Human Respiratory System As all living cells carry out respiration to release energy in order to maintain life, oxygen is needed and waste carbon dioxide

Human Respiratory Human Respiratory SystemSystem

• As all living cells carry out respiration to As all living cells carry out respiration to release energy in order to maintain life, release energy in order to maintain life, oxygen is needed and waste carbon oxygen is needed and waste carbon dioxide (toxic at high levels) produced dioxide (toxic at high levels) produced has to be gotten rid of continuouslyhas to be gotten rid of continuously

• Hence, all organisms have to exchange Hence, all organisms have to exchange gases with the surroundingsgases with the surroundings

• This process is called This process is called gas exchangegas exchange

Gas Exchange in Simple Gas Exchange in Simple AnimalsAnimals

O2

CO2

In small organisms, In small organisms, in which the surface in which the surface area-to-volume area-to-volume ratio is large (e.g.ratio is large (e.g. Amoeba Amoeba and and earthworm), gas earthworm), gas exchange occurs by exchange occurs by simple diffusion simple diffusion across the cell across the cell surfacesurface

Gas Exchange in Higher Order Gas Exchange in Higher Order AnimalsAnimals

• Larger organisms use specialized Larger organisms use specialized respiratory surfaces with a large respiratory surfaces with a large surface area-to-volume ratio for gas surface area-to-volume ratio for gas exchange as simple diffusion is not exchange as simple diffusion is not efficient enoughefficient enough

• e.g. fish use gills e.g. fish use gills

frogs use skin, mouth and lungsfrogs use skin, mouth and lungs

mammals (including humans) mammals (including humans) use lungsuse lungs

BreathingBreathing

Breathing Breathing involves two involves two processes:processes:

• VENTILATIONVENTILATION• GAS EXCHANGEGAS EXCHANGE

Ventilation vs. Gas Ventilation vs. Gas ExchangeExchange

• VentilationVentilation is the process of is the process of breathing in and breathing out of airbreathing in and breathing out of air

• Inhalation/InspirationInhalation/Inspiration – breathing in – breathing in • Exhalation/Expiration Exhalation/Expiration – breathing out– breathing out• Gas exchangeGas exchange is the exchange of is the exchange of

gases between the lungs and the gases between the lungs and the bloodblood



lungslungs

ribrib

heartheart

diaphragdiaphragmm

thoracithoracic c cavitycavity

Human Torso ModelHuman Torso Model

• Can you identify Can you identify all the parts that all the parts that are involved in are involved in breathing (i.e. the breathing (i.e. the breathing breathing system) in the system) in the human torso human torso model?model?

Nostrils and Nasal CavityNostrils and Nasal Cavity

• NostrilsNostrils – openings – openings on the noseon the nose

• Nasal cavityNasal cavity – the – the area inside the nosearea inside the nose

• The nasal cavity The nasal cavity and mouth cavity and mouth cavity are separated by are separated by the palate, allowing the palate, allowing a person to breathe a person to breathe and chew food at and chew food at the same timethe same time


• Air enters the nasal cavity through Air enters the nasal cavity through the two nostrilsthe two nostrils

• Inside the nasal cavity is Inside the nasal cavity is hairhair for for trapping large dust particlestrapping large dust particles

• The wall of the nasal cavity is lined The wall of the nasal cavity is lined with with ciliated epithelium (cilia)ciliated epithelium (cilia) and and mucus-secreting cellsmucus-secreting cells


• The mucus will moisten the incoming airThe mucus will moisten the incoming air• The mucus will also trap bacteria and The mucus will also trap bacteria and

dustdust• the beating cilia will move trapped the beating cilia will move trapped

particles towards the throat to be particles towards the throat to be coughed out or swallowedcoughed out or swallowed

• The nasal cavity also contains The nasal cavity also contains sensory sensory cellscells to detect chemicals in air to detect chemicals in air (sensation of smell)(sensation of smell)


• There are numerous blood vessels There are numerous blood vessels lying close to the surface of the nasal lying close to the surface of the nasal cavitycavity

• The blood vessels bring heat and help The blood vessels bring heat and help to warm up the incoming air to reach to warm up the incoming air to reach body temperaturebody temperature

• Therefore, air is warmed, moistened Therefore, air is warmed, moistened and filtered before entering the lungsand filtered before entering the lungs


Pharynx and LarynxPharynx and Larynx

• Air passes from the nasal cavity to the Air passes from the nasal cavity to the pharynxpharynx (a common passage for food (a common passage for food and air)and air)

• Air then enters the Air then enters the larynxlarynx, which is the , which is the beginning part of the beginning part of the tracheatrachea

• The larynx is consisted of The larynx is consisted of cartilagescartilages• The opening to the larynx is the The opening to the larynx is the glottisglottis• During swallowing, the During swallowing, the epiglottisepiglottis

covers the glottis to prevent food from covers the glottis to prevent food from entering the tracheaentering the trachea

