Functions of the respiratory system
-Allows for the exchange of gases (especially O2 and CO2) between the atmosphere and the blood.
Lower respiratory tract epithelia
-Lined by various kinds of epithelia.
-The trachea, bronchi, and larger bronchioles contain mucus-producing goblet cells.
-Structurally supported by nasal bones and cartilage
-Two nostrils are the entrances to the nasal cavity
Lateral walls of nasal cavity
-superior, middle, and inferior nasal conchae
-walls beneath each concha is a meatus, or air passageway. (Superior, middle, and inferior meatus).
-Soft palate normally elevates during swallowing, to ensure substances enter pharynx, and prevent substances
from entering nasal cavity.
Pharyngeal wall contains pharyngeal constrictors, the skeletal muscles involved in swallowing
Largest of nine pieces
V-shaped notch (easily palpated) is above the laryngeal prominence (or adam's apple) of the thyroid cartilage.
Elastic cartilage flap
Moves inferiorly and posteriorly, to block entrance to trachea, during swallowing
two ligaments, covered with epithelial tissue, that stretch from anterior to posterior across the
They are open during breathing, closed when holding one's
breath, and they vibrate during speech.
Extends from larynx (superiorly) to the bronchial branch point (inferiorly, at the level of the sternal angle).
Lining of pseudostratified, columnar, ciliated epithelium, like upper respiratory tract
Branch about 9 to 12 times in tota linto smaller bronchi
All bronchi have smooth muscle in walls, and cartilage to prevent collapse when pressure is low.
less than 1mm in diameter
Bronchioles are small enough that they don't need cartilage to prevent collapse. They have smooth muscle for
regulation of the amount of airflow.
respiratory portion of the respiratory tract
Where gas exchange actually occurs
Respiratory bronchioles and alveoli
The outer layer of the serous membrane
Lines the inside of the thoracic walls, the lateral surfaces of the mediastinum, and the superior surface of the
The two layers of the serous membrane reflect on each other at the hilum (see below).
This arrangement is similar to the serous pericardium of the heart.
Muscles of inhalation enlarge the thoracic cavity.
Because the thoracic cavity is airtight, the lungs also are enlarged. This decreases the pressure inside the lungs,
especially in the alveoli.
This draws air into the alveoli, where gas exchange occurs.
When the muscles relax, the thoracic cavity returns to its resting size, and air is expelled.
In forced exhalation, muscle contraction (including the internal intercostal muscles) leads to a more forceful
decrease in lung volume.
Each has its own air supply (separate tertiary bronchi)
Each has its own blood supply
Left and right lungs
Left lung smaller, to accommodate larger left ventricle of heart
Note cardiac impression and notch