Human Anatomy: The Respiratory System

Overview

• The respiratory system is responsible for gas exchange, taking in oxygen and releasing carbon dioxide.
• It comprises a network of structures, including the nose, pharynx, larynx, trachea, bronchi, and lungs.
• The process is primarily driven by pressure gradients.

Upper Respiratory Tract

• The nose, pharynx, and larynx form the upper respiratory tract.
• The nose filters, warms, and humidifies inhaled air.
• The pharynx (throat) is a common passageway for both air and food.
• The larynx (voice box) contains the vocal cords, which vibrate to produce sound.
• The epiglottis is a flap of cartilage that prevents food from entering the trachea during swallowing.

Lower Respiratory Tract

• The trachea, bronchi, and lungs form the lower respiratory tract.
• The trachea is a rigid tube, carrying air to the bronchi.
• The bronchi branch into smaller bronchioles, which further divide into alveoli.
• Alveoli are tiny air sacs where gas exchange occurs.
• The lungs are positioned in the thoracic cavity, protected by the ribs and diaphragm.

Mechanics of Breathing

• Breathing involves inhalation and exhalation, driven by pressure changes.
• Inhalation is an active process, characterized by diaphragm contraction and rib cage expansion.
• Exhalation is a passive process, with diaphragm relaxation and rib cage recoil.
• Pressure differentials between the lungs and the atmosphere drive air movement.
• Surface tension within the alveoli, regulated by surfactant, is vital for lung expansion.

Gas Exchange

• Gas exchange occurs across the thin walls of the alveoli.
• Oxygen diffuses from the alveoli into the bloodstream.
• Carbon dioxide diffuses from the bloodstream into the alveoli.
• Hemoglobin in red blood cells binds to oxygen, facilitating its transport throughout the body.

Control of Breathing

• Breathing is regulated by the respiratory center in the brainstem.
• This center responds to carbon dioxide and oxygen levels in the blood.
• Chemoreceptors monitor blood gas levels, triggering adjustments to breathing rate.

Diseases Affecting the Respiratory System

• Diseases such as asthma, bronchitis, emphysema, and lung cancer can affect the respiratory system.
• These conditions can cause inflammation, airway narrowing, or lung tissue damage.
• This often results in reduced gas exchange efficiency.

Breathing and Exercise

• Physical activity increases oxygen demand and carbon dioxide production.
• Breathing rate and depth increase to meet these elevated demands.
• This heightened respiratory activity enables the body to meet increased metabolic needs during exercise.

Respiratory Volumes and Capacities

• Tidal volume is the air inhaled or exhaled during a normal breath.
• Inspiratory reserve volume is the additional air inhaled forcefully.
• Expiratory reserve volume is the additional air exhaled forcefully.
• Residual volume is the air remaining in the lungs after forceful exhalation.
• These volumes combine to form respiratory capacities, representing the total air movement during different breathing maneuvers.