Download Respiratory system Lecture 12 File

Respiratory System
FUNCTIONAL
ANATOMY
(ZOO124.1.0)
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Respiration in animals
¢ External
respiration: not to be confused
with
cellular respiration, although purpose
is to provide oxygen and eliminate
carbon dioxide
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Respiration in animals
¢ Whether
they live in water or on land, all
animals must respire.
¢ Some
animals rely of simple diffusion
through their skin to respire.
While others…
¢ Have
developed large complex organ
systems for respiration.
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Respiration in animals
¢ Getting
air into the body is one challenge
¢ Circulatory
system needed to distribute
oxygen to the tissues
¢ Specialized blood cells can transport
oxygen
(solubility in plasma is very low)
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2
Process of Breathing
¢ Air
has much more oxygen than water
(20% vs 0.9%)
¢ Gas diffuses more rapidly in air; water is much
more dense and viscous
¢ Therefore
aquatic animals are highly efficient
at extracting oxygen form water
¢ However,
they must expend much more energy
to do so (up to 20% vs 1 - 2% of resting
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metabolism)
Process of Breathing
• Respiratory surfaces must be thin and wet so
that gas can diffuse through an aqueous
phase between environment and circulation
(also to maintain cells themselves)
• Air breathers have adapted specialized
invaginations of the body to “take in” air
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3
Process of Breathing
• Ventilation-mechanisms to move air into and
out of the body
• Evaginations (gills) for water breathing
Invaginations (lungs and tracheae) for air
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Aquatic Invertebrates
¢
Aquatic animals have naturally moist
respiratory surfaces, and some respire through
diffusion through their skin.
—
Example: protozoa, sponges, cnidarians,
some worm
Why is this possible????
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Invertebrate Respiration
¢ Because
—
—
—
large surface areas relative to their mass
All cell are in contact with air or water
If require diffusion they must be moist.
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Aquatic Invertebrates
¢ Some
larger aquatic animals like worms and
annelids exchange oxygen and carbon dioxide
through gills.
—
Gills are organs that have lots of blood
vessels that bring blood close to the surface
for gas exchange.
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Terrestrial Invertebrates
¢ Terrestrial
invertebrates have respiratory
surfaces covered with water or mucus. (This
reduces water loss)
¢ There
are many different respiratory
specialized organs in terrestrial invertebrates.
—
Spiders use parallel book lungs
—
Insects use openings called spiracles where
air enters the body and passes through a
network of tracheal tubes for gas exchange
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Terrestrial Invertebrates
—
Snails have a mantel cavity that is lined with
moist tissue and an extensive surface area of
blood vessels.
How does respiration in aquatic invertebrates differ
from that in terrestrial invertebrates?
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Invertebrate Respiratory
Systems
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Terrestrial Invertebrates
Larger (and/or flying
insects) require
ventilation
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Terrestrial Invertebrates
Air tubules
(trachea &
tracheoles)
throughout the
body which open
to the
environment via
spiracles
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Terrestrial Invertebrates
¢
¢
¢
Air is taken in through the
spiracles during inspiration
and expelled through
expiration.
Each spiracle is protected
by hairs and two lip-like
structures that can be
closed to reduce water loss,
allowing insects to live in
dry areas.
A rise in carbon dioxide
causes the spiracles to
open.
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Trachea
¢ Air
then passes into
tubes called trachea.
¢ Each
trachea is
prevented from collapse
by a spiral of chitin
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Tracheole
¢ Each
trachea ends in
microscopic tubes
called tracheoles.
¢ Tracheoles
lie within
individual cells and sit
in a pool of fluid which
allows rapid diffusion
of oxygen and carbon
dioxide in and out of
the cells.
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Insect Tracheal System
¢ In
insects oxygen is
delivered directly to
the cells (i.e. the
site of respiration).
¢ Insect
blood does not
carry oxygen
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Insect Tracheal System
¢ In
larger insects, muscular movement of
the abdomen and air sacs assist air
movement.
¢ This
system will not function well in
animals whose body size is greater than
5cm.
¢ Insects can
regulate their gas exchange
according to their metabolic rate.
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Insect Tracheal System
¢ If
an insect is resting and the
metabolic rate is low, the spiracles
close.
¢ When
the insect has a high metabolic
requirement, such as in flying,
spiracles are open to allow efficient gas
exchange between tracheoles and cells.
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Air Sacs
• Adaptations for more
effective air supply during
flight, i.e. high oxygen
expenditure.
•
•
•
Air sacs -Expansion of
lateral tracheal trunks.
Present in flying insects.
May take up large
proportion of body cavity.
Air sacs in honey bee
• Depends on adaptation of abdomen for
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“pumping” action.
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Lungs of Invertebrates
•
Book lungs used
•
Book lungs unique to
spiders; parallel air
pockets extend into
blood-filled chamber;
air enters chamber
through lit in body wall
•
Tracheae are tubes
that carry air from the
inside directly into the
tissues
Book lungs
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Invertebrate gills
¢ Closed
system
¢ Thin
membrane allowing
diffusion of oxygen
¢ Configuration,
extent,
location may be diagnostic
of taxon
internal chamber
(ODONATA:
ANISOPTERA)
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abdominal
(TRICHOPTERA)
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Invertebrate gills
¢
Found in aquatic spp.