Vocal CordsVocal Cords

• Inside the voice box (larynx) are two Inside the voice box (larynx) are two membranes called the membranes called the vocal cordsvocal cords

• When we talk, muscles contract to stretch When we talk, muscles contract to stretch the vocal cords and create tension. The the vocal cords and create tension. The gap between the cords becomes narrower, gap between the cords becomes narrower, leaving a very thin opening. As we talk, leaving a very thin opening. As we talk, we exhale air and this stream of air passes we exhale air and this stream of air passes through the narrow passage, causing the through the narrow passage, causing the vocal cords to vibrate and produce soundvocal cords to vibrate and produce sound

• Tension of the vocal cords determine the Tension of the vocal cords determine the pitch of voice pitch of voice

Damage to Vocal CordsDamage to Vocal Cords

• Screaming or Screaming or making excessive making excessive loud noises can loud noises can damage the damage the vocal cords, vocal cords, hardening them hardening them or leading to or leading to formation of formation of nodules or webs nodules or webs that make the that make the voice coarsevoice coarse

Trachea (Windpipe)Trachea (Windpipe)

• Air enters into the Air enters into the tracheatrachea (lying in (lying in front of the oesophagus) through the front of the oesophagus) through the glottisglottis

• The trachea is lined with ciliated The trachea is lined with ciliated epithelium and mucus-secreting cells epithelium and mucus-secreting cells to prevent entry of bacteria and dustto prevent entry of bacteria and dust

• The trachea is strengthened by The trachea is strengthened by C-C-shaped cartilagesshaped cartilages which support the which support the trachea and prevent it from collapsing trachea and prevent it from collapsing during inhalation and swallowingduring inhalation and swallowing

BronchiBronchi

• The trachea The trachea divides into two divides into two tubes called the tubes called the bronchi (singular: bronchi (singular: bronchus)bronchus)

• Left bronchus -> Left bronchus -> left lungsleft lungs

• Right bronchus -Right bronchus -> right lungs> right lungs

BronchiolesBronchioles

• Each bronchus Each bronchus subdivides into subdivides into many small many small tubes called the tubes called the bronchiolesbronchioles

Air Sacs/AlveoliAir Sacs/Alveoli

• The bronchioles end up in numerous tiny The bronchioles end up in numerous tiny balloon-like air sacs called balloon-like air sacs called alveoli alveoli (singular: alveolus)(singular: alveolus)

• The alveoli provide the respiratory surface The alveoli provide the respiratory surface where oxygen is taken into blood and where oxygen is taken into blood and carbon dioxide is released into the lungs carbon dioxide is released into the lungs by diffusionby diffusion

• There are numerous (~300 million) alveoli There are numerous (~300 million) alveoli to provide a large surface area (~140 mto provide a large surface area (~140 m22 , , size of a singles tennis court) for diffusion size of a singles tennis court) for diffusion of gasesof gases

Air Sacs/AlveoliAir Sacs/Alveoli

• The inner surface of alveoli is covered by a The inner surface of alveoli is covered by a fluid for oxygen to dissolve in before fluid for oxygen to dissolve in before diffusing across wall of alveolus into blooddiffusing across wall of alveolus into blood

• Wall of each alveolus is only one-cell thick Wall of each alveolus is only one-cell thick to provide a short distance for diffusion of to provide a short distance for diffusion of gasesgases

• The alveoli are surrounded by numerous The alveoli are surrounded by numerous capillaries (blood vessels) to provide a rich capillaries (blood vessels) to provide a rich blood supply to transport gases rapidly to blood supply to transport gases rapidly to maintain a steep diffusion gradient of maintain a steep diffusion gradient of gasesgases

LungsLungs• Located in the Located in the thorax (thoracic cavity)thorax (thoracic cavity)• Pink in colour (contains many blood Pink in colour (contains many blood

capillaries)capillaries)• Spongy (contains air sacs)Spongy (contains air sacs)• Protected by Protected by rib-cagerib-cage ( (vertebral columnvertebral column

at the back, at the back, ribsribs with with intercostal intercostal musclesmuscles along the sides and along the sides and sternumsternum at at the front)the front)

• The The diaphragmdiaphragm separates the thoracic separates the thoracic cavity from the abdomencavity from the abdomen

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LungsLungs• Each lung is surrounded by Each lung is surrounded by pleural membranespleural membranes• Outside of lungs – linked to Outside of lungs – linked to inner pleural inner pleural

membranemembrane• Inner surface of rib cage and diaphragm – Inner surface of rib cage and diaphragm –

linked to linked to outer pleural membraneouter pleural membrane• Pleural cavityPleural cavity – air tight space between the – air tight space between the

pleural membranespleural membranes• Pleural fluidPleural fluid – fluid inside the pleural cavity that – fluid inside the pleural cavity that

is secreted by pleural membranes. The fluid is secreted by pleural membranes. The fluid acts as a lubricate and can help to reduce the acts as a lubricate and can help to reduce the friction caused by the rubbing between the friction caused by the rubbing between the lungs and ribcagelungs and ribcage

Investigation #1:Investigation #1: Comparing the oxygen Comparing the oxygen

levels in inhaled and exhaled levels in inhaled and exhaled airair

Purpose of InvestigationPurpose of Investigation

• In this experiment, we are going to In this experiment, we are going to compare the amount of oxygen in compare the amount of oxygen in inhaled and exhaled air (i.e. does inhaled and exhaled air (i.e. does inhaled or exhaled air contain more inhaled or exhaled air contain more oxygen?)oxygen?)

