The Respiratory System
39.1 Systems of Gas Exchange
Introduction and Direct Diffusion
Respiratory processes that help organisms exchange O2 and CO2 range from simple direct diffusion to complex respiratory systems.
Skin and Gills and Tracheal Systems
Respiration can occur using a variety of respiratory organs in different animals, including skin, gills, and tracheal systems.
Mammalian Systems and Protective Mechanisms
The mammalian respiratory system equilibrates air to the body, protects against foreign materials, and allows for gas exchange.
39.2 Gas Exchange across Respiratory Surfaces
Basic Principles of Gas Exchange
The principles of gas exchange are based on the partial pressure of oxygen and carbon dioxide, which, as gases, move by diffusion.
39.3 Gas Exchange across Respiratory Surfaces
Lung Volumes and Capacities
Lung volumes measure the amount of air for a specific function, while lung capacities are the sum of two or more volumes.
Gas Pressure and Respiration
Gas pressures in the atmosphere and body determine gas exchange: both O2 and CO2 will flow from areas of high to low pressure.
Gas Exchange across the Alveoli
Differences in partial pressures of O2 create a gradient that causes oxygen to move from the alveoli to the capillaries and into tissues.
Types of Breathing
Types of breathing in humans include eupnea, hyperpnea, diaphragmatic, and costal breathing; each requires slightly different processes.
The Mechanics of Human Breathing
Both inhalation and exhalation depend on pressure gradients between the lungs and atmosphere, as well as the muscles in the thoracic cavity.
The Work of Breathing
Breathing includes several components, including flow-resistive and elastic work; surfactant production; and lung resistance and compliance.
Dead Space: V/Q Mismatch
Dead space is a broken down or blocked region of the lung that produces a mismatch of air and blood in the lungs (V/Q mismatch).
39.5 Transport of Gases in Human Bodily Fluids
Transport of Oxygen in the Blood
The majority of oxygen in the body is transported by hemoglobin, which is found inside red blood cells.
Transport of Carbon Dioxide in the Blood
Dissolution, hemoglobin binding, and the bicarbonate buffer system are ways in which carbon dioxide is transported throughout the body.