Download Respiratory system

Respiration Processes
 Breathing (ventilation): air into and out of
lungs
 External respiration: gas exchange between
air and blood
 Internal respiration: gas exchange between
blood and tissues
 Cellular respiration: oxygen use to produce
ATP; carbon dioxide as waste
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Organs of the Respiratory system
 Nose
 Pharynx
 Larynx
 Trachea
 Bronchi
 Lungs –
alveoli
Figure 13.1
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Components of the Upper Respiratory
Tract
Nose, pharynx
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Figure 10.2
Upper Respiratory Tract
 Functions:
 Passageway for respiration
 Receptors for smell
 Filters incoming air to block larger foreign
material
 Moistens and warms incoming air
 Resonating chambers for voice
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Components of the Lower Respiratory
Tract
Functions:
Larynx:
maintains an open
airway, routes
food and air
appropriately,
assists in sound
production
Trachea:
transports air to
and from lungs
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Figure 10.3
Lower Respiratory Tract
 Functions:
 Bronchi: branch
into lungs
 Lungs: transport
air to alveoli for
gas exchange
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Gas Exchange Between the Blood and
Alveoli
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Figure 10.8A
Respiratory Membrane (Air-Blood Barrier)
 Thin squamous epithelial layer lining alveolar walls
 Pulmonary capillaries cover external surfaces of
alveoli
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Figure 13.6
Mechanics of Breathing (Pulmonary
Ventilation)
 Completely mechanical process
 Depends on volume changes in the thoracic
cavity,
 Which cause pressure changes, which lead to
the flow of gases to equalize pressure
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Inspiration - flow of air into lung
 Diaphragm and
intercostal
muscles
contract
 size of thoracic
cavity increases
 air is pulled into
lungs due to
decrease in
intrapulmonary
pressure
Figure 13.7a
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Expiration– air leaving lung
passive process; uses
natural lung elasticity
As muscles relax, air is
pushed out of the lungs
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Pressure Differences in the Thoracic
Cavity
 Normal pressure within the pleural space is
always negative (intrapleural pressure)
 Differences in lung and pleural space
pressures keep lungs from collapsing
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Nonrespiratory Air Movements
 Can be caused by reflexes or voluntary
actions
 Examples
 Cough and sneeze – clears lungs of debris
 Laughing
 Crying
 Yawn
 Hiccup
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Respiratory Volumes and Capacities
 Normal breathing moves about 500 ml of air with
each breath (tidal volume [TV])
 Many factors that affect respiratory capacity
 A person’s size
 Sex
 Age
 Physical condition
 Residual volume of air – after exhalation, about
1200 ml of air remains in the lungs
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Respiratory Capacities
Figure 13.9
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External Respiration - gas exchange
between air and blood
 Oxygen moves into the blood
 alveoli have more O2 than
blood entering lungs
 O2 diffuses, binds to
hemoglobin in RBC
 Carbon dioxide moves out of
blood
 CO2 diffuses out of blood
 Carbonic acid shifts to CO2
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Gas Transport in the Blood
 Oxygen transport in the blood
 Inside RBCs attached to hemoglobin
(oxyhemoglobin [HbO2])
 O2 binds more readily at high pO2, neutral
pH, and lower temperature
 Only 2% is dissolved in the plasma
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Gas Transport in the Blood
 Carbon dioxide
 Most CO2 is transported in the plasma as
bicarbonate ion (HCO3–)
 20% is carried inside RBCs on
hemoglobin, but at different binding sites
than used by O2
 10% of CO2 is dissolved in plasma
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Internal Respiration
 Exchange of gases
between blood and body
cells
 Carbon dioxide
diffuses out of tissue
to blood
 Forms carbonic acid
inside RBCs. Lowers
pH and loosens O2
from hemoglobin
 Oxygen diffuses from
blood into tissue
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Respiration Summary
Figure 13.10
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Neural Regulation of Respiration
Neural control located
in medulla oblongata
and pons
Normal rate is 12–15
respirations per
minute
Hyperpnea is
increased respiratory
depth and vigor
Figure 13.12
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Factors Influencing Respiratory Rate and
Depth
 Chemical factors
 Carbon dioxide levels
 main regulatory chemical
 Increased CO2 increases respiration
 CO2 acts directly on the medulla
oblongata via pH of cerebrospinal fluid
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Factors Influencing Respiratory Rate and
Depth
 Chemical factors (continued)
 Oxygen levels
 O2 is detected by chemoreceptors in
aorta and carotid artery
 Alert sent to medulla oblongata
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Factors Influencing Respiratory Rate and
Depth
 Physical factors
 Increased body temperature
 Exercise
 Talking
 Coughing
 Volition (conscious control)
 Emotional factors
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Hyperventilation
 Hyperventilation - deep, rapid breathing
 Increases loss of CO2, so blood pH becomes
more alkaline
 Can lead to apnea (no breathing), cyanosis,
dizziness
 Treat by slowing respiration, rebreathing
same air (use bag), or closing mouth, one
nostril.
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Asthma
 hypersensitive bronchiole passages
 triggered by allergens (cat dander), exercise,
viral infection, cold temperature
 Bronchioles close down, swell shut;
produce more mucus
 Result: dyspnea, coughing, and wheezing
 Management includes monitoring vital
capacity, steroids
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Respiratory Disorders: Chronic
Obstructive Pulmonary Diseases (COPD)
 Ex. chronic bronchitis and emphysema
 Patients often with history of smoking
 Labored breathing (dyspnea) becomes
progressively more severe
 Coughing, frequent pulmonary infections
 victims retain CO2, are hypoxic and have
respiratory acidosis
 Ultimately, respiratory failure
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Chronic Obstructive Pulmonary Disease
(COPD)
Figure 13.13
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Lung Cancer
 Accounts for 1/3 of all cancer deaths in the
United States
 Associated with smoking
 Smoke contains free radicals (nitrosamine)
and other carcinogens that mutate DNA
 Lungs and other tissues exposed in smokers
 Metastasis common
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Sudden Infant Death syndrome (SIDS)
 Apparently healthy infant stops breathing and
dies during sleep
 Some cases could be a problem of the neural
respiratory control center
 One third of cases appear to be due to heart
rhythm abnormalities
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