• Since burning requires oxygen, we Since burning requires oxygen, we are going to use a burning candle to are going to use a burning candle to determine the amount of oxygen determine the amount of oxygen present in inhaled and exhaled airpresent in inhaled and exhaled air

How to collect exhaled airHow to collect exhaled air

• Fill a small gas jar with water and Fill a small gas jar with water and invert it over a trough of waterinvert it over a trough of water

• Breathe air through a rubber tubing Breathe air through a rubber tubing into the gas jar until no water is into the gas jar until no water is present in the jarpresent in the jar

• Use a glass plate to cover the Use a glass plate to cover the opening of the jar and stand it opening of the jar and stand it upright upright

ProcedureProcedure

ProcedureProcedure

Investigation #2:Investigation #2: Comparing the carbon Comparing the carbon

dioxide levels in inhaled and dioxide levels in inhaled and exhaled airexhaled air

Purpose of InvestigationPurpose of Investigation• In this experiment, we are going to In this experiment, we are going to

compare the amount of carbon dioxide compare the amount of carbon dioxide in inhaled and exhaled air (i.e. does in inhaled and exhaled air (i.e. does inhaled or exhaled air contain more inhaled or exhaled air contain more carbon dioxide?)carbon dioxide?)

• Hydrogencarbonate indicator solution/ Hydrogencarbonate indicator solution/ lime water can be used to test for lime water can be used to test for carbon dioxide (it will change from carbon dioxide (it will change from orange-red to yellow in colour/it will orange-red to yellow in colour/it will change from clear to milky and cloudy)change from clear to milky and cloudy)

ProcedureProcedureTo mouthTo mouth

boiling tubes

lime water

Clip YClip X

Open Clip X – Breathe in; Open Clip Y – Open Clip X – Breathe in; Open Clip Y – Breathe outBreathe out

GasGas Atmospheric Air/ Atmospheric Air/ Inhaled Air (%)Inhaled Air (%)

Exhaled Air (%)Exhaled Air (%)

OxygenOxygen 21%21% 16% (~5% used 16% (~5% used by cells)by cells)

Carbon Carbon DioxideDioxide

0.03%0.03% 4% (~4% 4% (~4% produced by produced by cells)cells)

NitrogenNitrogen 78%78% 78% (N78% (N22 is not is not used/produced used/produced by cells)by cells)

Other GasesOther Gases 1%1% 1%1%

Water VapourWater Vapour VariableVariable Saturated (from Saturated (from lungs surfaces)lungs surfaces)

TemperatureTemperature VariableVariable ~37~37ooC (air C (air warmed by body)warmed by body)

Gas ExchangeGas Exchange

• Gases are exchanged through the Gases are exchanged through the gas exchange surfacegas exchange surface

• In humans, the gas exchange surface In humans, the gas exchange surface is the air sacs/alveoli in the lungsis the air sacs/alveoli in the lungs

• Gases are exchanged between the Gases are exchanged between the air in the air sacs and the blood in air in the air sacs and the blood in the blood capillariesthe blood capillaries

Red blood cell Red blood cell with with haemoglobinhaemoglobin

Capillary wall Capillary wall (one-cell (one-cell thick)thick)

Plasma Plasma (liquid part (liquid part of blood)of blood)

Alveolar wall (one-cell Alveolar wall (one-cell thick)thick)

Mucus (film Mucus (film of moisture)of moisture)


• Oxygen gas breathed in through the Oxygen gas breathed in through the nostrils entering the alveoli will nostrils entering the alveoli will diffuse from the inhaled air to the diffuse from the inhaled air to the residual air inside the alveoli residual air inside the alveoli

• It will dissolve in the film of moisture It will dissolve in the film of moisture (mucus) lining the inner wall of each (mucus) lining the inner wall of each alveolusalveolus


• Dissolved oxygen then diffuses down Dissolved oxygen then diffuses down the concentration gradient across the concentration gradient across alveolar wall and capillary wall into alveolar wall and capillary wall into blood capillary (higher concentration blood capillary (higher concentration of oxygen in air than in blood)of oxygen in air than in blood)

