Transcript Organs of the Respiratory System

Organs of the Respiratory
System
Introduction
• Respiration
▫ Entire process of gas exchange between the
atmosphere and body cells
▫ Includes:
 1. movement of air in and out the lungs (breathing
or ventilation)
 2. gas exchange between blood and air in the lungs
 3. gas transport in blood between lungs and body
cells
 4. gas exchange between blood and body cells
Upper Respiratory Tract
•
•
•
•
Nose
Nasal cavity
Paranasal sinuses
Pharynx
Nose
• Bone and cartilage support it internally
• 2 nostrils = openings for air to enter and leave
• Internal hairs for protection
Nasal Cavity
• Hollow space behind nose
• Nasal septum divides cavity into right and left
portions
• Nasal conchae = bones that curl out from lateral
walls of cavity and divide the cavity into
passageways (figure 16.2)
• Mucous membranes line cavity
▫ Temperature regulation
▫ Moistens and protects
Paranasal Sinuses
• Air-filled spaces within the maxillary, frontal,
ethmoid and sphenoid bones of the skull and
opening into the nasal cavity
• Mucous membranes line the sinuses
• Reduce the weight of the skull
• Affect quality of the voice
Pharynx
• Behind the oral cavity and between the nasal
cavity and larynx
• Passageway for food
▫ Oral cavity to esophagus
• Passageway for air
▫ Between nasal cavity and larynx
• Helps produce sounds of speech
• 3 parts: naso-, oro- and laryngo-
Lower Respiratory Tract
•
•
•
•
Larynx
Trachea
Bronchial tree
Lungs
Larynx
• Enlargement in airway at top of trachea and
below pharynx
• Conducts air in and out of the trachea
• Prevents foreign objects from entering trachea
• Houses vocal cords
• Epiglottis = flaplike structure
▫ Stands upright, allows air to enter larynx
▫ During swallowing, presses downward to partially
cover opening into larynx
 Prevents foods and liquids from entering air passages
Trachea
• Flexible, cylindrical tube
• About 2.5 cm in diameter, 12.5 cm long
• Extends downward in front of esophagus and
into the thoracic cavity
• Splits into right and left bronchi
• Mucous membrane lines trachea
• About 20 c-shaped pieces of hyaline cartilage
Bronchial Tree
• Branched airways leading from trachea to air
sacs in lungs
• Primary bronchi
▫ Secondary bronchi
 Tertiary bronchi
 Alveolar ducts
▫ Alveolar sacs = clusters of smaller microscopic air sacs
called alveoli (lie within capillary nets)
• Structure of bronchus similar to trachea
▫ But, as tubes become smaller, cartilage lessons and
smooth muscle becomes more prominent
• Function: Air passages
▫ Large surface area for gas exchange
▫ Oxygen diffuses through and enters blood in capillary
networks
▫ Carbon dioxide diffuses from blood through walls and
enters alveoli
▫ Adult lung: about 300 million alveoli, total surface
area half the size of a tennis court
Lungs
• Soft, spongy, cone-shaped organs in thoracic
cavity
• Mediastinum separates right and left lungs
medially
• Diaphragm and thoracic cage enclose them
• Bronchi enter lungs on medial surface
• Visceral pleura (serous membrane) attaches to
each lung
▫ Folds back to become parietal pleura
▫ Forms part of the mediastinum
▫ Potential space between membranes = pleural
cavity
 Contains some fluid to reduce friction during
breathing
• Right lung is larger than the left
▫ Right has 3 lobes
▫ Left has 2 lobes
• Major branch of bronchial tree supplies each
lobe
• Lung includes:
▫ Air passages, alveoli, blood vessels, connective
tissues, lymphatic vessels and nerves