The human respiratory system is essential for delivering oxygen to the body and removing carbon dioxide. Understanding its structure and function is crucial for NEET aspirants.
Structure of the Respiratory System
1. Nasal Cavity:
- Filters, warms, and humidifies incoming air.
- Lined with mucous membranes and cilia to trap dust and pathogens.
2. Pharynx:
- Connects the nasal cavity to the larynx and esophagus.
- Passageway for both air and food.
3. Larynx:
- Contains the vocal cords and is responsible for sound production.
- Prevents food from entering the trachea during swallowing.
4. Trachea:
- Windpipe that conducts air to the bronchi.
- Lined with ciliated mucous membrane to trap particles.
5. Bronchi and Bronchioles:
- Bronchi are the main air passages into the lungs, dividing into smaller bronchioles.
- Bronchioles lead to alveolar sacs where gas exchange occurs.
6. Lungs:
- Pair of spongy organs where gas exchange takes place.
- Right lung has three lobes; left lung has two lobes.
7. Alveoli:
- Tiny air sacs at the end of bronchioles.
- Site of gas exchange with capillaries.
Gas Exchange
1. Oxygen Transport:
- Oxygen diffuses from alveoli into pulmonary capillaries.
- Binds to hemoglobin in red blood cells to form oxyhemoglobin.
- Transported to tissues via the bloodstream.
2. Carbon Dioxide Removal:
- Carbon dioxide diffuses from tissues into the bloodstream.
- Transported to the lungs as bicarbonate ions in plasma or bound to hemoglobin.
- Diffuses from capillaries into alveoli and is expelled during exhalation.
Regulation of Breathing
1. Respiratory Centers:
- Located in the medulla oblongata and pons of the brainstem.
- Control the rate and depth of breathing.
2. Chemoreceptors:
- Located in the carotid arteries and aorta.
- Detect changes in blood levels of carbon dioxide, oxygen, and pH.
- Send signals to respiratory centers to adjust breathing.
3. Breathing Mechanism:
- Inspiration: Diaphragm contracts and moves downward; intercostal muscles contract, expanding the chest cavity. Air is drawn into the lungs.
- Expiration: Diaphragm and intercostal muscles relax, reducing chest cavity volume. Air is expelled from the lungs.
Conclusion
The human respiratory system is vital for oxygen delivery and carbon dioxide removal. Understanding its structure, gas exchange processes, and regulation mechanisms is essential for NEET aspirants.
FAQs
What is the primary function of alveoli? The primary function of alveoli is gas exchange between the air and blood.
How is oxygen transported in the blood? Oxygen is transported in the blood bound to hemoglobin in red blood cells.
What role do chemoreceptors play in respiration? Chemoreceptors detect changes in blood levels of carbon dioxide, oxygen, and pH, and send signals to adjust breathing.
Where are the respiratory centers located? The respiratory centers are located in the medulla oblongata and pons of the brainstem.
What happens during inspiration? During inspiration, the diaphragm contracts and moves downward, expanding the chest cavity and drawing air into the lungs.