Respiratory System Lecture – Vocabulary Flashcards

A comprehensive set of 80 English vocabulary flashcards covering key terms, structures, functions, and physiological concepts of the respiratory system as presented in the lecture notes.

Ventilation

Movement of air between the atmosphere and the alveoli.

Perfusion

Blood flow through the pulmonary capillaries of the lungs.

Diffusion (respiration)

Transfer of oxygen and carbon dioxide between alveoli and blood.

Regulation (respiration)

Control of breathing by respiratory muscles and the nervous system.

Conducting Zone

Air passages that carry, filter, warm, and humidify air to the gas-exchange region.

Respiratory Zone

Site of gas exchange consisting of respiratory bronchioles, alveolar ducts, and alveolar sacs.

Nose

Provides airway; moistens, warms, and filters air; houses olfactory receptors; resonates speech.

Pharynx

Muscular throat divided into naso-, oro-, and laryngopharynx; pathway for air and food; contains tonsils.

Nasopharynx

Superior portion of the pharynx located behind the nasal cavity.

Oropharynx

Middle region of the pharynx located behind the oral cavity.

Laryngopharynx

Inferior section of the pharynx leading to larynx and esophagus.

Larynx

Voice box; produces sound, enables breathing, and protects trachea from food aspiration.

Epiglottis

Flexible cartilage flap that closes over the glottis during swallowing.

Trachea

Windpipe lined with ciliated columnar epithelium and mucus cells that sweep debris from lungs.

Bronchi

Two cartilage-supported air passages branching from the trachea to each lung, lined with mucus and cilia.

Bronchioles

Small airway branches beyond the bronchi leading to alveolar ducts and sacs.

Alveoli

Moist, thin-walled sacs where rapid gas exchange occurs; lined with surfactant.

Pulmonary Ventilation

Air movement into and out of lungs for continuous gas replacement in alveoli.

External Respiration

Gas exchange between pulmonary capillary blood and alveolar air.

Transport of Respiratory Gases

Circulatory movement of oxygen and carbon dioxide between lungs and tissues.

Internal Respiration

Exchange of gases between systemic capillary blood and tissue cells.

Cellular Respiration

Intracellular use of O2 to produce ATP from glucose with CO2 as waste.

Pulmonary Surfactant

Phospholipid-protein mixture that lowers alveolar surface tension and prevents collapse.

Type I Alveolar Cells

Squamous cells covering 95 % of alveolar surface to permit rapid diffusion.

Type II Alveolar Cells

Cuboidal cells that secrete surfactant and repair the alveolar epithelium.

Alveolar Macrophages

Phagocytic cells that remove debris and pathogens from alveoli.

Compliance (lung)

Measure of how easily the lungs and thorax expand with pressure change.

Pulmonary Fibrosis

Scarring of lung tissue that reduces compliance and impairs expansion.

Pulmonary Edema

Fluid accumulation in lungs that decreases compliance and gas exchange.

Respiratory Distress Syndrome

Condition of inadequate surfactant causing low compliance and alveolar collapse.

Inspiratory Reserve Volume (IRV)

Extra air inhaled beyond a normal inspiration.

Tidal Volume (VT)

Volume of air moved in or out during normal quiet breathing (~500 ml).

Expiratory Reserve Volume (ERV)

Additional air exhaled after a normal expiration.

Residual Volume

Air remaining in lungs after maximal exhalation.

Vital Capacity

Maximum air exhaled after maximal inspiration (IRV + VT + ERV).

Total Lung Capacity

Total volume of air in lungs after maximal inspiration (VC + RV).

Functional Residual Capacity

Air remaining in lungs after a normal exhalation (ERV + RV).

Inspiratory Capacity

Maximum air that can be inhaled after a normal exhalation (VT + IRV).

Oxygen-Hemoglobin Dissociation Curve

Graph relating PO2 to percentage saturation of hemoglobin with oxygen.

Bohr Effect

Rightward shift of Hb curve due to low pH or high CO2, decreasing O2 affinity.

Temperature Effect on Hemoglobin

Higher temperature lowers hemoglobin’s O2 affinity, enhancing unloading to tissues.

