Overview: Respiratory System
- The respiratory system has two functional portions: the conducting portion and the respiratory portion.
- Respiratory system is the organ system that moves air into the body and exchanges oxygen and carbon dioxide with the blood.
- The lungs are the paired organs where most gas exchange occurs.
- Airways are tubes that connect the lungs with the external environment.
- External environment means the outside air that enters the body during breathing.
- Conducting portion means the air-moving part of the respiratory system that carries air toward the lungs but does not perform major gas exchange.
- Respiratory portion means the gas-exchange part where oxygen enters blood and carbon dioxide leaves blood.
- Inspired air is air breathed into the respiratory tract.
- Oxygen is the gas needed by cells for aerobic energy production.
- Carbon dioxide is a waste gas produced by cell metabolism and removed through exhalation.
- Exchange means oxygen and carbon dioxide move across thin barriers between air spaces and capillary blood.
- Epithelia are lining tissues, and each respiratory region has an epithelium suited to its local function.
- Supporting structures include cartilage, smooth muscle, connective tissue, and elastic fibers that keep air passages open or adjustable.
- Glands in respiratory passages add mucus and watery secretions that help humidify air and trap particles.
- Regional specialization is a major idea because the lining changes from protective epithelium near the entrance to thin gas-exchange epithelium deep in the lungs.
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