Transcript Nerve activates contraction

LOWER
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Organs of the Lower Respiratory System
1. Main Bronchi or Bronchus
2. Secondary Bronchioli or Bronchioles
3. Lung

alveoli
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Bronchial (Respiratory) Tree Divisions
 Formed by division of the trachea
1. Primary bronchi
 Secondary bronchi
 Tertiary bronchi
2. Bronchioles
 Terminal bronchioles
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Bronchial (Respiratory) Tree Divisions
Figure 13.5a
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3. Lungs
 Occupy most of the thoracic cavity
(Heart occupies central portion of mediastinum within
the pericardium)
 Apex of lungs is near the clavicle (superior portion)
 Base rests on the diaphragm (inferior portion)
 Each lung is divided into lobes by fissures
 Left lung—two lobes
 Right lung—three lobes
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Coverings of the Lungs
 Serosa covers the outer surface of the
lungs
 Visceral pleura covers the lung
surface
 Parietal pleura lines the walls of the
thoracic cavity
 Pleural fluid fills the area between
layers of pleura to allow gliding
 These two pleural layers resist being
pulled apart and therefore attach the
lungs to the wall of the thoracic cavity
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Gas Exchange
Site of gas exchange = alveoli
only
Oxygen in the alveoli diffuse into
the pulmonary capillaries to be
sent to the cells of the body
Carbon dioxide diffuses from the
capillaries to the alveoli in order
to be expelled from the body
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Four Events of Respiration
1. Pulmonary ventilation—moving air in and out of
the lungs (commonly called breathing)
2. External respiration—gas exchange between
pulmonary blood and alveoli (the environment)
3. Respiratory gas transport— oxygen and carbon
dioxide move through out the body via the
bloodstream
4. Internal respiration—gas exchange between
blood and tissue cells (within the body)
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1. Pulmonary Ventilation
Mechanics of Breathing
 Completely mechanical (controlled by physical processes)
 Depends on volume changes in the thoracic cavity
 Volume changes lead to pressure changes
 Which lead to the flow of gases (in or out) to equalize
pressure
 Two phases
 Inspiration = inhalation
 flow of air into lungs
 Expiration = exhalation
 air leaving lungs
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The Diaphragm relaxed
The Diaphram will pull down when it contracts
What happens to the volume and pressure of the thoracic cavity?
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Inspiration (Inhale)
 Diaphragm contract
 The size of the thoracic cavity increases
 Increase in intrapulmonary volume
 Decrease in gas pressure
 External air is pulled into the lungs due to
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Expiration (exhale)
 Mainly passive
 As muscles relax, air is pushed out of the lungs
 Decrease in volume
 Increase in gas pressure
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Animation
 http://www.footprintsscience.co.uk/flash/Breathing.swf
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Respiratory Sounds
 Sounds are monitored with a stethoscope
 Two recognizable sounds can be heard with a
stethoscope
 Bronchial sounds—produced by air rushing
through trachea and bronchi
 Vesicular breathing sounds—soft sounds of
air filling alveoli
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2. External Respiration
 Oxygen loaded into the blood
 The alveoli always have more oxygen than the
blood
 Oxygen moves by diffusion towards the area
of lower concentration
 Pulmonary capillary blood gains oxygen
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External Respiration
 Carbon dioxide unloaded out of the blood
 Blood returning from tissues has higher
concentrations of carbon dioxide than air in
the alveoli
 Pulmonary capillary blood gives up carbon
dioxide to be exhaled
 Blood leaving the lungs is oxygen-rich and
carbon dioxide-poor
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External Respiration
Figure 13.11a
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3. Gas Transport in the Blood
 Oxygen transport in the
blood
 Most oxygen attached
to hemoglobin to form
oxyhemoglobin
(HbO2)
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Gas Transport in the Blood
 Carbon dioxide transport in the blood
 Most is transported in the plasma as
bicarbonate ion (HCO3–)
 A small amount is carried inside red blood
cells on hemoglobin, but at different binding
sites than those of oxygen
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4. Internal Respiration
 Exchange of gases
between blood and
body cells
 An opposite reaction to
what occurs in the
lungs
 Carbon dioxide
diffuses out of
tissue to blood
(called loading)
 Oxygen diffuses
from blood into
tissue (called
unloading)
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External Respiration, Gas Transport,
and Internal Respiration Summary
Figure 13.10
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FYI if interested: not test material
Nonrespiratory Air (Gas) Movements
Table 13.1
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