The Respiratory System Part A 22
Human Respiratory System Functions: • Works closely with circulatory system, exchanging gases between air and blood: • Takes up oxygen from air and supplies it to blood (for cellular respiration). • Removal and disposal of carbon dioxide from blood (waste product from cellular respiration). Homeostatic Role: • Regulates blood oxygen and carbon dioxide levels.
Human Respiratory System Components: Nasal cavity, throat (pharynx), larynx (voice box), trachea, bronchi, alveoli, and lungs. Pathway of Inhaled Air: • Nasal cavity • Pharynx (Throat) • Larynx (Voice Box) • Trachea (Windpipe) • Bronchi • Bronchioles • Alveoli (Site of gas exchange) Exhaled air follows reverse pathway.
Pressure Relationships Figure 22.12
Human Respiratory System 1. Nasal cavity: Air enters nostrils, is filtered by hairs, warmed, humidified, and sampled for odors as it flows through a maze of spaces. 2. Pharynx (Throat): Intersection where pathway for air and food cross. Most of the time, the pathway for air is open, except when we swallow. 3. Larynx (Voice Box): Reinforced with cartilage. Contains vocal cords, which allow us to make sounds by voluntarily tensing muscles. • More prominent in males (Adam’s apple).
Human Respiratory System 4. Trachea (Windpipe): Rings of cartilage maintain shape of trachea, to prevent it from closing. Forks into two bronchi. 5. Bronchi (sing. Bronchus): Each bronchus leads into a lung and branches into smaller and smaller bronchioles, resembling an inverted tree. 6. Bronchioles: Fine tubes that allow passage of air. Muscle layer constricts bronchioles. Epithelium of bronchioles is covered with cilia and mucus. • Mucus traps dust and other particles.
Human Respiratory System Alveoli (Sing. Alveolus): Grapelike clusters of tiny air sacs with very thin elastic walls through which gas exchange occurs. • Oxygen in air enters blood in capillaries. • Carbon dioxide in blood enters air in alveoli. There are several million alveoli in the human lungs, with a total surface roughly equivalent to a tennis court. The walls of the alveoli are very delicate. Alveolar macrophages are phagocytic cells that swallow inhaled particles (dust, bacteria, etc.) and digest them.
Respiratory Membrane Figure 22.9.c, d
Respiratory Membrane Figure 22.9b
Inspiration Figure 22.13.1
Expiration Figure 22.13.2