Overview of the Respiratory System and Its Functions

Respiration

Gas exchange of O2 and CO2.

Oxygen (O2)

Essential for aerobic ATP production in cells.

Carbon Dioxide (CO2)

Waste product of aerobic respiration.

Respiratory System

Facilitates gas exchange between atmosphere and body.

Upper Respiratory Tract

Includes nose, nasal cavity, pharynx, larynx.

Lower Respiratory Tract

Includes trachea, bronchi, bronchioles, alveoli.

Conducting Zone

Transports air from nose to terminal bronchioles.

Respiratory Zone

Involved in gas exchange in lungs.

Sinuses

Air-filled spaces that warm and humidify air.

Pharynx

Conduit for air and food; three regions.

Larynx

Contains vocal cords; directs air into trachea.

Trachea

Connects larynx to bronchi; contains ciliated cells.

Bronchi

Supported by cartilage; contain ciliated mucous cells.

Bronchioles

Lack cartilage; contain smooth muscle and ciliated cells.

Mucociliary Escalator

Mechanism to expel trapped debris from airways.

Respiratory Mucosa

Mucous membrane lining respiratory tract.

Goblet Cells

Produce mucus in respiratory epithelium.

Mucin Protein

Increases mucus viscosity; traps particles.

Histological Changes

Epithelium changes from nasal cavity to alveoli.

Simple Squamous Epithelium

Found in alveoli; facilitates gas exchange.

Stratified Squamous Epithelium

Found in high abrasion areas like vocal cords.

Carina

Cartilage ridge triggering cough reflex for expulsion.

Sputum

Mucus coughed up with saliva and substances.

Pleural Membrane

Two-layered membrane surrounding each lung.

Visceral Pleura

Layer tightly covering each lung.

Parietal Pleura

Lines inner thoracic cavity wall.

Pleural Cavity

Space between pleurae containing pleural fluid.

Pleural Fluid

Lubricates pleurae and provides a barrier.

Respiratory Bronchioles

Minimal smooth muscle structures in respiratory division.

Alveolar Ducts

Short conduits primarily made of connective tissue.

Alveolar Sacs

Grape-like clusters of individual alveoli.

Alveoli

Thin-walled structures for gas exchange.

Surface Area of Alveoli

Collectively 70 m², size of a tennis court.

Type I Pneumocytes

Simple squamous cells forming alveolar walls.

Type II Pneumocytes

Cuboidal cells that secrete surfactant.

Surfactant

Reduces surface tension in alveoli.

Dust Cells

Alveolar macrophages that scavenge particles.

Lysozyme

Antibacterial enzyme found in respiratory secretions.

Defensins

Antibacterial proteins in respiratory defense.

Immunoglobulin A

Antibody present in respiratory secretions.

Conducting Zone

Includes nasal cavity, larynx, trachea, excluding alveoli.

Macrophage

Immune cell type found in alveoli.

Dust Cells

Macrophages in alveoli that clear debris.

Alveolar type I

Thin cells facilitating gas exchange in alveoli.

Alveolar type II

Cells producing surfactant to reduce surface tension.

Fibroblasts

Cells providing structural support in lung tissue.

Pulmonary trunk

Major vessel carrying deoxygenated blood to lungs.

Pulmonary arteries

Transport deoxygenated blood from heart to lungs.

Lobar arteries

Branch from pulmonary arteries to supply lung lobes.

Capillary beds

Network of capillaries surrounding alveoli for gas exchange.

Venules

Small veins collecting oxygenated blood from capillaries.

Pulmonary veins

Carry oxygenated blood from lungs to heart.

Zone 1 pressure

Alveolar pressure exceeds arterial and venous pressure.

Zone 2 pressure

Arterial pressure exceeds alveolar and venous pressure.

Zone 3 pressure

Arterial and venous pressures exceed alveolar pressure.

V/Q ratio

Ventilation to perfusion ratio for gas exchange efficiency.

Alveolar dead space

Volume of air in non-exchanging alveoli.

Pulmonary ventilation

Air movement between atmosphere and alveoli.

Inspiration

Phase of breathing that brings air into lungs.

Expiration

Phase of breathing that forces air out of lungs.

Eupnea

Quiet, rhythmic breathing at rest.

Forced breathing

Vigorous breathing during exercise.

Airflow

Amount of air moving in and out per breath.

Pressure gradient

Difference in pressure causing air movement.

Boyle's Law

Pressure increases as gas particle amount increases.

P1V1 = P2V2

Relationship between pressure and volume of gas.

Boyle's Law

P1V1 = P2V2; gas pressure-volume relationship.

Airflow Equation

F = ∆P/R; flow calculation formula.

Flow (F)

Volume of air moving per unit time.

Pressure Gradient (∆P)

Difference between atmospheric and intrapulmonary pressure.

Resistance (R)

Opposition to airflow in the respiratory system.

Intrapulmonary Pressure

Pressure within the lungs during breathing.

Atmospheric Pressure

Pressure exerted by the weight of air.

Intrapleural Pressure

Pressure in the pleural cavity surrounding lungs.

Alveolar Pressure

Pressure within the alveoli during respiration.

Ventilation

Process of moving air into and out of lungs.

Inspiration

Bringing air into the lungs.

Expiration

Moving air out of the lungs.

Coughing

Forceful expulsion of air to clear airways.

Sneezing

Reflex action to expel irritants from nasal passages.

Yawn

Deep inhalation to increase oxygen intake.

Hiccup

Spasm of diaphragm causing rapid air bursts.

Valsalva Maneuver

Exhaling against a closed airway.

Partial Pressure

Contribution of a gas to total pressure.

Gas Exchange

Process of oxygen and carbon dioxide transfer.

Surfactant

Substance that reduces surface tension in alveoli.

Compliance

Lung's ability to stretch and expand.

Partial Pressure

Pressure exerted by a single gas in a mixture.

External Respiration

Gas exchange in lungs between air and blood.

Internal Respiration

Gas exchange in tissues between blood and cells.

Hemoglobin

Protein in red blood cells transporting oxygen.

Oxygen Saturation

Percentage of hemoglobin binding with oxygen.

Oxygen Reserve

Oxygen remaining bound to hemoglobin post-circulation.

Haldane Effect

CO2 binds more readily to deoxygenated hemoglobin.

Apnea

Temporary cessation of breathing.

Laryngitis

Inflammation of the larynx causing hoarseness.

Bronchitis

Inflammation of bronchi due to infection or irritants.

Acute Bronchitis

Short-term bronchitis following an infection.

Chronic Bronchitis

Long-term bronchitis with persistent cough and mucus.

Pneumonia

Lung infection causing fluid accumulation in alveoli.