Mammalian Physiology (BIOL 456): Respiratory System Overview and Gas Laws

Vocabulary flashcards covering the anatomy, structure, conditioning mechanisms, cellular components, and gas laws of the mammalian respiratory system.

Insensible Water Loss (IWL)

Water lost from the body each day through the skin and lungs that is difficult to measure precisely.

Conducting System

The passages or airways that lead from the external environment to the exchange surface of the lungs.

Alveoli

A series of interconnected sacs and their associated pulmonary capillaries that form the exchange surface of the lungs.

Upper Respiratory Tract

The division of the respiratory system composed of the mouth, nasal cavity, pharynx, and larynx.

Lower Respiratory Tract

The division of the respiratory system composed of the trachea, two primary bronchi, their branches, and the lungs.

Pharynx

A common passageway for food, liquids, and air located in the upper respiratory tract.

Larynx

An airway structure containing the vocal cords that connects the pharynx to the trachea.

Trachea

The main windpipe that conducts air from the larynx into the primary bronchi.

Diaphragm

A dome-shaped sheet of skeletal muscle that forms the floor of the thoracic cage.

Pleural Sacs

Two double-walled, fluid-filled membranous bags in the thorax that each enclose a lung.

Pleural Fluid

A thin film of fluid (total volume of about $25\text{--}30\text{ mL}$ in a $70\text{ kg}$ man) that holds pleural membranes together and provides a slippery surface for lung movement.

Air Conditioning (Respiratory System)

The process of warming inhaled air to $37\text{ }^\text{o}\text{C}$, adding water vapor to achieve $100\text{ }\text{\%}$ humidity, and filtering out foreign material before air reaches the alveoli.

Ciliated Epithelium

Epithelial tissue lining the trachea and bronchi that uses cilia to continuously move trapped particles and mucus upward toward the pharynx.

Goblet Cells

Epithelial cells lining the airways that secrete mucus to trap inhaled particles.

CFTR Channel

Cystic fibrosis transmembrane regulator channel; an apical anion channel that allows $\text{Cl}^-$ to enter the airway lumen, facilitating saline layer formation.

NKCC

$\text{Na}^+\text{-K}^+\text{-2Cl}^-$ symporter located on the basolateral membrane of respiratory epithelial cells that transports $\text{Cl}^-$ into the cell from the extracellular fluid.

Type I Alveolar Cells

Very thin alveolar epithelial cells specialized to allow rapid diffusion of gases between alveolar air and pulmonary capillary blood.

Type II Alveolar Cells

Alveolar epithelial cells that synthesize and secrete surfactant, and help minimize fluid volume in alveoli by transporting solutes and water out of alveolar air spaces.

Surfactant

A complex mixture of phospholipids, proteins, and neutral lipids that reduces surface tension in alveoli to aid lung expansion during breathing.

Mast Cells

Airway cells containing secretory granules with inflammatory mediators like histamine that induce bronchoconstriction, stimulate mucus secretion, and increase bronchial vessel permeability.

Ideal Gas Equation

The gas law $PV = nRT$, which simplifies to $V = \frac{1}{P}$ in the human body assuming constant moles and temperature.

Boyle's Law

A law stating that if the volume of a container of gas changes, the pressure changes inversely, represented as $P_1 V_1 = P_2 V_2$.

Dalton's Law

A law stating that the total pressure of a mixture of gases is equal to the sum of the partial pressures of the individual gases ($P_{\text{gas}} = P_{\text{atm}} \times \text{\% of gas}$).

Partial Pressure of Gas in Humid Air

The partial pressure calculated by subtracting water vapor pressure ($P_{\text{H}_2\text{O}}$) from total atmospheric pressure ($P_{\text{atm}}$) before multiplying by gas percentage: $P_{\text{gas}} = (P_{\text{atm}} - P_{\text{H}_2\text{O}}) \times \text{\% of gas}$.

Four Major Functions of the Respiratory System

1. Exchange of gases ($\text{O}_2$ and $\text{CO}_2$) between atmosphere, blood, and tissues. 2. Regulation of body pH by retaining or excreting $\text{CO}_2$. 3. Protection from inhaled pathogens and irritants. 4. Vocalization via air movement across vocal cords.

Insensible Water Loss (IWL)

Water lost from the body each day through the skin and lungs that is difficult to measure precisely.

Conducting System

The passages or airways that lead from the external environment to the exchange surface of the lungs.

