Transcript Chapter 5 Gases

Cecie Starr
Christine Evers
Lisa Starr
www.cengage.com/biology/starr
Chapter 35
Respiration
(Sections 35.6 - 35.8)
Albia Dugger • Miami Dade College
35.6 How You Breathe
• A respiratory cycle is one breath in (inhalation) and one
breath out (exhalation)
• Changes in volume of lungs and thoracic cavity during a
respiratory cycle alter pressure gradients between air inside
and outside the respiratory tract
• respiratory cycle
• One inhalation and one exhalation
• Inhalation is always active, driven by muscle contractions
The Respiratory Cycle
• Inhalation:
• Diaphragm contracts, moves down
• External intercostal muscles contract, lift rib cage upward
and outward
• Lung volume expands
• Exhalation:
• Diaphragm and external intercostal muscles return to
resting positions
• Rib cage moves down
• Lungs recoil passively
The Respiratory Cycle
The Respiratory
Cycle
Inward
flow of air
A Inhalation. Diaphragm contracts,
moves down. External intercostal
muscles contract, lift rib cage upward
and outward. Lung volume expands.
Outward
flow of air
B Exhalation. Diaphragm, external
intercostal muscles return to resting
positions. Rib cage moves down.
Lungs recoil passively.
Fig. 35.10, p. 586
The Heimlich Maneuver
• The Heimlich maneuver is used to rescue a person who is
choking on something lodged in the trachea
• The rescuer presses forcefully on a person’s abdomen to
force air out of the lungs and dislodge the object
• Heimlich maneuver
• Procedure designed to rescue a choking person
Heimlich Maneuver Instructions
1. Determine that the person is actually choking – a person who
has an object lodged in their trachea cannot cough or speak
2. Stand behind the person and place one fist below his or her
rib cage, just above the navel, with your thumb facing inward
3. Cover the fist with your other hand and thrust inward and
upward; repeat until the object is expelled
The Heimlich Maneuver
ANIMATION: Heimlich maneuver
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Respiratory Volumes
• Total lung volume
• Maximum volume of air that the lungs can hold
• ~5.7 liters in healthy adult males, 4.2 liters in females
• Tidal volume
• Volume that moves into and out of lungs during a
respiratory cycle, about half a liter
• vital capacity
• Maximum volume that moves in and out with forced
inhalation and exhalation
Respiratory Volumes
ANIMATION: Changes in lung volume and
pressure
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Control of Breathing
• Neurons in the medulla oblongata of the brain stem act as the
pacemaker for inhalation
• Nerves deliver signals calling for contraction to the diaphragm
and intercostal muscles and you inhale
• Between signals, the muscles relax and you exhale
• Breathing patterns can also be altered voluntarily
Control of Breathing (cont.)
• Breathing patterns change with activity level
• Activity increases CO2 production, which increases carbonic
acid levels in blood
• Chemoreceptors in walls of carotid arteries and the aorta
detect increased acidity and signal the brain, which responds
by altering the breathing pattern
Respiratory Response
to Increased Activity
Stimulus
CO2 concentration and
acidity rise in the blood
and cerebrospinal fluid.
Respiratory Response
to Increased Activity
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. 35.13, p. 587
STIMULUS
CO2 concentration
and acidity rise in the
blood and cerebrospinal
fluid.
