Lower Respiratory System The ciliary escalator keeps the lower respiratory system sterile. Branch Pharynx from the (throat) pulmonary Bronchiole artery Larynx- Blood Branch from (voice box) capillaries the pulmonary Trachea- Left lung vein (windpipe) Right lung Bronchus- Bronchiole Pleura Alveoli Diaphragm (breathing muscle) Heart Figure 24.2Lower Respiratory System • The ciliary escalator keeps the lower respiratory system sterile. Figure 24.2