• It combines with It combines with haemoglobinhaemoglobin in the in the red blood cells to form red blood cells to form oxyhaemoglobinoxyhaemoglobin

HaemoglobinHaemoglobin – protein molecule in RBC used to carry oxygen – protein molecule in RBC used to carry oxygen


• Blood now becomes Blood now becomes oxygenatedoxygenated and and bright red (with high oxygen content bright red (with high oxygen content and low concentration of carbon and low concentration of carbon dioxide)dioxide)

• Oxygen is carried by blood as Oxygen is carried by blood as oxyhaemoglobinoxyhaemoglobin from the lungs to from the lungs to the heart and the rest of the body the heart and the rest of the body through the through the pulmonary veinspulmonary veins


• On reaching tissue cells, On reaching tissue cells, oxyhaemoglobinoxyhaemoglobin is changed back into is changed back into haemoglobinhaemoglobin by releasing oxygen to the by releasing oxygen to the cells for respiration. Carbon dioxide cells for respiration. Carbon dioxide produced by the tissue cells is carried by produced by the tissue cells is carried by the plasma in the form of the plasma in the form of hydrogencarbonatehydrogencarbonate (HCO (HCO33

--) ions back to ) ions back to the alveoli through the the alveoli through the pulmonary artery pulmonary artery (some carbon dioxide can be carried by (some carbon dioxide can be carried by haemoglobin also)haemoglobin also)


• Dull red Dull red deoxygenateddeoxygenated blood (with blood (with low concentration of oxygen and high low concentration of oxygen and high concentration of carbon dioxide) is concentration of carbon dioxide) is carried to the lungs by the carried to the lungs by the pulmonary arterypulmonary artery from the heart from the heart

• The artery branches into numerous The artery branches into numerous capillaries on the surface of the capillaries on the surface of the alveolialveoli


• At the lungs, HCOAt the lungs, HCO33-- converts back into converts back into

COCO22 and diffuses down the concentration and diffuses down the concentration gradient across the capillary wall and gradient across the capillary wall and alveolar wall into the alveoli alveolar wall into the alveoli (concentration of carbon dioxide is (concentration of carbon dioxide is higher in blood than in air in lungs)higher in blood than in air in lungs)

• Carbon dioxide then leaves the alveoli Carbon dioxide then leaves the alveoli and is breathed out of the lungsand is breathed out of the lungs

• Exhaled air also contains water vapour Exhaled air also contains water vapour as the moisture inside alveoli evaporates as the moisture inside alveoli evaporates during exhalationduring exhalation

Exhaled air (4% COExhaled air (4% CO22 & 16% O & 16% O22))Inhaled air (21% OInhaled air (21% O22 & 0.03% CO & 0.03% CO22))

AdaptationAdaptation ReasonReason

Thin walls (one-cell Thin walls (one-cell thick)thick)

Large number of air Large number of air sacs presentsacs present

Water film covering Water film covering the air sacsthe air sacs

Dense network of Dense network of blood capillaries blood capillaries around air sacsaround air sacs

Shorter distance for gases Shorter distance for gases

to diffuse to diffuse

Large surface area for gas Large surface area for gas

exchange to occurexchange to occur

Oxygen can dissolve in Oxygen can dissolve in

water for diffusion to occurwater for diffusion to occur

Allow rapid transport of Allow rapid transport of

gasesgases

Artificial RespirationArtificial Respiration• Any measure that causes air to flow in and Any measure that causes air to flow in and

out of a person's lungs when natural out of a person's lungs when natural breathing is inadequate or ceases breathing is inadequate or ceases

• Mouth-to-mouth or mouth-to-nose Mouth-to-mouth or mouth-to-nose resuscitationresuscitation

• Oxygen in exhaled air maintains aerobic Oxygen in exhaled air maintains aerobic respirationrespiration

• Carbon dioxide in exhaled air stimulates Carbon dioxide in exhaled air stimulates breathing centre in brainbreathing centre in brain

• If there is no pulse either, then If there is no pulse either, then cardiopulmonary resuscitation is neededcardiopulmonary resuscitation is needed

Cardiopulmonary Cardiopulmonary ResuscitationResuscitation

• Check the victim to see if he/she Check the victim to see if he/she respondsresponds

• If not, call for help and follow the If not, call for help and follow the steps belowsteps below

• Turn the victim on to his/her backTurn the victim on to his/her back• Access the ABC’s (Airway, Breathing Access the ABC’s (Airway, Breathing

and Circulation) – make sure the and Circulation) – make sure the victim’s heart and lungs are workingvictim’s heart and lungs are working


• AirwayAirway - open the - open the mouth and check mouth and check for false teeth, for false teeth, vomit or food vomit or food debris. Use a debris. Use a finger to sweep the finger to sweep the airway clear, and airway clear, and tilt the victim’s tilt the victim’s chin upwardschin upwards


