Respiration in animals
•Whether they live in water or on land, all animals must
respire.
–To respire means to take in oxygen and give off carbon
dioxide.
•Some animals rely of simple diffusion through their
skin to respire.
•While others…
•Have developed large complex organ systems for
respiration.
Invertebrate respiration
•Invertebrate respiratory organs have
–large surface areas
–contact with air or water
–If require diffusion they must be moist.
Aquaticinvertebrates:havenaturallymoistrespiratory
surfaces,andsomerespirethroughdiffusionthrough
theirskin.
–Example:jellyfishandanemones
•Somelargeraquaticanimalslikewormsandannelids
exchangeoxygenandcarbondioxidethroughgills.
–Gillsareorgansthathavelotsofbloodvesselsthatbringblood
closetothesurfaceforgasexchange.
Section 29-2
Mollusk
Insect
Spider
Gill
Siphons
Movement of water
Book
lung
Airflow
Tracheal
tubes
Spiracles
Invertebrate Respiratory Systems
Vertebrate respiratory systems
•Chordates have one of two basic structures
for respiration:
–Gills –for aquatic chordates
•Example: tunicates, fish and amphibians
–Lungs -for terrestrial chordates
•Examples: adult amphibians, reptiles, birds, and
mammals
Aquatic Gills
•Water flows
through the mouth
then over the gills
where oxygen is
removed
•Carbon dioxide and
water are then
pumped out
through the
operculum
Vertebrate lungs
•As you move from amphibians to mammals the
surface area of the lungs increases
–Insures a greater amount of gas exchange (or a two way
flow of air).
•Birds, by contrast have lungs and air sacs which
have only a one-way flow of air.
–This allows for them to have constant contact with fresh
air.
–This adaptation enables them to fly at high altitudes
where there is less oxygen.
Section 33-3
Salamander Lizard PigeonPrimate
Nostrils, mouth, and
throat
Trachea
Lung
Air sac
Vertebrate Lungs
Gas exchange by Diffusion
•Some animals simply allow gases to diffuse
through their skins.
Fick’s Law of Diffusion
•Gas exchange involves the diffusion of gases across a
membrane
•Rate of diffusion (R) is governed by Fick’s Law:
•R = DA p
d
D= diffusion constant (size of molecule, membrane permeability, etc)
A= area over which diffusion occurs
p= pressure difference between sides of the membrane
d = distance across which diffusion must occur
Fick’s Law of Diffusion
R = DA p
d
To maximize diffusion, R can be increased by:
Increasing A (area over which diffusion occurs)
Increasing p(pressure difference between sides of
the membrane)
Decreasingd (distance across which diffusion must occur)
Evolutionary changes have occurred to maximize R
Figure 42.18 The role of gas exchange in bioenergetics
GAS EXCHANGE in “Animals”
•The part of the organism across which gases
are exchanged with the environment is the
respiratory surface
•Must be moist
–plasma membranes must be surrounded
by water to be stable
•Must be sufficiently large
–maximize A in Fick’s Law
1.Integument/skin –Protozoa –Annelids;
Echinoderms -Dermal papulae -starfish
2.Gills –Mollusca –Fishes -Aquatic Insects and amphibians
Mollusks -Monopectinate –Pila; Bipectinate –Freshwater mussel
Crustacean (Prawn) –Arthrobranch, Pleurobranch & Podobranch
Tracheal gills -aquatic insects
Prochordates –Pharyngeal gills
3.Trachea -Insects
4. Lungs –Amphibian –Mammals (advanced in Aves)
Diffusion lungs: Book lungs –Arachnids –Spiders & Scorpions
Ventilating lungs: Inspirational type -mammals and birds
Expirational –Amphibians & reptiles (except crocodiles)
MAJOR RESPIRATORY STRUCTURES IN ANIMALS
OTHER TYPES
1.Swim bladder –air breathing fishes
2.Alimentary mucosa -fishes
3.Labyrinthine organ –wavy plates in fish operculum
4.Arborescent organ –respiratory trees operculum
5.Epipodite –Crustaceans –prawn –Y shaped respiratory
filaments
6.Tracheal gills –Aquatic insects
7.Book gills –Limulus; Holothurians
8.Water lungs -Molluscans
9.Pulmonary chamber –empty sac lined with vascularized
membranes within mantle cavity -gastropods
Comparative Respiratory Systems
Respiratorysurface=asinglelayerofepithelialcellsseparatesouter