Upper Respiratory Tract

The division of the respiratory system composed of the mouth, nasal cavity, pharynx, and larynx.

Lower Respiratory Tract

The division of the respiratory system composed of the trachea, two primary bronchi, their branches, and the lungs.

Pharynx

A common passageway for food, liquids, and air located in the upper respiratory tract.

Larynx

An airway structure containing the vocal cords that connects the pharynx to the trachea.

Trachea

The main windpipe that conducts air from the larynx into the primary bronchi.

Thoracic Cage Muscles

Skeletal muscles including the intercostal muscles (internal and external), sternocleidomastoids, scalenes, and the dome-shaped diaphragm that assist in ventilation.

Pleural Sacs

Two double-walled, fluid-filled membranous bags in the thorax that each enclose a lung.

Pleural Fluid Functions

1. Creates a moist, slippery surface so opposing membranes slide across each other. 2. Holds the lungs tight against the thoracic wall.

Anatomical Lobes of the Lungs

The right lung is divided into three lobes (superior, middle, inferior), while the left lung is divided into two lobes (superior, inferior) and features a cardiac notch.

Airway Cross-Sectional Area and Airflow Velocity

As airways branch from trachea to bronchioles, total cross-sectional area increases dramatically, causing airflow velocity to be highest in upper airways and lowest in terminal bronchioles.

Air Conditioning (Respiratory System)

The process of warming inhaled air to $37\,^{\circ}\text{C}$, adding water vapor to achieve $100\%$ humidity, and filtering out foreign material before air reaches the alveoli.

Ciliated Epithelium and Mucociliary Escalator

Airway lining tissue where cilia continuously move a layer of mucus (containing trapped particles and immunoglobulins) upward toward the pharynx to be swallowed or expectorated.

Goblet Cells

Epithelial cells lining the airways that secrete mucus to trap inhaled particles.

CFTR Channel

Cystic fibrosis transmembrane regulator channel; an apical anion channel that allows $\text{Cl}^-$ to enter the airway lumen, drawing $\text{Na}^+$ and water to form the watery saline layer.

Cystic Fibrosis Pathophysiology in Airways

A genetic malfunction of the CFTR channel that prevents saline layer formation, trapping cilia in thick, sticky mucus and leading to impaired mucus clearance and recurrent lung infections.

NKCC

$\text{Na}^+\text{-K}^+\text{-2Cl}^-$ symporter located on the basolateral membrane of respiratory epithelial cells that transports $\text{Cl}^-$ into the cell from the extracellular fluid.

Type I Alveolar Cells

Very thin alveolar epithelial cells specialized to allow rapid diffusion of gases between alveolar air and pulmonary capillary blood.

Type II Alveolar Cells

Alveolar epithelial cells that synthesize and secrete surfactant, and help minimize fluid volume in alveoli by transporting solutes and water out of alveolar air spaces.

Surfactant

A complex mixture of phospholipids, proteins, and neutral lipids that reduces surface tension in alveoli to aid lung expansion during breathing.

Alveolar Macrophages

Immune cells residing within the alveolar air space that ingest and destroy foreign material and pathogens.

Mast Cells

Airway cells containing secretory granules with inflammatory mediators like histamine that induce bronchoconstriction, stimulate mucus secretion, and increase bronchial vessel permeability.

Ideal Gas Equation in Physiology

The gas law $PV = nRT$, which simplifies to $V = \frac{1}{P}$ in the human body assuming constant moles and temperature.

Boyle's Law

A gas law stating that if the volume of a container of gas changes, the pressure changes inversely ($P_1 V_1 = P_2 V_2$).

Bulk Flow in Ventilation

The movement of the entire gas mixture into or out of the respiratory system driven by pressure gradients created by changes in chest volume.

Dalton's Law

A law stating that the total pressure of a mixture of gases is equal to the sum of the partial pressures of the individual gases ($P_{\text{gas}} = P_{\text{atm}} \times \%\,\text{gas}$).

Partial Pressure of Gas in Humid Air

The partial pressure calculated by subtracting water vapor pressure ($P_{\text{H}_2\text{O}}$) from total atmospheric pressure ($P_{\text{atm}}$) before multiplying by gas percentage: $P_{\text{gas}} = (P_{\text{atm}} - P_{\text{H}_2\text{O}}) \times \%\,\text{gas}$.