Respiratory System Overview

Respiratory System

• The primary function is gas exchange, bringing oxygen into the body and removing carbon dioxide.
• This is essential for cellular respiration, ATP production.
• Maintaining blood pH balance through carbonic acid buffering.

Key Components

• Nose and Nasal Cavity: Filters, warms, and moistens incoming air. Cilia and mucus enhance filtration and humidification. Nasal conchae increase surface area.
• Pharynx (Throat): Shared passageway for air and food. Divided into nasopharynx, oropharynx, and laryngopharynx. Contains lymphatic tissue (tonsils) for immune defence.
• Larynx (Voice Box): Contains the epiglottis (prevents food aspiration) and vocal cords (sound production).
• Trachea (Windpipe): Lined with pseudostratified ciliated epithelium trapping debris and preventing infection. Supported by C-shaped cartilage rings for an open airway.
• Bronchi and Bronchioles: The primary bronchi split into smaller branches, regulating air flow via smooth muscle control.
• Lungs: Composed of lobes (3 right, 2 left) containing alveoli for gas exchange.
• Diaphragm and Intercostal Muscles: The diaphragm is the primary muscle for respiration. Intercostal muscles aid in thoracic expansion and contraction.

Breathing Process

• Inspiration (Inhalation): Diaphragm contracts, moving downward. Intercostal muscles lift the ribs increasing lung volume and reducing intrapulmonary pressure, drawing air in.
• Expiration (Exhalation): Diaphragm and intercostal muscles relax, reducing lung volume, increasing pressure, and pushing air out.
• Forced Breathing: Involves additional muscles (sternocleidomastoid and abdominal muscles) for deep or rapid breathing.

Gas Exchange

• External Respiration: Oxygen diffuses from alveoli into pulmonary capillaries. Carbon dioxide diffuses from capillaries into alveoli.
• Internal Respiration: Oxygen moves from blood to tissues. Carbon dioxide enters the bloodstream for transport to the lungs.
• Surfactant: Secreted by type II alveolar cells, reduces surface tension; preventing alveolar collapse.

Respiratory Regulation

• Chemoreceptors: Located in the medulla and carotid bodies; detect oxygen, carbon dioxide, and pH adjusting breathing rate.
• Pulmonary Stretch Receptors: Prevent over-inflation (Hering-Breuer reflex)
• Autonomic Nervous System: Controls involuntary breathing. Cerebral cortex allows voluntary control.

Additional Functions

• pH Regulation: Prevents acidosis by expelling CO2 through bicarbonate buffer system.
• Immune Defense: Mucociliary clearance and alveolar macrophages remove pathogens.
• Speech Production: Larynx and vocal cords generate sound modulated by tongue and lips.
• Olfaction (Smell): Olfactory epithelium in nasal cavity detects airborne molecules.

Effects of Aging and Development

• Infants: Underdeveloped alveoli, higher respiratory rates, weaker immunity, more prone to infections.
• Elderly: Decreased lung elasticity, weaker respiratory muscles, reduced vital capacity, increased susceptibility to conditions like pneumonia and COPD.

Explore the essential functions and components of the respiratory system. This quiz covers gas exchange, the key structures involved, and their roles in maintaining bodily functions. Test your knowledge on how the respiratory system supports cellular respiration and overall health.