Alveoli.
The pulmonary alveolus (plural: alveoli) is a small air sac that serves as the fundamental respiratory unit. It is a hollow cup-shaped cavity in the lung parenchyma that facilitates gas exchange. Lung alveoli are situated near the beginning of the respiratory zone in the acini. They are found infrequently in the respiratory bronchioles, lining the alveolar duct walls. The alveoli are found in the pulmonary lobules of the respiratory zone, in the alveolar sacs of the lungs. They are more prevalent in blind-ended alveolar sacs. Respiratory bronchioles connect to alveolar ducts, which are lined with alveoli. Each respiratory bronchiole produces two to eleven alveolar ducts. Each duct divides into five or six alveolar sacs, each of which contains a cluster of alveoli.
Trachea.
In most people, the trachea, often known as the windpipe, is a 4 inch long tube with a diameter of less than an inch. The trachea starts right below the larynx (voice box) and goes down beneath the breastbone (sternum). The trachea subsequently separates into two smaller tubes called bronchi, one for each lung. The trachea is made up of around 20 rings of strong cartilage. The back of each ring is formed of muscle and connective tissue. The mucosa, or moist, smooth tissue, coats the inside of the trachea. With each inhalation, the trachea slightly expands and lengthens before reverting to its resting size with each exhalation.
Epiglottis.
The epiglottis is a cartilaginous flap that extends in front of and above the laryngeal intake, also known as the rima glottidis (glottis). The epiglottis closes the laryngeal inlet during swallowing, preventing food and fluids from entering the lungs (aspiration). This is why we can’t (and shouldn’t attempt) to talk and breathe while swallowing. The epiglottis is found in the larynx and is connected to the thyroid cartilage and hyoid bone. Its motions are controlled by the tongue’s passive pressure as it pulls food down the pharynx, as well as the contractions of the aryepiglottic muscle.
Alveoli.
The pulmonary alveolus (plural: alveoli) is a small air sac that serves as the fundamental respiratory unit. It is a hollow cup-shaped cavity in the lung parenchyma that facilitates gas exchange. Lung alveoli are situated near the beginning of the respiratory zone in the acini. They are found infrequently in the respiratory bronchioles, lining the alveolar duct walls. The alveoli are found in the pulmonary lobules of the respiratory zone, in the alveolar sacs of the lungs. They are more prevalent in blind-ended alveolar sacs. Respiratory bronchioles connect to alveolar ducts, which are lined with alveoli. Each respiratory bronchiole produces two to eleven alveolar ducts. Each duct divides into five or six alveolar sacs, each of which contains a cluster of alveoli.
Trachea.
In most people, the trachea, often known as the windpipe, is a 4 inch long tube with a diameter of less than an inch. The trachea starts right below the larynx (voice box) and goes down beneath the breastbone (sternum). The trachea subsequently separates into two smaller tubes called bronchi, one for each lung. The trachea is made up of around 20 rings of strong cartilage. The back of each ring is formed of muscle and connective tissue. The mucosa, or moist, smooth tissue, coats the inside of the trachea. With each inhalation, the trachea slightly expands and lengthens before reverting to its resting size with each exhalation.
Epiglottis.
The epiglottis is a cartilaginous flap that extends in front of and above the laryngeal intake, also known as the rima glottidis (glottis). The epiglottis closes the laryngeal inlet during swallowing, preventing food and fluids from entering the lungs (aspiration). This is why we can’t (and shouldn’t attempt) to talk and breathe while swallowing. The epiglottis is found in the larynx and is connected to the thyroid cartilage and hyoid bone. Its motions are controlled by the tongue’s passive pressure as it pulls food down the pharynx, as well as the contractions of the aryepiglottic muscle.
Sources:
https://www.webmd.com/lung/picture-of-the-trachea
https://www.kenhub.com/en/library/anatomy/epiglottis
https://www.cancer.gov/publications/dictionaries/cancer-terms/def/alveoli