• BreathingBreathing - check - check to see if the chest to see if the chest is moving and also is moving and also feel for breath. If feel for breath. If the person is not the person is not breathing after 10 breathing after 10 seconds start seconds start artificial respiration artificial respiration (mouth-to-mouth)(mouth-to-mouth)


• CirculationCirculation - if - if there is no there is no movement or movement or coughing assume coughing assume the heart has the heart has stopped and start stopped and start cardiopulmonary cardiopulmonary resuscitation (CPR)resuscitation (CPR)


1.1. Tilt the head and lift the chinTilt the head and lift the chin2.2. Observe for breathing and signs of life for Observe for breathing and signs of life for

10 seconds. If victim is not breathing 10 seconds. If victim is not breathing give 2 breaths of artificial ventilation give 2 breaths of artificial ventilation whilst holding the nose closed whilst holding the nose closed

3.3. Push down on the chest 1.5 to 2 inches Push down on the chest 1.5 to 2 inches 15 times. Pump at the rate of 15 times. Pump at the rate of 100/minute, faster than once per second. 100/minute, faster than once per second.

4.4. Give 2 more ventilations then give a Give 2 more ventilations then give a further 15 compressionsfurther 15 compressions

5.5. Repeat the cycle until help arrivesRepeat the cycle until help arrives


Breathing MechanismBreathing Mechanism

• Movement of air over the respiratory Movement of air over the respiratory surface is called surface is called ventilationventilation and is and is achieved by the action of achieved by the action of breathingbreathing

• Breathing is brought about by the Breathing is brought about by the action of the action of the diaphragmdiaphragm and the and the intercostal musclesintercostal muscles

Inspiration /InhalationInspiration /Inhalation1)1) The diaphragm muscles The diaphragm muscles

contract and the contract and the diaphragm is diaphragm is flattenedflattened

2)2) The intercostal muscles The intercostal muscles contract and the rib cage contract and the rib cage is is raisedraised

3)3) The volume of the thoracic The volume of the thoracic cavity cavity increasesincreases

4)4) Pressure inside the lungs Pressure inside the lungs becomes becomes lowerlower than the than the atmospheric pressureatmospheric pressure

5)5) Air Air rushes intorushes into the lungs the lungs through the tracheathrough the trachea

Inspiration /InhalationInspiration /Inhalation

Expiration/ExhalationExpiration/Exhalation1)1) The diaphragm muscles The diaphragm muscles

relax and the diaphragm relax and the diaphragm returns to returns to dome-shapedome-shape

2)2) The intercostal muscles The intercostal muscles relax and the rib cage is relax and the rib cage is loweredlowered

3)3) The volume of the thoracic The volume of the thoracic cavity is cavity is reducedreduced

4)4) Pressure inside the thoracic Pressure inside the thoracic cavity increases and is cavity increases and is higherhigher than the atmospheric than the atmospheric pressurepressure

5)5) Air is Air is forced outforced out of the lungs of the lungs

Expiration/ExhalationExpiration/Exhalation

Bell Jar ModelBell Jar Model

• The action The action of the of the diaphragm diaphragm in breathing in breathing can be can be demonstratedemonstrated by the bell d by the bell jar model. jar model. How???How???

Feature in the modelFeature in the model Corresponding Corresponding structure in the structure in the breathing systembreathing system