Fetal Hemoglobin

Form of hemoglobin with greater affinity for oxygen than adult hemoglobin.

Right Shift (Hb Curve)

Curve displacement indicating decreased Hb affinity for O2 (low pH, high CO2, high temperature).

Left Shift (Hb Curve)

Curve displacement indicating increased Hb affinity for O2 (high pH, low CO2, low temperature).

Bicarbonate Ion (HCO₃⁻)

Main plasma form (≈70 %) in which carbon dioxide is transported.

Carbonic Acid (H₂CO₃)

Intermediate produced when CO2 combines with water inside red blood cells.

Chloride Shift

Exchange of bicarbonate out of RBCs for chloride into RBCs in systemic capillaries.

Carbonic Anhydrase Reaction

Enzyme-catalyzed conversion CO₂ + H₂O ⇌ H₂CO₃ ⇌ H⁺ + HCO₃⁻.

Carotid Body

Peripheral chemoreceptor in the carotid artery that senses blood O2, CO2, and pH.

Aortic Body

Chemoreceptor in the aortic arch monitoring arterial O2, CO2, and pH.

Medullary Chemoreceptors

Central receptors detecting CSF pH/CO2 to modulate respiration.

Hering-Breuer Reflex

Lung stretch reflex that inhibits inspiration to prevent overinflation.

Hypercapnia

Elevated arterial CO₂ (>43 mm Hg); common cause of acidosis.

Hypocapnia

Reduced arterial CO₂ (<37 mm Hg); common cause of alkalosis.

Acidosis

Condition where blood pH falls below 7.35.

Alkalosis

Condition where blood pH rises above 7.45.

Hyperventilation

Increased pulmonary ventilation that lowers CO₂ and raises blood pH.

Hypoventilation

Reduced ventilation that allows CO₂ buildup and lowers blood pH.

Cystic Fibrosis

Inherited disorder causing thick lung mucus due to defective chloride transport.

CFTR Gene

Gene encoding chloride channel; its mutation leads to cystic fibrosis.

Smoking Effects on Lungs

Adds CO₂, carcinogens, and nicotine that paralyze cilia and promote cancer and emphysema.

Emphysema

Disease where alveoli rupture, reducing surface area and elasticity, often due to smoking.

Nicotine

Toxic substance in tobacco smoke that paralyzes respiratory cilia.

Ambient PO₂

Partial pressure of oxygen in tissues; lower values enhance O2 unloading from Hb.

Hydrogen Ion (H⁺)

Proton released from carbonic acid; increased levels lower pH and stimulate breathing.

Respiratory Acidosis

Low blood pH caused by CO₂ accumulation from inadequate ventilation.

Respiratory Alkalosis

High blood pH due to excessive CO₂ loss from hyperventilation.

Diaphragm

Primary respiratory muscle; contraction draws air in, relaxation expels air.

Intercostal Muscles

Muscles between ribs that aid diaphragm in changing thoracic volume.

Inspiration

Phase of breathing where thoracic volume increases, air flows into lungs.

Exhalation (Expiration)

Phase where thoracic volume decreases, pushing air out of lungs.

Pleura

Double-layered serous membrane (parietal and visceral) enclosing each lung.

Pleural Fluid

Lubricating liquid between pleural layers that reduces friction during breathing.

Right Lung

Lung with three lobes supplied by the right main bronchus.

Left Lung

Lung with two lobes accommodating the cardiac notch for the heart.

Alveolar Surface Area

About 70 m² per lung provided by roughly 150 million alveoli for gas exchange.

Reverse Chloride Shift

Movement of Cl⁻ out of and HCO₃⁻ into RBCs in lungs to regenerate CO₂ for exhalation.

Most Potent Respiratory Stimulus

Change in blood pH (via CO₂ levels) is the strongest driver of ventilation.

Surfactant Function in Surface Tension Reduction

Surfactant lowers alveolar surface tension, making lung expansion easier.

Oxygen Transport in Blood

Approximately 98.5 % carried bound to hemoglobin; 1.5 % dissolved in plasma.