THE RESPIRATORY SYSTEMTHE RESPIRATORY SYSTEM

Air SupplyAir SupplyThe wind beneath my wingsThe wind beneath my wings

The Length and Breath of it..The Length and Breath of it..

• The Anatomy of the Respiratory TractThe Anatomy of the Respiratory Tract

• Mechanism of Respiratory movementsMechanism of Respiratory movements

• The measurements of Pulmonary FunctionThe measurements of Pulmonary Function

Respiratory OrgansRespiratory Organs

• Nose and nasal cavitiesNose and nasal cavities• PharynxPharynx• LarynxLarynx• TracheaTrachea• Bronchi -2Bronchi -2• Lungs and pleuraLungs and pleura• Muscles of respirationMuscles of respiration

The Nose JobThe Nose Job

• This cavity is divided into 2 halves separated by 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 noseFunctions 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 storyLook at your nose- the inside story

The PharynxThe Pharynx

• It is a tube around 12-14cm long which runs It is a tube around 12-14cm long which runs from the base of the skull to the position of from the base of the skull to the position of the 6the 6thth cervical vertebrae. cervical vertebrae.

• It is lined by mucous membrane and has a It is lined by mucous membrane and has a strong smooth muscle layer that helps to strong smooth muscle layer that helps to propel food into the oesophagus.propel food into the oesophagus.

• This lower end is narrower.This lower end is narrower.

Pharynx – the 3 actsPharynx – the 3 acts

Act 1 – Act 1 – NasopharynxNasopharynx• Nasal part above soft palateNasal part above soft palate• Auditory tubes drain into itAuditory tubes drain into it• Contains the nasal tonsils (adenoids) that Contains the nasal tonsils (adenoids) that

atrophy after age 7.atrophy after age 7.Act 2 - Act 2 - OropharynxOropharynx • Oral partOral part• Palatine tonsils – that usually get repeatedly Palatine tonsils – that usually get repeatedly

infected due its position.infected due its position.• The Uvula – that separates the oral and The Uvula – that separates the oral and

nasal cavities during the act of swallowing.nasal cavities during the act of swallowing.

Act 3 - Act 3 - LaryngopharynxLaryngopharynx• The laryngeal partThe laryngeal part• Composed of mucous membrane layer, fibrous Composed of mucous membrane layer, fibrous

layer and muscle layer layer and muscle layer

Functions of PharynxFunctions of Pharynx

• Passage for food and airPassage for food and air• Warming and humidifying airWarming and humidifying air• Taste – olfactory nerve ends in wallTaste – olfactory nerve ends in wall• Hearing – auditory tube allows sound Hearing – auditory tube allows sound

to enter the middle earto enter the middle ear• Protection – lymphatic tissue – the Protection – lymphatic tissue – the

tonsilstonsils

Larynx Larynx

• The voice box – extends from tongue The voice box – extends from tongue to the tracheato the trachea

• Composed of 3 main, different sized Composed of 3 main, different sized cartilages, attached to each other by cartilages, attached to each other by ligaments. ligaments.

• The smaller cartilages are involved in The smaller cartilages are involved in voice production.voice production.

Three of the ThroatThree of the ThroatThyroid • 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

roleEpiglottis • Responsible for closing the tracheal opening

when food is swallowed, to prevent choking.

Functions of LarynxFunctions 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 Trachea

• It is the continuation of the larynx beneath the 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 TracheaFunctions of TracheaSupport and patencySupport 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 breathingMucociliary escalatorMucociliary escalator• Upward movement of cilia make sure the mucous Upward movement of cilia make sure the mucous

moves upward as it cleans the air. With it being moves upward as it cleans the air. With it being either swallowed or expectoratedeither swallowed or expectorated

Also cough reflex on irritation of nerve endings, Also cough reflex on irritation of nerve endings, warming, humidifying and filtering of air.warming, humidifying and filtering of air.

