Thoracic Cavity and Respiration
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Alveoli
Respiratory Tree
Lungs
Diaphragm
Intercostal Muscles
Larry M. Frolich, Human Anatomy, Respiratory Function
Alveoli
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Key to lung function
Where O2 enters blood, CO2 leaves blood
Every alveoli is capillary covered sac
Lining of sac is squamous epithelium
Also cuboidal epithelial cells that secret surfactant
(keeps surfaces from sticking) and cilia (to move
mucous and particles up respiratory tree
Larry M. Frolich, Human Anatomy, Respiratory Function
Respiratory Tree
(how does air get to alveoli?)
• Branching pattern
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Trachea
Primary bronchi (left, right)
Secondary bronchi (each lobe)
Tertiary bronchi, bronchioles
Alveoli
• Vessels accompany respiratory tree to alveoli
Larry M. Frolich, Human Anatomy, Respiratory Function
Larry M. Frolich, Human Anatomy, Respiratory Function
LUNGS
• Located in Pleural Cavities
• Lateral to Mediastinum
• Location
– Apex posterior to clavicle
– Base lays on Diaphragm
Pg 618
– Costal Surface = Ant, Lat, Post surfaces contact wall of
chest cavity
• Root - all vessels, nerves enter each lung
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2 Pulmonary Veins = carries O2 blood from each lung to heart
1 Pulmonary Artery = carries De-O2 blood to each lung
Primary Bronchi
Nerves
–Lymph Vessels
Larry M. Frolich, Human Anatomy, Respiratory Function
LOBES OF LUNGS
• Left Lung = 2 lobes
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Upper
Lower
Oblique Fissure
Cardiac Notch
• Right Lung = 3 lobes
Pg 622
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Upper
Middle
Lower
Oblique fissure
Horizontal fissure
Larry M. Frolich, Human Anatomy, Respiratory Function
Specific Location of Lungs
• Right Lung
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1” above Rib 1
Crosses Costal Cartilage 6
Midclavicular at Rib 6
Midaxillary at Rib 8
Vertebral Border at Rib 10
Inferior border 2 rib widths above
diaphragm
• Left Lung
– 1” above Rib 1
– Deep to Manubroclavicular
joint
– Midsternally to Rib 4
– Jogs to left, continues to Rib 6
– Midaxillary Rib 8
– Vertebral Border at Rib 10
Larry M. Frolich, Human Anatomy, Respiratory Function
Action of the Diaphragm
• Primary muscle of respiration
(involuntary)
– Contraction during inspiration
• Increases volume of thoracic cavity
• Decreases pressure of thoracic cavity
• Air moves into lungs (highlow
pressure)
• Forced contraction (voluntary)
– Used for defecation, urination, labor
• Increases pressure in abdominal cavity
• Pushes on abdominal organs to move
contents out
Larry M. Frolich, Human Anatomy, Respiratory Function
Anatomy of the Diaphragm
• Skeletal Muscle
• Dome-shaped (relaxed)
• Divides thoracic &
abdominal cavities
• Attachments
– Origin: Inferior Internal rib
cage
– Insertion: Central tendon
Superior View
• Innervated by right + left
PHRENIC Nerves
Pg 288
Larry M. Frolich, Human Anatomy, Respiratory Function
INTERCOSTAL
MUSCLES
• Lift ribs to
expand chest
cavity for
inspiration
• Three layers
Larry M. Frolich, Human Anatomy, Respiratory Function