Respiratory Response
to Increased Activity
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. 35.13, p. 587
Key Concepts
• Respiratory Cycle
• Inhalation is always an active process; it occurs when a
part of the brain stem signals muscles to contract and
increase the size of the thoracic cavity
• Exhalation is usually passive; muscles relax, the chest and
lungs shrink, and air flows out of lungs
3D Animation: Respiratory Mechanics
ANIMATION: Pressure-Gradient Changes
During Respiration
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35.7 Gas Exchange and Transport
• Gases diffuse between air and fluid at alveoli, and are
transported to and from alveoli in blood
• Oxygen diffuses from an alveolus into a pulmonary capillary
at the lung’s respiratory membrane
• respiratory membrane
• Membrane consisting of alveolar epithelium, capillary
endothelium, and their fused basement membranes;
• Site of gas exchange in the lungs
The Respiratory Membrane
The Respiratory Membrane
Fig. 35.14a, p. 588
The Respiratory Membrane
A Surface view of the pulmonary
capillaries associated with alveoli
Fig. 35.14a, p. 588
The Respiratory Membrane
Fig. 35.14b, p. 588
The Respiratory Membrane
red blood
cell inside
pulmonary
capillary
pore for
air flow
between
adjoining
alveoli
air space
inside
alveolus
B Cutaway view of one of the alveoli
and adjacent pulmonary capillaries
Fig. 35.14b, p. 588
The Respiratory Membrane
Fig. 35.14c, p. 588
The Respiratory Membrane
alveolar
epithelium
capillary
endothelium
fused
basement
membranes of
both epithelial
tissues
C Three components of the
respiratory membrane
Fig. 35.14c, p. 588
Partial Pressure Gradient
• Oxygen and carbon dioxide diffuse passively across the
respiratory membrane
• The net direction of movement for these gases depends upon
concentration gradients (partial pressure gradients) of each
gas across the membrane
• partial pressure
• Pressure exerted by one gas in a mixture of gases
Oxygen Transport and Storage
• O2 follows its partial pressure gradient across the respiratory
membrane, into blood plasma, and finally into red blood cells
• Where O2 partial pressure is high, hemoglobin in red blood
cells binds O2 and forms oxyhemoglobin
• Hemoglobin consists of four globin chains, each associated
with an iron-containing heme group
• oxyhemoglobin
• Hemoglobin with oxygen bound to it
Hemoglobin
alpha globin
beta globin
Hemoglobin
alpha globin
beta globin
Fig. 35.15, p. 588
Oxygen Transport and Storage (cont.)
• Heme groups release O2 in places where the partial pressure
of O2 is lower than that in the alveoli
• Metabolically active tissues have traits that encourage release
of oxygen from heme, such as high temperature, low pH, and
high CO2 partial pressure
Carbon Dioxide Transport
• Carbon dioxide is transported to lungs in three forms:
• About 10% remains dissolved in plasma
• About 30% reversibly binds with hemoglobin and forms
carbaminohemoglobin (HbCO2)
• Most CO2 (60%) is transported as bicarbonate (HCO3–)
Carbon Dioxide Transport (cont.)
• CO2 follows its partial pressure gradient and diffuses from
cells to interstitial fluid, to blood
• Most CO2 reacts with water in red blood cells forming
bicarbonate – this reaction is reversed in the lungs
• In the lungs, CO2 diffuses out of blood into air inside alveoli,
and exhaled
Bicarbonate Formation
• Carbon dioxide combines with water, forming carbonic acid
(H2CO3), which splits into bicarbonate and H+:
CO2 + H2O ↔ H2CO3 (carbonic acid)
H2CO3 (carbonic acid) ↔ HCO3– (bicarbonate) + H+
• The enzyme carbonic anhydrase speeds this reaction
• carbonic anhydrase
• Enzyme in red blood cells that speeds the breakdown of
carbonic acid into bicarbonate and H+
Partial Pressures for O2 and CO2
DRY INHALED AIR
Partial
Pressures for
O2 and CO2
MOIST EXHALED AIR
120 27
160 0.03
pulmonary
arteries
40
alveolar sacs
104 40
45
pulmonary
veins
100 40
start of
systemic
veins
40
start of
systemic
capillaries
45
100
40
cells of body tissues
less than 40
less than 45
Fig. 35.16, p. 589
DRY INHALED AIR
Partial
Pressures for
O2 and CO2
MOIST EXHALED AIR
120 27
160 0.03
pulmonary
