Transcript Chapter 11: Respiratory system

Chapter 11: Respiratory system
• Chapter objectives:
– To learn the structures of the respiratory system and their
functions
– To understand the processes of inspiration and expiration
– To learn about the way in which gas exchange takes place
– To learn about problems with the nervous,
musculoskeletal, and pulmonary systems that can affect
breathing
– To understand the role of the lungs in acid-base balance
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Chapter 11: Respiratory system
• Functions:
– Maintains the exchange of oxygen and carbon dioxide in
the lungs and tissues
– Helps regulate the body’s acid-base balance
• Structures:
– Upper respiratory tract: nose, mouth, nasopharynx,
oropharynx, laryngopharynx, larynx
– Lower respiratory tract: trachea, bronchi, lungs
– Thoracic cavity: mediastinum, thoracic cage
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Chapter 11: Respiratory system
Upper respiratory tract
• Nostrils and nasal passages
– Vibrissae—small hairs in the nares that filter foreign
particles
– Septum—partition that separates the two nasal passages
– Conchae—cartilage of the posterior wall of the nasal
passages; warms and humidifies air before it passes into
the nasopharynx
– Cilia—small, hairlike projections that trap finer foreign
particles and carry then to the pharynx to be swallowed
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Chapter 11: Respiratory system
Upper respiratory tract
• Sinuses and nasopharynx
– Four paranasal sinuses in the frontal, sphenoid, and
maxillary bones
– Sinuses provide speech resonance
– Choanae—pair of posterior openings in the nasal cavity
that allow air passage into the nasopharynx
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Chapter 11: Respiratory system
Upper respiratory tract
• Oropharynx and laryngopharynx
– Oropharynx—located at the posterior wall of the mouth;
connects the nasopharynx and laryngopharynx
– Laryngopharynx—extends to the esophagus and larynx
• Larynx
– Contains the vocal cords; connects the pharynx with the
trachea
– Walls formed by muscle and cartilage, including thyroid
cartilage
Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
Chapter 11: Respiratory system
Lower respiratory tract
• Trachea
– Extends from the cricoid cartilage to the carina
– C-shaped cartilage rings reinforce and protect the trachea
• Bronchi
– Supply air to the lungs
– Right mainstem bronchus—shorter, wider, and more
vertical than the left
– Divide into secondary bronchi; enter pleural cavity at the
hilum
– Divide into bronchioles and then terminal bronchioles
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Chapter 11: Respiratory system
Lower respiratory tract
• Acinus
– Terminal bronchioles
divide into respiratory
bronchioles, which feed
directly into alveoli
– Alveolar sacs—clusters
of alveoli at the end of
alveoli ducts; where gas
exchange takes place
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Chapter 11: Respiratory system
Lungs and accessory structures
• Lungs
– Cone-shaped structures in the right and left pleural
cavities
– Right lung—three lobes; shorter, broader, and larger than
the left lung
– Left lung—two lobes
– Both lungs rest on the diaphragm
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Chapter 11: Respiratory system
Lungs and accessory structures
• Pleura and pleural cavities
– Pleura—membrane enclosing the lung; composed of a
visceral and parietal layer
– Pleural cavity—tiny area between the visceral and parietal
layers
• Functions:
– Lubricates the pleural surfaces
– Creates a bond between the layers that causes the
lungs to move with the chest wall during breathing
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Chapter 11: Respiratory system
Thoracic cavity
• Mediastinum—space between the lungs; contains the heart,
pericardium, thoracic aorta, pulmonary vessels, venae cavae,
azygos veins, thymus, lymph nodes and vessels, trachea,
esophagus, thoracic duct, vagus, cardiac, and phrenic nerves
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Chapter 11: Respiratory system
Thoracic cavity
• Thoracic cage
– Supports and protects the lungs, allowing them to expand
and contract
• Posterior thoracic cage—vertebral column and 12 pair of
ribs
• Anterior thoracic cage—manubrium, sternum, xiphoid
process, ribs
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Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
Chapter 11: Respiratory system
Inspiration and expiration
• Inspiration—active process
– Process: diaphragm descends to lengthen the chest
cavity  external intercostal muscles contract to expand
the anteroposterior diameter  intrapleural pressure
decreases  inspiration occurs
Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
Chapter 11: Respiratory system
Inspiration and expiration
• Expiration—relatively passive process
– Process: diaphragm rises  intercostal muscles relax 
intrapleural pressure increases  expiration occurs
Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
Chapter 11: Respiratory system
Inspiration and expiration
• Forced inspiration and active expiration
– Occurs when the body needs increased oxygenation
– Uses accessory muscles of respiration:
• Forced inspiration: pectoral muscles,
sternocleidomastoid muscles, scalene muscles,
posterior trapezius muscles
• Active expiration: internal intercostal muscles,
abdominal rectus muscles
Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
Chapter 11: Respiratory system
Inspiration and expiration
• External respiration
– Gas exchange in the lungs
– Takes place through:
• Ventilation—distribution of gases into and out of the
pulmonary airways
• Pulmonary perfusion—blood flow from the right side of
the heart, through pulmonary circulation, and into the
left side of the heart
• Diffusion—gas movement through a semipermeable
membrane from an area of greater concentration to one
of lesser concentration
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Chapter 11: Respiratory system
Inspiration and expiration
• Internal respiration
– Gas exchanges in the tissues
– Takes place through diffusion:
• Oxygen moves from the alveoli into the bloodstream
and is taken up by hemoglobin in red blood cells
• Carbon dioxide is displaced by the oxygen to the alveoli
and is removed during exhalation
Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
Chapter 11: Respiratory system
Acid-base balance
• Carbon dioxide forms bicarbonate (base) in the blood and
small amounts of carbonic acid (acid)
• Lungs convert bicarbonate to carbon dioxide and water for
excretion
• Medulla signals the lungs to change the rate and depth of
breathing in response to blood pH; allows for adjustments on
the amount of carbon dioxide lost
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Chapter 11: Respiratory system
Acid-base balance
• Metabolic alkalosis
– Results from excessive
bicarbonate retention
– Rate and depth of
ventilation decrease to
retain carbon dioxide
and lower pH
• Metabolic acidosis
– Results from excess acid
retention or excess
bicarbonate loss
– Rate and depth of
ventilation increase to
eliminate excess carbon
dioxide and raise pH
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