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Terminal bronchioles mark the end of the conducting division of air flow in the respiratory system while respiratory bronchioles are the beginning of the respiratory division where gas exchange takes place. The diameter of the bronchioles plays an important role in air flow. The bronchioles change diameter to either increase or reduce air flow.
Moving down the bronchioles, the cells get more cuboidal in shape but are still ciliated. Glands are abundant in the upper respiratory tract, but there are fewer lower down and they are absent starting at the bronchioles. The same goes for goblet cells, although there are scattered ones in the first bronchioles.
The conducting zone of the respiratory tract ends at the terminal bronchioles when they branch into the respiratory bronchioles. This marks the beginning of the terminal respiratory unit called the acinus which includes the respiratory bronchioles, the alveolar ducts, alveolar sacs, and alveoli. [27] An acinus measures up to 10 mm in diameter. [28]
In the respiratory tract, from the trachea to the terminal bronchioles, the lining is of respiratory epithelium that is ciliated. [8] The cilia are hair-like, microtubular-based structures on the luminal surface of the epithelium. On each epithelial cell there are around 200 cilia that beat constantly at a rate of between 10 and 20 times per ...
In humans, the pharynx is part of the digestive system and the conducting zone of the respiratory system. (The conducting zone—which also includes the nostrils of the nose, the larynx, trachea, bronchi, and bronchioles—filters, warms and moistens air and conducts it into the lungs). [1]
The cells in the respiratory epithelium are of five main types: a) ciliated cells, b) goblet cells, c) brush cells, d) airway basal cells, and e) small granule cells (NDES) [6] Goblet cells become increasingly fewer further down the respiratory tree until they are absent in the terminal bronchioles; club cells take over their role to some extent here. [7]
The respiratory system (also respiratory apparatus, ventilatory system) is a biological system consisting of specific organs and structures used for gas exchange in animals and plants. The anatomy and physiology that make this happen varies greatly, depending on the size of the organism, the environment in which it lives and its evolutionary ...
The digestive system has a complex system of motility and secretion regulation which is vital for proper function. This task is accomplished via a system of long reflexes from the central nervous system (CNS), short reflexes from the enteric nervous system (ENS) and reflexes from GI peptides working in harmony with each other. [4]