Y-shaped tubeY-shaped tube

BalloonsBalloons

Wall of bell jarWall of bell jar

Cavity in bell jarCavity in bell jar

Rubber sheetRubber sheet

Trachea and bronchusTrachea and bronchus

LungLungss

Thoracic wallThoracic wall

Pleural cavityPleural cavity

DiaphragmDiaphragm

Rubber sheet Rubber sheet pulled downpulled down

Rubber sheet Rubber sheet releasedreleased

Volume inside Volume inside bell jarbell jar

Pressure Pressure inside bell jarinside bell jar

Comparison Comparison with with atmospheric atmospheric pressurepressure

Direction of air Direction of air movementmovement

Shape of Shape of balloonsballoons

IncreasedIncreased DecreasedDecreased

DecreasedDecreased IncreasedIncreased

Lower than Lower than atmospheric atmospheric pressurepressure

Higher than Higher than

atmospheric atmospheric

pressurepressureDrawn into the Drawn into the

balloonsballoonsForced out from Forced out from

the balloonsthe balloons

InflatedInflated DeflatedDeflated

Condition in the Condition in the bell jar modelbell jar model

Actual condition Actual condition in the human in the human bodybody

Shape of Shape of diaphragm during diaphragm during exhalationexhalation

Shape of Shape of diaphragm during diaphragm during inhalationinhalation

Movement of Movement of thoracic cage in thoracic cage in breathingbreathing

Content of pleural Content of pleural cavitycavity

Any other Any other differencesdifferences

The rubber sheet is The rubber sheet is

flattenedflattenedThe diaphragm is The diaphragm is

dome-shaped dome-shaped

The rubber sheet is The rubber sheet is

pulled downpulled downThe diaphragm is The diaphragm is

flattenedflattened

The wall of the jar is The wall of the jar is

rigidrigid

The thoracic wall isThe thoracic wall is

flexible and can flexible and can

change shapechange shapeThe cavity of the jarThe cavity of the jar

is filled with airis filled with airThe pleural cavity isThe pleural cavity is

filled with pleural fluidfilled with pleural fluid

Controlled by handsControlled by handsControlled by musclesControlled by muscles

Rib Cage ModelRib Cage Model

• The action of the The action of the intercostal muscles intercostal muscles in breathing can be in breathing can be demonstrated by demonstrated by the rib cage model. the rib cage model. How??? How???

Feature in the modelFeature in the model Corresponding Corresponding structure in the structure in the breathing systembreathing system

Rod PRod P

Rod QRod Q

Rod RRod R

Elastic bandElastic band

BackboneBackbone

SternumSternum

RibRib

Intercostal muscleIntercostal muscle

Rib cage in the Rib cage in the human body human body

Rib cage modelRib cage model

InhalationInhalation

ExhalationExhalation

Contraction ofContraction of

intercostal musclesintercostal musclesShortening of theShortening of the

elastic bandelastic band

Upward and outward Upward and outward

movement of rib cagemovement of rib cage

Relaxation of Relaxation of

intercostal musclesintercostal muscles

Downward and inwardDownward and inward

movement of rib cagemovement of rib cage

Upward and outward Upward and outward

position of rods R and Qposition of rods R and Q

Lengthening of the Lengthening of the

elastic bandelastic band

Downward and inward Downward and inward

position of rods R and Qposition of rods R and Q

Condition in the Condition in the rib cage modelrib cage model

Actual condition Actual condition in the human in the human bodybody

DimensionDimension

Number of ribsNumber of ribs

Contraction and Contraction and relaxation of relaxation of intercostal intercostal musclesmuscles

Any other Any other differencesdifferences

Model is 2-D Model is 2-D

structurestructureThoracic cavity isThoracic cavity is

3-D structure3-D structure

Only two rods are Only two rods are

shownshown12 pairs of ribs12 pairs of ribs

Controlled by the Controlled by the

moving rodsmoving rodsIntercostal muscles Intercostal muscles

contract and relax contract and relax

by themselvesby themselves

Few intercostal Few intercostal

muscles are shownmuscles are shownMany intercostal Many intercostal

muscles are presentmuscles are present

• InhalationInhalation • ExhalationExhalation

Breathing MechanismBreathing Mechanism

Changes in Pressure in Changes in Pressure in LungsLungs

InspirationInspiration ExpirationExpiration

1. Diaphragm 1. Diaphragm musclesmuscles

2. Diaphragm2. Diaphragm

3. Intercostal 3. Intercostal musclesmuscles

4. Ribs and 4. Ribs and sternumsternum

5. Volume of 5. Volume of thoracic thoracic

cavitycavity

6. Pressure inside 6. Pressure inside cavitycavity

7. Movement of air7. Movement of air

8. Shape of lungs8. Shape of lungs

ContractContract RelaxRelax

FlattensFlattens Dome shapeDome shape

ContractContract RelaxRelax

RaisedRaised LowerLowereded

IncreasesIncreases DecreasesDecreases

DecreasesDecreases IncreasesIncreases

Rushes into lungsRushes into lungsForced out of lungsForced out of lungs

InflatedInflated DeflatedDeflated

Coughing and HiccuppingCoughing and Hiccupping

• A cough is a sudden, explosive A cough is a sudden, explosive movement of air that tends to clear movement of air that tends to clear materials from the airways. It is a materials from the airways. It is a complicated reflexcomplicated reflex

• Hiccup is the result of sudden Hiccup is the result of sudden contraction of the diaphragm often contraction of the diaphragm often caused by drinking or eating too fastcaused by drinking or eating too fast

CoughingCoughing

1.1. As you breathe in, As you breathe in, the glottis opens the glottis opens to allow air into to allow air into your lungsyour lungs

CoughingCoughing

2.2. The glottis then The glottis then closes, trapping closes, trapping the air inside the air inside your lungsyour lungs

CoughingCoughing

3.3. The glottis The glottis suddenly opens suddenly opens and air from and air from your lungs your lungs rushes out of rushes out of your mouth, your mouth, clearing the clearing the irritationirritation

HiccuppingHiccupping

1. The glottis is 1. The glottis is open and the open and the diaphragm is diaphragm is relaxedrelaxed


2. The diaphragm 2. The diaphragm contracts contracts causing a causing a sudden deep sudden deep inhalation of air inhalation of air into your lungsinto your lungs


3. As air rushes 3. As air rushes into the lungs, into the lungs, the glottis snaps the glottis snaps shut with a shut with a distinctive clickdistinctive click

