Biology Tutorial: Breathing, Gases, and Infections

Introduction to Breathing and Exchange of Gases

• Oxygen (O2) is utilized by organisms to break down simple molecules like glucose, amino acids, and fatty acids to derive energy.
• Carbon dioxide (CO2) is released during these catabolic reactions and needs to be removed from the body.

Respiratory Organs

• Different groups of animals have varying mechanisms of breathing depending on their habitats and levels of organization.
• Lower invertebrates like sponges, coelenterates, and flatworms exchange O2 with CO2 by simple diffusion over their entire body surface.
• Earthworms use their moist cuticle, while insects have a network of tubes (tracheal tubes) to transport atmospheric air within the body.

Human Respiratory System

• The system consists of nose, nasal chamber, pharynx, larynx, trachea, bronchi, bronchioles, and alveoli.
• Nose: pair of external nostrils opening into nasal chamber, which then opens into the pharynx.
• Pharynx: common passage for food and air, also containing the oropharynx.
• Larynx: cartilaginous box responsible for sound production, with a thin elastic cartilaginous flap called epiglottis to prevent food entry.
• Trachea: straight tube extending to the mid-thoracic cavity, dividing into right and left primary bronchi.
• Bronchi and bronchioles: undergo repeated divisions to form secondary and tertiary bronchi and bronchioles, ending in thin terminal bronchioles.
• Alveoli: thin, irregular-walled, and vascularised bag-like structures responsible for gas exchange.

This quiz covers topics related to breathing and gas exchange, as well as infectious diseases such as HIV and Gonorrhoea. It also touches on the importance of carbohydrates, proteins, and fats in organisms.