Organs Control of Respiration Respiratory System Organs Control of Respiration Homeostasis

Path of Air through the Respiratory System nasal cavity pharynx nose mouth glottis larynx trachea bronchus (pl: bronchi) bronchiole lung Made of alveoli (air sacs)

Functions of Respiratory Tract Organs Nasal Cavities: warm, moisten and filter air Larynx: vocal cords produce sound Trachea (windpipe): permits passage of air, ciliated cells move mucus and debris toward pharynx Bronchial Tree: bronchi and bronchioles permit passage of air Lungs: gas exchange vocal cords glottis

Applying Your Knowledge Pharynx Lung Larynx Bronchus Bronchiole Where are the vocal cords located? Which leads to an alveolus? Where does gas exchange take place? Which is shared between the respiratory and digestive systems?

Gas Exchange in Lungs: External Respiration Carries deoxygenated blood from heart Returns oxygenated blood to heart Sites of gas exchange Exchange occurs between air in the alveolus and blood in the surrounding capillaries: Oxygen from alveolus enters bloodstream, Carbon dioxide from blood enters alveolus

Ventilation: Inspiration and Expiration Action of intercostal muscles between ribs Dome-shaped muscle below lungs Ventilation: Inspiration and Expiration

Control of Ventilation Respiratory Center in Brain stimulates rhythmic inspiration, responding to levels of carbon dioxide and hydrogen ions Chemoreceptors in arteries send signals to respiratory center in response to changing oxygen levels

Diffusion Controls Gas Exchanges in the Body External Respiration gas exchange between air in alveoli and blood in pulmonary capillaries pO2 is higher in air, pCO2 is higher in blood O2 diffuses into blood, CO2 diffuses into lung air Internal Respiration gas exchange between blood in systemic capillaries and tissue fluid pO2 is higher in blood, pCO2 is higher in tissues O2 diffuses into tissues, CO2 diffuses into blood

Specialized Components Carbonic Anhydrase: enzyme involved in release of carbon dioxide Hemoglobin: oxygen-carrying molecule on surface of red blood cells Surfactant: layer of lipoprotein that lowers surface tension and prevents alveoli from closing

Tissue Structure Trachea: pseudostratified ciliated columnar epithelium Alveoli: simple squamous epithelium

Homeostasis Gas Exchange Regulation of Blood pH oxygen is needed for energy release through cellular respiration Regulation of Blood pH When CO2 is released by tissues, levels of H+ increase and pH is lowered When CO2 is released from lungs, H+ has been used to produce water, increasing pH to neutral level (7.4) Carbonic anhydrase bicarbonate ion hydrogen ion carbonic acid carbon dioxide water Bicarbonate Buffering System of Blood

Applying Your Knowledge Tissue Fluid Hemoglobin Carbonic Anhydrase Blood Alveolus Surfactant Diaphragm Columnar Epithelium Intercostal Muscle Squamous Epithelium Which enzyme assists in controlling blood pH? (Choices on left) For internal respiration, where is pCO2 greater? (Choices on left) Which one represents a muscle located below the lungs? (Choices on right)