BIO 202 Chapter 14 Lecture Notes

Human Biology Notes
BIO 202

Chapter 14: The Respiratory System: Movement of Air

SECTION 14.1:
THE RESPIRATORY SYSTEM HAS AN UPPER AND LOWER TRACT
● The cardiovascular system cooperates with the respiratory system which:
○ Delivers oxygen
○ Expels carbon dioxide
○ Filters incoming air
○ Maintains blood pH
○ Helps control fluid and thermal homeostasis
○ Produces sound
○ Contraction of the diaphragm promotes blood and lymph flow
● The respiratory system is divided into:
○ Upper Respiratory Tract: Nose, nasal cavity, Larynx
■ Warms, moistens, and filters air as it enters the body
● Lower Respiratory Tract: Trachea, Bronchi, Bronchial Tree, Lungs
○ Allows oxygen to enter the blood, and waste gasses to leave it

THE UPPER RESPIRATORY TRACT: NOSE
● External Portion of the Nose consists of nasal bones and hyaline cartilage covered by skin
and muscle
● External nares are the opening to the nose and the septum is formed from cartilage and
the perpendicular plate of ethmoid bone and the vomer
● Filtering by the mucous membranes
○ Coarse hairs in the nostrils filter out larger particles
○ Mucus of the nasal passages filters incoming air by trapping small particles
● The epithelium in the upper respiratory tract is pseudostratified ciliated columnar
epithelium
○ Cilia move mucus (containing trapped debris) away from lungs
○ The nasal epithelium has chemosensory neurons which provide the sense of smell
○ Large blood supply warms the nasal epithelium

THE UPPER RESPIRATORY TRACT: PHARYNX
● Nasopharynx (upper throat)
○ Functions only in respiration
○ The uvula, a fleshy tab of tissue that hangs down in the back of the throat,
contracts when touched by solids, moving upward and closing the nasopharynx

, ○ The Eustachian (auditory) tubes link the nasopharynx and the middle ear
■ When your ears “pop,” these tubes open to equalize air pressure between
the middle and outer ear
● •Oropharynx (directly behind the tongue)
○ Covered by the uvula when it hangs down
○ Functions in both digestion and respiration
○ The palatine and lingual tonsils are found here
● Laryngopharynx (the end of the laryngopharynx has two openings)
○ Functions in both digestion and respiration
○ The anterior opening leads to the larynx and the rest of the respiratory system
○ The posterior opening leads to the esophagus and the digestive system

THE UPPER RESPIRATORY TRACT: LARYNX
● The larynx divides the upper and lower respiratory tracts
○ Holds the respiratory tract open
○ Guards the lower tract against particulate matter
○ Produces the sounds of speech
● The larynx is called the “voice box” because it is the location of the vocal cords
● Composed of 3 single pieces of cartilage and 3 pairs of cartilage:
○ Thyroid cartilage
■ In the front of the larynx
■ Usually larger in men - testosterone stimulates its growth - thickening the
vocal folds; “Adam's apple” refers to the larger laryngeal cartilages in men
● Epiglottis
○ A leaflike flap of cartilage on the superior part of the larynx
○ Covers the opening to the lower respiratory tract
○ Prevents food from entering the lungs
● Cricoid cartilage

SECTION 14.2: THE LOWER RESPIRATORY TRACT EXCHANGES GASSES
● The main function of the lower tract is to move inhaled air to the respiratory membrane
○ Structures include the trachea, bronchial tree, lungs
● Conducting zone
○ Physiologically, the upper tract and the first portion of the lower tract
○ Conducts air from the atmosphere to the respiratory zone deeper in the body
○ Includes all the structures of the upper respiratory tract, as well as the trachea,
bronchi, bronchioles, and terminal bronchioles
● Respiratory zone
○ Lies deep within the lungs - where the actual exchange of gasses takes place
○ Includes only the respiratory bronchioles, alveolar ducts, alveolar sac and alveoli