respiratorymedium(airorwater)fromtheorganism’stransport
system(blood)
–Skin must be moist
–organisms with flat or
wormlike bodies so skin in
sufficient surface area
–or in frogs and some turtles
to supplement respiration
using lungs
•Skin (cutaneous respiration)
•Specialized region of body is folded and branched to
provide large surface area
•This maximizes A in Fick’s Law
•Also decrease d by bringing the respiratory medium
close to the internal fluid
•Three such systems:
–Gills(Aquatic organisms)
–Trachea(insects)
–Lungs(terrestrial vertebrates)
Diversity in the structure of gills, external body surfaces in gas exchange
Gills
•most aquatic organisms
•outfoldings of the body surface specialized
for gas exchange
•Water is the respiratory medium
Water as Respiratory Medium
•Respiratory surface always moist
•Oxygen content of water is much less than
that of air
•denser medium so harder to ventilate
Ventilation
•Any method that increases the flow of the
respiratory medium across the respiratory
surface
•This maximizes p in Fick’s Law
–By constantly have new air or new water with
more oxygen
Countercurrent Exchange
•Enhances gas exchange in the gills of fish
•blood is continually loaded with O
2b/c it
meets water with increasing O
2
concentration
–Increases p in Fick’s Law
Air as respiratory medium
•Higher oxygen concentration
•ventilation is easier b/c air is less dense
•respiratory surface loses water to air by
evaporation
Air as respiratory medium
•Solution…
–fold respiratory surface inside the body
Trachea
•Air tubes that branch throughout the body
•finest tubes (tracheoles) extend to nearly
every cell in the body
•gas diffuses across moist epithelium that
lines the terminal ends
Figure 42.22 Tracheal systems
Trachea
•Found in insects
•Open Circulatory system of insects is NOT
involved in transporting gases
•Ventilation
–diffusion
–body movements
Lungs
•Localized in one area of body
–circulatory system must transport gases
Section 33-3
Salamander Lizard PigeonPrimate
Nostrils, mouth, and
throat
Trachea
Lung
Air sac
Vertebrate Lungs
Expiration
Inspiration
Muscles
contract
Lungs
Air
Sternocleido-
mastoid muscles
contract
(for forced
inspiration)
Diaphragm
contracts
Muscles
relax
Diaphragm
relaxes
a.
b.
Abdominal
muscles contract
(for forced expiration)
Air
Negative pressure breathing
Nasal cavity
Nostril
Larynx
Trachea
Right lung
Left lung
Pharynx
Left
bronchus
Glottis
Diaphragm
Pulmonary
venule
Pulmonary
arteriole
Blood flow
Bronchiole
Alveolar
sac
Alveoli
Capillary
network on
surface
of alveoli
Smooth muscle
Lungs
Section 37-3
Flowchart
Oxygen and
carbon dioxide
exchange at
alveoli
Oxygen-rich
air from
environment
Bronchioles
Nasal
cavities
Pharynx Trachea Bronchi
BronchiolesAlveoli
Pharynx
Nasal
cavities
Carbon
dioxide-rich
air to the
environment
Bronchi
Trachea
Movement of Oxygen and Carbon Dioxide In
and Out of the Respiratory System
In the alveolus
•The respiratory
surface is made
up of the alveoli
and capillary
walls.
•The walls of the
capillaries and the
alveoli may share
the same
membrane.
Gas exchange
•Air entering the lungs
contains more oxygen
and less carbon
dioxide than the blood
that flows in the
pulmonary capillaries.
Oxygen transport
•Hemoglobin
binds to oxygen
that diffuses into
the blood
stream.
Carbon dioxide transport
•Carbon dioxide
can dissolve in
plasma, and about
70% forms
bicarbonate ions.
•Some carbon
dioxide can bind to
hemoglobin for
transport.
Lungs
•Ventilation
–air sacs act as bellows in birds
•air flows in one direction during both inhalation &
exhalation
Anterior
air sacs
Posterior
air sacs
Parabronchi of lung
Trachea
Inspiration Expiration
Inspiration Expiration
Cycle 2
Cycle 1
Trachea
Anterior
air sacs
Lung
Posterior
air sacs
a. b.
Lungs of Birds
Transport of Gases
•Occurs in the circulatory system when
needed
Transport of Gases
•O
2is transported by respiratory pigments
–hemoglobinon red blood cells or hemocyanin
in the plasma
Transport of Gases
•CO
2is transported by respiratory pigments
and dissolved in the plasma and in red
blood cells as bicarbonate ion (HCO
3
-
)