the lung
Inner lining of ciliated columnar epithelium
which contains mucous producing cells
Functions of Trachea
Support and patency
• The cartilages prevent kinking/obstruction in
head/neck movements
• As its attached to oesophagus –allows it’s
expansion
• Prevent collapse during pressure alteration
during breathing
Mucociliary escalator
• Upward movement of cilia make sure the mucous
moves upward as it cleans the air. With it being
either swallowed or expectorated
Also cough reflex on irritation of nerve endings,
warming, humidifying and filtering of air.
Bronchi and its branches
• The right (shorter) divides
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into 3 further lobar branches
– lobes of lungs, but only 2
for the left bronchus
They then become smaller
secondary and even smaller
tertiary bronchi
Those then divide into
smaller bronchioles &
Respiratory bronchioles
Bronchi and bronchioles
• Lined with ciliated columnar
epithelium
• No cartilage only thick smooth muscle
• The lining epithelium changes in
bronchiole – cuboidal epithelium
Non-breathing functions
• Control of air entry by muscle
contraction
• Warming, support and patency
• Cleansing & cough reflex
Walls that breathe- the Alveoli
• Single layer of squamous epithelium in
alveolar ducts and alveoli
• Surrounded by network of capillaries with
only 1 layer of cells separating- essential
exchange of gases
• Special chemical – Surfactant, which
maintains hydration, reduces surface tension
thereby preventing collapse of alveoli during
expiration
Functions
• External respiration
• Defence against microbes
• Warming and humidifying
Lung story
• 2, cone shaped, on either side of heart
Major markings
• Apex – top or supraclavicular
• Base – bottom on Diaphragm
• Costal surface – front/side, convex, with
costal cartilages, intercostal muscles &
ribs
• Medial surface – inner, concave, with
triangular hilum, point of entry/exit of
vessels
• Hilum- root of lung
Look
at the
Lung
Hilum – the passage
Structures that enter/exit through
the Hilum – for each lung
• 1 Bronchus
• 1 Pulmonary artery
• 2 Pulmonary veins
• 1 Bronchial artery
• Bronchial veins
• Lymph vessels
• ANS nerves
Pleura
• It is a closed sac of serous membrane
2 layers• Visceral Pleura – attached to lung
• Parietal Pleura – attached to thoracic cavity
• Space in between – pleural cavity containing
serous fluid – which allows frictionless
gliding of layers over each other during
respiration
• Serous fluid secreted by epithelial cells of
pleura and its puncture would lead to
collapsed lung.
Intercostal muscles
• Attached between Ribs
• Their contraction and
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expansion allow for rib
movement, increasing and
decreasing thoracic volume
Types- internal and external
Allow the rib cage to increase
in size laterally, anterioposteriorly and vertically
Diaphragm
• Dome shaped
with central
tendon- attached
to lower ribs.
• Moves upward in
expiration and
downwards in
inspiration
• Nerve supply –
Phrenic Nerve
Composition of Air
• Each gas has its own partial pressure
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Nitrogen
Oxygen
Carbon-dioxide
Water vapour
Inert gases
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corresponding to its proportion
The composition of alveolar air is
constant, contains more CO2 and
less O2
Gas exchange between the blood
and alveoli is continuous and
independent of the respiratory cycle
Dead space 150 ml of air – mix of
alveolar and atmospheric air
Respiration – Gas Exchange
• The exchange occurs
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when there is a
difference in the partial
pressures, across a
semi-permeable
membrane
Gases always move
from high to low
concentration until
equilibrium
Aided by huge surface
area of membrane and
slow flow of blood
External respiration
• Exchange between the
alveoli and blood. CO2
moves from high conc. in
capillary to alveoli and
opposite for O2
Internal respiration
• Exchange between blood
and body cells. O2 moves
from high conc. in blood to
low in cells and opposite
for CO2
Pulmonary Function
• Pulmonary function tests - a broad range of tests
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that measure how well the lungs take in and
exhale air and how efficiently they transfer oxygen
into the blood.
Spirometer - measures how well the lungs exhale.
The information gathered during this test is useful
in diagnosing certain types of lung disorders, but is
most useful when assessing for obstructive lung
diseases (especially asthma and chronic
obstructive pulmonary disease, COPD).
Lung function Measurement
Terminology and Definitions
• FVC - Forced Vital Capacity - after the patient has
taken in the deepest possible breath, this is the
volume of air which can be forcibly and maximally
exhaled out of the lungs until no more can be
expired. FVC is usually expressed in units called
liters. This PFT value is critically important in the
diagnosis of obstructive and restrictive diseases.
• FEV1 - Forced Expiratory Volume in One Second this is the volume of air which can be forcibly
exhaled from the lungs in the first second of a
forced expiratory maneuver. It is expressed as
liters. This PFT value is critically important in the
diagnosis of obstructive and restrictive diseases.
• PEFR - Peak Expiratory Flow Rate - this is maximum
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flow rate achieved by the patient during the forced
vital capacity maneuver beginning after full
inspiration and starting and ending with maximal
expiration - it can either be measured in L/sec or
L/min - this is a useful measure to see if the
treatment is improving obstructive diseases like
broncho-constriction secondary to asthma.
FEF - Forced Expiratory Flow - Forced expiratory
Flow is a measure of how much air can be expired
from the lungs. It is a flow rate measurement. It is
measured as liters/second or liters/minute. The FVC
expiratory curve is divided into quartiles and
therefore there is a FEF that exists for each quartile.
The quartiles are expressed as FEF25%, FEF50%, and
FEF75% of FVC.
• MVV - Maximal Voluntary Ventilation - this value is
determined by having the patient breathe in and out
as rapidly and fully as possible for 12 -15 seconds - the
total volume of air moved during the test can be
expressed as L/sec or L/min - this test parameter
reflects the status of the respiratory muscles,
compliance of the thorax-lung complex, and airway
resistance. Surgeons like this test value because it is a
quick and easy way to assess the strength of the
patient's pulmonary musculature prior to surgery.
MVV can therefore be viewed as a measure of
respiratory muscle strength. One major cautionary
note is that this test is effort dependent and therefore
can be a poor predictor of true pulmonary strength
and compliance.
BREATHE IN…
BREATHE OUT…….!
Dr Anjali Hariharan