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Respiration
Respiration
 Gas exchange (O2 and CO2)
 Diffusion down concentration gradient
 Specialized epithelial surfaces
 Moist
 Thin
 Large surface area
Respiration
 Fick’s Law—The larger the surface area and the
steeper the partial pressure gradient, the faster
diffusion will proceed.
 Ventilation
 Active movement of air
 Necessary in larger animals
 Enhances gas exchange rates
Respiratory Pigments
 Metal ions that bind to and
carry O2
 Hemoglobin
 All vertebrates; some




mollusks, annelids,
crustaceans
Iron ion
Oxygenated—red,
deoxygenated—dark red
In all Kingdoms, but not all
organisms
Structure of molecule varies
by species
Respiratory Pigments
 Hemocyanin
 Most mollusks, some arthropods
 Copper ion
 Oxygenated—blue, deoxygenated—colorless
 Second most common pigment
 Myoglobin
 Found in muscle tissue
 Can store O2 for later use
 Amounts vary between species
Invertebrate Respiration
 Integumentary Exchange
 Some aquatic animals
 Small, simple organisms

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Protozoans
Poriferans, Cnidarians,
Platyhelminthes, Annelids, etc.
 Short distance between O2 and
tissues
Invertebrate Respiration
 Gills
 Aquatic mollusks, arthropods
 Different than fish
 Outgrowth of body wall
 Highly folded
 Gas exchange to water
Invertebrate Respiration
 Book Lungs
 Most arachnids
 1-4 pairs
 Folded appearance
 Direct opening outside of body
Invertebrate Respiration
 Tracheal System
 Insects, millipedes, centipedes,
some arachnids
 Spiracles in integument
 Tubes branch several times
 Tips of finest branches end at
body cells in all tissues
Vertebrate Respiration
 Gills
 Aquatic vertebrates


Most internal
External in some fish larvae &
amphibians
 Finely branched
 Attached to firm supports
Vertebrate Respiration
 Countercurrent Flow


Blood flows in opposite
direction to water
Maximizes O2 exchange
Vertebrate Respiration
 Lungs
 All terrestrial
vertebrates, some fish
 Saclike internal organ
 Airways connect to
external environment
 Variable complexity
Vertebrate Respiration
 Amphibian respiration
 Larvae gills, adults lungs
 Some integumentary
exchange

Frogs/toads take O2 through
lungs, eliminate CO2 through
skin
 Small, simple lungs
 Positive pressure
 “Gulps” air into mouth
 Pushes air into lungs
 Body wall muscles contract,
forcing air out of lungs
Vertebrate Respiration
 Reptile respiration
 More developed lungs
 Negative pressure


Draw air into lungs
Expansion & contraction of ribs causes
ventilation
Vertebrate Respiration
 Avian respiration
 Rigid lungs

No alveoli
 Air sacs
 Air flow continuously
through lungs


Inhalation—air moves into
posterior air sacs & lungs
Exhalation—air moves from air
sacs into lungs, also exits lungs
 Ventilate by expanding &
contracting chest
Vertebrate Respiration
 Mammal respiration
 Diaphragm


Contracts, pulling chest cavity down
(negative pressure)
Relaxes, allowing outward flow
 Ribcage can expand & contract
 Exhalation not complete

O2-poor and O2-rich air mix
Mammal/Human Respiration
Nasal & Oral Cavities
Pharynx
Trachea
Bronchi
Glottis
Bronchioles
Larynx
Alveoli
Trachea
Mammal/Human Respiration
 Alveous (pl. alveoli)
 Only in mammals
 Spherical sacs
 Surrounded by capillaries
 Simple squamous epithelium
Respiratory Cycle
 Inhalation
 Ribs move out, diaphragm (if present) moves down
 Increases thoracic volume
 Draws air into lungs
 Active, requires energy
 Gas exchange
 Exhalation
 Intercostal muscles & diaphragm relax
 Thoracic volume returns to normal
 Reduction in volume forces air out
 Passive, no energy required
Special Situations
 High altitude
 Air pressure decreases w/
altitude
 This decreases O2 transport
 Hypoxia



Low blood O2
Heart & respiratory muscles work
harder
Hyperventilate
 Animals
 Hemoglobin has better affinity
for oxygen
 Carry more O2 at low pressure
Special Situations
 Humans born at high altitude


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Lungs have more alveoli & blood
vessels
Heart has larger ventricles to
pump more blood
Muscles have more mitochondria
 Humans born at low altitude



Can acclimate
Eventually produce more RBCs
Better oxygenation, but thicker
blood
Special Situations
 Deep Sea
 High pressure due to water
volume
 Forces nitrogen to be dissolved
in tissues
 Passes through cell membranes


If in neurons, disrupts signals
Nitrogen narcosis
 When ascend, N2 moves into
blood



If too rapid, bubbles form in
blood
“The Bends”
Pain in joints, obstructed blood
flow to organs
Special Situations
 Well-trained humans hold breath 3
min
 Human records
 Free-diving length: 9 min 8 sec
 Free-diving depth: 244m (800’)
 Deep-diving depth: 330m (1,082’)


10m to reach depth
8 hr 49 min to return to surface
Special Situations
 Animals
 Sperm whale: 2500m (8,200’,
1.5mi), 1.5-2 hr
 Leatherback sea turtle: 1,000m
(3,280’), 30 min
 Bottlenose dolphin: 550m
(1,804’), 10 min
Special Situations
 How????
 Fill lungs fully before dive


85-90% air exchange
Humans 15%
 As dive lengthens, blood directed away from most organs
 Preferentially to brain & heart
 Myoglobin up to 10 times humans
 41% of O2 stored in muscles (humans 13%)
 High lactic acid tolerance
 Can operate in anaerobic metabolism longer
 Mechanisms to avoid “bends”
 Air w/ N2 taken at surface (lower pressure)
 W/ depth, air moved to nonabsorptive areas, reducing gas exchange