Respiration - Del Mar College

Respiration
Chapter 39 Part 2
39.6 Cyclic Reversals
in Air Pressure Gradients
 Respiratory cycle
• One inhalation and one exhalation
 Inhalation is always active
• Contraction of diaphragm and external intercostal
muscles increases volume of thoracic cavity
• Air pressure in alveoli drops below atmospheric
pressure; air moves inward
Cyclic Reversals
in Air Pressure Gradients
 Exhalation is usually passive
• As muscles relax, the thoracic cavity shrinks
• Air pressure in the alveoli rises above
atmospheric pressure, air moves out
 Exhalation may be active
• Contraction of abdominal muscles forces air out
The Thoracic Cavity and
the Respiratory Cycle
Fig. 39-15a, p. 690
Inward
flow of air
A Inhalation. Diaphragm
contracts, moves down.
External intercostal muscles
contract, lift rib cage upward
and outward. Lung volume
expands.
Fig. 39-15a, p. 690
Fig. 39-15b, p. 690
Outward
flow of air
B Exhalation.
Diaphragm, external
intercostal muscles
return to resting
positions. Rib cage
moves down. Lungs
recoil passively.
Fig. 39-15b, p. 690
Animation: Respiratory cycle
First Aid for Choking
 Heimlich maneuver
• Upward-directed force on the diaphragm forces
air out of lungs to dislodge an obstruction
Animation: Heimlich maneuver
Respiratory Volumes
 Air in lungs is partially replaced with each breath
• Lungs are never emptied of air (residual volume)
 Vital capacity
• Maximum volume of air the lungs can exchange
 Tidal volume
• Volume of air that moves in and out during a
normal respiratory cycle
Respiratory Volumes
Animation: Changes in lung volume and
pressure
Control of Breathing
 Neurons in the medulla oblongata of the brain
stem are the control center for respiration
• Rhythmic signals from the brain cause muscle
contractions that cause air to flow into the lungs
 Chemoreceptors in the medulla, carotid arteries,
and aorta wall detect chemical changes in blood,
and adjust breathing patterns
Respiratory Responses
STIMULUS
CO2 concentration
and acidity rise in the
blood and cerebrospinal
fluid.
RESPONSE
Chemoreceptors
in wall of carotid
arteries and aorta
Respiratory center
in brain stem
Diaphragm,
Intercostal muscles
CO2 concentration
and acidity decline
in the blood and
cerebrospinal fluid.
Tidal volume and rate of breathing change.
Fig. 39-18, p. 691
STIMULUS
CO2 concentration
and acidity rise in the
blood and cerebrospinal
fluid.
RESPONSE
Chemoreceptors
in wall of carotid
arteries and aorta
Respiratory center
in brain stem
Diaphragm,
Intercostal muscles
CO2 concentration
and acidity decline
in the blood and
cerebrospinal fluid.
Tidal volume and rate of breathing change.
Stepped Art
Fig. 39-18, p. 691
39.7 Gas Exchange and Transport
 Gases diffuse between a pulmonary capillary
and an alveolus at the respiratory membrane
• Alveolar epithelium
• Capillary endothelium
• Fused basement membranes
 O2 and CO2 each follow their partial pressure
gradient across the membrane
The Respiratory Membrane
red blood
cell inside
pulmonary
capillary
pore for
air flow
between
adjoining
alveoli
air space
inside
alveolus
a Surface view of
capillaries associated
with alveoli
b Cutaway view of one of
the alveoli and adjacent
pulmonary capillaries
alveolar
epithelium
capillary
endothelium
fused
basement
membranes
of both
epithelial
tissues
c Three components
of the respiratory
membrane
Fig. 39-19, p. 692
Oxygen Transport
 In alveoli, partial pressure of O2 is high; oxygen
binds with hemoglobin in red blood cells to form
oxyhemoglobin (HbO2)
 In metabolically active tissues, partial pressure
of O2 is low; HbO2 releases oxygen
 Myoglobin, found in some muscle tissues, is
similar to hemoglobin but holds O2 more tightly
Hemoglobin and Myoglobin
Fig. 39-20a, p. 693
alpha globin
beta globin
alpha globin
beta globin
Fig. 39-20a, p. 693
Fig. 39-20b, p. 693
heme
Fig. 39-20b, p. 693
Carbon Dioxide Transport
 Carbon dioxide is transported from metabolically
active tissues to the lungs in three forms
