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7.2 –7.2 – THE RESPIRATORY THE RESPIRATORY

STRUCTURES & STRUCTURES & BREATHING BREATHING

MECHANISMS IN MECHANISMS IN HUMANS & HUMANS &

ANIMALSANIMALS

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LEARNING LEARNING OUTCOMESOUTCOMES

State the respiratory structures in humans State the respiratory structures in humans & some animals;& some animals;Make an inference on the various Make an inference on the various adaptations of the respiratory structures;adaptations of the respiratory structures;Describe the characteristics of respiratory Describe the characteristics of respiratory surfaces in humans & other organisms;surfaces in humans & other organisms;Describe the breathing mechanisms in Describe the breathing mechanisms in humans & other organisms.humans & other organisms.Compare & contrast the human respiratory Compare & contrast the human respiratory system with that of other organisms.system with that of other organisms.

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BREATHINGBREATHING - Involvement of - Involvement of inhalation of O2 & exhalation of CO2inhalation of O2 & exhalation of CO2

Each organisms have their special Each organisms have their special structure with the adaptation for structure with the adaptation for gaseous exchange:-gaseous exchange:- LargeLarge surface area to volume ratio surface area to volume ratio – –

increase the rate of exchangeincrease the rate of exchange Very Very thinthin walls walls – one cell thick – one cell thick A A richrich supply of blood supply of blood – covered with – covered with

blood capillariesblood capillaries A A moistmoist surface surface – easier for the – easier for the

gases to diffusegases to diffuse

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PROTOZOAPROTOZOA Unicellular organismsUnicellular organisms – –

Amoeba & ParameciumAmoeba & Paramecium Have a large surface area Have a large surface area

to volume ratioto volume ratio, the , the external area is fully external area is fully permeable to the gasespermeable to the gases

No need specificNo need specific respiratory respiratory sturucturesturucture

Gases Gases diffuse in & outdiffuse in & out of of the organisms the organisms over the over the whole cellwhole cell membrane. membrane.

Depends on the Depends on the concentrationconcentration of respiratory of respiratory gases in & out of the cellgases in & out of the cell

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FISHFISH A bony fish has A bony fish has four pairs of gillsfour pairs of gills, , support by a bony archsupport by a bony arch

The gills consist of The gills consist of two rows of two rows of gill filamentgill filament numerous gill numerous gill lamelalamela

Each Each gill lamela is foldedgill lamela is folded into gill into gill plate, have plate, have thin wallsthin walls & well & well supplied with supplied with blood capillariesblood capillaries to to increase the surface areaincrease the surface area of of the gillsthe gills

Characteristics Characteristics :-:- bony/gill archesbony/gill arches – to support the – to support the

filamentsfilaments FilamentsFilaments –numerous –numerous (increase the (increase the

surface area for gaseous exchange)surface area for gaseous exchange) Thin membraneThin membrane (to ease the gases (to ease the gases

absorption)absorption) Many Many blood capillariesblood capillaries (efficients (efficients

transportation)transportation)

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Breathing Mechanism of Breathing Mechanism of FishFish

Open its mouthOpen its mouth – – lower the floorlower the floor of the of the mouth- mouth- volumevolume of the mouth is of the mouth is increasedincreased –the –the pressure insidepressure inside the the mouth mouth fallsfalls below that of the external below that of the external pressure- water with high conc. of O2 pressure- water with high conc. of O2 enter-operculum close. enter-operculum close.

FloorFloor of the mouth is of the mouth is raise upraise up - Gaseous - Gaseous exchange occurs as water flows past the exchange occurs as water flows past the gills –the gills –the pressurepressure in the mouth is in the mouth is increasedincreased. – . – water then passes outwater then passes out though the operculum though the operculum operculum operculum then opensthen opens

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BREATHING MECHANISMBREATHING MECHANISM

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INSECTSINSECTS The body is The body is protected by the exoskeletonprotected by the exoskeleton, ,

which is impervious to the gases.which is impervious to the gases.

