Upper Respiratory Tract (Nasal Cavity) | Human Respiratory System | Class 11 Biology PTB 2025

In this video, we explain the Upper Respiratory Tract (Nasal Cavity) from the new Class 11 Biology Punjab Textbook 2025 in a simple and easy way. You will learn about: Structure of the nasal cavity Functions of nostrils and nasal septum Role of blood vessels, mucus, and nose hairs How the nasal cavity helps in smell and taste Why gas exchange does not occur here This lecture is designed for FSc Part 1 students, following the Punjab Curriculum & Textbook Board (PTB) 2025 syllabus. Perfect for exam preparation, board exams, and MDCAT foundation. Subscribe for more biology lectures and stay updated with the latest Class 11 PTB syllabus! #Class11Biology #RespiratorySystem #UpperRespiratoryTract #NasalCavity #PTB2025 #FScBiology #YousufBiologyAcademy MCQs (with Answers) The organs of the respiratory system form a continuous system of passages called: a) Circulatory tract b) Digestive tract c) Respiratory tract ✅ d) Excretory tract The respiratory tract is divided into: a) Trachea and bronchi b) Lungs and diaphragm c) Upper and lower respiratory tract ✅ d) Nose and mouth Which of the following is NOT part of the upper respiratory tract? a) Nasal cavity b) Pharynx c) Larynx d) Trachea ✅ The main function of the upper respiratory tract is: a) Gas exchange b) Humidification and warming of air ✅ c) Blood circulation d) Food digestion Gas exchange in humans occurs in: a) Nasal cavity b) Pharynx c) Larynx d) Lungs ✅ The nasal cavity is divided into two parts by: a) Pharynx b) Nasal septum ✅ c) Larynx d) Trachea The mucous membrane of nasal cavity mainly helps in: a) Digestion of food b) Trapping foreign particles ✅ c) Producing sound d) Gas exchange Hairs present in the nose: a) Produce mucus b) Help in trapping dust and particles ✅ c) Warm the air d) Assist in smell The sense of smell is possible due to: a) Mechanoreceptors b) Photoreceptors c) Chemoreceptors ✅ d) Thermoreceptors Contribution of nasal cavity in taste occurs because: a) It warms food b) It connects with oral cavity c) It contains chemoreceptors ✅ d) It filters air Short Questions + with Answers Q: What is the respiratory tract? Ans: A continuous system of passages that allows air to move into and out of the body. Q: Name the two divisions of the respiratory tract. Ans: Upper respiratory tract and lower respiratory tract. Q: Which organs form the upper respiratory tract? Ans: Nasal cavity, pharynx, and larynx. Q: Does gas exchange occur in the upper respiratory tract? Ans: No, only air passage, cleaning, humidifying, and warming occur. Q: What are nostrils? Ans: External openings of the nose that lead to the nasal cavity. Q: What is the function of the nasal septum? Ans: It divides the nasal cavity into two parts. Q: How does nasal cavity warm and humidify inhaled air? Ans: By blood vessels present close to its surface. Q: How are large foreign particles filtered in the nasal cavity? Ans: By nose hairs and mucus secreted by mucous membranes. Q: Which receptors are present in nasal cavity for smell? Ans: Chemoreceptors. Q: How does nasal cavity contribute to the sense of taste? Ans: By chemoreceptors which detect chemicals and assist in taste perception.