Transcript An overview of the Phylum

Respiration and Circulation
Chapters 22 and 23
Introduction: Surviving in Thin Air
– The process of gas exchange is called
respiration, the interchange of
– O2 and the waste product CO2
– Between an organism and its
environment
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22.1 Gas Exchange
• Three phases
1. Breathing
2. Transport of oxygen and carbon dioxide in
blood
3. Body tissues take up oxygen and release
carbon dioxide
• Cellular respiration requires a continuous
supply of oxygen and the disposal of carbon
dioxide
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O2
1
Breathing
CO2
Lung
Circulatory
system
2
Transport
of gases by
the circulatory
system
Mitochondria
3
Exchange
of gases
with
body
cells
O2
CO2
Capillary
Cell
22.2 exchange across moist body surfaces
• Respiratory surfaces
Diffusion through skin – amphibians, worms
Lungs in birds, mammals, reptiles,
amphibians
Book lungs in spider
Tracheal tubes in insects
Gills in fishes; amphibians
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Cut
Cross section
of respiratory
surface (the
outer skin)
CO2
O2
Capillaries
22.3
• Cold water holds more oxygen than warm
water
• Fresh water holds more oxygen than salt
water
• Turbulent water holds more oxygen than
still water
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22.4
• Compared to water, using air to
breathe has two big advantages
– contains higher concentrations
of O2
– lighter and easier to move
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Air sacs
Tracheae
Opening
for air
Body
cell
Tracheole
Air
sac
Trachea
O2
CO2 Body wall
Oxygen-rich
blood
Nasal
cavity
Pharynx
Larynx
(Esophagus)
Oxygen-poor
blood
Bronchiole
Alveoli
Left lung
Trachea
Right lung
Bronchus
Blood
capillaries
Bronchiole
Diaphragm
(Heart)
Lung
Heart
22.8 Pressure and Ventilation
• Breathing is the alternate inhalation and
exhalation of air (ventilation)
• Inhalation occurs when
1. The rib cage expands
2. The diaphragm moves downward
3. The pressure around the lungs decreases
4. And air is drawn into the respiratory tract
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22.8
• Exhalation occurs when
1. The rib cage contracts
2. The diaphragm moves upward
3. The pressure around the lungs increases
4. And air is forced out of the respiratory tract
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22.9
• Breathing is usually under automatic control
• Breathing control centers in the brain sense
and respond to CO2 levels in the blood
• A drop in blood pH increases the rate and
depth of breathing
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Cerebrospinal
fluid
Brain
Pons
2 Breathing control
1 Nerve signals
trigger contraction
of muscles
Medulla
centers respond
to pH of blood
3 Nerve signals
indicating CO2
and O2 levels
CO2 and O2
sensors in aorta
Diaphragm
Rib muscles
22.11
• Most animals transport O2 bound to proteins
called respiratory pigments
– Copper-containing pigment is used by
– Molluscs
– Arthropods
– Iron-containing hemoglobin
– Is used by almost all vertebrates and many
invertebrates
– Transports oxygen, buffers blood, and transports CO2
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Iron atom
O2 loaded
in lungs
O2 unloaded
in tissues
Heme group
Polypeptide chain
O2
O2
22.12
– A human fetus
– exchanges gases with maternal blood in the placenta
– In the placenta, capillaries of maternal blood and fetal
blood run next to each other
– The fetus and mother do not share the same blood
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The Path
1. Oxygen in lungs (alveoli) move into capillaries
2. CO2 moves from capillaries into lungs
3. O2 is bound to hemoglobin (red blood cells)
and is transported throughout the body
4. O2 moves out of capillaries into fluid around
cells and into cells
5. CO2 moves out of cells into fluid and into
capillaries
6. CO2 is coverted to bicarbonate and carried to
lungsconverted back to CO2
Right
atrium
To lung
To lung
Left atrium
From lung
From lung
Semilunar
valve
Semilunar
valve
Atrioventricular
(AV) valve
Atrioventricular
(AV) valve
Right
ventricle
Left
ventricle
The Path
1. Leaves left ventricle to aorta
2. Moves from aorta to arteries to arterioles to
capillaries
3. Exchanges gases and nutrients with cells
4. Moves from capillaries to venules to veins
5. Moves to right atriumto right ventricle
6. Moves to lungs for gas exchange
7. Moves to left atriumto left ventricle
Epithelium
Epithelium
Smooth
muscle
Connective
tissue
Capillary
Basal lamina
Valve
Epithelium
Smooth
muscle
Connective
tissue
Artery
Vein
Arteriole
Venule
Red
blood
cell
Nuclei of
smooth
muscle
cells
Capillary
23.8 Blood pressure
– Highest in arteries
– Lowest in veins
measured as
– Systolic pressure—caused by
ventricular contraction
– Diastolic pressure—low pressure
between contractions
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