Transcript Respiratory System - Volunteer State Community College

Human
Heart
Respiratory System
Chapter 42, Campbell, 6th edition
Nancy G. Morris
Volunteer State Community College
Gas Exchange In Animals
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supplies O2 for cellular respiration
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disposes of CO2 (Figure 42.17)
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occurs between respiratory medium and
organism
air is 21% oxygen but the amount of
dissolved O2 in water varies due to
temperature, solute concentrations, etc
Respiratory surface
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place where gas exchange with
respiratory medium occurs
O2 diffuses in; CO2 diffuses out
surface must be wet (gases must
dissolve in water)
surface must be extensive enough to
provide for the entire body
Variation of Respiratory Surfaces
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entire surface – protozoa & unicellular
organisms
plasma membrane of each cells contacts
the outside environment – sponges,
cnidarians, flatworms
moist skin over dense capillaries –
earthworm and amphibians – must live in
moist damp places to keep exchange
surface moist
Variation of Respiratory Surfaces
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most other animals lack sufficient body surface
to exchange gases for the entire body
they possess a region of body surface that is
extensively branched or folded
 aquatic animals: gills are present & in
direct contact with water
 terrestrial animals: internal respiratory
surfaces that open to the atmosphere
through narrow tubes: lungs & insect
trachea
Gills: Adaptations of Aquatic Organisms
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outfoldings of the body surface specialized
for gas exchange -excresence
Figure 42.18
some have flap-like gills that extend from
each segment (annelids)
localized gills on a body region where surface
is subdivided to provide for large surface
area (mollusks, fish)
Gills must be efficient
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water has lower O2 concentration than air, SO
fish expend a lot of energy to ventilate
(increasing the flow of the respiratory medium
over the respiratory surface)
fish possess a unique arrangement in their gills
which maximizes O2 uptake from water
COUNTERCURRENT EXCHANGE – blood flows
opposite to the direction in which water passes
over the gills, maintaining a constant
concentration gradient (Figures 42.19 & 42.20)
Counter Current Mechanism
Counter Current Mechanism
Adaptations of Terrestrials
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air has advantages over water as
respiratory medium:
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higher O2 concentration
O2 and CO2 diffuse faster through air
respiratory surfaces do not have to be
ventilated as thoroughly
disadvantage is that respiratory surface
is continuously desiccated
Tracheal System
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air enters through openings called spiracles
and diffuses through small tubes extending
to the surface of most cells
tubes are lines with chitin
some insects are so small they rely on
diffusion to move O2 through the system;
other rely on rhythmic body movements
major reason why open circulatory system
works for insects.
Tracheal System
Lungs
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highly vascularized invaginations of the body
surface
the circulatory system must transport oxygen
from the lungs to the rest of the body
land snails use an internal mantle as a lung
spiders possess booklungs
frogs have simple balloon like w/ limited surface
area
mammals have highly subdivided lungs with with a
large surface area
Human Respiratory System
Mammalian Respiratory Systems
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lungs in thoracic cavity
surround by the plural lining – two layers
held together by the surface tension of
fluid between layers
air entering nostrils is filtered by cilia,
warmed and moistened
travels through the pharynx, through the
glottis, and into the larynx (which
possesses vocal cords & a voice box)
Mammalian Respiratory Systems
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enters the cartilage-lined trachea that forks
into two bronchi which further branch into
finer bronchioles that dead-end in alveoli
alveoli are lined with a thin layer of epithelium
which serves as the respiratory surface
O2 dissolves in the moist film covering the
epithelium & diffuses across the capillaries
covering each alveolus
CO2 diffuses in the opposite direction
Alveoli: SEM
Ventilating the Lungs
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vertebrates ventilate by breathing
(alternate inhalation & exhalation of air)
frogs ventilate by positive air pressure –
gulping air
mammals ventilate by negative air pressure
shallow inhalation results from contraction
of the diaphragm (Figure 42.23)
Respiration
Ventilating the Lungs
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contraction of the rib muscles pulls
the ribs upwards, which expands the
rib cage
lung volume increases, resulting in
negative pressure within the alveoli,
causing air to rush in
exhalation occurs when diaphragm &
rib muscles relax
Pneumatic Lungs of Birds
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besides lungs, birds have 8 or 9 air sacs,
which are present in the bones
functions: trims body density, act as heat
sinks for heat dissipation by metabolism of
flight muscles, serve as bellows, to keep air
moving
air moves through the entire system in only
one direction whether inhaling or exhaling
thus providing a constant supply of oxygen
Pneumatic Lungs
Breathing Control
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breathing is automatic (thankfully!)
breathing control centers of the brain
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1) medulla oblongata
2) pons
10 – 14 times per minute
medulla’s control center also monitors
blood and cerebrospinal pH
as CO2 concentrations increase, pH
decreases
Respiratory Pigments
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Oxygen transporting pigments:
1) hemocyanin – arthropods & mollusks
contains copper (rather than iron) which
results in blue color
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2) myoglobin – a single subunit of heme
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3) hemoglobin – most vertebrates
found in the skeletal muscle
consists of four polypeptides with central
iron-containing heme which binds O2
Cooperativity
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the binding of O2 to hemoglobin is
reversible
binding of O2 to one subunit of heme
changes the shape which increases the
affinity of the other three subunits for
oxygen
the unloading of oxygen from one heme
group results in conformational change
that stimulates unloading from the other
three
Carbon dioxide transport
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CO2 is transported in three forms:
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1) dissolved CO2 in the plasma (7%)
2) bound to the amino groups of
hemoglobin (23%)
3) as bicarbonate ions in the plasma
(70%)
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Deep-diving mammals stockpile
oxygen and consume it slowly
WeddellSeal