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| 1. |
Humans respiratory system |
| Answer» Respiratory system in human beings:The respiratory system in human beings consists of the nose, pharynx, larynx, trachea, bronchi and lungs.\tAir is taken in through the nostrils.\tNostrils further continue into the nasal cavity.\tThere is a bony plate called the palate, which separates the oral cavity from the nasal cavity.\tNasal cavity opens into the pharynx.\tThe pharynx is a muscular chamber acting as a common passage for the windpipe or trachea and the food pipe or oesophagus.\tIt is connected to the larynx through a slit-like opening called the glottis.\tThe larynx connects the pharynx to the trachea.\tThe trachea shows the presence of cartilaginous rings.\tThe cartilaginous rings provide flexibility thus, facilitating continuous air flow.\tThe inner wall of the trachea is lined by a mucous membrane consisting of ciliated columnar epithelium.\tThe trachea divides into two branches or tubes called bronchi, one of which enters the right lung and the other enters the left lung.\tThe bronchi have cartilaginous rings for distention.\tEach bronchus divides into fine secondary bronchi. These bronchi further divide into finer tertiary bronchi. In the lungs, each bronchus finally divides into finer and smaller branches called bronchioles.\tThe bronchioles further divide to form smaller terminal bronchioles.\tThe bronchioles divide repeatedly to form a cluster of tiny air chambers called air sacs or alveoli.\tAlveoli have thin and moist walls which enable gaseous diffusion with blood capillaries.\tThe lungs are a pair of spongy and elastic respiratory organs protected by a bony rib cage.\tThe base of the lungs rests on the diaphragm.\tEach lung is covered by two membranes. The inner membrane is called the inner or visceral pleura and the outer membrane is called the outer or parietal pleura.\tThe diaphragm is a curved, musculo-fibrous sheath which separates the thoracic cavity from the abdominal cavity.\tThe diaphragm plays a major role during respiration. | |