Q. Which of the following statements about the human respiratory system are INCORRECT?
I. During swallowing, glottis can be covered by a thin elastic cartilaginous flap called epiglottis to prevent the entry of food into the larynx.
II. The trachea is a straight tube extending up to the mid-thoracic cavity, which divides at the level of the fourth thoracic vertebra into a right and left primary bronchi.
III. The trachea, primary, secondary and tertiary bronchi, and initial bronchioles are supported by incomplete cartilaginous rings made up of hyaline cartilage.
IV. The respiratory part transports the atmospheric air to the alveoli, clears it from foreign particles, humidifies and also brings the air to body temperature.

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Solution:

During swallowing the glottis can be covered by a thin elastic flap called epiglottis. This prevents entry of food into larynx. Trachea is a straight tube that extends through the thoracic cavity and divided at the level of fifth thoracic vertebrae into right and left primary bronchi. The region is known as carinaThe trachea, bronchi and initial bronchioles show presence of incomplete cartilaginous rings. The nasal epithelium transports the atmospheric air to the alveoli, clears it from foreign particles and brings it to body temperature. This is the nasal part.