Air reaches the body cells via an Air reaches the body cells via an elaborated system of elaborated system of branching tubes branching tubes called called tracheaetracheae (singular : trachea) (singular : trachea)

Air enters the tracheaeAir enters the tracheae throughthrough a series of a series of openings along the sides of the body – openings along the sides of the body – spiraclesspiracles

Reinforced with the Reinforced with the chitinchitin, the trachea are , the trachea are subdivided in subdivided in numerous tiny numerous tiny tracheoles tracheoles (singular : tracheole)(singular : tracheole) thin, permeable thin, permeable walls & intimate contact with the body cellswalls & intimate contact with the body cells

Tracheal system provides a Tracheal system provides a large surface large surface area for gaseous exchangearea for gaseous exchange

O2 dissolves in the fluidO2 dissolves in the fluid found in the found in the tracheoles & passes directly to the body tracheoles & passes directly to the body cells through diffusioncells through diffusion

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BREATHING MECHANISM OF BREATHING MECHANISM OF INSECTSINSECTS The The rhythmic rhythmic expansion & contractionexpansion & contraction

of the abdominal wallof the abdominal wall help to drive the help to drive the air in & out of the bodyair in & out of the body

ContractionContraction flattens the body, flattens the body, decreases the volume of the tracheadecreases the volume of the trachea, , force the air outforce the air out

Abdomen expandsAbdomen expands, air is drawn into , air is drawn into the trachea through the spiraclesthe trachea through the spiracles

Each Each spiracle is controlled by a system spiracle is controlled by a system of valvesof valves operated by tiny muscles operated by tiny muscles

The The level of CO2 in the body level of CO2 in the body determines the sizedetermines the size of the spiracles of the spiracles apertureaperture

SomeSome insect (such as grasshopper) insect (such as grasshopper) have air sacshave air sacs connected to the trachea connected to the trachea that can pump the air throughout the that can pump the air throughout the tracheal systemtracheal system

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AMPHIBIANAMPHIBIANSS

Respire through 4 different organs – the gills, lungs, skin & mucous lining of the mouth have moist surfaces & have a good supplies of the blood capillaries

The tadpoles breathe through the skin & gills.

The adult frog – lungs, skin & mucous lining of the mouth many blood capillaries

Many folds inside the lung sacs – increase the respiratory surface

In water, O2 enters through its skin

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AMPHIBIAAMPHIBIANN

InspirationInspiration – – nostrilsnostrils open, the open, the mouthmouth closes, the closes, the glottisglottis closses closses & the floor of the & the floor of the mouth cavitymouth cavity is is loweredlowered

Air pressureAir pressure inside the mouth inside the mouth reducedreduced. Air is drawn through . Air is drawn through the nostrils into the mouth cavitythe nostrils into the mouth cavity

The noistrils close & the floor of The noistrils close & the floor of the mouth cavity is raised to the mouth cavity is raised to force the air through the glottis force the air through the glottis into the lungs.into the lungs.

The The lungs expandlungs expand & gaseous & gaseous exchange takes place.exchange takes place.

ExpirationExpiration – nostrils open, the – nostrils open, the muscles of the body wall muscles of the body wall contract to force the air from the contract to force the air from the lungs to the mouth cavity & lungs to the mouth cavity & nostrilsnostrils

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HUMANSHUMANS Consist of Consist of a series of tube-like a series of tube-like structuresstructures connecting a pair of connecting a pair of lungslungs

Nasal passage, pharynx, larynx, Nasal passage, pharynx, larynx, trachea, bronchitrachea, bronchi (singular : (singular : bronchus), bronchus), bronchioles & alveolibronchioles & alveoli (singular : alveolus)(singular : alveolus)

Lungs Lungs – large sac-like organs, made – large sac-like organs, made up of mainly the up of mainly the bronchioles, alveolibronchioles, alveoli & a network of & a network of blood capillariesblood capillaries

Left lungLeft lung – 2 lobes, – 2 lobes, right lungsright lungs – 3 – 3 lobeslobes

A A double membranedouble membrane called the called the pleurapleura surrounds each lungs. surrounds each lungs.

Outer pleural membraneOuter pleural membrane attached attached to the chest wall, inner pleural to the chest wall, inner pleural membrane attached to the lungs.membrane attached to the lungs.

Each lungs is packed with Each lungs is packed with 1.5 – 2.5 1.5 – 2.5 million of alveoli.million of alveoli.

