ch39 respiration how animals breath

8/6/2019 Ch39 Respiration How Animals Breath

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How Do AnimalsBreathe?

Chapter 39

Why Do We Breathe?

Animals get most of their energy fromcellular respiration, which requiresoxygen

Oxygen is mainly used for the chemical

process of breaking down fuel molecule,producing CO2 and releasing energy.

C6H6O6 + 6 O2 30 ATP + 12 H2O + 6 CO2

Glucosebasic

energyform



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What is the respiration?

Respiration is a process of uptakingoxygen from the environment andreleasing the waste gas, carbondioxide, to the environment.

Oxygen must be distributed to all

cells of the body Aquatic animals use gills; terrestrial

animals use lungs to exchangeoxygen and carbon dioxide

How do the physics of gasesand liquids determine the

structure of gills and lungs?



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Oxygen uptake

Oxygen can only be taken by thebody when dissolved in water

Land animals must have wet surfacein lungs for oxygen to dissolve intothe blood

Aquatic animals can extract oxygendirectly from water

Mechanism of Respiration

21% of air is oxygen

Mechanism of gas exchange:

Diffusion of gases from areas of highpressure and concentration to areas of low pressure and concentration



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Gas Pressure

Gas molecules are far apart

Speed of gas molecules depends ontemperature

Gas molecules exert force onsurfaces when they strike thesurface — pressure

Pressure depends on number of molecules and their speed(temperature)

Partial Pressure

Each type of gas molecule exerts aseparate pressure

The pressure exerted by each type of

molecule is its partial pressure



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Equilibrium

Gas molecules can dissolve in liquid

Gas molecules can also escape fromthe liquid — evaporation

Equilibrium is reached when thenumber of molecules escaping is the

same as the number dissolving Concentration at equilibrium depends

on partial pressure and temperature

Surface Area

Rate at which gas moleculesdissolve in a liquid depends ontemperature, partial pressure andsurface area

Molecules diffuse from highconcentration to low concentration

Large surface area will increaserate of diffusion



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Surface to Volume Ratio

Small organisms have high surface tovolume ratio

Large animals must increase surfacearea with special structures for gasexchange

Evagination—

surface folded outward;invagination — surface folded inward

Respiration over celland skin surfaces

Single cells (aquatic): exchangegases across membrane surfacesby diffusion

Aquatic multicelled animals: largesurface area of outer layer of cellsused as respiratory surfaces

Some animals: Respiration throughskin supplemented by lungs or gills



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Respiration using special organs

Large multicellular animals meetincreased oxygen needs byusing:

Tracheal systems

Gills

Lungs

Insect Respiration

Does not move oxygen incirculation, does not have lungsor gills

Uses trachea, opens passages tobody cells



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Tracheal System

The tracheal system (invagination of body surface) is a branchingnetwork of microscopic air-filledtubes (trachea).

The air enters through openings of tracheal system called spiracles.

Trachea originate at spiracle andinterconnect to form a pair of longitudinaltrunks that extend the length of thorax

and abdomen.

The tracheoles endwith moist epithelium,

where the oxygenand carbon dioxideexchange takes

place.



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Gills System

Gills are evagination of bodysurface (a turning outward) usedby large aquatic animals foroxygen/CO2 exchange (orrespiration )

Gill Function

Oxygen diffuses directly from waterinto surface of gills

Animals either move water or their

gills to get oxygen-rich water Aquatic animals use a process called

countercurrent flow to efficientlyuptake oxygen from water



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Terrestrial Solutions

Gills collapse and dry out in air,are not rigid

Spiders keep gills inside theirbodies — book lung — and havesupporting bars

Some animals breathe throughskin or mouths

Most land animals have lungs

Bird Respiration

Air moves in one direction and is fullyoxygenated, using sacs in airways



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Lung System

Lungs are made up of microscopic air sacs (aninvagination structure) that arecovered with blood vessels andcoated with a thin film of moisture.

Lungs

Lungs are organs for gas exchangeassociated with circulation

Internal localization protects lungs;they are less likely to collapse or dryout



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How do we breathe?

The general plan

Breathing: movement of air into andout of the lungs

inspiration: taking air into the lungs

expiration: expelling air from the lungs

Mechanism: oxygen diffuses fromblood to tissue fluid to cells; carbondioxide diffuses back from cells toblood



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Internal respiration is theexchange of oxygen and carbondioxide between the blood andtissue fluid.

External respiration is exchange of gases at the lungs.

Human Respiratory System

Lungs

Airways

Muscles that move air Circulation



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Air enters mouth or nose, moves topharynx

Pharynx becomes trachea

Trachea forks into bronchi

Bronchi branch into bronchioles

Bronchioles end at alveoli—

site of gasexchange

Airways

Airway Cells

Epithelial cells line airways andalveoli

Trachea, bronchi and bronchioleshave ciliated and mucus-producingcells

Mucus captures dust and bacteria

Cilia beat to move mucus up tothroat, removing dust and bacteria



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Nasal cavity

The air is warmed and moistenedas it swirls around in the nasalcavities.

The epithelial tissue covered withtiny, hair-like projections called cilia

stays moist with a thin layer of secreted mucus and trap dust andparticles in the air.

The cilia beat in unison, creating acurrent in the mucus that carriesthe trapped particles toward thethroat.



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The Pharynx and Larynx

Pharynx, or throat, extends frombehind the nasal cavities to theopening of esophagus and larynx.

