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Respiratory System - Coggle Diagram
Respiratory System
OVERALL FUNCTIONS OF THE LUNGS (RESPIRATION)
Primary Function: Gas Exchange (Respiration)
External Respiration: Exchange of O2 and CO2 between the air in the alveoli and the pulmonary capillary blood.
Internal Respiration: Exchange of O2and CO2 between the systemic capillaries and the body's tissue cells.
Acid-Base Balance (PH Regulation)
Mechanism: Lungs control blood PH by regulating the excretion of CO2 (which forms carbonic acid in the blood).
Non-Respiratory Functions
Vocalization: Production of speech and sound using the vocal cords.
Defense: Mucociliary escalator (cilia and mucus) and alveolar macrophages trap and remove pathogens.
ACE Activation: The lungs are the main site for converting Angiotensin I to the potent vasoconstrictor Angiotensin II (involved in blood pressure control).
ANATOMY OF THE RESPIRATORY TRACT
Conducting Zone (Air Transport)
Function: Transports, warms, humidifies, and filters incoming air. No gas exchange occurs here.
Structures: Nose, pharynx, larynx, trachea, bronchi, and bronchioles.
Epithelium: Primarily lined with ciliated pseudostratified columnar epithelium.
Respiratory Zone (Gas Exchange Site)
Function: The sole site where gas exchange occurs
Structures: Respiratory bronchioles, alveolar ducts, and alveoli
ALVEOLI AND THE RESPIRATORY MEMBRANE
Alveoli: Thin-walled air sacs surrounded by pulmonary capillaries, forming the respiratory membrane.
Three Types of Alveolar Cells (Pneumocytes)
Type I Alveolar Cells: Simple squamous cells; form the structure for gas exchange (90% of the surface area)
Type II Alveolar Cells: Cuboidal cells that secrete surfactant.
Surfactant Function: Reduces surface tension, preventing the small alveoli from collapsing during exhalation.
Alveolar Macrophages: Mobile phagocytic cells that engulf dust particles and pathogens.
PULMONARY MECHANICS (PRESSURE & VOLUME)
Muscles of Breathing
Inspiration (Inhalation): Primarily the Diaphragm and External Intercostals (Contracting these increases thoracic volume)
Expiration (Exhalation): Primarily a passive process due to elastic recoil of the lungs and chest wall. Forced expiration involves the Internal Intercostals and Abdominal Muscles
Intra-Pleural Pressure (IPP)
Characteristic: Always negative (sub-atmospheric pressure) throughout the breathing cycle.
Function: Acts as a "suction" force, keeping the visceral and parietal pleurae adhered, preventing the lungs from collapsing
CONTROL MECHANISMS OF BREATHING PATTERN
Chemical Control (Chemoreceptors)
Central Chemoreceptors (Brainstem)
Stimulus: Most sensitive to a rise in CO2 PCO2 in the blood/CSF, which indicates acidosis
Result: Triggers an immediate increase in breathing rate and depth to "blow off" the excess CO2
Peripheral Chemoreceptors (Carotid & Aortic Bodies)
Stimulus: Primarily responsive to severe low O2 (hypoxemia) or significant acidosis (low PH).
Result: Triggers a large, rapid increase in ventilation.
Neurological and Cortical Control (Higher Centers)
Cerebral Cortex: Enables Voluntary Control (e.g., breath-holding, singing, speaking, swallowing). This temporarily overrides the automatic centers.
Limbic System/Hypothalamus: Links breathing to emotional states (e.g., fear/anxiety causes hyperventilation).