Anatomy & Physiology

Anatomy & Physiology Study Guide

©2018 Achieve Page 308 The Apneustic and Pneumotaxic Centers of the Pons The apneustic centers and the pneumotaxic centers of the pons are paired nuclei that adjust the output of the respiratory rhythmicity centers. Their activities regulate the respiratory rate and the depth of respiration in response to sensory stimuli or input from other centers in the brain. During quiet breathing, stimulation from the apneustic center helps increase the intensity of inhalation over the next two seconds. Under normal conditions, after two seconds the apneustic center is inhibited by signals from the pneumotaxic center on that side. During forced breathing, the apneustic centers also respond to sensory input from the vagus nerves regarding the amount of lung inflation. The pneumotaxic centers inhibit the apneustic centers and promote passive or active exhalation. 22.8 Aging Many factors reduce the efficiency of the respiratory performance in the elderly. As one's age increases, elastic tissue deteriorates throughout the body, altering the compliance of the lungs and lowering their vital capacity. Chest movements are restricted by arthritic changes in the rib articulations and by decreased flexibility at the costal cartilages. Some degree of emphysema is normal in individuals over age 50. 22.9 Chapter Twenty-Two Review An introduction to the respiratory system: • Body cells must obtain oxygen and eliminate carbon dioxide. The respiratory surfaces where gas exchange occurs are inside the lungs. The respiratory system, divided into an upper/lower system, has several basic functions: • The respiratory system provides an area for gas exchange between air and circulating blood; moving air to and from exchange surfaces; protecting respiratory surfaces from environmental variations and defending the respiratory system and other tissues from invasion by pathogens; producing sounds, and facilitating the detection of olfactory stimuli. • The respiratory system includes the upper respiratory system, composed of the nose, nasal cavity, paranasal sinuses, and pharynx, and the lower respiratory system, which includes the larynx, trachea, bronchi, bronchioles, and alveoli of the lungs. • The respiratory tract consists of the conducting airways that carry air to and from the alveoli. The passageways of the upper respiratory tract filter and humidify incoming air. The lower respiratory tract includes delicate conduction passages and the alveolar exchange surfaces. • The respiratory mucosa (respiratory epithelium and underlying connective tissue) lines the conducting portion of the respiratory tract. • The respiratory epithelium changes in structure along the respiratory tract. It is supported by the lamina propria, a layer of areolar tissue. • Contamination of the respiratory system is prevented by the respiratory defense system. of 368