Larynx (or vocal box), a cartilaginousbox shaped like a triangle, lies at the

beginning of the trachea. Trachea is the air passageway that

bring the air to the lungs.

Movement of vocal cords

Vocal cords are two folds of elastictissue covered with a mucousmembrane.

Vocal cords works as a “backup”

for the epiglottis to cover theglottis during swallowing.



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Vocal cords and sound

Vocal cords also produce thesounds as the air rushes by andcauses them to vibrate.

Vocal cords can produce a varietyof pitches of sound.

The mouth with lips and a tongueto form the sounds into words.

The trachea

The trachea is a tube-like tissuereinforced with rings of cartilage.

The inner walls of trachea are linedwith ciliated epithelium thatcovered with a thin layer of mucus.



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Bronchi and branches

The bronchi and their branches

Primary bronchi: one to eachlung

Secondary bronchi: branches to

right and left lobes of each lung

Bronchioles and Alveoli

Respiratory bronchioles: smallerbranches of secondary bronchi

Alveoli: clusters of tiny air sacs linewalls of bronchioles and are thesites of gas exchange

Single epithelial layer surroundsalveolar sacs; network of capillariesunderneath



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Surface Tension in Alveoli

Surface tension of liquid coveringinside alveoli resists expansion

Alveoli produce surfactant(detergent) to reduce surfacetension

Premature babies may lacksurfactant; must be provided withsubstitute surfactant

Breathing

Lungs are in the thoracic cavitysurrounded by ribs, diaphragm and fluid-filled sac

Alveoli are dead ends; active breathingmoves air in and out



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Mechanics of breathing

Inspiration: diaphragm contractsand moves down ribs contract expands cavity reduces pressure air flows in

Expiration: diaphragm relaxes andmoves up ribs relax volume of cavity decreased increasedpressure forces air out

Gas in Circulation

Transport of gases assisted by thecirculatory system

Oxygen diffuses into red blood cells,

binds with hemoglobin Blood carries hemoglobin to tissues



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More oxygen in blood than intissues; oxygen leaveshemoglobin in blood and movesto tissue fluid and then to cells

by diffusion

O2 from blood to cells

CO2 from cells to blood

More carbon dioxide in tissuesthan in blood; CO2 is converted to

bicarbonate in blood and movesto lungs



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Gas Exchange

Capillaries surround alveoli to increasesurface area

Plasma from blood leaks into alveoli to

wet surfaces

Epithelial cells of alveoli are thin toallow diffusion of oxygen and carbondioxide

Tobacco Smoke

Tar blocks surfaces of lung, causesmutations

Nicotine paralyzes cilia, eventuallydestroying them

Smoke irritates lungs, which secreteextra mucus

Must cough to clear lungs; bacteria andviruses accumulate

Coughing breaks alveoli, decreasingsurface area



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Smoker’ s cough

The mucus and cilia work togetheras an “up escalator” for anyparticles or microbes existed.

A chronic cough, often called smoker’ scough, is triggered by accumulations of

mucus below the larynx.

How does hemoglobin pickup oxygen in the lungs

and drop it off in the

tissues?



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Hemoglobin

Invertebrates have oxygen-carryingpigments (hemocyanin) dissolved in blood

Vertebrates have hemoglobin in red bloodcells

Hemoglobin is 4 peptide chains, each with aheme group that binds 1 oxygen

Hemoglobin Loading

Hemoglobin changes shape to bindand release oxygen

At high partialpressure of

oxygen,hemoglobinbinds

At low partialpressure,releases



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Other Factors

Hemoglobin’ s affinity for oxygen isaffected by pH; acidity decreasesaffinity

Bound carbon dioxide decreasesaffinity for oxygen

BPG decreases affinity for oxygen

Active cells induce release of oxygen from hemoglobin

How do blood and thelungs rid the tissues of

waste carbon dioxide?



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Carbon Dioxide Transport

Carbon dioxide (CO2) is wasteproduct of cellular respiration

CO2 is carried in blood in threeways:

Dissolved in plasma

Combines with hemoglobin Forms bicarbonate

In the lungs, diffuses into alveoli,exhaled

Oxygen Homeostasis

Increases breathing rate withexertion

At high altitudes (oxygen partial

pressure is lower), makes morered blood cells and hemoglobinwith hormone erythropoietin

Increases levels of BPG



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Regulation of Breathing

Receptors in brain stem detect acidlevels of blood

Carbon dioxide as bicarbonatereleases hydrogen ions, decreasespH

Stimulates deeper and more rapidbreathing

Brain stem controls heart rate

Health Connections

Choking: A common respiratoryemergency

Chronic obstructive pulmonarydisease



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Choking: A common respiratoryemergency

Choking: foreign object becomeslodged in the glottis, larynx ortrachea

Heimlich maneuver

no sound means no air can pass

quick sharp upward abdominalthrusts should clear blockage

Chronic obstructive pulmonarydisease

A group of disorders that blocksairways and impairs breathing

Chronic bronchitis: inflammation of the bronchi and bronchioles

Emphysema ( 肺氣腫): mucus plugsprevent air movement out of alveoli; have coughing, alveolarrupture and loss of elasticity



Key Concepts Most animals use gills or lungs to obtain

oxygen and dispose of carbon dioxide

Gills and lungs have large, wet surfaceareas that increase the exchange of oxygen and carbon dioxide

In mammals, the diaphragm and themuscles of the rib cage pull air intoairways that lead to oxygen-absorbingsurfaces

ch39 respiration how animals breath

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