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RESPIRATION
RESPIRATION
Respiratory system
Functions
O2 uptake
CO2 expulsion
2
Atmospheric Gasses
Nitrogen (N2)
78%
PN2 593 mmHg
Oxygen (O2)
21%
PO2 160 mmHg
Carbon dioxide (CO2)
0.05%
PCO2 0.4 mmHg
760 mm Hg
3
Elements of Gas Exchange
Movement directed by concentration &
pressure gradients
Diffusion
Concentration: [high] [low]
Pressure: H L
Factors affecting rates of diffusion
Temperature
Moisture
4
Mechanisms of Gas Exchange
Cutaneous respiration (integumentary
exchange)
E.g., Annelida, Platyhelminthes, Amphibia
5
Mechanisms of Gas Exchange
Tracheal respiration
E.g., Insecta
6
Mechanisms of Gas Exchange
Gills
E.g., mollusks, aquatic arthropods, fish,
amphibians
7
Gills
FISH GILL
water flows
over gills,
then out
mouth
open
operculum
closed mouth
closed
operculum
open
8
Gills
gill arch
filament
of gill
Countercurrent flow
Efficient O2 uptake
direction
of water
flow
surface for gas
exchange
direction
of blood
flow
9
Mechanisms of Gas Exchange
Lungs
Compromise efficiency for water retention
Gas exchange requires pressure differential
inside / outside body
E.g., mammals, birds, reptiles, amphibians (most)
10
Lungs
Slide 10
Fig. 41.8, p. 713
AMPHIBIAN
(salamander;
still rather like
fishes, early
amphibians)
REPTILE
(lizard;
adapted
to dry
habitats)
AMPHIBIAN
(frog; only
adults are
adapted
to dry
habitats)
MAMMAL
(human;
adapted to
dry habitats)
11
Quick Quiz: The primary function of
the respiratory system of any animal
is…
A) Gas Exchange
B) Removal of wastes from the body
C) Breathing
D) Circulation
12
Mechanics of Breathing
Boyle’s Law
The pressure of a gas varies
inversely with its volume
volume, pressure
= inhalation
volume, pressure
= exhalation
13
Amphibian Respiratory System
frog_respiration 14
Avian Respiratory System
air
sacs
trachea
air
sacs
Structures
Lungs
Air sacs
Oxygenated air
continually passes
over lungs
Need for increased
efficiency?
bird_respiration 15
Human Respiratory System
Primary structures
Oral / Nasal cavities
Pharynx
Larynx
Epiglottis
Vocal folds
Trachea
Bronchi
Bronchioles
Alveoli
human_respiration 16
Human Respiratory System
Other structures
Hyaline cartilage
Ciliated epithelia
Mucus cells
Diaphragm
17
Mechanics of Breathing
Inhalation
Diaphragm contracts
Moves downward
External intercostals
contract
Elevates rib cage
Effect
Volume pressure
Air forced into lungs
INWARD BULK
FLOW OF AIR
18
Mechanics of Breathing
Exhalation
Diaphragm relaxes
Moves upward
Internal intercostals contract
Depresses rib cage
Recoil properties of lungs
Effect
Volume pressure
Air forced out of lungs
OUTWARD BULK
FLOW OF AIR
breathing 19
Quick Quiz: Breathing depends on …
A) Changing pressure inside the chest cavity
B) Changing volume of the chest cavity
C) The contraction and relaxation of the
diaphragm
D) All of the above
20
Lung Capacities
Total lung capacity
6 L (adult male)
Tidal volume
Normal breath
0.5 L
Vital Capacity
Max. inhale & exhale
5 L
Residual volume
Air not forcibly exhaled
1 L
21
Gas Exchange & Transport
The surface of the lung
Alveoli
Capillaries
22
Gas Exchange & Transport
O2 transport
Red blood cells
Binds to hemoglobin (98%)
4 O2 / Hb
CO2 transport
Red blood cells
Some binds to hemoglobin ( 30%)
Most converted to bicarbonate ion
Plasma
Free CO2 ( 10%)
Bicarbonate ( 60%)
Buffer 23
Gas Exchange &
Transport
Movement based on
partial pressure
gradients for O2 &
CO2
alveolar sacs
cells of body tissue
MOIST
EXHAILED AIR
120 27
pulmonary
arteries
40 45
start of
systematic
veins
40 45
DRY
INHAILED AIR
160 0.03
pulmonary
veins
100 40
start of
systematic
capillaries
100 40
more than 45 less than 40 24
Quick Quiz: Oxygen moves to the
tissues because…
A) Oxygen concentration is higher in the blood
than in the tissues
B) Oxygen concentration is lower in the blood
than in the tissues
C) Oxygen partial pressure is higher in the
blood than in the tissues
D) Oxygen partial pressure is lower in the
blood than in the tissues 25
Respiratory Control
Voluntary
Diaphragm (skeletal muscle)
Involuntary
Respiratory centers in medulla oblongata & pons
Control rate & depth of breathing
Influenced most by [CO2]
26
Respiratory Disease
27
Environmental Effects on Respiration
Altitude
pressure ( PO2)
Less O2 available
pressure differential
Decreased force of diffusion
28
Altitude
Effects (short term)
Breathing difficulty
Muscular / neurological dysfunction
Altitude sickness (>8,000 ft; ~2,400 m)
29
Altitude
Acclimatization
Change in breathing patterns
2-3 L/min
Increase cardiac output
Increased rbc production
Increased lung & heart mass
30
Environmental Effects on Respiration
Depth
external pressure
1 atm / 10 m (33 ft)
Human divers
SCUBA
Maintain alveolar pressures relative to water
pressure
Nitrogen narcosis & “the bends”
Descent of 100 ft or more
N2 forced into blood tissues
CNS “intoxication”
Rapid ascent
N2 rapidly released from tissues & bubbles 31
Depth
Diving mammals Sperm whales
Submerge > hour
Depths > 1,000 m
Mechanisms Increased O2 storage
Increased rbc / hemoglobin content
O2 bound to myoglobin (muscle)
Decreased O2 usage
Decreased metabolic rate
Shunting (selective use)
Anaerobic metabolism
32
Quick Quiz: Changes in altitude are
detrimental because…
A) Your ears pop and that makes the oxygen
come out of your lungs
B) The blood can’t get oxygen out of the air
C) Air is too dense
D) Oxygen partial pressure in the lungs are
different than they are at sea level
33