¢ Book
gills in cheliserata
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Lungs of Invertebrates
Confined to a specific region of the body
Pulmonate snails, spiders, scorpions, some
crustaceans) have rudimentary lungs
(book lungs unique to spiders)
Use muscle movements to provide rhythmic
exchange of air
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Other structure of Invertebrates
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Vertebrate Respiratory
Systems
Chordates have one of two basic structures for
respiration:
Gills – for aquatic chordates
Example: Jawless fish, tunicates, fish and
amphibians
Lungs - for terrestrial chordates
Examples: adult amphibians, reptiles,
birds, and mammals
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14
e Skin
Cutaneous respiration amphibian
Continued
has a major
smoregulation
moregulation
s highly
has a high
ea, and is a
rce of gas
.
S
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Cutaneous respiration -oxygen is
absorbed directly into the bloodstream
then veins and arteries carry it to and
from the heart.
Vertebrate Gills
• Specialized extensions of tissue that project into
H2O
•Two types
• Internal gills - fish jawless fish
•External gills - amphibians
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Internal Gills
• Develop from evaginations of pharyngeal
pouches
• Visceral grooves opposite the pharyngeal
pouches separated from pharyngeal pouches by a
thin layer of tissue – Closing Plate
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Internal Gills
• General structure of mature gills
• Rakes
• Rays
• Filaments
• Lamellae
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Internal Gills
• Gills of 3 morphology
• Holoranch - Jawed fishes
• Hemibranch - Sharks
• Pseudo ranch – Teleost fish
Hemibranch
Holo B
Pseudo B
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Fish Gill variations
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Gills - Hag fish (Jawless fish)
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Gills - Hag fish (Jawless fish)
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Vertebrate Gills Elasmobranchs
Cartilaginous Fish
¢5
naked gill slits
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Vertebrates – Fish gills
Boney Fish
¢5
gill slits
¢ operculum projects backward
chambers
¢ Inter-branchial
or absent
over gill
septa are very short
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Fish Gills
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Vertebrate Gills
• Gills of bony fishes are located between the
oral (buccal or mouth) cavity and the opercular
cavities
• These two sets of cavities function as pumps
that alternately expand
• Move water into the mouth, through the gills,
and out of the fish through the open operculum
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or gill cover
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AS Biology Unit 2
Inspiration
Inspiration
E
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1. The mouth opens.
1. The mouth closes.
2. The muscles in the mouth contract, lowering the 2. The mouth and op
floor of the mouth, and the opercula muscles
contract, pushing the opercula outwards.
the floor of the buc
page 9
3. This increases the volume of the buccal cavity 3. This decreases the
n
Expiration
and the opercular cavity.
Expiration
4. This decreases the pressure of water in the 4. This increases the
buccal cavity below the outside water pressure.
buccal cavity above
5. The outside water pressure closes the opercular 5. This pressure force
valve.
6. Water flows in through the open mouth and 6. Water flows out o
over the gills from high pressure to low pressure.
opercula valve fr
pressure.
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1. The mouth closes.
These pressure changes are shown in this graph. The rule is that water alwa
contract, lowering the 2. The mouth and opercular muscles relax, raising
he opercula muscles
to a low pressure. This graph shows that water flows in one direction only.
the floor of the buccal cavity.
ula outwards.
of the buccal cavity 3. This decreases the volume of the buccal cavity.
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Vertebrate Gills
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External gills
• Develop from the skin ectoderm
E.g. Amphibian Larvae
• All chordates have gill slits at some point
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Vertebrates
• Larger animals (amphibians, eels) supplements
breathing with cutaneous respiration
• Skins are heavily vascularized
• Hibernating frogs and turtles can exchange all
gases through skin while submerged
•
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Vertebrate Lungs
• Gills were replaced in terrestrial animals because
• Air is less supportive than water
• Water evaporates
• The lung minimizes evaporation by moving air
through a branched tubular passage
• A two-way flow system
• Except birds
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Amphibian Lungs
• Lungs of amphibians are formed as saclike outpouchings of the gut
• Frogs have positive pressure breathing
• Force air into their lungs by creating a
positive pressure in the buccal cavity
• Reptiles have negative pressure breathing
• Expand rib cages by muscular contractions,
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creating lower pressure inside the lungs
Amphibian Lungs
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Birds Lungs
• Respiration in birds occurs in two cycles
• Cycle 1 = Inhaled air is drawn from the
trachea into posterior air sacs, and exhaled
into the lungs
• Cycle 2 = Air is drawn from the lungs into
anterior air sacs, and exhaled through the
trachea
• Blood flow runs 90o to the air flow
• Crosscurrent flow
• Not as efficient as countercurrent flow
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Birds Lungs
Birds have lost part of their digestive systems
and make room for air sacs
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Birds Lungs
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Mammalian Lungs
• Lungs of mammals are packed with millions of
alveoli (sites of gas exchange)
• Inhaled air passes through the larynx, glottis,
and trachea
• Bifurcates into the right and left bronchi,
which enter each lung and further subdivide
into bronchioles
• Alveoli are surrounded by an extensive
capillary network
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Mammalian Lungs
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Mammalian Lungs
• Gas exchange is driven by differences in partial
pressures
• Blood returning from the systemic circulation,
depleted in oxygen, has a partial oxygen pressure
(PO2) of about 40 mm Hg
• By contrast, the PO2 in the alveoli is about 105
mm Hg
• The blood leaving the lungs, as a result of this gas
exchange, normally contains a PO2 of about 100 54
mm
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