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Adaptation of the Adaptation of the alveoli for gaseous alveoli for gaseous exchange :exchange : A large surface A large surface

areaarea Very thin wallsVery thin walls A moist surfaceA moist surface A rich supply of A rich supply of

bloodblood

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BREATHING MECHANISM OF BREATHING MECHANISM OF HUMANSHUMANS

The The diaphragm is a dome-shaped sheet of diaphragm is a dome-shaped sheet of musclesmuscles that separates the thorax from the that separates the thorax from the abdomenabdomen

2 sets of intercostal muscles2 sets of intercostal muscles are located are located between the ribs – external & internal between the ribs – external & internal intercostal musclesintercostal muscles

INSPIRATION/INHALATIONINSPIRATION/INHALATION The The external intercostal contractexternal intercostal contract while the while the

internal relax.internal relax. the ribs & sternum move the ribs & sternum move upwards & outwardsupwards & outwards

The The diaphragm muscles contractdiaphragm muscles contract & & flatternsflatterns

The movement of the ribs & the diaphragm The movement of the ribs & the diaphragm increase the volume of the thoracic cavityincrease the volume of the thoracic cavity

Increasing the volume of the thoracic Increasing the volume of the thoracic cavitycavity until it is less than the atmospheric until it is less than the atmospheric pressure pressure air drawn into the lungs air drawn into the lungs

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BREATHING MECHANISM OF BREATHING MECHANISM OF HUMANSHUMANS

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EXPIRATION/EXHALATIONEXPIRATION/EXHALATION The The internal intercostal muscles internal intercostal muscles contractcontract while the external relax while the external relax ribs & sternum move downwardsribs & sternum move downwards & & inwards back to its resting positioninwards back to its resting position

The The diaphragm muscles relaxdiaphragm muscles relax & arches & arches upwards.upwards.

The movement of the rib cage & the The movement of the rib cage & the diaphragm diaphragm decrease the volume of the decrease the volume of the thoracic cavitythoracic cavity increases the increases the pressure inside until it is greater pressure inside until it is greater than the atmospheric pressure.than the atmospheric pressure.

Air is forced outAir is forced out of the lungs. of the lungs.

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COMPARISON BETWEEN COMPARISON BETWEEN THE HUMAN THE HUMAN

RESPIRATORY SYSTEM RESPIRATORY SYSTEM WITH THAT OF OTHER WITH THAT OF OTHER

ORGANISMSORGANISMSORGANISORGANISMM

RESPIRATORESPIRATORY RY

STRUCTURSTRUCTUREE

CHARACTERISTICS CHARACTERISTICS OF ADAPTATIONOF ADAPTATION

BREATHING BREATHING MECHANISMMECHANISM

ProtozoProtozoaa

NoneNone Large TSA – minute Large TSA – minute sizesizePM is thin & moist, PM is thin & moist, >rate of diffusion>rate of diffusion

NoneNone

FishFish GillsGills Numerous lamella - Numerous lamella - > the TSA for > the TSA for diffusion.diffusion.Gill filament – thin, Gill filament – thin, moist membranes moist membranes with a network of with a network of blood capillaries.blood capillaries.

Action of Action of the floor of the floor of the mouth the mouth

& the & the operculumoperculum

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ORGANISORGANISMM

RESPIRATORESPIRATORY RY

STRUCTURSTRUCTUREE

CHARACTERISTICS CHARACTERISTICS OF ADAPTATIONOF ADAPTATION

BREATHING BREATHING MECHANISMMECHANISM

InsectsInsects Tracheal Tracheal systemsystem

Many fine Many fine branches of branches of tracheoles to tracheoles to increase the TSAincrease the TSAA layer of A layer of moisture on the moisture on the walls of the walls of the tracheoles.tracheoles.

Action of Action of abnominal abnominal muscles muscles

(rhythmic (rhythmic movement)movement)

AmphibiAmphibiansans

Skin, Skin, mouth, mouth, lungslungs

Thin & moist Thin & moist respiratory respiratory surfacessurfaces

Network of blood Network of blood capillaries in the capillaries in the skin.skin.

Action of Action of muscles in muscles in the mouth the mouth

cavity.cavity.

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ORGANISORGANISMM

RESPIRATORESPIRATORY RY

STRUCTURSTRUCTUREE

CHARACTERISTICS CHARACTERISTICS OF ADAPTATIONOF ADAPTATION

BREATHING BREATHING MECHANISMMECHANISM

HumanHuman LungsLungs Numerous alveoliNumerous alveoliThin & moist Thin & moist alveoli epitheliumalveoli epitheliumNetwork of blood Network of blood capillaries at the capillaries at the alveoli of lungsalveoli of lungs

Action of Action of intercostal intercostal muscles & muscles & diaphragm diaphragm

musclesmuscles

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