• 10% dissolved in plasma
• 30% carbaminohemoglobin (HbCO2)
• 60% bicarbonate (HCO3-)
 Carbonic anhydrase in red blood cells
catalyzes the formation of bicarbonate
CO2 + H2O
→ H2CO3 → HCO3- + H+
Partial Pressures for
Oxygen and Carbon Dioxide
DRY
INHALED AIR 160 0.03
pulmonary
arteries
40 45
120 27
alveolar sacs
104 40
start of
systemic
veins
MOIST
EXHALED AIR
pulmonary
veins
100 40
start of
systemic
capillaries
100 40
40 45
cells of body tissues
less than 40
more than 45
Fig. 39-21, p. 693
DRY
INHALED AIR 160 0.03
pulmonary
arteries
40 45
120 27
alveolar sacs
104 40
start of
systemic
veins
MOIST
EXHALED AIR
pulmonary
veins
100 40
start of
systemic
capillaries
100 40
40 45
cells of body tissues
less than 40
more than 45
Stepped Art
Fig. 39-21, p. 693
Animation: Partial pressure gradients
The Carbon Monoxide Threat
 Carbon monoxide (CO)
• A colorless, odorless gas that can fill up O2
binding sites on hemoglobin, block O2 transport,
and cause carbon monoxide poisoning
 Carbon monoxide poisoning often results when
fuel-burning appliance are poorly ventilated
• Symptoms include nausea, headache, confusion,
dizziness, and weakness
39.4-39.7 Key Concepts
Gas Exchange in Vertebrates
 Gills or paired lungs are gas exchange organs in
most vertebrates
 The efficiency of gas exchange is improved by
mechanisms that cause blood and water to flow
in opposite directions at gills, and by muscle
contractions that move air into and out of lungs
39.8 Respiratory Diseases and Disorders
 Interrupted breathing
• Brain-stem damage, sleep apnea, SIDS
 Potentially deadly infections
• Tuberculosis, pneumonia
 Chronic bronchitis and emphysema
• Damage to ciliated lining of bronchioles and walls
of alveoli; tobacco smoke is the main risk factor
Cigarette Smoke and Ciliated Epithelium
Fig. 39-22a, p. 694
free surface
of a mucussecreting cell
free surface
of a cluster of
ciliated cells
Fig. 39-22b, p. 694
Risks Associated With Smoking
and Emphysema
Fig. 39-23b-c, p. 695
39.8 Key Concepts
Respiratory Problems
 Respiration can be disrupted by damage to
respiratory centers in the brain, physical
obstructions, infectious disease, and inhalation
of pollutants, including cigarette smoke
39.9 High Climbers and Deep Divers
 Altitude sickness
• Hypoxia can result when people who live at low
altitudes move suddenly to high altitudes
• People who grow up at high altitudes have more
alveoli and blood vessels in their lungs
 Acclimatization to altitude includes adjustments
in cardiac output, rate and volume of breathing
• Hypoxia stimulates erythropoietin secretion
Adaptation to High Altitude
 Llamas that live at high altitudes have special
hemoglobin that binds oxygen more efficiently
Deep-Sea Divers
 Water pressure increases with depth; human
divers using compressed air risk nitrogen
narcosis (disrupts neuron signaling)
 Returning too quickly to the surface from a deep
dive can release dangerous nitrogen bubbles
into the blood stream (‘the bends”)
 Without tanks, trained humans can dive to 210
meters; sperm whales can dive 2,200 meters
Adaptations for Deep Diving
 Leatherback turtles dive up to one hour
• Move air to cartilage-reinforced airways
• Flexible shell for compression
 Four ways diving animals conserve oxygen
•
•
•
•
Deep breathing before diving
High red-cell count, large amounts of myoglobin
Slowed heart rate and metabolism
Conservation of energy
Deep Divers
39.9 Key Concepts
Gas Exchange in Extreme Environments
 At high altitudes, the human body makes shortterm and long-term adjustments to thinner air
 Built-in respiratory mechanisms and specialized
behaviors allow sea turtles and diving marine
mammals to stay under water, at great depths,
for long periods
Animation: Bicarbonate buffer system
Animation: Globin and hemoglobin
structure
Animation: Pressure-gradient changes
during respiration
Animation: Structure of an alveolus
Animation: Vocal cords
ABC video: Blood test for lung cancer
Video: Up in smoke