Bronchi and its branchesBronchi and its branches

• The right (shorter) divides The right (shorter) divides into 3 further lobar branches into 3 further lobar branches – lobes of lungs, but only 2 – lobes of lungs, but only 2 for the left bronchusfor the left bronchus

• They then become smaller They then become smaller secondary and even smaller secondary and even smaller tertiary bronchitertiary bronchi

• Those then divide into Those then divide into smaller bronchioles & smaller bronchioles & Respiratory bronchiolesRespiratory bronchioles

Bronchi and bronchiolesBronchi and bronchioles• Lined with ciliated columnar

epithelium• No cartilage only thick smooth muscle• The lining epithelium changes in

bronchiole – cuboidal epitheliumNon-breathing functions• Control of air entry by muscle

contraction• Warming, support and patency• Cleansing & cough reflex

Walls that breathe- the AlveoliWalls 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 storyLung story

• 2, cone shaped, on either side of heartMajor 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 Look at the at the LungLung

Hilum – the passageHilum – the passage

Structures that enter/exit through Structures that enter/exit through the Hilum – for each lungthe Hilum – for each lung

• 1 Bronchus1 Bronchus• 1 Pulmonary artery1 Pulmonary artery• 2 Pulmonary veins2 Pulmonary veins• 1 Bronchial artery1 Bronchial artery• Bronchial veinsBronchial veins• Lymph vesselsLymph vessels• ANS nervesANS nerves

Pleura Pleura

• It is a closed sac of serous membraneIt is a closed sac of serous membrane2 layers-2 layers-• Visceral Pleura – attached to lungVisceral Pleura – attached to lung• Parietal Pleura – attached to thoracic cavityParietal Pleura – attached to thoracic cavity• Space in between – pleural cavity containing Space in between – pleural cavity containing

serous fluid – which allows frictionless serous fluid – which allows frictionless gliding of layers over each other during gliding of layers over each other during respirationrespiration

• Serous fluid secreted by epithelial cells of Serous fluid secreted by epithelial cells of pleura and its puncture would lead to pleura and its puncture would lead to collapsed lung. collapsed lung.

Intercostal musclesIntercostal muscles

• Attached between RibsAttached between Ribs• Their contraction and Their contraction and

expansion allow for rib expansion allow for rib movement, increasing and movement, increasing and decreasing thoracic volumedecreasing thoracic volume

• Types- internal and externalTypes- internal and external• Allow the rib cage to increase Allow the rib cage to increase

in size laterally, anterio-in size laterally, anterio-posteriorly and verticallyposteriorly and vertically

Diaphragm Diaphragm

• Dome shaped with Dome shaped with central tendon- central tendon- attached to lower attached to lower ribs. ribs.

• Moves upward in Moves upward in expiration and expiration and downwards in downwards in inspirationinspiration

• Nerve supply – Nerve supply – Phrenic NervePhrenic Nerve

Composition of AirComposition of Air

• NitrogenNitrogen• OxygenOxygen• Carbon-dioxideCarbon-dioxide• Water vapourWater vapour• Inert gasesInert gases

• Each gas has its own partial pressure Each gas has its own partial pressure corresponding to its proportioncorresponding to its proportion

• The composition of alveolar air is The composition of alveolar air is constant, contains more CO2 and constant, contains more CO2 and less O2less O2

• Gas exchange between the blood Gas exchange between the blood and alveoli is continuous and and alveoli is continuous and independent of the respiratory cycleindependent of the respiratory cycle

• Dead space 150 ml of air – mix of Dead space 150 ml of air – mix of alveolar and atmospheric airalveolar and atmospheric air

Respiration – Gas ExchangeRespiration – Gas Exchange

• The exchange occurs 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 FunctionPulmonary Function

• Pulmonary function tests - a broad range of tests 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 MeasurementLung function MeasurementTerminology 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 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 IN… BREATHE OUT…….!BREATHE OUT…….!

Dr Anjali HariharanDr Anjali Hariharan