Lungs DiseasesLungs Diseases

1)1) AsthmaAsthma

2)2) BronchitisBronchitis

3)3) Cystic fibrosisCystic fibrosis

4)4) EmphysemaEmphysema

5)5) PneumoniaPneumonia

6)6) PneumothoraxPneumothorax

7)7) Lung cancerLung cancer

Rate of BreathingRate of Breathing

• How “fast” a person is breathingHow “fast” a person is breathing• Expressed in terms of the number Expressed in terms of the number

of breaths in a minuteof breaths in a minute• When a person is at rest, the rate When a person is at rest, the rate

of breathing is about 15 times per of breathing is about 15 times per minute and only diaphragm minute and only diaphragm movement is involvedmovement is involved

• When a person is active, breathing When a person is active, breathing also involves both the diaphragm also involves both the diaphragm and the intercostal musclesand the intercostal muscles

Breathing Rate Before and After Breathing Rate Before and After ExerciseExercise


1. What is the effect of exercise on the rate of 1. What is the effect of exercise on the rate of breathing?breathing?

The rate of breathing increasesThe rate of breathing increases

2. Is there any other change in breathing after 2. Is there any other change in breathing after exercise?exercise?The depth of breathing increasesThe depth of breathing increases

3. What is the significance of these changes?3. What is the significance of these changes?

These changes provide the muscles with more These changes provide the muscles with more oxygen for increased rate of respiration to oxygen for increased rate of respiration to release more energy for muscle contractionrelease more energy for muscle contraction

These changes also help the body to remove the These changes also help the body to remove the additional amount of carbon dioxide produced additional amount of carbon dioxide produced by respirationby respiration


Depth of BreathingDepth of Breathing

• How “deep” a person is breathingHow “deep” a person is breathing• The volume of air breathed in after The volume of air breathed in after

an exhalationan exhalation• The depth of breathing at rest is The depth of breathing at rest is

about 0.5 litre about 0.5 litre • Can be measured using a Can be measured using a spirometerspirometer

Effect of Exercise on Rate and Depth of Effect of Exercise on Rate and Depth of BreathingBreathing

• Exercise can increase the number of capillaries in the lungs, increase the size of alveoli and strengthen the intercostal muscles and diaphragm muscles

• Regular exercise makes a person more fit. The person can breathe deeper with each breath during exercise and his/her breathing rate does not increase as much as an unfit person

Changes in Lung Volume Before and Changes in Lung Volume Before and After ExerciseAfter Exercise


Rate of breathing:Rate of breathing:

6 x (60/20) = 18 breaths per 6 x (60/20) = 18 breaths per minuteminute

Depth of breathing:Depth of breathing:

2500 - 2000 = 500 cm2500 - 2000 = 500 cm33

Volume of air breathed in per Volume of air breathed in per minute :minute :

18 X 500 = 9000 cm18 X 500 = 9000 cm33


Rate of breathing:Rate of breathing:

9 x (60/20) = 27 breaths 9 x (60/20) = 27 breaths per minuteper minute

Volume of air breathed in Volume of air breathed in per minute: per minute:

27 x 2000 = 54000 cm27 x 2000 = 54000 cm33

Depth of breathing:Depth of breathing:

3500 - 1500 = 2000 cm3500 - 1500 = 2000 cm33


The volume of oxygen retained in the body The volume of oxygen retained in the body per minute:per minute:

At restAt rest 18 x 500 x (21 - 16)% = 450 18 x 500 x (21 - 16)% = 450 cmcm33

During exerciseDuring exercise 27 x 2000x (21 - 16)% = 27 x 2000x (21 - 16)% = 2700 cm2700 cm33

The volume of carbon dioxide produced by The volume of carbon dioxide produced by the body per minute:the body per minute:

At restAt rest 18 x 500 x (4 - 0.03)% = 18 x 500 x (4 - 0.03)% = 357.3 cm357.3 cm33

During exercise 27 x 2000 x (4 - 0.03)% During exercise 27 x 2000 x (4 - 0.03)% = 2143.8 cm= 2143.8 cm33

Volumes of AirVolumes of Air

Tidal volume increases during exercise while vital capacity Tidal volume increases during exercise while vital capacity remains unchangedremains unchangedVital capacity can only be increased by Vital capacity can only be increased by

prolonged trainingprolonged training

Volumes of Air Volumes of Air • Tidal volumeTidal volume – during – during

quiet breathing, the quiet breathing, the volume of air moved volume of air moved into and out of the into and out of the lungs (~0.5 litre)lungs (~0.5 litre)

• Tidal airTidal air – air that – air that can be breathed in can be breathed in and out the lungs and out the lungs in each breathin each breath

Volumes of Air Volumes of Air

• Vital Capacity Vital Capacity – the – the maximum volume maximum volume of air that can be of air that can be forced out of the forced out of the lungs after the lungs after the deepest inspiration deepest inspiration (~3-5 litres)(~3-5 litres)

