Human Digestion and Respiratory System Functions Explained
Physiology of Digestion
The transformation process experienced by food within the digestive tube consists of two primary processes:
- Mechanical: Grinding and motion.
- Chemical: Digestive enzymes in gastric juices break down macromolecules into molecules that can be absorbed in the intestine into the blood as nutrients.
Location of Mechanical Digestion
- Mouth: Crushing and deglutition.
- Stomach: Mixing food with gastric juice.
- Intestine: Peristaltic movements to propel food forward.
The Respiratory System
This system is responsible for circulating air between the organism and the environment through external respiration. The ducts that circulate air are called the respiratory tract.
Upper Respiratory Tract
Includes the nose, pharynx, and larynx.
Lower Respiratory Tract
Includes the trachea, bronchi, and bronchioles, ending in blind sacs called alveoli.
Key Respiratory Components
- Nostrils: The air inlet passages of the respiratory system. From there, air passes into the pharynx, a cavity shared with the digestive system.
- Pharynx and Larynx: The larynx is a funnel-shaped cartilaginous structure with tough walls, palpable in the anterior neck. It houses the vocal cords.
- Epiglottis: A cartilaginous valve that covers the entrance of the larynx, moving up and down to prevent food from entering the trachea and causing choking.
- Trachea: A flexible tube that remains open via cartilage rings to allow air passage.
- Lungs: Two organs located in the thoracic cavity, protected by the ribs. They have a conical shape with a concave base resting on the diaphragm, a vault-shaped muscle that separates the chest from the abdomen.
- Bronchioles: Tubes similar to the trachea that branch out. Initially, there are two main bronchi, which subdivide into finer tubes called bronchioles, which lack cartilage.
- Pulmonary Alveoli: Small pockets with thin walls located at the end of the finest bronchioles. Surrounded by countless blood capillaries, this is where gas exchange occurs.