Respiratory System Overview

General Structure and Function

The respiratory system is responsible for gas exchange, supplying oxygen to the body and removing carbon dioxide. It consists of various organs and tissues that work together to facilitate breathing.

• Organs of the Upper Respiratory System: Includes the nose, nasal cavity, pharynx, and larynx. These structures filter, warm, and moisten incoming air.

• Organs of the Lower Respiratory System: Includes the trachea, bronchi, bronchioles, and lungs. These structures conduct air to the alveoli, where gas exchange occurs.

• Shared Organs: The pharynx is shared by both the respiratory and digestive systems.

• Lobes of the Lungs: The right lung has three lobes (superior, middle, inferior), while the left lung has two lobes (superior, inferior).

• Apex of the Lungs: The apex is the uppermost portion of the lung, located just beneath the clavicle.

Airflow Pathway

Air travels through a specific pathway from the external environment to the alveoli, where gas exchange occurs.

1. Nose or mouth

2. Pharynx

3. Larynx

4. Trachea

5. Bronchi

6. Bronchioles

7. Alveoli

Example: Breathing through the nostrils is preferred because the nasal passages filter, warm, and humidify the air more effectively than the mouth.

Respiratory System Physiology

Functions and Reflexes

• Turbinates: Structures in the nasal cavity that increase surface area, helping to warm and humidify incoming air.

• Hering-Breuer Reflex: A protective reflex that prevents over-inflation of the lungs by inhibiting inspiration when the lungs are stretched.

• Interlobular Septa: Thin walls that divide the lobes of the lungs, providing structural support and compartmentalization.

• Epiglottis: A flap of cartilage that covers the trachea during swallowing, preventing food from entering the airway.

• Adam's Apple: Another name for the laryngeal prominence, formed by the thyroid cartilage.

Respiratory Defense System

The respiratory system has several defense mechanisms to protect against pathogens and debris.

• Mucus: Traps dust, microbes, and other particles; produced by goblet cells in the respiratory tract.

• Cilia: Hair-like structures that move mucus and trapped particles out of the respiratory tract.

• Respiratory Defense System: Includes mucus, cilia, and immune cells that protect the lungs from infection and damage.

Respiratory System Disorders

Asthma

Asthma is a chronic inflammatory disease of the airways characterized by episodes of wheezing, breathlessness, chest tightness, and coughing. It is caused by hypersensitivity of the airways to various stimuli.

RDS Syndrome

Respiratory Distress Syndrome (RDS) is a condition often seen in premature infants, caused by insufficient surfactant production, leading to collapsed alveoli and impaired gas exchange.

Respiratory System Anatomy

Cartilages and Bronchi

• Thyroid Cartilage: The largest cartilage of the larynx, commonly referred to as the Adam's apple.

• Bronchi: The right lung is supplied by three bronchi (one for each lobe), and the left lung by two bronchi.

Gas Laws in Respiration

Boyle's Law and Dalton's Law

Gas exchange and movement in the respiratory system are governed by physical laws.

• Boyle's Law: The pressure of a gas is inversely proportional to its volume at constant temperature.

• Dalton's Law: The total pressure of a mixture of gases is equal to the sum of the partial pressures of each individual gas.

Summary Table: Key Structures and Functions

Additional info:

• Breathing through the nose is preferred over the mouth because the nasal passages provide better filtration and conditioning of air.

• The respiratory defense system includes both physical barriers (mucus, cilia) and immune responses.