Respiratory System Study Guide

Comprehensive vocabulary flashcards covering the processes of respiration, airway anatomy and histology, respiratory mechanics, lung volumes and capacities, gas exchange and transport, neural and chemical control, and respiratory disorders.

Pulmonary Ventilation

breathing, air moves in and out of the lungs.

External Respiration

Gas exchange between the alveoli and pulmonary blood

$O_2$ moves from alveoli into the blood

$CO_2$ moves from the blood into the alveoli.

Internal Respiration

Gas exchange between systemic capillary blood and body tissues

$O_2$ moves from blood into body tissues

$CO_2$ moves from body tissues into the blood.

Bicarbonate Equation

$$CO_2 + H_2O \rightleftharpoons H_2CO_3 \rightleftharpoons H^+ + HCO_3^-$$

Cellular Respiration Equation

breaking down glucose in the presence of oxygen to yield energy: $C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + \text{ATP}$

Mucociliary Escalator

Protective mechanism in the trachea, specialized cells in your airways trap inhaled particles in mucus and move them up and out of your lungs

Trachealis Muscle

Smooth muscle ant the open posterior boundary of each C-shaped hyaline cartilage ring in the trachea, directly facing the esophagus.

Terminal Bronchioles

The final anatomical passages marking the end of the conducting zone within the bronchial tree.

Respiratory Bronchioles

First Airway involved in gas exchange

Paranasal Sinuses

Air-filled cavities within the bones of the skull that lighten the skull bones, produce mucus, warm and humidify inspired air, and contribute resonance to the voice.

Pleural Cavity

A fluid-filled potential space situated between the visceral pleura covering the lungs and the parietal pleura lining the chest wall.

Respiratory Membrane

The thin tissue barrier in the lungs composed of alveolar and capillary walls across which gases diffuse between the alveolar air and pulmonary capillary blood via simple diffusion.

Type I Alveolar Cells

Thin, flat, squamous, scale-like cells that cover approximately $95\%$ of the alveolar surface area and facilitate simple gas exchange between lungs and blood.

Type II Alveolar Cells

Smaller, cuboidal cells covering approximately $5\%$ of the alveolar surface that produce pulmonary surfactant to reduce surface tension and act as caretakers capable of dividing and differentiating into Type I cells if lung tissue is damaged.

Intrapulmonary Pressure ($P_{pul}$)

The pressure of air exerted inside the alveoli of the lungs.

Intrapleural Pressure ($P_{ip}$)

The pressure inside the pleural cavity, which is normally negative relative to atmospheric and alveolar pressure to keep the lungs expanded.

Transpulmonary Pressure ($P_{tp}$)

The difference between alveolar pressure and intrapleural pressure ($P_{tp} = P_{pul} - P_{ip}$) that creates the outward pull keeping the lungs held open.

Boyle's Law

A gas law stating that pressure and volume are inversely related when temperature remains constant, represented by the relationship $P_1V_1 = P_2V_2$.

Forced Expiration Muscles

Muscles including the internal intercostals (which pull the ribs down and in) and abdominal muscles (which contract and push abdominal contents against the diaphragm) to forcefully expel air.

Accessory Muscles of Forced Inspiration

Muscles utilized during deep or difficult inhalation alongside the diaphragm and external intercostals, including the sternocleidomastoid (elevates the sternum), scalenes (elevate the first two ribs), and pectoralis minor (elevates the ribs when the shoulder girdle is fixed).

Tidal Volume (TV)

The volume of air inhaled or exhaled during a single, normal, quiet breath, averaging approximately $500\,\text{mL}$.

Inspiratory Reserve Volume (IRV)

The extra volume of air that can be forcefully inhaled beyond a normal quiet tidal inhalation, typically measuring between $2000\,\text{mL}$ and $3000\,\text{mL}$.

Expiratory Reserve Volume (ERV)

The extra volume of air that can be forcefully exhaled following a normal quiet tidal exhalation, typically measuring between $700\,\text{mL}$ and $1500\,\text{mL}$.