arteries
40
alveolar sacs
104 40
45
100 40
start of
systemic
veins
40
pulmonary
veins
start of
systemic
capillaries
45
100
40
cells of body tissues
less than
less than
Stepped Art
Fig. 35.16, p. 589
Animation: Partial Pressure Gradients
The Carbon Monoxide Threat
• Carbon monoxide (CO) is dangerous because hemoglobin
has a higher affinity for CO than for O2
• When CO builds up in air, it blocks O2 binding sites on
hemoglobin, preventing O2 transport and causing carbon
monoxide poisoning
• Symptoms: Nausea, headache, confusion, dizziness, and
weakness
Effects of Altitude
• Oxygen in air decreases with altitude
• People from a low altitude acclimatize to high altitude
through altered breathing patterns, increased red blood
cell production, and other changes
• Atmospheric pressure decreases with altitude
• When people from low altitudes suddenly ascend to high
altitudes, cells get less oxygen – altitude sickness results
• Symptoms: Shortness of breath, headache, nausea
Key Concepts
• Gas Exchanges
• Oxygen moves from air in the lungs into pulmonary
capillaries, where it binds with hemoglobin
• Hemoglobin releases oxygen near active tissues
• Carbon dioxide is converted to bicarbonate in blood
• At the lungs, bicarbonate is converted back into carbon
dioxide and water that can be exhaled
ANIMATION: Globin and hemoglobin
structure
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Animation: Oxygen-Hemoglobin Saturation
Curve
35.8 Respiratory
Diseases and Disorders
• Interrupted breathing, infectious organisms, and chronic
inflammation can impair respiratory function
• Interrupted breathing disorders include apnea and sudden
infant death syndrome (SIDS)
• Respiratory diseases include tuberculosis, pneumonia,
bronchitis, and emphysema
• Smoking causes or worsens many respiratory problems
Interrupted Breathing
• Sleep apnea
• Breathing repeatedly stops and restarts spontaneously,
especially during sleep
• Sudden infant death syndrome (SIDS)
• Occurs when an infant does not awaken from an episode
of apnea
• Infants are more at risk if their mother smoked or was
exposed to smoke during pregnancy
Tuberculosis and Pneumonia
• Tuberculosis (TB)
• About one in three people is infected by Mycobacterium
tuberculosis but have no symptoms
• An active case of TB can be fatal
• Antibiotics can cure most cases of TB
• Pneumonia
• A general term for lung inflammation caused by an
infection by bacteria, viruses, or fungi
Pneumonia
• X-ray shows
infected tissues
filled with fluid and
white blood cells
Bronchitis and Asthma
• Bronchitis
• An inflammation of the ciliated, mucus-producing
epithelium of the bronchi
• Bacteria can colonize the mucus, leading to more
inflammation, more mucus, and more coughing
• Asthma
• An inhaled allergen or irritant triggers inflammation and
constriction of the airways, conditions that make breathing
difficult
Emphysema
• Emphysema
• Tissue-destroying bacterial enzymes digest the thin,
elastic alveolar wall, respiratory surface declines, and
lungs become distended and inelastic, leaving the person
constantly short of breath
• Some people inherit a genetic predisposition
• Tobacco smoking is by far the main risk factor
Key Concepts
• Respiratory Problems
• Interrupted breathing (apnea), infectious diseases(such as
tuberculosis), and inflammatory conditions (such as
asthma and bronchitis) interfere with normal respiratory
function
Up in Smoke (revisited)
• Tobacco is the only legal consumer product that kills half of its
regular users
• Globally, cigarette smoking kills 4 million people each year;
about 70% of deaths occur in developing countries
• Nonsmokers also die of cancers and disease brought on by
breathing secondhand smoke
Effects of Smoking
• Shortened life expectancy
• Chronic bronchitis, emphysema
• Cancer of lungs, mouth, larynx, esophagus, pancreas, and
bladder
• Heart attacks, strokes, and atherosclerosis
• Stillbirths and low birthweight
• Allergic responses, destruction of white blood cells
(macrophages) in respiratory tract
• Slow bone healing
Lungs of Nonsmoker and Smoker
lungs of a nonsmoker
lungs of a smoker