Volumes of Air Volumes of Air • Residual volumeResidual volume – –

volume of air left volume of air left inside the lungs after inside the lungs after the greatest the greatest expiration (~1.5 expiration (~1.5 litres)litres)

• Residual air Residual air – the – the air that cannot be air that cannot be exchanged with exchanged with the atmospherethe atmosphere

Volumes of Air Volumes of Air

• Total lung capacity Total lung capacity – – total amount of air that total amount of air that can be present inside can be present inside the lungs (~4-7 litres)the lungs (~4-7 litres)

Total lung capacity = Vital capacity + Residual Total lung capacity = Vital capacity + Residual VolumeVolume

Estimation of Vital Capacity of Estimation of Vital Capacity of the Lungsthe Lungs

Air breathed Air breathed outout

Plastic Plastic bottlebottle

Rubber Rubber tubingtubing

Water troughWater trough

SpirometerSpirometer

Control of BreathingControl of Breathing• An increase in the concentration of An increase in the concentration of

carbon dioxide in blood will cause an carbon dioxide in blood will cause an immediate increase in the rate and immediate increase in the rate and depth of breathingdepth of breathing

• A decrease in the concentration of A decrease in the concentration of oxygen in blood can also cause an oxygen in blood can also cause an increase in the rate and depth of increase in the rate and depth of breathing (e.g. at high altitudes)breathing (e.g. at high altitudes)

• Breathing is automatically controlled by Breathing is automatically controlled by the breathing centres in the medulla the breathing centres in the medulla oblongata of the brainoblongata of the brain

Smoking and Health Smoking and Health HazardsHazards

• Tobacco smoke Tobacco smoke contains over 4,000 contains over 4,000 different chemicals. different chemicals. At least 43 are At least 43 are known carcinogens known carcinogens (cause cancer in (cause cancer in humans)humans)

• The smoke can The smoke can irritate the bronchi to irritate the bronchi to become narrowed become narrowed

• Heat can damage Heat can damage the alveolithe alveoli


1) Tar1) Tar• CarcinogenicCarcinogenic• Increases the secretion of mucus and stops Increases the secretion of mucus and stops

the action of ciliathe action of cilia• As a result, tar and dirt particles will cover the As a result, tar and dirt particles will cover the

alveoli alveoli • Smoker will cough a lot and produce a lot of Smoker will cough a lot and produce a lot of

phlegmphlegm• Can lead to infection, chronic bronchitis and Can lead to infection, chronic bronchitis and

emphysemaemphysema• Tar can stain teeth, nail, etc.Tar can stain teeth, nail, etc.


• Breakdown of Breakdown of alveoli wall can alveoli wall can reduces surface reduces surface area for gaseous area for gaseous exchangeexchange

• This leads to This leads to emphysemaemphysema


2) Carbon monoxide2) Carbon monoxide• Combines more readily with Combines more readily with

haemoglobin and as a result reduce haemoglobin and as a result reduce the oxygen-carrying capacity of the oxygen-carrying capacity of bloodblood

• Can lead to heart diseaseCan lead to heart disease


3) Nicotine3) Nicotine• Causes dependencyCauses dependency• Increases heart rate and blood Increases heart rate and blood

pressurepressure• Causes the build-up of fats along the Causes the build-up of fats along the

arterial walls, leading to heart diseasearterial walls, leading to heart disease• Retards growth of foetusRetards growth of foetus• Stimulate the brainStimulate the brain

Lung CancerLung Cancer

Conclusion:Conclusion:

The more The more cigarettes a cigarettes a person smokes person smokes per day, the per day, the greater the greater the chance of dying chance of dying from lung cancer.from lung cancer.


Conclusions:Conclusions:

The risk of getting The risk of getting lung cancer is lung cancer is greatly reduced greatly reduced after quittingafter quitting

Non-smokers may Non-smokers may also die from lung also die from lung cancer though the cancer though the risk is very low risk is very low (passive smoking)(passive smoking)


Conclusion:Conclusion:

Cigarettes smoking Cigarettes smoking is more hazardous is more hazardous to health than to health than other types of other types of tobacco smokingtobacco smoking


Conclusions:Conclusions:

The higher the The higher the age, the greater age, the greater the risk of dying the risk of dying from coronary from coronary diseasedisease

The more The more cigarettes cigarettes smoked daily, smoked daily, the greater the the greater the risk of dying risk of dying from coronary from coronary heart diseaseheart disease

Relationship between no. of Relationship between no. of cigarettes smoked daily and the cigarettes smoked daily and the annual death rate from coronary annual death rate from coronary heart diseaseheart disease


The Smoking MachineThe Smoking Machine

Documents

Human Respiratory System As all living cells carry out respiration to release energy in order to maintain life, oxygen is needed and waste carbon dioxide