The lungs are designed to maximize the area for gas exchange through the following features:
- Alveoli: Tiny air sacs with thin walls (one cell thick) that provide a large surface area for gas exchange.
- Capillary Network: Dense network of capillaries surrounding each alveolus to facilitate the efficient exchange of oxygen and carbon dioxide.
- Elastic Fibers: Alveoli are surrounded by elastic fibers that help maintain their shape and increase surface area during inhalation.
- Surfactant: A substance secreted within the alveoli that reduces surface tension, preventing the alveoli from collapsing and ensuring they remain open for gas exchange.
MCQs Based on the above question
Question 1: What structures provide a large surface area for gas exchange in the lungs?
a) Bronchi
b) Alveoli
c) Trachea
d) Diaphragm
Answer: b) Alveoli
Question 2: What surrounds each alveolus to facilitate efficient gas exchange?
a) Lymphatic vessels
b) Nerve endings
c) Dense capillary network
d) Elastic cartilage
Answer: c) Dense capillary network
Which substance is secreted within the alveoli to reduce surface tension?
a) Mucus
b) Serotonin
c) Surfactant
d) Histamine
Answer: c) Surfactant
Question 4: What helps maintain the shape of alveoli and increases surface area during inhalation? a) Collagen fibers b) Cartilage rings c) Elastic fibers d) Adipose tissue
Answer: c) Elastic fibers