Respiratory System Notes

Gas Distribution: The respiratory system serves to bring air into the body, facilitate gas exchange, and expel air.
Molecular Exchange: Exchange of oxygen (O2) and carbon dioxide (CO2) occurs between air and blood in the lungs and between blood and systemic tissues.
Cellular respiration: Oxygen is utilized in cellular metabolism to produce ATP, generating CO2 as a byproduct.

Overview of Components: Includes the nose, nasal passages, pharynx, larynx, trachea, bronchi, bronchioles, and alveoli.
Divisions:
- Upper Respiratory Tract: Nose, nasal cavity, pharynx, larynx.
- Lower Respiratory Tract: Trachea, bronchi, bronchioles, lungs, and alveoli.
Zones:
- Conducting Zone: Pathways that transport air (nose to terminal bronchioles).
- Respiratory Zone: Sites of gas exchange (respiratory bronchioles and alveoli).

Respiratory Mucosa: The entire respiratory tract is lined with mucous membranes (epithelium + lamina propria) that secrete mucus by goblet cells and serous glands.
Thinning of Epithelium: The epithelium progressively thins from the nasal cavity to the alveoli.

Air Passageway: Conducts air to the lungs.
Gas Exchange: Transfer of O2 and CO2 between air and blood.
Olfaction: Houses receptors for smell.
Sound Production: Vibrates vocal cords to produce sound.
Blood pH Regulation: Participates in acid-base balance by regulating CO2 levels in blood.

Functions:
- Warming, cleansing, and humidifying incoming air.
- Detecting odors and amplifying voice.
Nasal Cavity Structure:
- Divided by the nasal septum into two halves, each containing conchae which increase surface area for air processing.
- Paranasal Sinuses: Connect to the nasal cavity, aiding in air conditioning and resonance for voice.

Connection: The pharynx connects the nasal cavity to the larynx, divided into three regions:
- Nasopharynx: Houses pharyngeal tonsils.
- Oropharynx: Contains palatine and lingual tonsils.
- Laryngopharynx: Connects to larynx and esophagus.

Functions: Provides air passage, sound production, and prevents food aspiration during swallowing.
Structure: Composed of nine cartilages; epiglottic, thyroid (Adam's apple), cricoid (connects to trachea), and paired cartilages (arytenoid, corniculate, cuneiform).

Trachea: Flexible tube anterior to esophagus, supported by C-shaped cartilage rings.
Bronchial Tree: Trachea divides into left and right main bronchi, branching into lobar and segmental bronchi, leading to bronchioles.

Alveoli: Microscopic air sacs where gas exchange occurs; surround by pulmonary capillaries.
Type I Cells: Simple squamous cells facilitating gas exchange.
Type II Cells: Secrete surfactant to reduce surface tension, preventing alveolar collapse.

Composition: Formed by alveolar epithelium, fused basement membrane, and capillary endothelium, allowing O2 and CO2 to diffuse across.
Efficiency Factors: Surface area and membrane thickness significantly affect gas exchange efficacy.

Pulmonary Ventilation: Moving air into/out of the lungs (inspiration/expiration).
Gas Exchange:
- Pulmonary Gas Exchange: Between lungs and blood.
- Tissue Gas Exchange: Between blood and systemic tissues.
Gas Transport: Through hemoglobin and blood plasma.

Partial Pressure Gradients: Gases move from high to low partial pressures, influencing how O2 and CO2 are exchanged.
Chemical Factors: Blood pH, temperature, and levels of CO2 influence gas binding and release from hemoglobin.

Tidal Volume (TV): About 500 mL per breath.
Inspiratory Reserve Volume (IRV), Expiratory Reserve Volume (ERV), Residual Volume (RV), and various capacities measured through spirometry indicate lung function and health.
Minute Ventilation: Volume of air breathed per minute, critical for diagnosing respiratory issues.

Understanding conditions like asthma, COPD, and pneumonia can aid in identifying respiratory complications.
Homeostatic Imbalances: Conditions impacting respiratory efficiency include airway obstructions and disorders associated with the skeletal and muscular systems affecting breathing.