Residual Volume (RV)

The air volume remaining trapped in the lungs after a maximum, forceful exhalation ($1200\text{--}1500\,\text{mL}$), which prevents alveoli and lungs from collapsing and maintains gas exchange between breaths.

Inspiratory Capacity (IC)

The maximum volume of air that can be inhaled following a normal exhalation, calculated as $\text{IC} = \text{TV} + \text{IRV}$.

Functional Residual Capacity (FRC)

The volume of air remaining in the lungs after a normal, passive tidal exhalation, calculated as $\text{FRC} = \text{ERV} + \text{RV}$.

Vital Capacity (VC)

The maximum amount of air that can be exhaled following the deepest possible inhalation, calculated as $\text{VC} = \text{IRV} + \text{TV} + \text{ERV}$.

Total Lung Capacity (TLC)

The total volume of air contained within the lungs after a maximum inspiratory effort, calculated as $\text{TLC} = \text{VC} + \text{RV}$.

Lung Compliance

A measurement of the stretchability and ease of expansion of the lungs, quantified as the change in lung volume per change in pressure ($\Delta V / \Delta P$).

Surfactant

A substance produced by Type II alveolar cells that reduces surface tension inside alveoli, preventing alveolar collapse and making lungs easier to inflate.

Dalton's Law

A physical law stating that the total pressure of a gas mixture is equal to the sum of the partial pressures exerted by each individual gas, with gases diffusing down their individual partial pressure gradients.

Henry's Law

The physical principle describing how gases dissolve in a liquid in proportion to their partial pressure and solubility.

Oxyhemoglobin

The complex formed when oxygen molecules bind to hemoglobin, accounting for $98.5\%$ of all oxygen transported in the bloodstream.

Bohr Effect Factors

Physiological changes occurring in active tissues—decreased pH (acidosis), increased $P_{CO_2}$, and increased temperature—that decrease hemoglobin's affinity for $O_2$, causing more $O_2$ to unload to tissues.

Chloride Shift

An ionic exchange mechanism where bicarbonate leaves RBCs for the plasma in systemic tissues while chloride enters to maintain electrical neutrality, and reverses in pulmonary capillaries ($HCO_3^-$ moves in, $Cl^-$ moves out).

Dorsal Respiratory Group (DRG)

A neural control cluster in the medulla oblongata responsible for generating normal quiet breathing rhythm and integrating sensory feedback from peripheral receptors.

Ventral Respiratory Group (VRG)

A neural region in the medulla that recruits muscles for forced inspiration and forced expiration during elevated metabolic demands like exercise.

Pontine Respiratory Centers

Neural clusters located in the pons that modify the rhythmic output generated by the medulla to smooth the transitions between inhalation and exhalation.

Central Chemoreceptors

Sensory receptors located in the medulla oblongata and brainstem that monitor the pH of cerebrospinal fluid and brain interstitial fluid caused by changes in $CO_2$.

Peripheral Chemoreceptors

Receptors located in the carotid and aortic bodies that detect arterial hypoxia (low $O_2$), hypercapnia (high $CO_2$), and low pH (acidosis) to signal breathing rate adjustments.

Chronic Obstructive Pulmonary Disease (COPD)

A collective classification of progressive lung diseases that cause persistent and irreversible airflow limitation.

Chronic Bronchitis

A respiratory disorder characterized by chronic inflammation of the bronchi coupled with excessive mucus production.

Emphysema

A pulmonary disorder marked by the destruction of alveolar walls and loss of elastic recoil, meaning the lungs can stretch easily but cannot recoil effectively.

Asthma

A respiratory disorder marked by reversible airway narrowing due to bronchial inflammation and bronchoconstriction.

Pneumonia

An inflammatory condition where the alveolar air spaces become filled with fluid and inflammatory exudate.

Hyperventilation

Excessive or rapid breathing that expels $CO_2$ beyond metabolic production, resulting in decreased blood $CO_2$ and an elevated blood pH.

Pneumothorax

A pathological state where free air enters the pleural cavity, disrupting negative intrapleural pressure.

Atelectasis

The partial or complete collapse of alveoli or lung tissue.